A geological based reservoir zonation scheme in a sequence stratigraphic framework: A case study from the Permo–Triassic gas reservoirs, Offshore Iran

Accepted Manuscript A geological based reservoir zonation scheme in a sequence stratigraphic framework: a case study from the Permo–Triassic gas reservoirs, Offshore Iran Amir Hossain Enayati–Bidgoli, Hossain Rahimpour–Bonab PII:

S0264-8172(16)30039-3

DOI:

10.1016/j.marpetgeo.2016.02.016

Reference:

JMPG 2469

To appear in:

Marine and Petroleum Geology

Received Date: 19 December 2015 Revised Date:

28 January 2016

Accepted Date: 8 February 2016

Please cite this article as: Enayati–Bidgoli, A.H., Rahimpour–Bonab, H., A geological based reservoir zonation scheme in a sequence stratigraphic framework: a case study from the Permo–Triassic gas reservoirs, Offshore Iran, Marine and Petroleum Geology (2016), doi: 10.1016/j.marpetgeo.2016.02.016. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

(not restored)

2

3

West

(not restored)

6

Musandam Mountains, UAE (Maurer et al., 2009) East - Northwest

~450 km

~250 km

SN#01

KS-3

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Lagoon

Peritidal

Channel

Facies Group Fore Shoal

Claystone

Back Shoal

Dolostone Anhydrite

Off Shoal Third order Sequences

SN#02 Lithology ratios Limestone

Central Shoal

Lagoon

Fore Shoal

Claystone

Channel

Facies Group

Peritidal

Dolostone Anhydrite

Off Shoal Third order Sequence

Lithology ratios Limestone

Back Shoal

Lagoon

Channel

Peritidal

Fore Shoal

Back Shoal

KS-1

Central Shoal

Facies Group

KS-2

Claystone

Central Shoal

5 Off Shoal Third order Sequence

Lithology ratios Limestone Dolostone Anhydrite

Saiq Plateau, Oman (Koehrer et al, 2010)

Salman Field

4 LN#01

1

2

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KS-4

Persian Gulf

3

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Golshan

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Southeast

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Lavan Field

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Zagros Mountains-Offshore Fars, Iran (Insalaco et al., 2006) 300 km 350 km

South Pars

4 Lavan Salman

5

6

Musandam Mountains

7 Saiq Plateau

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A geological based reservoir zonation scheme in a sequence stratigraphic framework: a

Amir Hossain Enayati–Bidgoli, Hossain Rahimpour–Bonab*

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case study from the Permo–Triassic gas reservoirs, Offshore Iran

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School of Geology, College of Science, University of Tehran, Tehran, Iran

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*Corresponding author, email: [email protected]; [email protected]

ABSTRACT

Reservoir zonation can lead to an insight about the lateral and vertical distribution of reservoir and non–reservoir zones from bore hole to regional scales. Based on the available data sets, scale

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of study and purposes, there are various reservoir zonation schemes, but correlatability is crucial in any reservoir zonation procedure. In this study, it is attempted to create a reservoir zonation scheme based on geological attributes in the Permo–Triassic successions of the eastern Persian Gulf area, which can be used to inter–field (regional) investigation and correlation. Then, the

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applicability of two routinely used reservoir zonation procedures including hydraulic flow units (HFU) and flow units based on a stratigraphic modified Lorenz plot was examined. The

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petrophysical based HFUs were not correlatable between the studied wells and fields. The larger scale flow units were correlatable at the field and to some extent inter–field scales. But, the identified geological reservoir zones (GRZs) were correlatable at both intra– and inter–field scales in a sequence stratigraphic framework. GRZs were defined based on sharp changes in depositional facies, diagenetic features or both and also any meaningful accompaniment in diagenetic features and pore types which show similar sequence stratigraphic positions. This indicates a close relationship between the depositional sequences and post–depositional diagenetic processes, and therefore GRZs are linked to a sequence stratigraphic framework. The GRZ concept may be applicable to reservoir characterization of the Permo-Triassic successions 1

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in the Persian Gulf and adjacent areas. However, this concept can only be applied if the combined depo-diagenetic processes and the resulting reservoir quality are controlled by sequence stratigraphic position without pervasive and non-facies related late diagenetic

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overprints.

Key words: Reservoir zonation, Flow unit, Dalan Formation, Kangan Formation, Permo–

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Triassic, Offshore Iran.

1. Introduction

Carbonate reservoir quality, external geometry and internal architecture depend on several factors including spatial distribution of depositional facies, secondary alterations (diagenetic

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processes) and sequence stratigraphic position. Understanding reservoir quality and controlling factors requires detailed facies analysis along with diagenetic studies (e.g., Dunnington, 1967; Slatt, 2006; Lucia, 2007; Ahr, 2008). Sequence stratigraphy provides a genetic framework for

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correlation and prediction of vertical and lateral facies changes and associated variations in reservoir quality (Posamentier and Vail, 1988; Van Wagoner et al., 1990; Posamentier and Allen,

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1999; Plint and Nummedal, 2000; Ahr, 2008). The Permo–Triassic Dalan and Kangan formations (Deh Ram group; Szabo and Kheradpir, 1978) and their equivalent (Khuff Formation) host numerous gas reservoirs in the Arabian Platform including the Persian Gulf and Zagros basins (Kashfi, 1992; Alsharhan and Nairn, 2003; Insalaco et al., 2006; Figs. 1A and 2). Previous studies on the Permo–Triassic successions in the Persian Gulf area and Arabian Platform revealed that these gas reservoirs show stratiform/layer cake geometries and various depositional and/or reservoir units are correlatable 2

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at the inter–well, inter–field and even regional scales (e.g. Insalaco et al., 2006; Alsharhan, 2006; Rahimpour–Bonab et al., 2009, 2010; Koehrer et al., 2010, 2011, 2012; Esrafili–Dizaji and Rahimpour–Bonab, 2013; Rahimpour–Bonab et al., 2014; Mohsenian et al., 2014; Enayati–

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Bidgoli et al., 2014; Fig. 1C).

In this study, the Permo–Triassic Dalan and Kangan formations in the eastern Persian Gulf area

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(Salman and Lavan gas/oilfields; Fig. 1A) were analyzed based on depositional, diagenetic and reservoir characteristics. In order to evaluate the reservoir quality and its changes at the inter–

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field scale, two conventional reservoir/flow zonation approaches and a newly performed reservoir zonation scheme were applied. These approaches are Hydraulic Flow Unit (HFU) based on Flow Zone Indicator (FZI; Amaefule et al., 1993), Stratigraphic Modified Lorenz Plot (SMLP; Gunter et al., 1997) and Geological Reservoir Zone (GRZ). In a recent study, the

al., 2014).

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applicability of HFU and SML plot methods were examined at the field scale (Enayati–Bidgoli et

GRZs are defined and separated based on several depositional and diagenetic characteristics

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which can be considered as large scale depo–diagenetic units. For reservoir evaluation at the field scale and regional description, upscaling is crucial and careful selection of reservoir zones

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may reduce or eliminate the necessity of up–scaling reservoir models for simulation (e.g. Bhattacharya et al., 2008). However, well correlations based on geological reality requires subsurface information including well, seismic and dynamic data (Borgomano et al., 2008) in order to decrease the uncertainty of the model constructed. Correlations presented in this study however would need to be checked against dynamic and high-resolution seismic data in order to perform accurate hydrocarbon production predictions. The identified geological reservoir zones (GRZs) are upscaled in nature (are not generalized and detailed as depositional sequences and 3

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flow units, respectively) and are usable for sub-regional (inter–field) and regional reservoir investigation and correlation in a sequence stratigraphic framework.

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2. Geological background Since the Infracambrian, a NNE–SSW–trending structural high – the Qatar–South Fars Arch (QSFA) – has divided the Persian Gulf Basin into two troughs: the ESE and the WNW sub–

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basins (Fig. 1A). It was particularly prominent during the Infracambrian, Early Silurian, Late Permian, Late Triassic, Late Jurassic and Cenozoic (Murris, 1980; Alsharhan and Nairn, 2003;

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Pollastro, 2003; Bordenave, 2008; Perotti et al., 2011).

In the northern Arabian Plate, the Permo–Triassic succession is dominated by a thick shallow– marine carbonate–evaporite succession developed on the northern passive margin of Gondwana (Edgell, 1996; Pillevuit, 1993; Sharland et al., 2001; Figs. 1B and C). Deposition of Permo–

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Triassic shallow marine carbonates and evaporites over an extensive epicontinental platform was initiated by an extensive marine transgression on the Arabian Plate during the late Permian. This transgression was related to rifting across the Zagros that led to the opening of the Neotethys

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Ocean and creation of a passive margin in the northeastern part of the Arabian Plate in 182– 255Ma (Pillevuit, 1993; Edgell, 1996; Sharland et al., 2001; Ziegler, 2001; Alsharhan and Nairn,

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2003; Figs. 1B). These widespread carbonate–evaporite intervals are correlatable over extensive distances throughout the Persian Gulf basin and adjacent areas which in general show a stratiform or “layer–cake” geometry (Insalaco et al., 2006; Alsharhan, 2006; Ehrenberg et al., 2007; Koehrer et al., 2010, 2012; Zeller et al., 2011; Fig. 1C). In the Lavan and Salman fields (Fig.1A), gas is mainly accumulated in the Permo–Triassic Dalan and Kangan formations (Fig. 2). The Dalan Formation is stratigraphically subdivided into three

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members including the lower Dalan, the Nar evaporite and the upper Dalan (Edgell, 1977; Figs. 1C and 2B). The upper Dalan has great reservoir potential and is further subdivided into two reservoir units: K4 (limestone–dolostone) and K3 (mainly dolostone to anhydritic dolostone with

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some anhydrite intercalations; Fig. 2B). The early Triassic Kangan Formation overlies the Dalan Formation above the Permo–Triassic unconformity (Szabo and Kheradpir, 1978; Heydari et al., 2001; Vaslet et al., 2005; Rahimpour–Bonab et al., 2009; Tavakoli and Rahimpour–Bonab,

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2012) and terminates to the Dashtak Formation (Figs. 1C and 2B). The Kangan Formation comprises two reservoir units: K2 (limestone–dolostone and anhydrite) and K1 (anhydritic

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dolostone, dolostone and limestone; Fig. 2B).

The dominance of evaporites and hypersaline facies in the Dalan and Kangan formations (Khuff Formation) throughout the Arabian Plate (e.g. Szabo and Kheradpir, 1978; Alsharhan and Kendall, 1994; Ziegler, 2001; Alsharhan, 2006; Insalaco et al., 2006; Maurer et al., 2009) reflects

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the prevailing arid paleoclimatic conditions (sub–tropical and tropical palaeogeography; Golonka, 2000; Konert et al., 2001; Fig. 1B).

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3. Dataset and methods

This study was based on more than 670m whole core and slabs and 2030 semi–stained thin

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sections from the Permo–Triassic Dalan and Kangan formations which were obtained from three exploration/appraisal wells (LN#01, SN#01 and SN#02) of the Lavan and Salman oil/gasfields (Offshore Iran; Fig. 1). To investigate the depositional facies distribution and diagenetic features, high resolution petrographic analyses (microfacies analysis and diagenetic studies) were integrated with microscopic image analysis and quantitative/qualitative analysis of all prepared samples. Facies analysis was carried out using standard models and microfacies descriptions (e.g. Wilson, 1975; Flügel, 2010). 5

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To determine the factors that controlled the reservoir quality, an integrated approach was performed through depositional facies analysis and reconstruction of their diagenetic history within a sequence stratigraphic framework. The sequence stratigraphic framework of the Permo–

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Triassic reservoir intervals were used as the basis for a geological–based reservoir zonation. In order to construct such a framework and determine the main sequence surfaces (sequence boundaries, SBs; and maximum flooding surfaces, MFSs), various data were used. Such data

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included the results of facies analysis and wireline logs (especially gamma–ray and density). Sequence boundaries were identified by rapid changes in depositional environment or facies and

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distinct diagenetic effects related to relative sea–level falls.

More than 1730 poroperm data from core plugs measured using a helium porosimeter and air permeameter for flow unit determination and petrophysical evaluation of GRZs. Two routinely used flow zonation approaches were adopted. First, hydraulic flow units were determined based

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on flow zone indicator (FZI) values (Amaefule et al., 1993; Abbaszadeh et al., 1996), and then, flow units were identified using the Stratigraphic Modified Lorenz plot (SML plot) method

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(Gunter et al., 1997).

