Wettability alteration and interfacial tension (IFT) reduction in enhanced oil recovery (EOR) process by ionic liquid flooding

Accepted Manuscript Wettability alteration and interfacial tension (IFT) reduction in enhanced oil recovery (EOR) process with ionic liquid flooding

Abbas Khaksar Manshad, Mansooreh Rezaei, Siamak Moradi, Iman Nowrouzi, Amir H. Mohammadi PII: DOI: Reference:

S0167-7322(16)32551-X doi:10.1016/j.molliq.2017.10.009 MOLLIQ 7970

To appear in:

Journal of Molecular Liquids

Received date: Revised date: Accepted date:

1 September 2016 24 September 2017 2 October 2017

Please cite this article as: Abbas Khaksar Manshad, Mansooreh Rezaei, Siamak Moradi, Iman Nowrouzi, Amir H. Mohammadi , Wettability alteration and interfacial tension (IFT) reduction in enhanced oil recovery (EOR) process with ionic liquid flooding. The address for the corresponding author was captured as affiliation for all authors. Please check if appropriate. Molliq(2017), doi:10.1016/j.molliq.2017.10.009

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ACCEPTED MANUSCRIPT Wettability Alteration and Interfacial Tension (IFT) Reduction in Enhanced Oil Recovery (EOR) Process with Ionic Liquid Flooding

Abbas Khaksar Manshad,a* Mansooreh Rezaei,a Siamak Moradi,a Iman Nowrouzi,b Amir H

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Mohammadi c,d *

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Department of Petroleum Engineering, Abadan Faculty of Petroleum Engineering, Petroleum University of Technology (PUT), Abadan, Iran Department of Petroleum Engineering, Islamic Azad University, Omidiyeh Branch, Omidiyeh, Iran

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Institut de Recherche en Génie Chimique et Pétrolier (IRGCP), Paris Cedex, France

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Discipline of Chemical Engineering, School of Engineering, University of KwaZulu-Natal, Howard College Campus, King George V Avenue, Durban 4041, South Africa

Abstract - Nearly half of the world’s known oil reserves are in the carbonate rocks.

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Waterflooding recovery from these reservoirs is low and therefore, these reservoirs are good candidates for enhanced oil recovery (EOR) processes. Surfactant flooding which is subset of chemical enhanced oil recovery (CEOR) can increase the recovery from these reservoirs by reduction of interfacial tension (IFT) and alteration of wettability. The purpose of this study was to investigate wettability alteration and IFT reduction by ionic liquids (ILs) as a new family of surfactants. The work started by screening four ILs, namely [C12mim][Cl], [C18mim][Cl], [C8Py][Cl] and [C18Py][Cl], based on pendant drop and contact angle tests for measurement of interfacial tension and wettability. Then, coreflooding test was then performed to study the effect of the selected ILs on ultimate oil recovery in core plug from carbonate oil reservoir. Based on the screening process, [C18mim][Cl] was found to be the optimum IL. Coreflooding with the selected IL revealed 13% increase in oil recovery compared to flooding with brine.

Keywords - Ionic Liquid (IL); Surfactant; Interfacial Tension (IFT); Wettability; Enhanced Oil Recovery (EOR). 

Corresponding authors email addresses: A. Khaksar Manshad, [email protected] and A.H. Mohammadi: [email protected] & [email protected]

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ACCEPTED MANUSCRIPT 1. Introduction In mature oilfields, the production of oil is continuously declining. Therefore, the application and development of chemical flooding gives an alternative to reach stable oil

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production. Among chemical flooding techniques, the surfactant flooding has high potential [1].

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Decreasing the oil trapping is the fundamental goal of EOR techniques. Capillary forces

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are important factors that cause oil trapping [2]. Half of known oil reserves are in carbonate fractured formations [3-8] which are commonly oil wet [4-9]. For this type of reservoirs, water-

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flooding recoveries are low, because these reservoirs are mixed to oil wet. In such reservoirs, production depends on spontaneous imbibition of water to expel the oil from the matrix into the

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fracture system, but this is only efficient when the matrix blocks are water wet [7]. Hence,

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wettability alteration of the oil-wet rocks to water-wet improves oil recovery efficiency for this

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type of reservoirs [6, 10]. Fluid properties such as the viscosity of the phases and IFT also play a role in the capillary imbibition recovery rate [7]. The main mechanisms during EOR to mobilize

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trapped oil in the reservoirs are IFT reduction and wettability alteration. Surfactant flooding

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utilizes these two main techniques to modify capillary number in the oil reservoirs consequently increases the oil recovery efficiency [11].

