Effective integration of core and log date

SITE INVESTIGATIONS:BOREHOLES The limitations of a standard 1-D inversion applied to multidimensional (synthetic) data are investigated. Simple correction procedures for interpreting field data distorted by 3-D structures are suggested. Two different transmitter/ receiver configurations of the transient electromagnetic (TEM) sounding method are examined: a central loop configuration for the near zone (sometimes called short offset) and a fLXed transmitter/moving receiver configuration for the far zone (long offset). In all cases, 1-D interpretation of the central loop soundings recovers geoelectric parameters of the section with good reliability. The I-D interpretation of long offset soundings does not, in most eases, show the actual structures. In all cases considered, the distortion of central loop soundings caused by 3-D effects is systematic and could, therefore, be corrected by simple procedures. (from Authors)

951134 Audio-frequency mognctoteHuric imaging of an active strike-slip fault Y. Ogawa, M. Uyeshima, Y. Honkura, H. Utada & S. Koyama, Journal of Geomagnetism & Geoelectrieity, 46(5), 1994, pp 403-408. A tensor audio-frequency magnetotelluric method was used to image the Kita-Izu fault system, a typical active strike-slip fault in Japan. Regional strike direction (N55°E) was first determined after decomposing tensor impedances. Local anisotropy and site gain were then corrected for each site. Finally, the impedances were inverted using two-dimensional modeling with a smoothness constraint. (from Authors)

951135 In situ determination of thermal properties of sediments using a friction-heated probe source Tien-Chang Lee & R. P. Von Herzen, Journal of Geophysical Research, 99(B6), 1994, pp 12,121-12,132. Marine heat flow measurements usually require inserting temperature sensor probes into seafloor sediments. The probe entry displaces the sediments and causes frictional heating along the probe-sediment interface. Since the probe cools at a rate dependent primarily upon the sediment's thermal conductivity and heat capacity, analysis of the cooling data can yield not only ambient equilibrium temperature but also thermal properties. This paper describes a study which simulates the cooling process with a finite element method. (from Authors)

951136 Interferometur kao pretvornik relativnog pomaka njihala seizmometra (Interferometer as seismometer displacement transducer) I. Sovic, Geofizica, 10, 1993, pp 47-59. Displacements of the pendulum of S-13 Teledyne Geotech seismometer were measured using a small Michelson interferometer. The oscillations of the pendulum were simultaneously recorded by the PDAS-100 digital seismograph. These records were integrated and compared with those made by the interferometer. The pendulum was stimulated by sine (0.5, 1 and 2 I-Iz) and random signals. The transducer would be able to record oscillations of the pendulum caused by an earthquake with magnitudes between 1.1 and 5.2 at epicentral distance of 0.1 o, and could therefore find the application in a displacement strong-motion seismograph. (from English summary) 951137 Traveltime and amplitude anomalies at the seismic broadband array GRF M. Weber, Geophysical Journal International, 118(1), 1994, pp 57-74.

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Traveltime and amplitude residuals of P waves from teleseismic events show a positive correlation at the stations of the German seismic broad-band array GRF. Fast arrivals consistently have reduced amplitudes in the four frequency ranges considered. With the exception of the WWSSN-LP filter, 40-60% of the average of the relative traveitime and almost 100% of the average of the amplitude residuals at individual stations, with respect to the reference station A1, can be explained by near-surface sediment layers. Even after the removal of these station averages, large azimuthal- and distance-dependent relative traveltime and magnitude residuals can be observed across the array. The main features of the residual patterns correlate well with the main fault systems and inhomogeneities near the array, some of which have been postulated previously. The fact that local effects like sedimentary covers are responsible for 40% or more of the station average residuals demonstrates again that site effects should be removed before tomographic methods are employed. (from Author) 951138 Experiences in seismic profiling and processing S. Mars & R. J. Vriesendorp, Hydrographic Journal, 73, 1994, pp 29-33. This paper outlines some recent advances in the field of digital, shallow water, high resolution seismic profiling and data processing. A short description of system characteristics is followed by an account of some practical field operations. Intended primary applications are in the dredging and offshore industries. Recent applications have been in more diverse fields of interest ranging from charting aggregates to the detection of directionally drilled pipelines. (Authors)

Borehole and core logging 951139 Acoustic measurements on cores as a tool for calibration and quantitative interpretation of sonic logs D. P. Marion & F. M. Pellerin, SPE Formation Evaluation, 9(2), 1994, pp 100-104. An upscaling technique is developed for acoustic measurements on cores to present core data as a log for improved comparison between laboratory and sonic measurements. The method combines a laboratory study performed over a wide range of frequency, pressure, and saturation conditions on a series of core samples and construction of a synthetic log that includes upscaling of core measurements at the sonic wavelength and simulation of the log response for various spacing of the tool receivers. A comparison of core and sonic measurements in a carbonate reservoir illustrates the benefit of comparing core and log measurements at the same scale. (from Authors)

951140 Effective integration of core and log data P. F. Worthington, Marine & Petroleum Geology, 11(4), 1994, pp 457-466. The primary purpose of core to log data integration is to reduce the uncertainty associated with formation evaluation. In so doing, advantage is taken of both the higher precision of core data and the larger scale of investigation of log data. It is particularly important that when tying logs back to core, the calibration algorithm is as well defined as possible. A basic requirement is the definition of a common reference depth scale. A second requirement is to reconcile the different vertical resolutions by the depth averaging of core data, the signal enhancement of log data, or both. Essential to this process is the adoption of 'key intervals' as control zones for