4. Depositional characteristics

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4.1. Facies analysis and depositional setting For facies analysis, several parameters including allochemical components (skeletal and non– skeletal), sedimentary texture, micrite content, bulk mineralogy or lithology and depositional features were investigated in detail, at both microscopic and macroscopic scales, which led to the identification of 16 facies in the studied Permo–Triassic successions at the eastern Persian Gulf basin (Table. 1 and Fig. 3). To evaluate their depositional settings and up–scaling, these facies

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were compared with modern and ancient analogues that are documented in the literatures (e.g. Insalaco et al., 2006; Alsharhan, 2006; Esrafili–Dizaji and Rahimpour–Bonab, 2009; Koehrer et al., 2010, 2012). The identified facies were grouped into seven facies assemblages or groups

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(FGs) including peritidal (FG1), lagoon (FG2), back–shoal (FG3), central–shoal (FG4), fore– shoal (FG5), channel (FG6) and off–shoal (FG7; Table. 1 and Fig. 3). Main characteristics and

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mean poroperm of the defined facies and facies groups are illustrated in Table. 1.

According to the identified facies and facies groups and other studies of the Permo–Triassic

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successions in the northern part of the Arabian Plate (Dasgupta et al., 2002; Insalaco et al., 2006; Alsharhan, 2006; Maurer et al., 2009; Koehrer et al., 2010, 2012), the Dalan and Kangan formations are deposited on a broad epeiric carbonate–evaporite platform in the northern passive margin of Gondwana (Fig. 4A) with disperse and discrete shoal bodies in a vast lagoonal setting which its terrestrial setting has been near to the Arabian Shield and open marine setting towards

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the Zagros suture zone. So, the Salman field has been located on more landward setting (more peritidal facies) than the Lavan field (Figs. 1C and 4). Relative position, distribution and main depositional properties of facies and facies groups are shown in Fig. 4A. The relative frequency

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pie diagrams show that lagoon and shoal facies (F9 to F12) and facies groups (FG2 to FG4) are

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more frequent in the studied intervals (Fig. 4B). 4.2. Reservoir potential of depositional facies Mean poroperm values of the recognized facies and facies groups are illustrated in Table. 1. Among the identified facies, Ooid Grainstones (F13) and Nodular Dolo/Lime Mudstones (F1) show the highest and lowest poroperm values, respectively. At a larger scale, the central shoal (FG4: F12 and F13) and peritidal facies groups (FG1: F1 and F5) have the highest and lowest

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poroperm values, respectively. Generally, shoal facies (back and central) have the highest frequency and poroperm values (Fig. 4B and Table. 1). However, almost all studied samples

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show various degrees of diagenetic alterations. 5. Diagenetic processes and features

The Permo–Triassic carbonate–evaporite strata in the Arabian Plate and Zagros basin have been

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endured several diagenetic alterations which dolomitization, anhydrite cementation and dissolution are the most important processes (e.g. Dasgupta et al., 2002; Bashari, 2005; Insalaco

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et al., 2006; Alsharhan, 2006; Maurer et al., 2009; Esrafili–Dizaji and Rahimpour–Bonab, 2009; Rahimpour–Bonab et al., 2010; Fontana et al., 2010; Koehrer et al, 2010, 2012; Rahimpour– Bonab et al., 2014; Esrafili–Dizaji and Rahimpour–Bonab, 2014).

Several diagenetic processes and products are recognized in the Dalan and Kangan formations of

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the studied fields, which are grouped into five general categories (mainly on the basis of mineralogy) including syn–depositional processes, calcite cementation, dolomitization, anhydrite cementation and chemical compaction (Figs. 5 to 8; Table 2). These diagenetic processes and

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products along with their effects on the reservoir quality are illustrated in Table 2. Also,

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dissolution effect is presented as moldic and vuggy pore types (Fig. 9). 5.1. Paragenetic sequence All recognized diagenetic processes and products (Table 2) show that the studied successions, have endured three diagenetic realm including marine/sub–aerial, meteoric and burial (shallow and deep; Fig. 10). Syn–depositional diagenetic processes are related to the marine and sub– aerial/Sabkha environments. Dissolution and all types of calcite cements (except the blocky type) created during the meteoric (phreatic) diagenesis (Fig. 10). Generally, anhydrite cementation and 8

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dolomitization are related to the shallow diagenetic environment which followed by deep burial processes including recrystallization, chemical compaction, saddle dolomitization and gypsum

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cementation (Fig. 10). 6. Depositional sequences

To correlate every rock unit across the studied region, a sequence stratigraphic framework was

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established (e.g. Rahimpour–Bonab et al., 2014). Sequence stratigraphic correlations are not unduly sensitive to field–scale well spacing in the case of wide and flat sedimentary profiles

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(Borgomano et al., 2008), such as the Permo–Triassic Khuff platform (Insalaco et al., 2006; Koehrer et al., 2010, 2012).

The Dalan–Kangan successions can be considered as a second–order transgressive–regressive sequence, and the gas reservoirs occur in the regressive hemisequence (Strohmenger et al.,

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2002). These formations and their equivalent Khuff Formation composed of five sequences or megacycles (KS–1 to KS–5; Sharland et al., 2001; Bashari, 2005; Figs. 2B and 11). However, based on the studied areas on the Arabian Plate, the Permo–Triassic successions (Khuff

et al., 2012).

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Formation) composed of five to seven third order sequences (Strohmenger et al., 2002; Koehrer

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In this study, based on parameters such as facies and facies association changes, allochemical component, early diagenetic features, and gamma–ray and density well logs patterns, four third– order sequences (KS–1 to KS–4) were recognized in the Kangan and (Upper) Dalan successions. Sequence boundaries were detected based on the presence of peritidal evaporites, the shallowest facies in the facies column, and sub–aerial (Sabkha/meteoric) diagenetic features. The KS–4 to KS–1 sequences, are described briefly below. Generally, in the studied wells they can be correlated with the K4 to K1 reservoir units, respectively (Fig. 11). 9

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KS–4: This sequence is cored in the Salman field (well SN#01) and mainly composed of shoal (back to central) and lagoon facies dominated by dolostones, although anhydritic dolostones are present especially in the uppermost parts (Fig. 11). Shoal and lagoon facies alternate from the

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basal part of the cored interval towards the MFS (TST), with decreasing trend in both gamma and density logs towards the MFS (Fig. 11). The HST is characterized by a slight increasing trend in the density log from the MFS to the SB and a thickening upward pattern, which has the

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highest density values, and a change from shoal and lagoonal facies to lagoonal and peritidal

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facies (Fig. 11).

KS–3: This sequence (and also the KS–1 sequence) represents the deposits of a shallower–water setting compared to the other sequences, with higher volumes of lagoonal and peritidal facies and dolomitic/anhydritc lithologies (Fig. 11). The TST hemi–sequence (only cored in the LN#01 well) is composed of thinning–upward lagoonal and shoal (back and central) deposits with

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increasing trend in gamma ray and density logs (Fig. 11). The MFS is characterized by off–shoal facies, and the gamma–ray and density logs do not show significant responses. The HST is composed of alternating lagoonal and shoal (back) facies in a thickening upward pattern, and

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gamma–ray and density logs values gradually decrease from the MFS to the SB (lowest values of

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gamma and density well logs; Fig. 11). The KS–3 sequence terminates at the Permo – Triassic boundary at the top, which has been recognized as an unconformity or sequence boundary (Types I and II) throughout the Arabian Plate and Persian Gulf area in several studies (Strohmenger et al., 2002; Vaslet et al., 2005; Alsharhan, 2006; Ehrenberg et al., 2008; Rahimpour– Bonab et al., 2009; Tavakoli and Rahimpour–Bonab, 2012; Rahimpour– Bonab et al., 2014).

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KS–2: This sequence is defined in all three studied wells (Fig. 11). In the LN#01 well, this sequence begins with Lower Triassic thrombolitic facies (above the PTB; Fig. 11). TST deposits are characterized by thinning–upward shoal and lagoon limestones. Both gamma–ray and density

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logs decrease from the base (PTB) to the MFS. The HST is defined by an abrupt increase in the density log, with shallowing and thickening upward facies with dolomitic and anhydritic

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lithologies.

KS–1: This final depositional sequence of the Deh Ram group composed of shallow–water

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deposits including lagoonal and peritidal facies and dolomitic/anhydritc to limy lithologies (Fig. 11). The TST is composed of lagoonal and shoal (back and central) deposits with very slight increasing trend in gamma ray and sharp decreasing trend in density logs (Fig. 11). The MFS is characterized by rapid decreasing and lowest values in density log. The lower to middle part of the HST hemi–sequence is composed of alternating peritidal to shoal facies, and gamma–ray and

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density logs values gradually increase from the MFS to the SB which tends to high gamma and dense shalley, andydritic and dolomitic unit near to the SB and finally the Aghar shale Member

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of the Dashtak Formation (Figs. 2 and 11).

The identified depositional sequences are correlatable between the studied fields (must be

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confirmed by high resolution seismic data) and also throughout the Zagros and Arabian Plate (in a 1000km distance; Figs. 11 and 12). This lateral continuity of depositional sequences or units is unique in the Permo–Triassic Khuff platform of the Middle East which led to the regional correlation of various reservoir and non–reservoir units throughout the Persian Gulf area (e.g. Insalaco et al., 2006; Koehrer et al., 2010, 2012; Rahimpour–Bonab et al., 2014). 7. Reservoir zonation schemes

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Reservoir zonation can lead to an insight about the lateral and vertical distribution of reservoir and non–reservoir units or zones at bore hole to regional scales. Based on the available data sets (such as lithology, well log and production) there are various reservoir zonation schemes that are

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usable in various scales for different purposes. For example, according to the geological, seismic and well log attributes, five main reservoir units were detected in the Permo–Triassic Dalan and Kangan successions of the Persian Gulf area and Arabian Plat (Fig. 2; Insalaco et al., 2006;

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Alsharhan, 2006). These units are very large scale and possibly do not show a unique stratigraphic position (e.g. Insalaco et al., 2006; Koehrer et al., 2012). There are several

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correlatable smaller scale reservoir and non–reservoir units in the main reservoir units (Rahimpour–Bonab et al., 2014; Enayati–Bidgoli et al., 2014). However, final goals and correlatability (which must be proved by seismic and dynamic data) are crucial in the reservoir zonation procedure.

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7.1. Geological reservoir zone (GRZ)

In this section our attempt is to create a reservoir zonation scheme based on geological attributes

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which can be used to regional (inter–field) investigation and correlation, and then its results are compared with routinely used reservoir zonation procedures such as flow unit concept. However,

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various petrophysical characteristics of rocks (without any reservoir fluids) are governed by depo–diagenetic processes. Moreover, defined reservoir zones must be correlatable at long distances, so, linking identified reservoir zones to a sequence stratigraphic framework is crucial. In the studied Permo–Triassic successions all geological characteristics including depositional and (post- depositional) diagenetic features and pore types are used to subdividing these intervals into correlatable units which are named Geological Reservoir Zones (GRZs). Correlation of

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these zones between the studied wells must be validated by high resolution seismic and dynamic (production) data (Bashore et al., 1994; Jennings, 2000; Borgomano et al., 2008). It must be noted that the main difference between the correlation of GRZs and depositional sequences

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(rather than higher scale of depositional sequences) is (post-depositional) diagenetic features which included in the determination of GRZs and may be compatible with depositional

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sequences.

In the studied wells, the Upper Dalan and Kangan cored intervals are subdivided into 12 GRZs

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(Fig. 13). The main idea behind this scheme was separating the intervals based on sharp changes in depositional facies, diagenetic features or both of them and also any meaningful accompaniment in diagenetic features and pore types. So, the identified GRZs in the studied wells showed comparable sequence stratigraphic positions which indicate a close relationship between the depositional sequences and post–depositional diagenetic processes or features (Fig.

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13). On the other hand, distribution of diagenetic features is sequence stratigraphically controlled and/or confined to a special sequence stratigraphic position. If diagenetic processes or products are not confined to a unique sequence stratigraphic position or cross cut these surfaces (harsh late

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diagenetic alteration), this scheme shows a high degree of uncertainty. However, in some cases,

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development of post-depositional diagenetic processes such as stylolite related dolomitization are related to depositional facies and show a unique sequence stratigraphic position (RahimpourBonab et al., 2012). The main geological characteristics (poroperm values) of the defined GRZs are summarized in Table. 3 and described as follows: GRZ–1: this late HST (KS–1) dolomitic to limy zone composed of peritidal to shoal facies which its limy lithology, shoal facies and calcite cements increase from the SNs wells toward the LN#01 (Fig. 13). The estimated porosity is fair (mean: 4%) and pore types are mainly moldic, 13

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vuggy and intercrystalline which its accompaniment by 20–100 and >100µm crystal size can lead to high permeability values (Fig. 13; Table 3). Higher solution seam development in the

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SN#01 decreased the porosity volume more than the other wells (Fig. 13). GRZ–2: this middle HST (KS–1) dolomitic to limy zone is mainly composed of lagoonal and subsequent shoal and peritidal facies which its limy lithology increases from the SNs wells

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toward the LN#01, but calcite cements are rare (Fig. 13). The estimated porosity is fair (mean: 3.3%) and include various pore types which their association with 20–100µm crystal size (in

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SN#01 and #02 wells) leading to relatively low permeability values (Fig. 13; Table 3). Higher solution seam development and mud dominated facies in this zone decreased the porosity than GRZ–1 in LN#01 (Fig. 13). The GRZ–1 and GRZ–2 contact is defined on the basis of abrupt changes and/or separations in various diagenetic features or processes (such as calcite and

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anhydrite cementation, dolomitization and pore-types in Fig. 13).