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IFT reduction is the most effective mechanism in surfactant flooding and research on this topic has been well developed. The Marangoni effect and mass transfer on IFT measurements occur through diffusion, convection, or both of these two mechanisms [12]. The ionic liquids increase the interfacial tension between water and oil through increasing the length of the hydrophobic chain. In fact, the longer the length of the hydrophobic chain, the more their adhesion to two different phases, due to the distancing of the two heads with various hydrophilic and hydrophobic properties. These two heads form more stable emulsions that cause the trapped oil to

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ACCEPTED MANUSCRIPT be moved [13]. Measurement of interfacial tension at various concentrations is a common method for estimating critical micelle concentration (CMC), and thus the concentration at the minimum IFT point is reported as the CMC. In fact, CMC is the maximum permissible surfactant concentration.

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In addition to CMC, the absorption rate should also be added to the permitted concentration [14,

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15]. Another method for estimating CMC is to measure electrical conductivity at different

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concentrations of surfactant. In a comparison between these two methods conducted by Arabloo

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et al., the values obtained from the latter two methods were found close to each other [15]. PH is one of the factors affecting the adsorption, interfacial tension and wettability of carbonate reservoir

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rocks in the process of surfactant injection. When the PH of the liquid phase is low, the solid

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surface becomes positive or non-negative. Therefore, the adsorption of anionic interfacial tension reducing materials increases the positive surface and cationic absorption decreases [16]. The

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opposite of this situation, i.e. the rise of PH, is also correct. PH changes affect molecules of

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interfacial tension reducing materials, which can change the strong adsorption property of molecules and make them neutral. For instance, calcite is positive in neutral PH, but it becomes

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negative due to the presence of NaHCO3/ Na2CO3 in the brine. The oil remains in the oil-wet

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cavities due to capillary action. If the alkaline reducing materials solution reduces the interfacial tension and makes wettability hydrophilic, oil displacement occurs according to the ascending mechanism [17].

For the first time, in 1927 Howard [18] used surfactant solution for recovery of petroleum from oil bearing sands. There are massive studies on the surfactant flooding (see Table 1). Although, during the past decades, several types of surfactants were proposed and utilized, it is argued that conventional surfactants lose high portion of their functionality in reservoir harsh

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ACCEPTED MANUSCRIPT condition of high salinity and high temperature [11]. Investigations on the exposure of surfactants to the tough conditions of reservoirs are still developing. For example, Dehghan et al. studied heavy and acidic reservoir oils [23]. In a study by Daghlian Sofla, the wettability was changed by some surfactants. While reporting the factors effective on interfacial tension and wettability, such

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as the characteristics and type of the rocks, reservoir fluid, and salinity levels, they indicated that

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for optimal performance in using these materials, there is an optimal salinity level [24].

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According to these problems, there is still a need for a new family of surfactants that can

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tolerate harsh conditions of reservoir and at the same time have a high efficiency. For this purpose, ionic liquids have been proposed because a large number of cations and anions can be combined

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to make a great number of these materials for any desired applications [26]. Among these countless

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substances, there are ILs that may be utilized for different reservoirs, different crude oils and brines. In fact, ionic liquids are organic salts which are liquid in the environment and have some

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properties such as non-volatility, non-flammability, high thermal stability [27], better performance

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in high salinity in terms of reducing the interfacial tension between water and oil, and the lower concentration of CMC [12]. However, they have disadvantages such as high toxicity, high

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corrosion, and high cost. These disadvantages should be considered and proper strategies should

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be adopted for them.

According to the recent works [11, 26-29] and the fact that these materials would have high efficiency to reduce IFT between oil and brine, we have extended the previous studies for a reservoir with different salinity and coreflooding tests.

2- Experimental procedure

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ACCEPTED MANUSCRIPT 2-1- Methodology We synthesized ILs including [C12mim][Cl], [C18mim][Cl], [C8Py][Cl] and [C18Py][Cl] from two different families. IFT values between surfactant solutions and oil were measured in the presence and absence of salinity. Then, contact angle measurement and Amott wettability

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measurement were done to determine the surface wettability changes. By analyzing the results of

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experiments and screening of surfactants, the optimum surfactant would be chosen. Finally, injection parameters were obtained from surfactant flooding. Figure 1 shows a flow-chart of the

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experimental procedure used in this study.

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2-2- Materials

According to the reported procedure [11], the ILs ([C12mim][Cl], [C18mim][Cl], [C8Py][Cl]

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and [C18Py][Cl]) were synthesized by reacting 1-methylimidazolium or pyridine with excess

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amount of the 1-chlorododecane or 1-chlorooctane without any additional solvent in a roundbottomed flask fitted with a reflux condenser (heating and stirring at 70 ºC for 48–72 h). The

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resulting viscous liquid was cooled down to room temperature, and then washed up using diethyl

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ether. After drying overnight at 100 ◦C, the purity of the products was assessed by H-NMR spectroscopy [11]. The chemicals used in this study were purchased from Aldrich with a typical purity higher than 99 mole%. Crude oil and brine were obtained from one of Iranian south-west carbonate oil reservoirs (Sarvestan oilfield). The compositions of the used crude oil and formation brine are given in

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Table 2 and

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ACCEPTED MANUSCRIPT Table 3, respectively.

2-3- Core-flooding experiment The schematic of core displacement apparatus is illustrated in Figure 2. Before each test,

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the core was cleaned with toluene and methanol and characterized for two basic parameters, the

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porosity and the absolute permeability. The sample was initially placed under vacuum for two

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hours and aged in the formation brine for another 12 hours. Then, core sample was placed in a Hassler-Type core holder and overburden pressure was performed to form a tight seal between

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core and core sleeve. To determine the absolute liquid permeability of the implemented core

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sample and reach complete saturation, the core was flooded with several pore volumes of the same brine utilized during core saturation. After permeability measurement, to reach connate water

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saturation, oil was injected at very low flow rate into the core which contains formation brine.

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Then, the procedure of the water flooding with/without surfactant was performed on the carbonate core sample.

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The position of the core retaining chamber during the saturation of the water and the primary

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oil was carried out to take the gravitational force vertically into account and injection was carried

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out from bottom to top. During injection, the core retaining ionic solution was placed horizontally.

2-4- IFT measurement The pendant drop apparatus was used for measuring the IFT (see Figure3). The apparatus was designed in a way that it is possible to analyze the IFT and contact angle using an online image capturing system which enables us to record the data periodically upon our desire. In general, the

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ACCEPTED MANUSCRIPT analysis of IFT measurement is performed by injecting a drop from the needle with 2.05 mm diameter into a bulk phase under the desired pressure and temperature. Dilute surfactant solutions were prepared and used in all the tests. To make the dilute surfactant solutions, pure surfactants were dissolved in the distilled water/brine. To select the

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optimum surfactant, different ILs concentrations were prepared and IFT between the crude oil and

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surfactant solutions in brine or distilled water were measured by the pendant drop method. The solutions that have the minimum IFT values were chosen to measure wettability

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alteration capability. All measurements were conducted at constant temperature of 80 ℃ (reservoir

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2-5- Wettability measurement

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temperature).

Flat polished rock pieces were first cleaned using Soxhlet extractor with toluene and were

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dried in the 100°C oven. The flat polished rock pieces were placed under vacuum for at least two hours and aged in the formation brine for another 12 hours. After that, the clean pellets must be

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aged with oil so we could achieve an oil-wet reservoir rock sample. In this step, the crude oil was

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used. The pellets were fully drowned in oil for three weeks at atmospheric pressure and reservoir temperature (80 ℃). After aging in the crude oil, the flat polished rock pieces were subjected to formation brine in order to verify the surface plates’ wettability and after observing the contact angle to be oil-wet, (i.e. oil still sticks to the plate) the surface plates were immersed in ILs solution including the [𝐶18 𝑃𝑦][𝐶𝑙] and [𝐶18 𝑚𝑖𝑚][𝐶𝑙] to study the effect of these surfactants on wettability alteration. In this stage, aging was carried out at 80 ℃ for two weeks. Then, a brine drop was injected on the carbonate pellets through a syringe needle and the second and final contact

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ACCEPTED MANUSCRIPT angles were measured. In order to consider the difference between up and down surfaces of the sample surface plates, one side of the sample surface plates was marked by a marker pen. The contact angles were measured in unmarked surface. This procedure was repeated in order to

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consider human and equipment errors.

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2-6- Imbibition Studies

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Spontaneous imbibition of the cores was conducted in Amott cells at reservoir temperature. The oil saturated cores were placed vertically in the Amott cells and were immersed in different

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aqueous solutions. The volume of produced oil for a period of time could be read from the scale

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3- Results and discussion

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of the upperpart of Amott cell.