GRZ–3: this dolomitic zone is composed of peritidal to shoal facies in the SNs wells which is replaced by wholly limy lagoonal facies in the LN#01 well (early HST; KS–1; Fig. 13; Table 3).

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Rather than lithological and facies differences there are several similar diagenetic processes and products (Fig. 13; Table 3). The estimated porosity (mean: 2.75%) is low in the LN#01 and

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SN#01 wells, but is higher in the SN#02 well. However, there are several pore types in the Salman field including moldic, vuggy and intercrystalline (Fig. 13). Mud dominated and chemically compacted (lagoonal) facies created a relatively dense unit in the LN#01 well. Except similar sequence stratigraphic position, lower calcite cementation is the main difference with GRZ–2 (Fig. 13).

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GRZ–4: this porous and dolomitic reservoir unit composed of lagoonal and shoal facies (TST hemi sequence of KS–1) in the studied fields (Fig. 13; Table 3). Moldic, vuggy and intercrystalline pore types, good estimated porosity (mean: 8.25%) and 20–100 and >100µm

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crystal size led to high reservoir potential which confirmed by poroperm data (Table 3). However, dolomitization and dissolution (molds and vugs) have had positive impact on the reservoir potential enhancement. This zone in the SN#02 well shows high limy content and there

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are several types of calcite cement (Fig. 13). Several characteristics including lithology, facies, sequence stratigraphic position and pore types (porosity) differentiate this unit from the GRZ–3

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(Fig. 13).

GRZ–5: this late HST (KS–2) dolomitic–anhydritic zone is mainly composed of peritidal and lagoonal facies which show low reservoir potential (mean estimated porosity: 1.8%; Fig. 13; Table 3). This geological reservoir zone is differentiable from the GRZ–4 via its facies

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composition, high anhydrite cements and sequence stratigraphic position (Fig. 13). However, 20 to 100µm crystal sizes can lead to fair permeability values (Table 3).

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GRZ–6 and 7: these limy zones are recognizable in the Lavan field which composed of central and off–shoal and back–shoal facies, respectively. But in the Salman field these zones are

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composed of dolomitic back to central shoal facies and are un–differentiable from each other (Table 3). The equivalent of GRZ–6 and –7 in the SNs wells, show different diagenetic features such as fabric destructive dolomitization and patchy pore-filling and poikilotopic anhydrite cement (Fig. 13). Also, its pore types are inter–grain, inter–crystalline and vuggy (due to pre– dolomitization dissolution). These zones are recognizable as the most grain dominated (shoal facies) part (KS–2 sequence) of the K2 reservoir unit in the Kangan Formation which is the

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second most important reservoir unit of the Permo–Triassic successions in the Persian Gulf area (e.g. Esrafili–Dizaji and Rahimpour–Bonab, 2013; Rahimpour–Bonab et al., 2014).

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GRZ–8: this zone is approximately located below the PTB and composed of dolomitic lagoonal and shoal facies (Fig. 13; Table 3). Some traces of primary (pre–dolomitization) calcite cements such as isopachous marine, equant and microspar are visible in the studied wells. Intergranular

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and moldic pore types (mean estimated porosity: 5.25%) with 20–100µm crystal size can lead to fair reservoir potential. There are sharp differences between the GRZ–8 and GRZ–6 and –7

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including lithology (dolostone vs. limestone, mainly in the Lavan Field), facies type (lagoon vs. shoal), sequence stratigraphic position (KS–3 vs. KS–2) and type of anhydrite cement (poikilotopic vs. pore-filling).

GRZ–9: this is a dolomitic, lagoonal and early HST succession which shows various types of

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anhydrite and also remained calcite cements (Fig. 13; Table 3). Due to primary texture (mud dominated lagoonal facies), anhydrite cementation and chemical compaction, the estimated porosity (mean: 4%) is lower than overlying GRZ–8 (Fig. 13). However, 20–100µm crystal size

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and moldic (pre–dolomitization dissolution) and interparticle pore types indicate relatively fair reservoir potential. In comparison with GRZ–8, this zone has higher lagoonal facies, anhydrite

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and blocky calcite cements and estimated porosity. GRZ–10: this dolomitic–anhydritic succession only cored in the LN#01 well which composed of lagoon to shoal (mainly back–shoal) facies. Based on core and log data, this zone encompasses the TST part of the KS–3 depositional sequence (Fig. 13; Table 3). This zone is completely plugged by uniform to patchy pore-filling and poikilotopic anhydrite cements (Fig. 13). High anhydrite plugging and cementation as well as solution seam development led to low reservoir

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potential (mean estimated porosity: 0.7%; Fig. 13; Table 3). Higher anhydrite content in the SN#01 well indicates lower reservoir potential of this zone in the Salman Field. GRZ–10 has

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more shoal facies, anhydrite cement and lower estimated porosity than GRZ–9. GRZ–11: recovered cores from the SN#01 well showed that this late HST zone is an anhydritic dolostone with lagoon and shoal facies (Fig. 13; Table 3). The shoal related parts of this unit

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contain some un–filled vuggy and moldic pores (mean: 6%). Regarding fair (estimated) porosity and crystal size (20–100µm), this rock unit shows more reservoir potential and less anhydrite

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cement than its overlaying GRZ–11.

GRZ–12: beside the sequence stratigraphic position (early HST), this zone has higher lagoon and back–shoal facies, lower pore-filling anhydrite cement, gypsum cement and also higher and lower intergranular and moldic pores than GRZ–11, respectively (Fig. 13; Table 3). There are

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some un–filled vuggy and moldic pores (mean: 7%) in the shoal related facies and also due to 20–100µm crystal size, reservoir potential of this rock unit is similar GRZ–11. In general, based on sedimentological attributes, the identified geological reservoir zones in a

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descending order of reservoir/flow potential are as follows: GRZ–4, GRZ–6&7, GRZ–8, GRZ– 12, GRZ–11, GRZ–9, GRZ–1, GRZ–2, GRZ–3, GRZ–5, and finally GRZ–10 (Fig. 13), but

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regarding poroperm data (arithmetic means) this ranking is changed: GRZ–4, GRZ–6&7, GRZ– 1, GRZ–11, GRZ–3, GRZ–12, GRZ–2, GRZ–5, GRZ–8, GRZ–10, and finally GRZ–9. 7.2. Flow unit concept

Flow unit as a part of a reservoir which has lateral and vertical continuity and homogeneous flow and bedding characteristics (Hearn et al., 1984) can be used to divide a reservoir into zones (geobodies) appropriate for flow simulation (Bhattacharya et al., 2008). Flow units representing 17

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reservoir heterogeneity at different scales from the well–bore to the field scale (Ebanks et al., 1992; Slatt and Galloway, 1992).

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The identification of flow units based on poroperm data using FZI (Flow Zone Indicator) and SMLP (Stratigraphic Modified Lorenz Plot) is routinely used in various formations and reservoirs (e.g. Chopra et al., 1989; Grier and Marschall, 1992; Amaefule et al., 1993;

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Abbaszadeh et al., 1996; Gunter et al., 1997; Jongkittinarukorn and Tiab, 1997; Elgaghah et al., 1998, 2001; Aguilera, 2004; Slatt, 2006; Aggoun et al., 2006; Gomes et al., 2008; Burrowes et

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al., 2010; Nooruddin and Hossain, 2012; Rahimpour–Bonab et al., 2014). In a recent study (Enayati–Bidgoli et al., 2014) these methods were used to differentiate flow, baffle and barrier units in the Permo–Triassic reservoir succession at the central Persian Gulf area (South Pars gasfield) which led to a better understanding of the lateral and vertical distribution of reservoir and non–reservoir units at the field scale. Also, in this study in order to investigate the

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applicability of these methods (FZI and SMLP) for regional or inter–field correlations and their relationship with the identified GRZs, flow units are determined and correlated between the studied wells. It is very important that any correlation of flow units without dynamic data will

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have a degree of un–certainty.

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7.2.1. Hydraulic flow units (HFU) based on FZI HFUs provide small scale and high resolution reservoir zonation scheme which are determined on the base of a parameter known as the Flow Zone Indicator (FZI; Eqs 1 to 3; Amaefule et al., 1993).

FZI = RQI/Φz

(Eq. 1) 18

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RQI = 0.0314 (K/Φe)0.5

(Eq. 2)

Φz = Φe/(1– Φe)

(Eq. 3)

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Where RQI is in units of µm; K is in mD; and Φe (effective porosity) is fractional. Finally, a normal probability diagram for calculated log FZI values (Abbaszadeh et al., 1996) is drawn (Fig. 14A) which led to six HFU types (HFUs 1 to 6). Flow properties deteriorate from

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HFU1 to 6 as FZI values decrease (Fig. 14A). RQI–Φz cross–plot shows good separation of the determined HFUs with relatively high correlation coefficient (Fig. 14B; Amaefule et al., 1993).

values from HFU1 to HFU6 (Fig. 14C).

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A poroperm cross–plot for HFUs 1 to 6 shows that there is a general decreasing in permeability

A comparison between the studied wells (Fig. 15) shows that each HFU encompass a wide range of poroperm (Fig. 14C) that is visible in different parts of the studied intervals and only general

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similarities or differences are recognizable. However, there are some obvious differences such as the concentration of HFU5 in the lower part of the K3 reservoir unit in the SN#01 well which replaced by HFUs 2 and 3 in the LN#01 well (Fig. 15). Moreover, in the K2 unit of the LN#01

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well there is a concentration of weak flow units including HFUs 4 and 5 that is not visible in the

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SN#01 and #02 wells. Also, there is a concentration of HFU4 in the K1 reservoir unit of the SN#02 well (Fig. 15). Tracing of fine–scale HFUs can be problematic at the field scale, even using high resolution seismic data (Enayati–Bidgoli et al., 2014). 7.2.2. Flow units (FU) based on SML plot In this method, a reservoir interval can be subdivided into large–scale flow units, from several meters to tens of meters thick based on both petrophysical and geological properties (for more

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details see Enayati–Bidgoli et al., 2014; Fig. 15). The quality of a reservoir is defined by its hydrocarbon storage and flow capacities (Φh and Kh; Grier and Marschall, 1992) which are a

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function of porosity–permeability and depth (Eqs 4 and 5). The stratigraphic modified Lorenz plot (SML plot) as a plot of cumulative flow capacity (Khcum; Eq 6) versus cumulative storage capacity (Φhcum; Eq 7) shows the minimum numbers of flow

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units in the studied interval (Fig. 16; Gunter et al., 1997). From an inspection of the SML plot for the Upper Dalan – Lower Kangan succession at the studied wells (e.g. SN#01 well with more

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cored intervals; Figs. 15 and 16), it appears that at least 20 flow units can be identified (FUs 1– 20).

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Flow capacity, Kh = K1 (h1–h0), K2 (h2–h1),…, Kn (hn–hn–1)

(Eq. 5)

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Storage capacity, Фh = Ф1 (h1–h0), Ф2 (h2–h1),…., Фn (hn–hn–1)

(Eq. 4)

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where K is permeability (mD), h is sample depth (m), and Ф is fractional porosity.

Khcum = K1 (h1–h0)/Khtotal + K2 (h2–h1)/Khtotal +…. + Kn (hn–hn–1)/Khtotal (Eq.6)

Фhcum = Ф1 (h1–h0)/Фhtotal + Ф2 (h2–h1)/Фhtotal +…. + Фn (hn–hn–1)/Фhtotal (Eq.7)

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The stratigraphic flow profile (Fig. 15) shows the lithologic and facies properties, poroperm values, flow/storage capacities and sequence/stratigraphic position of the defined flow units (for more details see Enayati–Bidgoli et al., 2014). The identified flow units can be grouped into four

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types (Figs. 15 and 16): (i) super–permeable units with high flow capacity and low storage capacity, and steep slopes in the SML plot (e.g. FU3 and FU5 in well LN#01; FU8 and FU10 in well SN#01); (ii) normal flow units, with fair or equal values of flow and storage capacities (e.g.

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FU7 in well LN#01; FU3 and FU5 in well SN#01); (iii) baffle units, with low flow capacity and high storage capacity (e.g. FU1 and FU8 in well LN#01; FU11 in well SN#01); and (iv) barrier

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units, with very low flow and storage capacities which correspond to horizontal segments in the SML plot (e.g. FU2 in well LN#01; FU12 in well SN#01).