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3-1- Surface activity

The concentration of surfactant at which association occurs is named critical micelle

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concentration (CMC). The CMC is one of the critical properties of surfactants in solutions. There are different procedures to find the CMC, but the most common technique is to plot IFT versus surfactant concentration. Before reaching the CMC, the IFT decreases sharply and after the CMC it remains constant. In this study, the IFT values of ILs solutions were measured and plotted versus concentration of IL to find the CMC. As, it is shown in Figure4 (a), the CMC of [C8Py][Cl] is

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ACCEPTED MANUSCRIPT 1000 ppm where the IFT value is 11.5 mN/m from original value of 26.32 mN/m. While, for [C18 Py][Cl] Figure4 (b), the CMC is 500 ppm and IFT decreases from 26.32 mN/m to 2.59 mN/m in the CMC which shows that the capability of [C18 Py][Cl] is higher compared to [C8Py][Cl] for IFT reduction. It is observed that after CMC, further increase in [C18 Py][Cl] concentration to 7000

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ppm, decreases the IFT to 1.61 mN/m. Figure5(a), shows that the CMC for 1-dodecyl-3-

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methylimidazolium chloride ([C12 mim][Cl]) is 500 ppm where the IFT is 2.99 mN/m while

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Figure5(b) shows interestingly that for [C18 mim][Cl] the CMC is 100 ppm where the IFT reaches 1.38 mN/m from original value of 26.32 mN/m. From the results, it can be concluded that in the

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same family of ILs, as the length of the hydrophobic chain increases the capability of IL based

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IL increases a sharp CMC will be observed.

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surfactant to decrease the IFT increases. Thus, it can be deduced that as the hydrophobic chain of

It is worth mentioning that the calculation of CMC was conducted while taking into

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account the minimum value of interfacial tension outside the porous medium, that is, in addition

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to the calculation of CMC, the adsorption value should also be taken into account; and the maximum permissible concentration of surfactant should be calculated for the enhanced recovery

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and core flooding. Figure 6 shows the adsorption values at 500ppm concentration of optimum

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ionic solution [C18 mim] [Cl] at different times, obtained using the Freundlich isotherm method. Figure 7 indicates the effect of IL concentration on IFT reduction using two different families (imidazolium and pyridinium) with same chain length. As can be seen from the chart, the capability of 1-octadecyl-3-methylimidazolium chloride ([C18 mim][Cl]) for IFT reduction is higher than [C18 Py][Cl].

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ACCEPTED MANUSCRIPT 3-2- Wettability alteration In this section, we studied the wettability alteration of carbonate surface with two of the ILs that had the best IFT reduction ([C18 mim][Cl] and [C18 Py][Cl]). The contact angles measured for treated carbonate surface with [C18 mim][Cl] and [C18 Py][Cl] were 149° and 142°, respectively

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where the initial angles were 124° and 120°. It can be concluded that [C18 mim][Cl] can alter the

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wettability toward water-wet condition better than [C18 Py][Cl] (see Figure 8).

3-3- Effect of presence and absence of ions on IFT

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In this section, the effect of ILs on the reduction of IFT in the presence and the absence of

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ions were investigated. The results are listed in

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Table 4 and

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ACCEPTED MANUSCRIPT Table 5 and Figure 9 and Figure 10. From the data, it can be seen that on the contrary of conventional surfactants, ILs are more effective when salinity is high. This behavior can be described in this way that in the absence of ions, because of repulsive forces between cationic head group of IL based surfactants, the ILs molecules cannot freely arrange in the water-oil interface.

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It should be mentioned that in the calculation of IFT, the drop of oil drowned in aqueous

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medium requires sufficient time to be stabilized. This means that the chemical and physical mechanisms involved in opposing two phases should have the time to act and react. Hence, in the

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interfacial tension experiments, the stability time was considered until the interfacial tension becomes approximately fixed. Figure 11 shows an example of interfacial tension variations versus

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3-4- Spontaneous Imbibition

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time to fixing the IFT value for optimal concentrations.

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To investigate the effect of wettability on oil recovery spontaneous imbibition was performed. In this study, tests were conducted with carbonate core plugs with properties addressed

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in

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ACCEPTED MANUSCRIPT Table 6. Results of oil recovery from cores through spontaneous imbibition for both surfactants ([C18 mim][Cl], [C18 Py][Cl]) and the formation brine are shown in Figure 612. It is worth noting that the changes in wettability occur by water formation; and in carbonate rocks, changes in wettability are controlled by the ions in opposition to the surface of the rock,

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especially Mg2+, Ca2+, SO42+, and its mechanisms have been developed. As Zhang et al. stated,

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Ca2+ reacts with the carboxylic group adsorbed onto the surface of the rock and releases it, and

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replaces the ion of Mg2+ with the Ca2+-carboxylate complex [30]. Rezaei Doust et al. also

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suggested that SO42+ would reduce the positive charge of the surface and increase the ability of

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3-5- Displacement efficiency

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cations to approach the carboxylic acid adsorbed on the rock [31].

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The main goal of this section, after choosing the optimum surfactant solution for oil

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recovery by IFT reduction and wettability alteration was to study the practical feasibility of selected IL in chemical enhanced oil recovery as follows: FB flooding as base state

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Surfactant flooding with concentration of 500+170 ppm

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The injection rate was 0.5 ml/min. This value was considered as the closest value to the flow in the reservoir. A carbonate sample was used in these tests with properties reported in

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ACCEPTED MANUSCRIPT Table 7. The base state was coreflooding with formation brine. Figure 13 shows the relationship between cumulative oil production and injected pore volume. The recovery of water-flooding after 2.95 PV formation brine injection was 38 %. Figure8 14 shows the relationship between pressure

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drop and injected pore volumes. The pressure drop increased from 165.474 to 324.053 kPa at

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breakthrough time, then decreased from 324.053 to 220.632 kPa and became stable at that

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pressure. After that, the core was flooded by IL solution. Recovery of chemical flooding after 2.7

about 13% in a lower pore volume injected fluid.

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pore volume injection of IL was 47%. In comparison with water flooding, oil recovery increased

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As shown in Figure 14, the pressure drop has not been improved with increased recovery

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rates. It is likely that the changes in wettability and the high reduction of interfacial tension lead to the increased oil production; and consequently increased pressure of system and descended

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curve. Also, the viscosity of the infusion phase was not so high that causes the piston-like

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displacement, and therefore the gradual production has no significant effect on the pressure and the production is compensated by the drop in pressure. In addition, the shorter plug length may

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have triggered a gradual production. In fact, there is a probability of occurrence of a fingering

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phenomenon that can be solved by the pre-infusion of polymer.

4- Conclusions On the contrary of conventional surfactants, ILs are more effective when salinity is high. It was inferred that 1-octadecyl-3-methylimidazolium chloride ([C18 mim][Cl]) is capable of dramatically reducing the IFT of brine/oil especially at low concentration and also gives the

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ACCEPTED MANUSCRIPT highest oil recovery through spontaneous imbibition. Coreflooding with the selected IL revealed an increase in oil recovery compared to flooding with brine. Wettability measurements proved that the ILs have intermediate effect on wettability, and thus they increase in oil production is mostly because of the IFT reduction; however, the wettability alteration is another reason of it.

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Although mechanisms other than the changes in the wettability and interfacial tension are

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used when ILs is employed and this method is influenced by many properties such as rock and

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fluid properties; the most effective mechanism herein was to reduce the interfacial tension. On the

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other hand, optimizing and selecting the type and concentration of surfactants using interfacial tension tests seems to be the main mechanism of this method, especially when the rest of the

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conditions, such as rock conditions and reservoir fluid, are considered identically in the

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comparisons. In fact, here before flooding, the concentration and type of fluid injected was determined using the screen method, and then ionic liquids were compared in terms of their ability

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to reducing the interfacial tension. Flooding was done solely to obtain the recovery factor by the

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optimal material at a specific concentration, and no comparison with other tested materials and

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Although the reduction in interfacial tension by the surfactants has been reported more

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compared to what was reported in this study, ionic liquids also have a relatively acceptable performance in reducing interfacial tension. In particular, it does not lose its properties when it is exposed to high water salinity and even performs better in this case. This can reduce the many costs of water treatment and the use of water with low salinity. Another thing to note is that due to the high cost of these materials, appropriate injection patterns should be used, such as the use of suitable polymers and ILs. The better performance of ionic liquids at their low concentrations, can somewhat justify the high cost of materials.

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ACCEPTED MANUSCRIPT It is suggested that in the future, other problems and challenges for the methods of surfactant flooding and the ways to deal with them to be investigated. The results of this study can be further developed at various pressures and temperatures. Also, the use of other ionic liquids and the study of the effect of reservoir fluid composition on their performance can be studied.