SML plots of the wells are compared in Fig. 16 based on numbers of flow units in each reservoir unit. SML plots and flow profiles of the studied wells show that there are different numbers of

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flow units in same reservoir units (Figs. 15 and 16 and Table 4). On the other hand, numbers of detected flow units using the SML plot are similar at the field scale (e.g. Enayati–Bidgoli et al., 2014) and different at the inter–field scale (Figs. 1, 15 and 16 and Table 4). However, these flow

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units are correlatable between the studied fields based on relative sequence/stratigraphic position

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(regarding main sequence stratigraphic surfaces) and depositional characteristics (Fig. 15) which must be validated by dynamic and seismic reflectors. Main sedimentological and petrophysical properties of the detected flow units are presented in Table 4. 8. Discussion and interpretation In this study, the Permo–Triassic successions of two gasfields at the eastern Persian Gulf area were subdivided into several zones or units, using three approaches including HFU, SML plot

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and a newly established GRZ that each of them was based on petrophysical, both petrophysical and geological and geological data, respectively (Figs. 15 and 17). Investigations show that pure petrophysical based HFUs are not correlatable between the studied wells of a unique field

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(Enayati–Bidgoli et al., 2014) and also at the inter–field scale do not show any correlation due to their high variability and small scale (Fig. 17). The large scale SML plot derived flow units which are basically defined using petrophysical poroperm data (Khcum and Φhcum) and some

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geological attributes (Gunter et al., 1997) are correlatable at the field scale (Enayati–Bidgoli et al., 2014) and to some extent for inter–field correlations (Fig. 15 and Table 4) to perform

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regional correlations. So, in order to regional correlations and evaluations, only (geological) depo–diagenetic properties were used for recognition of GRZs which must be confirmed by seismic and dynamic data. The recognized FUs and GRZs are compared in Table 4 and show a general compatibility. However, there are some differences between the position of a unique

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flow unit and its equivalent in a certain GRZ (e.g. GRZ–3 and GRZ–4; Table 4). These differences are due to poroperm variations between the studied fields and use of a poroperm based zonation scheme (SML plot).

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It seems that the correlation of GRZs at both intra– and inter–field scales in a sequence

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stratigraphic framework is more reliable (must be validated by seismic and dynamic data) than the petrophysical based flow units. So, only (pure) geological parameters are used to their creation. Rather than depositional characteristics, the application of post–depositional diagenetic features or processes was helpful in the differentiation of GRZs, but it may be problematic in highly post-depositionally altered (harsh late diagenesis) carbonate reservoirs. However, petrophysical well logs have important role in the recognition and correlation of depositional sequences. It must be considered that there are some depo–diagenetic differences between the 22

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defined GRZs at the inter–field scale, but they are sensible and logical regarding the scale of the study and paleo–environmental positions (facies changes and diagenetic trends). For example, GRZ–1 in the LN#01 well composed of various types of calcite cement, but in the SNs wells,

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due to a later dolomitization phase, only some remaining of precursor calcite cement is visible (see the facies and diagenesis sections; Fig. 13). The relatively high thickness of the defined

resolution seismic data and to trace them across the field.

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9. Conclusions

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GRZs (tens of meters; naturally upscaled) may be appropriate for their combination with high

1- In this study, the Permo–Triassic Dalan and Kangan formations in the eastern Persian Gulf area were analyzed based on depositional, diagenetic and reservoir characteristics. Detailed facies analyses led to the identification of 16 facies and seven facies groups including peritidal, lagoon, back–shoal, central–shoal, fore–shoal, channel and off–shoal.

groups.

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The highest and lowest poroperm values belonged to the central shoal and peritidal facies

2- Several diagenetic processes were recognized in the studied formations including syn–

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depositional processes, dissolution, calcite cementation, dolomitization, anhydrite

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cementation and chemical compaction which indicate marine/sub–aerial, meteoric and burial diagenetic realms.

3- Based on several depo–diagenetic features, and well logs, four third–order sequences were recognized in the Kangan and (Upper) Dalan successions which were correlatable with their equivalents in the Zagros and Persian Gulf basins and Arabian Plate. 4- The studied Permo–Triassic successions were subdivided into several intervals (12) based on sharp changes in depositional facies, diagenetic features or both. In addition, any 23

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meaningful accompaniment in diagenetic features and pore types (pure sedimentological characteristics) which were named Geological Reservoir Zones or GRZ, were considered for this purpose. Similar sequence stratigraphic positions in the studied wells indicate a

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close relationship between the depositional sequences and post depositional diagenetic modifications, so GRZs are linked to a sequence stratigraphic framework.

5- The purely petrophysical based HFUs were not correlatable between the studied wells

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and did not show any correlation at the inter–field scale due to their high variability and small scale. The larger scale flow units (SML plot derived) were correlatable at the field

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and to some extent inter–field scales.

6- It seems that the correlation of GRZs at both intra– and inter–field scales in a sequence stratigraphic framework is more reliable (which must be confirmed by dynamic and seismic data) and possible depo–diagenetic differences between the defined GRZs at the

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inter–field scale are logical regarding the scale of study and paleo–environmental conditions.

7- The relatively high thickness of the defined GRZs (tens of meters) may be appropriate for

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their combination with high resolution seismic data and to trace them across the field.

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Acknowledgements

The University of Tehran is thanked for providing facilities for this research. The authors acknowledge IOOC for sponsorship and data preparation. We also acknowledge the anonymous reviewer and editorial staff of the Journal of Marine and Petroleum Geology (JMPG) which improved and published this manuscript.

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Captions for figures and tables

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Fig. 1. (A) Location map of the studied Lavan and Salman fields, main Permo–Triassic gasfields, and the Qatar – South Fars Arch. (B) Paleogeographic and plate tectonic reconstruction of the Arabian Plate during deposition of the Dalan–Kangan (Khuff) formations (modified from Sharland et al., 2001). (C) A conceptual cross section of the Permo–Triassic successions (Khuff and Dalan and Kangan formations), and their lateral lithological changes from the Arabian Shield to the Persian Gulf and Zagros Suture Zone (modified from Strohmenger et al., 2002; Alsharhan, 2006).

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Fig. 2. (A) Stratigraphic column for the eastern Persian Gulf area (Lavan and Salman fields) and the stratigraphy of the Permo–Triassic succession (compiled from Sharland et al., 2001; Alavi, 2004; Heydari, 2008; IOOC). (B) Reservoir subdevision at the Lavan and Salman fields showing the studied interval.

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Fig. 3. Main defined facies groups (FG1to FG7) and facies (F1 to F16) in the Permo-Triassic Dalan and Kangan formations. More details of all facies and facies groups are presented in Table. 1. Fig. 4. (A) Schematic depositional model and relative positions of the defined facies in the studied intervals. (B) Pie diagrams of facias and facies groups in the studied wells (for more details see text).

EP

Fig. 5. Main syn-depositional features in the Dalan and Kangan formations. (A) Micritization. (B) Micritic envelop. (C) Bioturbation. (D) Mud crack. (E and F) Brecciation.

AC C

Fig. 6. Main calcite cement types in the Dalan and Kangan formations. (A) Marine sopachous. (B) Vadose dog tooth. (C) Bladed. (D) Equant. (E) Drusy. (F) Blocky. Fig. 7. Main dolomitization types and fabrics in the Dalan and Kangan formations. (A) Dolomicrite. (B) Fabric retentive. (C) Fabric destructive. (D) Fabric selective. (E and F) Mixing. (G) Stylolite related. (H) Recrystallized. (I) Saddle. Fig. 8. Main calcium sulfate cements in the Dalan and Kangan formations. (A) Gypsum single crystal. (B) Pore-filling anhydrite. (C) Intercrystalline anhydrite. (D) Pore-filling anhydrite. (E) Poikilotopic anhydrite. (F) Fracture filling anhydrite. Fig. 9. Stratigraphic distribution of diagenetic processes and products in the Dalan and Kangan formations at the studied fields. 34

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Fig. 10. Paragenetic sequence of diagenetic processes in the Dalan and Kangan formations. Fig. 11. Correlation of the detected depositional sequences (3rd order) in the studied wells.

RI PT

Fig. 12. Regional correlation of KS-1 to KS-4 depositional sequences from the Zagros and Persian Gulf basins to the NE parts of the Arabian Plat. Fig. 13. Correlation of the recognized GRZs between the studied wells and fields.

SC

Fig. 14. (A) Normal probability diagram for the logarithmic values of FZI and six hydraulic flow unit types in the studied wells. (B) Φz-RQI cross-plot of the detected HFUs. (C) Poroperm crossplot for the identified HFUs.

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Fig. 15. Correlation of the defined flow units between the studied wells. The presence of different HFUs in an individual flow unit reflects poroperm heterogeneities in vertical and horizontal directions.

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Fig. 16. SML plots of cumulative flow capacity (Khcum) versus cumulative storage capacity (Φhcum) for the studied wells. Due to different coring lengths and intervals (reservoir units) there are different numbers of preliminary flow units (based on inflection points) in the studied wells. In the studied fields there are different numbers of flow units in a unique reservoir unit for example the K1 reservoir unit composed of five and eight flow units in the Lavan field (LN#01) and Salman (SN#01 and SN#02) wells, respectively. There are same and different numbers of flow units in a unique reservoir unit at intra-field and inter-field scales, respectively. Fig. 17. A comparison between the results of three applied reservoir zonation schemes in the studied wells.

EP

Table 1. Main characteristics and mean poroperm values of the identified facies and facies groups in the Permo–Triassic Dalan and Kangan formations.

AC C

Table 2. Main recognized diagenetic processes and products in the studied Permo-Triassic successions and their effects on the reservoir quality. Table 3. Main characteristics of the recognized geological reservoir zones in the studied Permo– Triassic successions. Table 4. Main characteristics of the determined flow units in the three studied wells based on SML plots. Their equivalents (GRZs) are shown.

35

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Table 1.

F2

Nodular Dolo/Lime Mudstone

F3

Dolomudstone

F4

Fenestral Dolo/Lime Mudstone

F5

Boundstone Stromatolite/Thrombolite

F6

Pellet Mud/Grainstone

F7

Bioclast/Peloid Wacke/Packstone

Anhydrite Dolostone – Limestone Dolostone Dolostone – Limestone Limestone– Dolostone – Anhydrite Dolostone – Limestone– Anhydrite Dolostone – Limestone– Anhydrite

Skeletal –– Fine bioclasts, ostracoda, bivalve –– Bivalve fragments, ostracoda, gastropod, sponge spicule Algal filaments, ostracoda, bivalve fragments, benthic foram

Non–skeletal ––

Mean permeability (mD)

Arithmetic

Geometric

Arithmetic

1.945

1.339

1.343

Geometric

––

6.054

4.090

2.859

0.0001

5.609

4.733

2.107

0.00001

Peloid, pellet

3.911

3.317

0.792

0.056

Peloid, pellet

7.568

4.695

13.854

0.158

Bivalve, ostracoda, benthic foram, gastropod, green algae

Pellet, peloid

9.833

7.258

Benthic foram, green algae, ostracoda, bivalve, gastropod

Peloid

Fine bioclasts, benthic foram, bivalve fragments, ostracoda, sponge spicule Bivalve, benthic foram, green algae, gastropod, ostracoda Bivalve, benthic foram, green algae, gastropod, echinoderm fragments

F8

Shale/Mudstone

Limestone

F9

Peloid/Bioclast Mud/Packstone

Limestone

F10

Peloid/Ooid/Bioclast Pack/Grainstone

Limestone – Dolostone

F11

Bioclast/Peloid/Ooid/Oncoid Pack/Grainstone

Limestone – Dolostone

Bivalve, benthic foram, green algae, echinoderm fragments, gastropod

F12

Bioclast/Ooid Grainstone

Dolostone – Limestone

Bivalve, green algae, benthic foram, gastropod, echinoderm fragments

F13

Ooid Grainstone

Dolostone – Limestone

––

F14

Ooid/Peloid Coarse bioclast Pack/Grainstone

Limestone

F15

Intraclast/Bioclast/Peloid/Ooid Pack/Grainstone

Dolostone – Limestone

F16

Bioclast Wacke/Mudstone

Limestone

7.785

28.236

Mean permeability (mD)

Arithmetic

Geometric

Arithmetic

Geometric

FG1

Peritidal

6.098

3.705

8.566

0.007

FG2

Lagoon

7.558

5.434

22.834

0.047

FG3

Back–shoal

8.916

7.024

26.405

0.089

FG4

Central– shoal

11.134

8.619

67.668

0.096

0.230

5.304

7.506

0.016

Peloid, pellet, intraclast

6.139

4.532

17.971

0.028

Peloid, ooid, micritized ooid

8.548

6.684

20.059

0.052

9.236

7.205

33.425

0.180

10.951

8.425

60.142

0.061

12.187

9.808

105.764

1.091

Ooid, peloid, intraclast

4.248

3.832

0.020

0.004

FG5

Fore–shoal

4.248

3.832

0.020

0.004

Intraclast, peloid, ooid, micritized ooid, oncoid

9.972

8.248

15.262

0.101

FG6

Channel

9.972

8.248

15.262

0.101

––

5.517

4.472

0.467

0.005

FG7

Off–shoal

5.517

4.472

0.467

0.005

EP

AC C

Mean porosity (%)

0.068

6.990

Ooid

Echinoderm, brachiopod and bryozoan fragments, gastropod, green algae, bivalve, ostracoda, benthic foram Diverse bioclasts such as echinoderm, brachiopod, bryozoan and bivalve fragments, gastropod, green algae, bivalve, ostracoda, benthic foram, sponge spicule Echinoderm, brachiopod, bryozoan and bivalve fragments, ostracoda, benthic foram

53.611

Peloid, pellet

Peloid, ooid, micritized ooid, oncoid, intraclast Ooid, micritized ooid, oncoid, peloid

Depositional setting

0.0001

––

10.427

Facies group

RI PT

Anhydrite

Mean porosity (%)

Main allochems

SC

F1

Main lithology

M AN U

Facies name

TE D

Facies code

1

ACCEPTED MANUSCRIPT

Table 2.

Calcite cementation

Figure number

Micritization

5A & B

Bioturbation Mud crack Brecciation

5C 5D 5E & F

Dissolution

6D & E

Isopachous

5A & 6A

Dog tooth Bladed

6B 6C

Equant

6D

Drusy

Blocky

Microspar

Early (Dolomicrite)

Post– depositional processes

AC C

EP

Anhydrite/gypsu m cementation

6B, D & E 6A & F 6C & F; 5A & B 7A; 3F2 to F4

Fabric retentive

7B

Fabric destructive Fabric selective Mixing Stylolite related Recrystallization Saddle Gypsum Intergrain Intercrystalline Pore-filling Poikilotopic Fracture filling Chemical compaction Fracturing

7C 7D 7E & F 7G 7H 7I 8A 8B 8C; 7E 8D; 5C 8E 8F 5E & F; 3F2 8F

TE D

Dolomitization

Effect on reservoir quality Lead to lower reservoir potential via decreasing grain solubility Higher reservoir heterogeneity Increasing (vuggy and moldic pore types which mainly overprinted by later dolomitization phases) Preservation of primary (intergrain) porosity Decreasing (as porefilling cement) Decreasing (as porefilling cement) Main reservoir quality decreasing cement type in the limy intervals (as porefilling cement).

RI PT

Syn– depositional processes

Diagenetic process

SC

Type of diagenetic process based on mineralogy

M AN U

Relative time of diagenetic processes

2

Decreasing (as porefilling cement) Decreasing (as porefilling cement) Decreasing -

It depends on primary (limy) texture Increasing Slight increasing Increasing Decreasing Decreasing Decreasing Decreasing Decreasing Decreasing Decreasing Decreasing Decreasing

Both increasing and decreasing

ACCEPTED MANUSCRIPT

Table 3.

Late HST

GRZ–2

Dolostone – Limestone

Lagoon – shoal

Middle HST

GRZ–3

Limestone – Dolostone

Lagoon – shoal

Early HST

GRZ–4

Dolostone

Lagoon to shoal

TST

GRZ–5

Dolostone – Anhydrite

Peritidal – Lagoon

Late HST

GRZ–6&– 7

Limestone – Dolostone

Shoal

TST to Early HST

GRZ–8

Dolostone

Lagoon to shoal

Late HST

GRZ–9

Dolostone

Lagoon to back shoal

Early HST

GRZ–10

Anhydritic dolostone

Lagoon to back shoal

TST

GRZ–11

Anhydritic dolostone

Dalan

Lagoon and shoal

AC C

Kangan

GRZ–12

Anhydritic dolostone

Lagoon to (central) shoal

Late HST

Early HST

Mean porosity (%)

Main diagenetic features Various calcite cement types, fabric destructive and stylolite related dolomitization, patchy pore-filling anhydrite cementation, stylolitization, dissolution Blocky and microspar calcite cement, fabric destructive dolomitization, patchy pore-filling anhydrite cementation, brecciation, chemical compaction, dissolution Blocky and microspar calcite cement, fabric destructive, saddle (Salman) and stylolite related (Lavan) dolomitization, patchy pore-filling anhydrite cementation, chemical compaction Fabric destructive dolomitization, patchy pore-filling and poikilotopic anhydrite cementation, chemical compaction, dissolution Fabric destructive dolomitization, anhydrite cementation including uniform and completely plugged pore-filling and poikilotopic, chemical compaction Various calcite cement types (in the Lavan field) and isopachous, fabric destructive dolomitization, patchy pore-filling anhydrite cementation, chemical compaction, dissolution Pre–dolomitization isopachous, equant and microspar calcite cement and dissolution, fabric destructive and saddle dolomitization, patchy poikilotopic anhydrite cementation, chemical compaction Pre–dolomitization isopachous, blocky and microspar (calcite) cement and dissolution, fabric destructive dolomitization, patchy to uniform pore-filling, poikilotopic and intergrain anhydrite cementation, chemical compaction Pre–dolomitization isopachous, blocky and microspar (calcite) cement and dissolution, fabric destructive dolomitization, patchy to uniform pore-filling and poikilotopic anhydrite cementation, chemical compaction Pre–dolomitization isopachous calcite cement and dissolution, fabric destructive dolomitization, patchy intergrain, porefilling and poikilotopic anhydrite cementation, chemical compaction (stylolitization) Pre–dolomitization isopachous calcite cement and dissolution, fabric destructive dolomitization, patchy poikilotopic anhydrite cementation, intergrain and single crystal gypsum cement, chemical compaction (stylolitization)

Mean permeability (mD)

Arithmetic

Geometric

Arithmetic

Geometric

8.8

6.551

51.065

0.291

RI PT

Dolostone – Limestone

Peritidal to central shoal

GRZ–1

Sequence stratigraphic position

9.055

5.983

16.024

0.238

7.384

4.907

20.547

0.213

14.133

10.936

108.074

5.463

3.592

1.910

12.008

0.230

11.617

9.028

52.388

0.780

9.164

7.263

5.478

0.677

7.817

6.530

2.144

0.086

5.683

4.630

3.14

0.010

5.285

4.574

38.399

0.0004

5.867

5.366

18.032

0.003

SC

Main facies group

M AN U

Main lithology

TE D

Geological Reservoir Zone

EP

Formation

3

ACCEPTED MANUSCRIPT

Table 4. Reservoir unit

K1

Geological Reservoir Zone

GRZ–1

Flow unit

Main lithology

FU1

Limestone Dolostone

Lavan Field Dominant Φm facies (%) Peritidal to Shoal

7.7

Km (mD)

1.5

Kh %

0.6

Φh %

Flow unit

Main lithology

FU1

Dolostone Limestone

FU2

Dolostone

12.7

FU3 GRZ–2 FU2

Limestone

Lagoon

3.2

0.3

0.1

5.5

FU4

GRZ–3 Back– shoal

12.5

307.0

44.0

4.5

FU6

Dolostone

FU4

Dolostone

Central– shoal

7.0

1.6

0.1

0.1

FU7

Dolostone

FU5

Dolostone

Lagoon Shoal

FU6

Anhydritic Dolostone

FU7

Anhydritic Dolostone Limestone

Peritidal to Lagoon Shoal to off–shoal

FU8

Limestone

Shoal

K2 GRZ–5

K3

GRZ–8

GRZ–9

Anhydritic Dolostone

FU10

Anhydritic Dolostone

FU11

Anhydritic Dolostone

FU12

Anhydritic Dolostone

240.0

4.5

0.4

FU13 FU14

K4

AC C

Dalan

Anhydritic Dolostone Anhydritic Dolostone

31.5

10.0

0.1

2.3

15.5

50.0

14.5

16.6

7.4

0.3

0.1

9.3

13.2

13.3

3.5

11.0

9.0

2.1

0.50

7.0

10.0

10.0

2.5

7.5

6.0

2.0

0.5

4.5

EP

GRZ–10

FU9

Lagoon to Shoal Lagoon – Back– shoal Lagoon – Back– shoal Lagoon – Back– shoal

16.2

TE D

GRZ–7

Dolostone Limestone

Limestone Dolostone

GRZ–4

GRZ–6

Dolostone

FU3

M AN U

Kangan

Dolostone

SC

FU5

Shoal

9.8

6.5

1.5

6.5

Lagoon

7.5

4.6

0.5

2.5

GRZ–11

Φh %

12.8

0.3

2.8

91.0

11.0

4.6

77.7

9.8

5.7

3.3

0.1

1.5

51

10.0

10.5

17.5

1.0

5.2

1.4

0.1

2.0

70

8.7

9.8

FU9

Dolostone Anhydrite

Peritidal to Shoal

4.6

40.7

10.7

5.1

FU10

Dolostone Limestone

Shoal

14.7

114

9.6

4.6

FU11

Dolostone

Lagoon – Back– shoal

6.9

1.8

1.1

15.5

FU12

Anhydritic Dolostone Anhydrite

–

3.1

0.001

0

7.6

FU13

Anhydritic Dolostone

0.5

2.9

FU16

Dolostone Anhydritic Dolostone Anhydritic Dolostone

No–data FU17

Dolostone

FU18

Anhydritic Dolostone

FU19 FU20

4

Kh %

Dolostone Anhydrite

FU15

–

Km (mD)

FU8

FU14

GRZ–12

Salman Field Dominant Φm facies (%) Peritidal to 7.2 Shoal Peritidal to 10.7 Shoal Lagoon – 13.0 Shoal Peritidal to 10.0 Shoal Peritidal to 14.0 Shoal Lagoon – 8.1 Shoal Peritidal to 8.0 Shoal Peritidal to 15.0 Shoal

RI PT

Formation

Dolostone Anhydritic Dolostone

Peritidal – Lagoon Shoal

3.8

2.3

8.5

146.0

19

3.5

Shoal

5.1

22.0

3.6

2.7

Shoal

4.6

0.1

0.02

2.5

7.5

49.0

12.0

5.0

0.2

2.2

Shoal – Lagoon Shoal – Lagoon –

5.5

1.8

6.7

12.0

2.2

3.9

–

4.4

0.5

0.08

2.4

ACCEPTED MANUSCRIPT to Early Jurassic Permian-Triassic Gas Fields (255-182 Ma) B Mid-Permian 30

A

B

o

o

20 N

(On shore Iran and Persian Gulf)

IRANIAN TERRANES PALAEO-TETHYS OCEAN

NE

O-

IRAN Ku

Da

h-E

ub

y

ar

G

ond

nd

ast

n da h re Zi

o

28

a

an

ss

ng

h ye

u al

an

w

av

i

ss

ak

AFRICAN PLATE

o

26

Nasr

Bu Haseer Satah Al Razboot

Zakum

A

Progressive onlap in Late Permian; deposition of thick and broad carbonate and evaporite intervals

UAE

o

Onshore Saudi Arabia

B PALAEOTETHYS

NEO-TETHYS

AFRICAN PLATE

o

54

Zagros High (clastic source)

24

IRANIAN TERRANES

ARABIAN PLATE

Persian Gulf

Zagros Suture Zone

Kangan formation (Early Triassic) Permian-Triassic

Khuff formation

(Middle Permian-Early Triassic)

Khuff Siliciclastics in western Arabia (Early Permian)

Unconformity

Dalan formation

Middle Anhydrite (Nar Member in Iran)

(Middle-Late Permian)

nfo

co

Un

Proterozoic Basement Rocks

rm

ity

TE D

Upper Unayzah (Early Permian)

AC C

EP

Cambro- Ordovician

o

20 S

Schematic Plate Cross-section

Hail

100 Km

INDIA-PAKISTAN PLATE

GONDWANA

Eastern Persian Gulf Basin

Hair Dalmah

Arabian Shield

o

0N

ARABIAN PLATE

M AN U

Qa

tar -S Arouth ch Fa r

s

C

TIBET

SC

Umm Shaif

o

AFGHAN TERRANES

Mi at sfar fo rm

Salman & Lavan Fields

Fateh

Abu Al Bukhoosh

52

in

Pl

Broad carbonate - evaporite shelf in a passive margin setting

Salman

o

rg

A

>140Km Minab

50

Ma

Bastak

Kish

Satah

ive

Zagros High

Lavan

North Field

Arzanah

OC

Arabian Shield

South Pars

QATAR

Pa

Palmyra Trough

ul

Va r

bn Ta

Golshan

Ne

HailRutbah Arch

Early Jurassic rifting in eastern Mediterranean

Sh

A

er rd Bo

Ka

TURKEY

om

r

Ferdows

Mardin swell

Ba

H

YS

N

r

-M

Na

TH

EA

ha

Da

Western Persian Gulf Basin North Pars

Ag

lan

TE

o

20 N

RI PT

N

Devonian Silurian

Lower Unayzah (Early Permian)

ACCEPTED MANUSCRIPT Alavi Sharland et al Megasequences Megasequences (2004) (2001)

Heydari Super Sequences (2008)

Mishan Asmari Jahrum

X IX VIII

Ardavan

AP 8

Mehrdad

VII

Jurassic

AP 7

VI

Farhad

V Triassic

IV Ashk

AP 6

Pabdeh Gurpi

Gurpi

Ilam Lafan Sarvak Kazhdumi Daryan Gadvan Fahliyan

Ilam Surgah Sarvak Kazhdumi Daryan Gadvan Fahliyan

Hith

Hith

Surmeh

Surmeh

Neyriz

Neyriz

Dashtak

Dashtak

Kangan

Kangan

Dalan

AP 4

AP 3

Darioush

?