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The interfacial tension of the solution with various concentrations, [C12mim] [CI],

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mentioned in the reference number [32], in the presence of acidic and aromatic oils, and in the

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presence of heavy oil, mentioned in the reference number [26], as well as [C8Py] [CI] at different

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concentrations, mentioned in the reference number [32], when exposed to the acidic and aromatic oil, and various concentrations mentioned in the reference number [12], when exposed to the acidic

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and aromatic oil, were examined using the droplet method. By comparing these with ionic liquids

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in the presence of acidic, light and bright oil (paraffinic), the efficiency of ionic liquids was found similar; although the interfacial tension is dependent on the fluid composition. By reviewing these

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articles and the work done in the present study, it can be concluded that the performance of these

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materials is less dependent on the composition of the crude oil; however, this result can only be

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true for the samples used in the latter studies.

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Fuels, 2015. 29(2): p. 649-658. Hou, B.-f., Y.-f. Wang, and Y. Huang, Mechanistic study of wettability alteration of oilwet sandstone surface using different surfactants. Applied Surface Science, 2015. 330: p. 56-64. 22.

M. Rahmati, M. Mashayekhi, R. Songolzadeh, A. Daryasafar., Effect of Natural Leafderived Surfactants on Wettability Alteration and Interfacial Tension Reduction in Wateroil System: EOR Application. Journal of the Japan Petroleum Institute, 2015. 58(4): p. 245-

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ACCEPTED MANUSCRIPT 251. 23.

A. A. Dehghan, M. Masihi, Sh. Ayatollahi,. Interfacial Tension and Wettability Change Phenomena during Alkali–Surfactant Interactions with Acidic Heavy Crude Oil. Energy & Fuels, 29(2), 649-658.

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S. J. Daghlian Sofla, M. Sharifi, A. H. Sarapardeh,. Toward mechanistic understanding of

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natural surfactant flooding in enhanced oil recovery processes: The role of salinity, surfactant concentration and rock type. Journal of Molecular Liquids, 222, 632-639. Ravi, S., S. Shadizadeh, and J. Moghaddasi, Core Flooding Tests to Investigate the Effects

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of IFT Reduction and Wettability Alteration on Oil Recovery: Using Mulberry Leaf Extract. Petroleum Science and Technology, 2015. 33(3): p. 257-264. Hezave, A.Z., et al., Dynamic interfacial tension behavior between heavy crude oil and

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ionic liquid solution (1-dodecyl-3-methylimidazolium chloride ([C12mim][Cl] + distilled

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or saline water/heavy crude oil)) as a new surfactant. Journal of Molecular Liquids, 2013.

Wasserscheid, P., Chemistry: volatile times for ionic liquids,.Nature 2006, 439, 797.

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R. L. Gardas, R. Ge, N. Ab Manan, D. W. Rooney, C. Hardacre., Interfacial tensions of

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imidazolium-based ionic liquids with water and n-alkanes. Fluid Phase Equilibria, 2010. 294(1): p. 139-147. 29.

J. F.B.Pereira, R. Costa, N. Foios, J. A.P.Coutinho., Ionic liquid enhanced oil recovery in sand-pack columns. Fuel, 2014. 134: p. 196-200.

30.

Zhang P., Tweheyo M. T., and Austad T., “Wettability alteration and improved oil recovery by spontaneousimbibitions of seawater into chalk: Impact of the potential determining ions

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ACCEPTED MANUSCRIPT Ca2+, Mg2+, SO42-,” Colloids and Surfaces A: Physicochemical and Engineering Aspects, Vol. 301, pp. 199-208, 2007. 31. Rezaei Doust A., Puntervold T., Strand S. and Austad T., “Smart water as wettability modifier in carbonate and sandstone/differences in the chemical mechanisms,” Energy & Fuels.,

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Hezave AZ, Dorostkar S, Ayatollahi S, Nabipour M, Hemmateenejad B. Effect of different families (imidazolium and pyridinium) of ionic liquids-based surfactants on interfacial

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tension of water/crude oil system. Fluid Phase Equilibria. 2013 Dec 25;360:139-45.

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Vol. 23, pp. 4479-4485, 2009.

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ACCEPTED MANUSCRIPT Table 1: A review of previous works. Year Author

Material

Investigated parameter Phase behavior

Alkyl aryl sulphunates IFT Alkyl propoxylated sulphates

T

2004 Seethepalli et al. [8]

IP

Wettability

CR

DTAB

SDBS

wettability alteration

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2009 Golabi et al. [10]

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DTAB

Adsorption

2012 Jarrahian et al. [5]

ED

C12TAB

M

Triton X-100

TritonX-100

wettability alteration

The leaves of Z. spina Christi

IFT

CE

PT

SDS

Pordel Shahri et al. 2012

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[7]

Saponin extracted from Z. spina IFT 2013 Ahmadi et al. [3] christi leaves

recovery

23

ACCEPTED MANUSCRIPT

IFT 2014 Ahmadi et al. [2]

mulberry leaf oil recovery

IFT

SDS

Wettability

IP

T

AES

2014 Qi et al. [1]

CR

GD70

oil

(imbibition)

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CTAB

Static

AN

Surfactant derived from the roots of

2015 Ahmadi et al. [19]

SDS

Wettability Oil recovery

ED

CTAB

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Glycyrrhiza Glabra

CE

PT

TritonX-100

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2015 Dehghan et al. [20]

SURF1

IFT

SURF3

Contact angel

SURF4

Amott cell tests IFT

CTAB IR 2015 Hou et al. [21]

TX-100 AFM POE Zeta potential

24

recovery

ACCEPTED MANUSCRIPT contact angle Imbibition studies

Plant surfactants (Mulberry Leaf

IFT

AN

US

CR

Extract and Henna leaf extract)

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2015 Rahmati et al. [22]

T

CMC

Plant surfactant (Mulberry Leaf

ED

Extract)

M

2015 Ravi et al. [25]

Contact angel CMC IFT Wettability the

ability

of

this

surfactant to enhance oil recovery of carbonate and

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sandstone rocks

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ACCEPTED MANUSCRIPT Table 2: Composition of reservoir oil.

Mole %

CO2

1.22

C1

38.63

C2

6.97

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Component

C3

4.77

i-C4

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1.60

n-C4

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3.98

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n-C5

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i-C5

C6+

1.60 1.72 39.51

PT

MWC6+ = 235

CE

SGC6+ = 0.8673

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Bubble point pressure at depth 960.12 m = 25131.388 kPa at reservoir temperature 176 oF or 80 oC viscosity = 1.0033 p at 101.325 kPa and 15.55 oC

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ACCEPTED MANUSCRIPT Table 3: Formation brine composition.

Concentration (ppm)

Na+

22356

Ca2+

5200

Mg 2+

1400

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Cl-

34506

SO4 2-

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95

HCO3 -

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67

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PT

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T. D. S T. H

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Ion

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62000 6600

ACCEPTED MANUSCRIPT Table 4: Effect of IL solution prepared by distilled water on IFT reduction of crude oil at reservoir temperature.

Interfacial Tension (mN/m) IL concentration Prepared by Distilled Water

T

ppm

27.55

27.55

100

23.24

8.12

500

22.10

6.47

17.06

4.74

1000

20.25

15.46

2.46

3000

19.89

2.95

7.83

1.95

5000

19.54

2.00

7.14

1.44

19.05

1.81

6.33

1.20

PT

27.55

21.97

7.68

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ED

M

4.32

AC

CE

7000

27.55

CR

0

AN

IP

[C8Py][Cl] [C18Py][Cl] [C12mim][Cl] [C18mim][Cl]

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ACCEPTED MANUSCRIPT Table 5: Effect of IL solution prepared by formation brine on IFT reduction of crude oil at reservoir temperature.

Interfacial Tension (mN/m) Prepared by Formation Brine

T

IL concentration ppm

26.32

100

16.12

4.15

7.51

1.38

500

13.61

2.59

2.99

0.85

1000

11.50

2.03

2.90

0.78

3000

10.46

1.85

2.83

0.70

5000

10.03

1.78

2.74

0.65

9.27

1.61

2.69

0.65

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ED

AC

CE

PT

CR

26.32

US

26.32

7000

26.32

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0

IP

[C8Py][Cl] [C18Py][Cl] [C12mim][Cl] [C18mim][Cl]

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ACCEPTED MANUSCRIPT Table 6: Carbonate core plugs properties.

L

D

Φg

Φ

K

PV

BV

OOIP

Swi

Soi

(m)

(m)

(%)

(%)

(mD)

(m3)

(m3)

(m3)

(%)

(%)

C#12

0.0737

0.037

22.27

21.15

15.99

0.000017 0.000079 0.000012

28.40

71.60

C#11

0.0751

0.037

22.83

22.88

29.16

0.000018 0.000081 0.000014

24.20

75.60

C#9

0.0742

0.037

22.20

21.18

24.71

0.000017 0.000080 0.000012

28.95

71.05

AC

CE

PT

ED

M

AN

US

CR

IP

T

Core

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ACCEPTED MANUSCRIPT Table 7: Carbonate core plug properties.