Ordovician

Camboojiyeh

Kourosh AP 2

Cambrian AP 1

Dalan Faraghan

II I

Hakhamanesh

Arabian Plate Basement

AC C

EP

TE D

Precambrian

Reservoir Units

Main Lithology

K1

K2

K3

K4

Nar

Lower Dalan

Lower Silurian

III

Member

SC

Devonian

AP 5

B

K5

Limestone

Claystone

Dolostone

Sandstone

Marl

Siltstone

M AN U

Paleozoic

Permian

Asmari Jahrum

Studied Interval

AP 9

Sassan

Upper Dalan

AP 10

Aghajari

RI PT

Ardeshir

on

XI

ati

AP 11

rm

Mesozoic

Cretaceous

Lithology

Kharg

Miocene Oligocene Eocene Paleocene

Salman Field Formation Main

Formation

Fo

Pliocene

Lithology

Kangan

Cenozoic

Quaternary

Lavan Field Formation Main

Formation

Dalan

A Age

Grey Marl

Anhydrite

Shale

Salt

ACCEPTED MANUSCRIPT FG1:F1

FG1:F2

Poro: 2.7 (%) - Horizontal Perm: 0.03 (mD)

1mm

Poro: 5.0 (%) - Horizontal Perm: 0.2 (mD)

1mm

Poro: 9.0 (%) - Horizontal Perm: 5.1 (mD)

FG2:F7

Poro: 5.5 (%) - Horizontal Perm: 0.02 (mD)

200 µm

Poro: 6.4 (%) - Horizontal Perm: 3.1 (mD)

FG2:F9

1mm

Poro: 7.0 (%) - Horizontal Perm: 0.5 (mD)

EP

Poro: ---- (%) - Horizontal Perm: ---- (mD)

1mm

FG5:F14

Poro: 6.2 (%) - Horizontal Perm: 0.5 (mD)

1mm

1mm

1mm

Poro: 14 (%) - Horizontal Perm: 15 (mD)

Poro: 2.2 (%) - Horizontal Perm: 0.007(mD)

Poro: 2.5 (%) - Horizontal Perm: 0.007 (mD)

1mm

Poro: 8.1 (%) - Horizontal Perm: 2.3 (mD)

1mm

FG4:F13

1mm

Poro: 17 (%) - Horizontal Perm: 25 (mD)

1mm

FG7:F16

FG6:F15

1mm

Poro: 8.2 (%) - Horizontal Perm: 9.1 (mD)

FG3:F10

FG4:F12

AC C

Poro: 6.7 (%) - Horizontal Perm: 0.02 (mD)

1mm

FG2:F8

TE D

FG2:F8

1mm

FG2:F6

M AN U

FG2:F6

Poro: 5.2 (%) - Horizontal Perm: 0.1 (mD)

RI PT

FG2:F5

Poro: 1.9 (%) - Horizontal Perm: 0.008 (mD)

FG3:F11

1mm

SC

FG1:F4

FG1:F3

1mm

Poro: 1.9 (%) - Horizontal Perm: 0.009 (mD)

1mm

ACCEPTED MANUSCRIPT Open marine

Shore

A Depositional profile

FG-1

Facies Groups distribution (FGs)

Peritidal

Sub-environments

H.T L.T FWWB

FG-4

FG-2

FG-3

Lagoon

Back Shoal

FG-7

FG-5

FG-6 Central Shoal Channel

Fore Shoal

Offshoal

Main Lithology Anhydrite

Dolomite-Limestone

Dolomite

Grain/mud content

Limestone Grain dominated

Mud dominated Increasing in grain size

Grain size Energy level

Low energy

RI PT

SC

Facies distribution

F2:Nodular Dolo/Lime Mudstone F3:Dolomudstone F4:Fenestral Dolo/Lime Mudstone F5:Stromatolite/Thrombolite Boundstone F6:Pellet Mud/Grainstone F7:Bioclast/Peloid Wacke/Packstone F8:Shale/Mudstone F9:Peloid/Bioclast Mud/Packstone F10:Peloid/Ooid/Bioclast Pack/Grainstone F11:Bioclast/Peloid/Ooid/Oncoid Pack/Grainstone F12:Bioclast/Ooid Grainstone F13:Ooid Grainston F14:Ooid/Peloid Coarse bioclast Pack/Grainstone F15:Intraclast/Bioclast/Peloid/Ooid Pack/Grainstone F16:Bioclast Wacke/Mudstone

B All wells

M AN U

Facies groups frequency in the Dalan and Kangan Formations

SN#01 well

LN#01 well FG6 FG7 2% 2%

FG5 FG6 FG7 1% 3% 2%

FG1 10%

FG4 29%

FG4 24%

F6

F7

F8

F9

F10

F11

AC C

F12

F13

FG2 13%

FG2 34%

TE D

F5

EP

F4

FG1 12% FG4 41%

FG3 31%

SN#01 well

LN#01 well

F3

FG7 1%

FG3 18%

Facies frequency in the Dalan and Kangan Formations

F2

FG5 FG6 0% 2%

FG1 13%

FG4 32%

FG3 23%

SN#02 well

FG7 1%

FG2 39%

FG3 22%

All wells

FG6 2%

FG5 0%

FG1 8%

FG2 34%

F1

Low energy

High energy

F1:Anhydrite

FG5 1%

Mud dominated Increasing in grain size

Mainly calcarenite

F13 F14 4% 0%

F15 F16 F1 F2 F3 F4 2% 1% 3% 2% 1% 0%

F5 7%

F12 28%

F6 5%

SN#02 well F14 0%

F13 9%

F7 9%

F15 F16 F1 F2 2% 0% 0% 0% F5 11%

F12 31%

F10 12% F11 6%

F14

F15

F16

F9 16%

F8 4%

F3 0%

F6 0%

F4 0%

F7 8% F8 0% F9 5% F10 12%

F11 20%

ACCEPTED MANUSCRIPT B

Poro: 1.9 (%) - Horizontal Perm: 0.01 (mD)

200 µm

200 µm

E

1mm

Poro: 2.8 (%) - Horizontal Perm: 0.1 (mD)

TE D EP AC C

1mm

F

1mm

M AN U

Poro: 8.9 (%) - Horizontal Perm: 2.4 (mD)

Poro: 5.0 (%) - Horizontal Perm: 0.02 (mD)

SC

D

Poro: 3.0 (%) - Horizontal Perm: 0.03 (mD)

C

RI PT

A

1cm

ACCEPTED MANUSCRIPT A

B

Poro: 3.7 (%) - Horizontal Perm: 0.006 (mD)

200 µm

Poro: 10.3 (%) - Horizontal Perm: 0.3 (mD)

200 µm

E

Poro: 4.5 (%) - Horizontal Perm: 0.01 (mD)

1mm

F

200 µm

Poro: 17.4 (%) - Horizontal Perm: 0.1 (mD)

200 µm

Poro: 1.7 (%) - Horizontal Perm: 0.01 (mD)

AC C

EP

TE D

M AN U

Poro: 29.9 (%) - Horizontal Perm: 0.2 (mD)

SC

RI PT

D

C

1mm

ACCEPTED MANUSCRIPT B

Poro: 2.5 (%) - Horizontal Perm: 0.007 (mD)

1mm

Poro: 12 (%) - Horizontal Perm: 0.03 (mD)

1mm

E

Poro: 10.2 (%) - Horizontal Perm: 0.05 (mD)

200 µm

Poro: 17.6 (%) - Horizontal Perm: 0.2 (mD)

H

200 µm

Poro: 6.2 (%) - Horizontal Perm: 0.5 (mD)

EP AC C

200 µm

Poro: 20.5 (%) - Horizontal Perm: 3263.2 (mD)

200 µm

I

TE D

Poro: 3.1 (%) - Horizontal Perm: 0.01 (mD)

200 µm

F

M AN U

G

Poro: 7.0 (%) - Horizontal Perm: 5.1 (mD)

SC

D

C

RI PT

A

200 µm

Poro: 20.5 (%) - Horizontal Perm: 3263.2 (mD)

200 µm

ACCEPTED MANUSCRIPTC B

Poro: 10.1 (%) - Horizontal Perm: 0.8 (mD)

1mm

200 µm

E

500 µm

F

Poro: 7.7 (%) - Horizontal Perm: 0.1 (mD)

1mm

Poro: 15 (%) - Horizontal Perm: 0.5 (mD)

AC C

EP

TE D

M AN U

Poro: 22.8 (%) - Horizontal Perm: 0.7 (mD)

1mm

Poro: 20 (%) - Horizontal Perm: 2945 (mD)

SC

D

Poro: 2.6 (%) - Horizontal Perm: 0.01 (mD)

RI PT

A

500 µm

3685

3645 3635

EP

3625 3615

Upper Permian Upper Dalan Member K4 K3

GR (API)

gr/cc

Dolostone Anhydrite

Claystone

3505 3495

3525 3515

3555

3705

Limestone

RHOB

3575

3745

3585

3785 3765

3595

3605

3825 3805

Facies Group

Dolostone Anhydrite Claystone

Peritidal Lagoon

Limestone

RHOB

Pore Type

0

100

Facies Group

3625

3605

3645

3665

3535

3685

PTB 3705

3725

Syndepositional

Syndepositional

SN#01 Main diagenetic processes and products

Calcite Cementation

3545

3565

3485

3585

Calcite Cementation

Dolomitization Anhydrite cementation

3524

Dolomitization

Porosity

4Km

Chemical Mold filling compaction cement

3540

0

(%)

30

Anhydrite cementation

Depth (m)

Dolostone Anhydrite Claystone

Peritidal Lagoon

gr/cc

Limestone

Main diagenetic processes and products Chemical Mold filling compaction cement

0

RHOB

Pore Type

Channel Off Shoal Micritization Micrite envelope Bioturbation Mud crack Brecciation Isopach Dog tooth Bladed Equant Drusy Blocky Microspare Dolomicrite Fabric retentive Fabric destructive Fabric selective Mixing Stylolite related Recrystallization Saddle <20 Micron 20-100 Micron >100 Micron Gypsum Intergrain Intercrystal Porefilling Poikilotopic Fracture Filling Completely plugged Uniform Patchy Stylolite Solution seam Fitted fabric Calcite Dolomite Anhydrite Intergranular Intragranular Fenestral Moldic Vuggy Intercrystalline Fracture

Central Shoal Fore Shoal

2.95

100

GR (API)

Back Shoal

1.95

Cored Interval

0

(Visually estimated)

Reservoir Units

Formation

Epoch

RI PT

Channel Off Shoal Micritization Micrite envelope Bioturbation Mud crack Brecciation Isopach Dog tooth Bladed Equant Drusy Blocky Microspare Dolomicrite Fabric retentive Fabric destructive Fabric selective Mixing Stylolite related Recrystallization Saddle <20 Micron 20-100 Micron >100 Micron Gypsum Intergrain Intercrystal Porefilling Poikilotopic Fracture Filling Completely plugged Uniform Patchy Stylolite Solution seam Fitted fabric Calcite Dolomite Anhydrite Intergranular Intragranular Fenestral Moldic Vuggy Intercrystalline Fracture

Central Shoal Fore Shoal

2.95

gr/cc

Back Shoal

1.95

GR (API)

Dashtak Aghar

Depth (m) Cored Interval

140Km

Lower Triassic Kangan K1

Epoch Formation Reservoir Units

Porosity

K2

3475

M AN U

3465

Dashtak Aghar

3457

SC

Lower Triassic Kangan K1

30

TE D

3545

K2

(%)

Pore Type

Channel Off Shoal Micritization Micrite envelope Bioturbation Mud crack Brecciation Isopach Dog tooth Bladed Equant Drusy Blocky Microspare Dolomicrite Fabric retentive Fabric destructive Fabric selective Mixing Stylolite related Recrystallization Saddle <20 Micron 20-100 Micron >100 Micron Gypsum Intergrain Intercrystal Porefilling Poikilotopic Fracture Filling Completely plugged Uniform Patchy Stylolite Solution seam Fitted fabric Calcite Dolomite Anhydrite Intergranular Intragranular Fenestral Moldic Vuggy Intercrystalline Fracture

3675

(Visually estimated)