L

D

Φg

Φ

K

PV

BV

OOIP

Swi

Soi

(m)

(m)

(%)

(%)

(mD)

(m3)

(m3)

(m3)

(%)

(%)

0.0744

0.037

22.61

21.69

18.62

0.000017

0.00008

0.000013

24.86

75.14

IP CR US AN M ED PT CE AC

C#7

T

Core

31

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ACCEPTED MANUSCRIPT

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Figure 1: Flow-chart of the experimental procedure.

32

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Figure 2: Schematic of the core flooding apparatus.

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Figure3: Schematic of the high pressure - high temperature pendant drop interfacial tension

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measurement apparatus (VIT-6000). 1: bulk fluid pump, 2: light source, 3: pressure and

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temperature display unit, 4: high pressure valve, 5: view cell, 6: CCD camera, 7: needle, 8: vent,

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9: droplet pump, 10: PC

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Figure4: Effect of different concentrations of pyridinium based ILs solutions prepared in

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formation brine on the IFT. (a) [C8Py][Cl] and (b) [C18Py][Cl].

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ACCEPTED MANUSCRIPT

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Figure5: Effect of different concentrations of imidazolium based ILs solutions prepared in

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formation brine on the IFT. (a) [C12 mim][Cl] and (b) [C18 mim][Cl].

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ACCEPTED MANUSCRIPT

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1

0.5

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Adsorption Density [mg/g]

1.5

3

6

9

12

15 18 Time [hr]

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0

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0

21

24

27

30

33

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Figure 6: Adsorption values at 500 ppm of optimized ionic liquid [C18mim][C1] solution at 80 ºC

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and atmospheric pressure at different times.

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ACCEPTED MANUSCRIPT 30

20

T

15

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10

CR

5 0 1000

2000

3000 4000 5000 IL Concentration (ppm)

6000

7000

8000

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0

[C18mim][Cl]

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[C18Py][Cl]

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Figure 7: Effect of IL concentration on IFT reduction using formation brine.

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Interfacial Tension (mN/m)

25

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ACCEPTED MANUSCRIPT

After

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[C18 Py][Cl]

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[C18 mim][Cl]

Before

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Figure 8: Contact angel measurements.

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ACCEPTED MANUSCRIPT

25 20 15

T

10

IP

Interfacial Tension (mN/m)

30

5

2000

[C18Py][Cl]

[C12mim][Cl]

AN

[C8Py][Cl]

4000 IL Concentration (ppm)

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0

CR

0

6000

8000

[C18mim][Cl]

Figure 9: Effect of ILs solution prepared by distilled water on IFT reduction of crude oil at

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reservoir temperature.

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ACCEPTED MANUSCRIPT

25 20

T

15

IP

10 5

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Interfacial Tension (mN/m)

30

0 1000

3000 4000 5000 IL Concentration (ppm)

[C18Py][Cl]

[C12mim][Cl]

AN

[C8Py][Cl]

2000

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0

6000

7000

8000

[C18mim][Cl]

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Figure 10: Effect of ILs solution prepared by formation brine on IFT reduction of crude oil at

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reservoir temperature.

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ACCEPTED MANUSCRIPT

20

T

15

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10

CR

5

600

900 1200 1500 1800 Time (s) [C8Py][Cl]-1000ppm [C18Py][Cl]-500ppm

AN

300

M

[C12mim][Cl]-500ppm

[C18mim][Cl]-100ppm

PT

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Figure 11: Dynamic IFT versus time for ILs at optimum concentrations.

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0

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0

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Interfacial Tension (mN/m)

25

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ACCEPTED MANUSCRIPT 60

50

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T

30

20

CR

Recovery, %

40

10

0

10

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0 20

30

40

50

60

Py

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FW

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Time, Day

Mim

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Figure 62: Oil recovery from cores through spontaneous imbibition for both surfactants ([C18

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PT

mim][Cl], [C18 Py][Cl]) and the formation brine.

43

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Figure73: Cumulative oil production as a function of injected pore volume.

44

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Figure84: Pressure drop profile as a function of injected PV.

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ACCEPTED MANUSCRIPT

Research Highlights

Coreflooding was performed to study the effect of ionic liquid (IL) on oil recovery for a typical carbonate oil reservoir.



The effect of wettability alteration and interfacial tension (IFT) reduction by IL was investigated.



Four ILs based on their surface activity and wettability measurements were studied.



[C18mim][Cl] was found to be the optimum IL.



Coreflooding with the selected IL revealed 13% increase in oil recovery compared to flooding with brine.

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

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