Central Shoal Fore Shoal

3665

3965

3945

3985

AC C

3695

Nar Member

3655

0

Back Shoal

Chemical Mold filling compaction cement

100

Pore Type

Channel Off Shoal Micritization Micrite envelope Bioturbation Mud crack Brecciation Isopach Dog tooth Bladed Equant Drusy Blocky Microspare Dolomicrite Fabric retentive Fabric destructive Fabric selective Mixing Stylolite related Recrystallization Saddle <20 Micron 20-100 Micron >100 Micron Gypsum Intergrain Intercrystal Porefilling Poikilotopic Fracture Filling Completely plugged Uniform Patchy Stylolite Solution seam Fitted fabric Calcite Dolomite Anhydrite Intergranular Intragranular Fenestral Moldic Vuggy Intercrystalline Fracture

100

Main diagenetic processes and products

2.95

2.95

0

LN#01

Peritidal Lagoon

1.95

Central Shoal Fore Shoal

Back Shoal

Peritidal Lagoon

Claystone

0

Depth (m) Cored Interval Dolostone Anhydrite

Dolomitization Anhydrite cementation

1.95

Epoch Formation Reservoir Units

Limestone

Calcite Cementation

Cored Interval

K1

RHOB Syndepositional

Depth (m)

Lower Triassic Kangan

gr/cc

Facies Group

Reservoir Units

PTB GR (API)

Epoch

K2

N

Formation

Upper Permian Upper Dalan Member K3

ACCEPTED MANUSCRIPT

Facies Group Syndepositional

SN#02

Calcite Cementation

Main diagenetic processes and products

3560

3600

3580

3640

3620

3660

3700

3680

3720

3565

3865

3845

3885

3905

3925

4015 4005

(Visually estimated)

Porosity (%)

30

Dolomitization Anhydrite cementation

S

Chemical Mold filling compaction cement

0

(Visually estimated)

Porosity (%)

30

ACCEPTED MANUSCRIPT Burial

Diagenetic Environments Diagenetic Processes or Products

Syn-deposition Subareal Marine

Meteoric

Shallow

Deep

Dolomicrite Mud crack Brecciation Micritization Bioturbation Isopach calcite cementation

Dissolution Dog tooth calcite cementation Bladed calcite cementation Equant calcite cementation Drusy calcite cementation

RI PT

Blocky calcite cementation Fabric selective dolomitization Fabric retentive dolomitization Mixing dolomitization Fabric destructive dolomitization Pore filling anhydrite cementation Intergrain anhydrite cementation Intercrystalline anhydrite cementation

SC

Poikilotopic anhydrite cementation Microspar Chemical compaction Stylolite related dolomitization

M AN U

Fracture filling anhydrite Dolomite recrystallization Saddle dolomitization

AC C

EP

TE D

Gypsum cementation

3685

3705

0 RHOB

1.95

GR (API)

gr/cc

Dolostone Anhydrite

Claystone 2.95

100

K1

3495

3605

3625

3555

3725

3705

3565

3575

3745

3765

3865 3845

Grain Size Energy Level Sedimentary Texture

Limestone

FG-1

FG-2

3700

3905

3925

4005

3720

Facies

KS-2

3585

K2

3485

K1

KS-1

3640

KS-1

Fore Shoal

Cored Interval

Depth (m)

Reservoir Units

Lutite

F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 FG-5 F15 FG-6 F16 FG-7 Peritidal

Boundstone

Grainstone

Packstone

Wackestone

Mudstone

High

Medium

Low

Rudite

Arenite

4Km

3540

3580

Cored Interval

Depth (m)

Reservoir Units

Off Shoal Sequence Name Third order Sequence

Channel

Fore Shoal

Central Shoal

Back Shoal

Lagoon

RI PT Aghar

3545

KS-2

3565

SC

Aghar 3524

FG-3 FG-4

Dolostone Anhydrite

FG-3 FG-4

Claystone

Facies Group

High

Medium

Limestone

FG-1

3885

3965

3945

3985

4015

FG-2

FG-3 FG-4

Back Shoal

Fore Shoal

SN#02 Facies Group Off Shoal Third order Sequences Third order Sequences

Channel

Facies Central Shoal

Sedimentary Texture

Lagoon

F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 FG-5 F15 FG-6 F16 FG-7 Peritidal

Boundstone

Grainstone

Packstone

Energy Level Wackestone

Grain Size Mudstone

2.95

Low

RHOB

Rudite

gr/cc

Lutite

1.95

100

Arenite

GR (API)

Off Shoal Third order Sequences Third order Sequences

3685

FG-2

0

Channel

3535

FG-1

Facies Group

Fore Shoal

3665

Facies

Central Shoal

3675

SN#01

Lagoon

3525

KS-3

3645

M AN U

3515

Sedimentary Texture

Back Shoal

3615 Claystone

2.95

KS-4

3625

KS-5

3805

Limestone

F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 FG-5 F15 FG-6 F16 FG-7 Peritidal

3825

gr/cc

Energy Level

Boundstone

3665

Channel

140Km

Grainstone

3605 RHOB

Packstone

3595 Dolostone Anhydrite

Grain Size

Wackestone

3635

3785

TE D

3545

K2

3475 1.95

100

Mudstone

3645

EP

3585

K3

3465 GR (API)

High

3655

K4

3457 0

Medium

3695

Nar

FG-3 FG-4

Off Shoal Sequence Name Third order Sequence

Facies Group

Low

FG-2

Back Shoal

LN#01

Rudite

FG-1

Central Shoal

Facies

Lagoon

F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 FG-5 F15 FG-6 F16 FG-7 Peritidal

Boundstone

Grainstone

Packstone

Wackestone

Mudstone

High

Medium

Low

Rudite

Sedimentary Texture

Arenite

3505

KS-1

Lutite

Claystone 2.95

Arenite

Limestone

KS-2

Depth (m) Cored Interval gr/cc

Energy Level

KS-3

Epoch Formation

Reservoir Units

RHOB

Grain Size

AC C

K1

Dolostone Anhydrite 100

Lutite

Lower Triassic Kangan

1.95

GR (API)

Cored Interval

PTB 0

Depth (m)

K2

N

Reservoir Units

Upper Permian Upper Dalan Member K3

ACCEPTED MANUSCRIPT

S

3560

3600

3620

3660

3680

?

(not restored)

2

3

West

(not restored)

6

Musandam Mountains, UAE (Maurer et al., 2009) East - Northwest

~450 km

~250 km

SN#01

KS-3

RI PT

Lagoon

Peritidal

Channel

Facies Group Fore Shoal

Claystone

Back Shoal

Dolostone Anhydrite

Off Shoal Third order Sequences

Lithology ratios Limestone

Central Shoal

Channel

SN#02 Off Shoal Third order Sequence

Lagoon

Claystone

Fore Shoal

Facies Group

Peritidal

Dolostone Anhydrite

Back Shoal

5

Lithology ratios Limestone

Central Shoal

Lagoon

Channel

Peritidal

Fore Shoal

Back Shoal

KS-1

Central Shoal

Facies Group

KS-2

Claystone

Off Shoal Third order Sequence

Lithology ratios Limestone Dolostone Anhydrite

Saiq Plateau, Oman (Koehrer et al, 2010)

Salman Field

4 LN#01

SC

1

2

KS-4

Persian Gulf

3

M AN U

Golshan

TE D EP

Southeast

7

Lavan Field

AC C

1

ACCEPTED MANUSCRIPT

Zagros Mountains-Offshore Fars, Iran (Insalaco et al., 2006) 300 km 350 km

South Pars

4 Lavan Salman

5

6

Musandam Mountains

7 Saiq Plateau

gr/cc

Dolostone Anhydrite

Claystone

3635

3705

RHOB

Limestone 3785 3765

3595

3825 3805

3615

3845

Facies Group

3585

3625

3605

3645

3665

3685

3705

3555

3865

3985

Syndepositional

3745

3885

3925

Calcite Cementation Dolomitization Anhydrite cementation

3640

Chemical Mold filling compaction cement

GRZ-3

Limestone

Main diagenetic processes and products 0

RHOB

3600

3700

Micritization Micrite envelope Bioturbation Mud crack Brecciation Isopach Dog tooth Bladed Equant Drusy Blocky Microspare Dolomicrite Fabric retentive Fabric destructive Fabric selective Mixing Stylolite related Recrystallization Saddle <20 Micron 20-100 Micron >100 Micron Gypsum Intergrain Intercrystal Porefilling Poikilotopic Fracture Filling Completely plugged Uniform Patchy Stylolite Solution seam Fitted fabric Calcite Dolomite Anhydrite Intergranular Intragranular Fenestral Moldic Vuggy Intercrystalline Fracture

Sequence

Channel Off Shoal

Central Shoal Fore Shoal

0

100

Facies Group

Pore Type

(%)

GRZ-1

Claystone

Peritidal Lagoon

Dolostone Anhydrite

2.95

gr/cc

Back Shoal

1.95

Cored Interval

Depth (m)

Reservoir Units

GR (API)

3680

GRZ-4

Pore Type

Geological Reservoir Zone

30

KS-1

(%)

KS-2

0

Aghar

4Km

RI PT Porosity

GRZ-1

(Visually estimated)

K1

3565

Chemical Mold filling compaction cement

K2

3545

Dolomitization Anhydrite cementation

GRZ-5 GRZ-4 GRZ-3 GRZ-2

100

Main diagenetic processes and products

GRZ6&7

3524

SC

Micritization Micrite envelope Bioturbation Mud crack Brecciation Isopach Dog tooth Bladed Equant Drusy Blocky Microspare Dolomicrite Fabric retentive Fabric destructive Fabric selective Mixing Stylolite related Recrystallization Saddle <20 Micron 20-100 Micron >100 Micron Gypsum Intergrain Intercrystal Porefilling Poikilotopic Fracture Filling Completely plugged Uniform Patchy Stylolite Solution seam Fitted fabric Calcite Dolomite Anhydrite Intergranular Intragranular Fenestral Moldic Vuggy Intercrystalline Fracture

Sequence

Channel Off Shoal

Central Shoal Fore Shoal

2.95

0

SN#01

GRZ-8

M AN U

Peritidal Lagoon Back Shoal

1.95

Cored Interval

Depth (m)

Reservoir Units

Geological Reservoir Zone

Claystone

Calcite Cementation

GRZ-9

3485

KS-1

Aghar

GRZ-1

Limestone

Syndepositional

GRZ-10

3535

KS-2

K1

GRZ-2

Dolostone Anhydrite

Facies Group

GRZ-11

3575

gr/cc

GRZ-12

3725

KS-3

3515

K2

3525

GRZ-3

3495

TE D

3545

GRZ-4

3505

K3

GRZ-5

3475

RHOB

KS-4

3585

GRZ-6

Pore Type

GR (API)

KS-5

3605

GRZ-7

140Km Syndepositional

(Visually estimated)

Porosity 30

Geological Reservoir Zone

3685

30

EP

GRZ-8

(%)

Micritization Micrite envelope Bioturbation Mud crack Brecciation Isopach Dog tooth Bladed Equant Drusy Blocky Microspare Dolomicrite Fabric retentive Fabric destructive Fabric selective Mixing Stylolite related Recrystallization Saddle <20 Micron 20-100 Micron >100 Micron Gypsum Intergrain Intercrystal Porefilling Poikilotopic Fracture Filling Completely plugged Uniform Patchy Stylolite Solution seam Fitted fabric Calcite Dolomite Anhydrite Intergranular Intragranular Fenestral Moldic Vuggy Intercrystalline Fracture

3655

K4

3645

GRZ-9

0

Sequence

3695

Nar Member

3665 3945

AC C

3675

GRZ-10

Porosity

Channel Off Shoal

GR (API)

(Visually estimated)

Back Shoal

LN#01

Central Shoal Fore Shoal

Micritization Micrite envelope Bioturbation Mud crack Brecciation Isopach Dog tooth Bladed Equant Drusy Blocky Microspare Dolomicrite Fabric retentive Fabric destructive Fabric selective Mixing Stylolite related Recrystallization Saddle <20 Micron 20-100 Micron >100 Micron Gypsum Intergrain Intercrystal Porefilling Poikilotopic Fracture Filling Completely plugged Uniform Patchy Stylolite Solution seam Fitted fabric Calcite Dolomite Anhydrite Intergranular Intragranular Fenestral Moldic Vuggy Intercrystalline Fracture

Sequence

Channel Off Shoal

0

100

Chemical Mold filling compaction cement

100

2.95

Central Shoal Fore Shoal

Back Shoal

1.95

Dolomitization Anhydrite cementation

2.95

Depth (m)

Cored Interval

Main diagenetic processes and products

Peritidal Lagoon

KS-1

Epoch Formation Reservoir Units

Peritidal Lagoon

Claystone

0

3625 Dolostone Anhydrite

Calcite Cementation

1.95

PTB Limestone

Syndepositional

Cored Interval

3565 gr/cc

Facies Group

Depth (m)

K1 3465

RHOB

KS-2

Lower Triassic Kangan 3457

GR (API)

KS-3

K2

N

Reservoir Units

Upper Permian Upper Dalan Member K3

Calcite Cementation

SN#02 Main diagenetic processes and products

3620

3720

3905

3965

4015

4005

Dolomitization Anhydrite cementation Chemical Mold filling compaction cement

0

(Visually estimated)

Porosity (%)

Pore Type

30

Geological Reservoir Zone

ACCEPTED MANUSCRIPT

S

3540

3560

3580

GRZ-2

3660

GRZ-5 GRZ6&7

ACCEPTED MANUSCRIPT

A

HFU1

HFU2 HFU3 HFU4 HFU5

RI PT

HFU6

M AN U

SC

B

AC C

EP

TE D

C

ACCEPTED MANUSCRIPT

3725

FU-6 3565

3745

FU-7

3825

PTB 3845 3625

FU-9

EP

FU-10 3645

3865

TE D

K3

KS-2

3805

FU-8

3605

3885

FU-7

3680

FU-9

3700

FU-10

FU-18

40

20

(%)

0

Phih

(%)

40

KH

20

3

0

-3

0

3

1000

0

HFU

(mD)

1

40

0

20

0

20

HFU6: Log FZI<-1.5

FU-13

0.01

0 10 20 30 40 0.0001

Sequence

Off Shoal

Channel

40

HFU4: -1
FU-19

Fore Shoal

3

HFU2: 0.7
FU-20

Central Shoal

Claystone

Back Shoal

Dolostone Anhydrite

Lagoon

2.95

gr/cc

Limestone

0

HFU5: -1.5
FU-14

(%)

0

HFU3: -0.5
FU-12

Porosity Permeability Log FZI

?

HFU1: Log FZI>1

FU-17

Facies Group

-3

?

FU-9

3720

4005

Lithology ratios

1

?

4015

Peritidal

100

0

Depth (m)

RHOB 1.95

Reservoir Units

GR (API)

3

FU-8

FU-8

FU-11

FU-6 FU-7

KS-1

3640

3660

3985

FU-14

3705

1000

FU-4

FU-6

KS-4

K4

FU-13

0.01

Sequence

FU-1 FU-2 FU-3 FU-5

K1

FU-4

FU-5

Flow Unit

3580

3620

3965

3685

(%)

FU-3

3925

FU-12

(%)

3600

FU-15

3945

Phih

3560

FU-16

AC C

KS-3

FU-11

KH

3540

3905

3665

HFU

(mD)

(%) 0 10 20 30 40 0.0001

Fore Shoal

Off Shoal

Channel

Lagoon

Back Shoal

Claystone

Central Shoal

2.95

gr/cc

Dolostone Anhydrite

Peritidal

100

0

Depth (m)

1.95

Reservoir Units

0

20

40

0

20

40

3

0

0

-3

RHOB

Limestone

Porosity Permeability Log FZI

KS-3

3765

3785

(API)

Facies Group

Lithology ratios

KS-2

3705

GR

FU-2

Log Data

K2

3685

3585

FU-1

KS-2

KS-1

3665

FU-5

(%)

Flow Unit

Aghar

3525

3545

(%)

M AN U

KS-1

3625

3645

FU-3 FU-4

Phih

SC

3505

K1

K1

3605

Lower Triassic Kangan

1

3565

3585

K2

3

3545

3485

FU-2

KH

K2

Aghar

FU-1

Upper Permian Upper Dalan Member K3

1000

0.01

Sequence

(mD)

(%)

3524

3465

HFU

S

SN#02

4Km

Porosity Permeability Log FZI

0 10 20 30 40 0.0001

Fore Shoal

Off Shoal

Channel

Lagoon

Claystone

Back Shoal

Dolostone Anhydrite

Central Shoal

gr/cc

2.95

RHOB

Limestone

Peritidal

100

0

Depth (m)

(API)

Facies Group

Lithology ratios

RI PT

3457

GR

1.95

0

Reservoir Units

(%)

20

(%)

Flow Unit

40

0

Phih

20

KH

40

3

0

0

-3

1

3

1000

0.01

Sequence

HFU

(mD)

(%)

SN#01

140Km

Porosity Permeability Log FZI

0 10 20 30 40 0.0001

Fore Shoal

Off Shoal

Channel

Claystone

Lagoon

Dolostone Anhydrite

Back Shoal

Limestone

Central Shoal

gr/cc

2.95

RHOB

Facies Group

Lithology ratios Peritidal

(API)

100

0

Depth (m)

LN#01 GR

1.95

Epoch

Formation Reservoir Units

N

Flow Unit

FU-10

ACCEPTED MANUSCRIPT

13 14 11 12

10 6

8 9 7

5

15

18 20 17 19 16

12 13

10

K4

9

K3

8 67

K2

5

K1

TE D

34 12

9

8

5 4

AC C

3

2

1

7

EP

6

M AN U

14 11

SC

2 3

1

RI PT

4

10

gr/cc

Dolostone Anhydrite

Claystone

Limestone

RHOB

Facies Group Syndepositional

Calcite Cementation 3845

3635

3885 3865

3905

3665

3925

3945

FU-12 3965

3985

Dolomitization

Anhydrite cementation Chemical Mold filling compaction cement

Main diagenetic processes and products

0

(Visually estimated)

Porosity

Pore Type

(%)

30

FU-5

FU-4

FU-7

FU-10

3640

FU-8 3680

FU-9 3700

(%)

GRZ-3

FU-1

GRZ-4

FU-3

Claystone

PorosityPermeability (mD)

RHOB

3600

Micritization Micrite envelope Bioturbation Mud crack Brecciation Isopach Dog tooth Bladed Equant Drusy Blocky Microspare Dolomicrite Fabric retentive Fabric destructive Fabric selective Mixing Stylolite related Recrystallization Saddle <20 Micron 20-100 Micron >100 Micron Gypsum Intergrain Intercrystal Porefilling Poikilotopic Fracture Filling Completely plugged Uniform Patchy Stylolite Solution seam Fitted fabric Calcite Dolomite Anhydrite Intergranular Intragranular Fenestral Moldic Vuggy Intercrystalline Fracture

Sequence

Channel Off Shoal

Central Shoal Fore Shoal

2.95

gr/cc

Back Shoal

Limestone

FU-2

GRZ-1

Dolostone Anhydrite

Peritidal Lagoon

1.95

0

RI PT 100

Cored Interval

Depth (m)

Reservoir Units

Flow Unit

KS-1

40

20

0

40

20

0

3

0

-3

0

3

1000

1

0.01

0 10 20 30 40 0.0001

(%)

Aghar

0

100

Geological Reservoir Zone

Phih

(%)

KS-2

Micritization Micrite envelope Bioturbation Mud crack Brecciation Isopach Dog tooth Bladed Equent Drusy Blocky Microspare Dolomicrite Fabric retentive Fabric destructive Fabric selective Mixing Stylolite related Recrystallization Saddle <20 Micron 20-100 Micron >100 Micron Gypsum Intergrain Intercrystal Porefilling Poikilotopic Fracture Filling Completely plugged Uniform Patchy Stylolite Solution seam Fitted fabric Calcite Dolomite Anhydrite Intergranular Intragranular Fenestral Moldic Vuggy Intercrystalline Fracture

Sequence

Channel Off Shoal

KH

K1

2.95

Central Shoal Fore Shoal

Back Shoal

Peritidal Lagoon

1.95

Cored Interval

Depth (m)

Reservoir Units

SC

3565

HFU

K2

GRZ-1

3545

Log FZI

Calcite Cementation

Main diagenetic processes and products

Log FZI

Dolomitization

HFU

Anhydrite cementation Chemical Mold filling compaction cement

0

40

3825

GRZ-5 GRZ-4 GRZ-3 GRZ-2

3524

(mD)

Syndepositional

0

FU-8

(%)

Facies Group

20

3615

Porosity (%)

30

Pore Type

3620

3720

KH Phih

(%) (%)

Geological Reservoir Zone

(Visually estimated)

GRZ-2

FU-6 3660

GRZ6&7

FU-11

3805

FU-12

FU-14 FU-15

FU-13

FU-17

FU-16

FU-18

4005

FU-20

FU-19

4015

Flow Unit

SN#02 40

20

0

40

HFU

20

Log FZI

0

3

0

(mD)

-3

PorosityPermeability

0

3

1000

(%)

1

0.01

0 10 20 30 40 0.0001

4Km

40

3595

PorosityPermeability

GR (API)

0

FU-14 3785

Pore Type

30

20

3745

(%)

3

3705

3725

Porosity

0

FU-13

3685

0

-3

FU-9

3705

GRZ6&7

3665

GRZ-8

3645

(Visually estimated)

3

FU-10

3625

M AN U

3605

Chemical Mold filling compaction cement

0

3695

3765

GRZ-9

3585

Anhydrite cementation

1000

FU-11

SN#01

1

FU-7

RHOB

Dolomitization

0.01

3575

FU-6

gr/cc

Main diagenetic processes and products

0 10 20 30 40 0.0001

3655

Claystone

Calcite Cementation

GRZ-10

FU-5

Limestone

Syndepositional

Log Data

FU-3 FU-4

Dolostone Anhydrite

Facies Group

GRZ-11

FU-2

GR (API)

GRZ-12

3485

KS-1

FU-1

TE D

3535

Flow Unit

KS-2

(%)

KS-3

Phih

(%)

Aghar

KH

KS-4

3515

40

20

0

40

20

0

3

0

HFU

K1

3

-3

0

1000

1

0.01

0 10 20 30 40 0.0001

Geological Reservoir Zone

Log FZI

K2

GRZ-1

140Km

Geological Reservoir Zone

3675 (mD)

KS-5

3585

(%)

EP

3555

K3

GRZ-2

3495

PorosityPermeability

K4

3525

GRZ-3

LN#01

Nar Member

3545

GRZ-4

3505

GRZ-5

3475

GRZ-6

Pore Type

30

AC C

3605

GRZ-7

(%)

Sequence

GRZ-8

Porosity

Micritization Micrite envelope Bioturbation Mud crack Brecciation Isopach Dog tooth Bladed Equant Drusy Blocky Microspare Dolomicrite Fabric retentive Fabric destructive Fabric selective Mixing Stylolite related Recrystallization Saddle <20 Micron 20-100 Micron >100 Micron Gypsum Intergrain Intercrystal Porefilling Poikilotopic Fracture Filling Completely plugged Uniform Patchy Stylolite Solution seam Fitted fabric Calcite Dolomite Anhydrite Intergranular Intragranular Fenestral Moldic Vuggy Intercrystalline Fracture

3645

GRZ-9

(Visually estimated)

Channel Off Shoal

GR (API) 0

Central Shoal Fore Shoal

3685

GRZ-10

Chemical Mold filling compaction cement

Back Shoal

Anhydrite cementation

100

Micritization Micrite envelope Bioturbation Mud crack Brecciation Isopach Dog tooth Bladed Equant Drusy Blocky Microspare Dolomicrite Fabric retentive Fabric destructive Fabric selective Mixing Stylolite related Recrystallization Saddle <20 Micron 20-100 Micron >100 Micron Gypsum Intergrain Intercrystal Porefilling Poikilotopic Fracture Filling Completely plugged Uniform Patchy Stylolite Solution seam Fitted fabric Calcite Dolomite Anhydrite Intergranular Intragranular Fenestral Moldic Vuggy Intercrystalline Fracture

Sequence

Channel Off Shoal

0

100

Dolomitization

2.95

2.95

Central Shoal Fore Shoal

Back Shoal

1.95

Cored Interval

Depth (m)

Main diagenetic processes and products

Peritidal Lagoon

KS-1

Epoch Formation Reservoir Units

Calcite Cementation

0

3625

RHOB Syndepositional

1.95

PTB gr/cc

Peritidal Lagoon

Claystone

Facies Group

Depth (m)

K1

N

Cored Interval

3565 Dolostone Anhydrite

KS-2

Lower Triassic Kangan 3457 Limestone

KS-3

K2 3465

GR (API)

Reservoir Units

Upper Permian Upper Dalan Member K3

ACCEPTED MANUSCRIPT

S

KH Phih

(%) (%)

Flow Unit

3540

3560

3580

FU-1 FU-2 FU-3

FU-6 FU-7 FU-8

FU-5

FU-4

GRZ-5

FU-9 FU-10

ACCEPTED MANUSCRIPT

In this study, it is attempted to create a geological based reservoir zonation scheme

•

Hydraulic flow and flow unit methods were also used for reservoir zonation

•

The identified HFUs were not correlatable between the studied wells and fields

•

The larger scale flow units were correlatable at the field scale

•

Geological reservoir zones were correlatable at both intra– and inter–field scales

AC C

EP

TE D

M AN U

SC

RI PT

•