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SITE INVESTIGATIONS:BOREHOLES

data integration. These procedures can result in a reduced uncertainty, which transmits through to reservoir appraisal through a better petrophysical definition of constituent lithological units. (from Author)

951141 Optimal control of three-dimensional steamflooding processes Wei Liu & F. Ramirez, Journal of Petroleum Science & Engineering, 11(2), 1994, pp 137-154. A system science approach using optimal control theory of distributed parameter systems has been developed to determine operating strategies that maximize the economic profitability of the steamflooding processes. Necessary conditions of optimization are established by using the discrete form of calculus of variations and Pontryagin's Maximum Principle. The performance of this approach is investigated through two actual three-dimeusional steamflooding projects. (from Authors)

951142 Evaluation of rheologicni models and application to flow regime determination S. Khataniar, G. A. Chukwu & Hua Xu, Journal of Petroleum Science & Engineering, 11(2), 1994, pp 155-164. In this study, the following rbeological models were used to predict shear stress as a function of shear rate in several mud samples: Bingham Plastic, Power Law, Hcrschei-Bulkley and Robertson-Stiff. The first objective of this study was to identify the model that provided the best overall match of the experimentally observed rhenlogical data. The RobertsonStiff model provided the best, and the Bingham Plastic model provided the worst overall prediction of rbeologieal behavior. The second objective was to develop a new method for determination of flow regimes in pipe flow using the Hcrscbel-Bulkley and Robertson-Stiff models. The proposed method has been shown to predict the onset of turbulence in pipe flow more accurately than the conventional method for Bingham Plastic and Power Law models. (from Author)

951143 A systematic approach for the prevention and treatment of formation damage caused by nsphnitene deposition K. J. Leontaritis, J. O. Amaefule & R. E. Charles, SPE Production & Facilities, 9(3), 1994, pp 157-164. Asphaltene plugging is a known cause of near-weUbore formation damage. Deposited asphaltenes can reduce effective hydrocarbon mobility by: 1) blocking the pore throats; 2) adsorbing onto the rock, thereby altering the formation wettability from water-wet to oil-wet; and 3) increasing hydrocarbon viscosity by nucleating water-in-oil emulsions. This paper presents a systematic approach to successful diagnosis, prevention, and mitigation of asphaltene problems during recovery of asphaltenic oils. A mechanism of asphaltene fiocculation and deposition is proposed and analyzed, and the previously defined concept of asphaltene deposition envelope is further refined. Diagnostic technology is presented that can test the compatibility of drilling and completion fluids with any asphaltenic oil. Finally, the paper presents a methodology for restoring unfavorable wettability changes caused by asphaltene deposition. (from Authors)

951144 Well kill (quenching) study of thermal producers in the South Belridge field, California J. W. Fram, SPE Production & Facilities, 9(3), 1994, pp 165170.

This paper presents a field study confirming that damage occurs during kill (quenching) operations of thermal producers in the South Belridge field, Kern County, CA. Implementation of the recommendations from this study are expected to decrease damage that occurs during quenching by an average of 0.5 BOPD/kill. Results indicate that producers completed with openhole, gravel-packed, slotted liners in high-permeability sandstones can sustain substantial, irreversible damage when subjected to unfiltered producedwater kills. The damage results when previously produced sand and fines, which have settled in the towline, are reinjected into the wellbore. Methods of determining waterquality specifications needed to minimize damage that occurs during well kills are outlined. The approach presented can be used to identify and quantify damage in any field where producers require kills before workover operations. The current recommended kill procedure is also included. (from Author) 951145 Simple method predicts downhole shaped-charge gun performance R. E. Ott, W. T. Bell, J. W. Harrigan Jr & T. G. Golian, SPE Production & Facilities, 9(3), 1994, pp 171-178. A simple method is proposed for predicting downhole shaped-charge gun performance based on the use of API RP 43, Edition 5, Sec. 1 data. The validity of the proposed method is demonstrated, allaying past concerns regarding the translation of data from Sec. 1 nonrock, nonstressed concrete targets to downhole conditions. The new method is based on an observed linear relationship between Edition 5, Sec. I and Sec. 2 penetration information. The applicability of the wellknown Thompson relationship between formation compressive strength and perforator penetration to Edition 5, Sec. 2 and therefore to Sec. I data is shown. Incorporating necessary corrections for casing entrance hole size, downbole effective formation stress, and casing configurations different from those in the API test completes the translation of surface data to downhole conditions. (from Authors) 951146 Aspects of wellbore heat transfer dm-ing two-phase flow A. R. Hasan & C. S. Kabir, SPE Production & Facilities, 9(3), 1994, pp 211-216. Welibore fluid temperature is governed by the rate of heat loss from the wellbore to the surrounding formation, which in turn is a function of depth and production/injection time. An approach to estimate wellbore fluid temperature during steady-state two phase flow is presented. The method incorporates a new solution of the thermal diffusivity equation and the effect of both conductive and convective heat transport for the wellbore/formation system. A field example is used to illustrate the fluid temperature calculation procedure and shows the importance of accounting for convection in the tubing/easing annulus. A sensitivity study shows that significant differences exist between the predicted wellhead temperature and the formation surface temperature and that the fluid temperature gradient is nonlinear. The expression for fluid temperature developed for single-phase flow should not be applied when multiphase flow is encountered. (from Authors) 951147 The use of borehole imaging techniques in the exploration for stratigraphic traps: an example from the Middle Devonian GHwood channels in north-centrni Alberta R. N. Dueck & E. F. W. Paauwe, Bulletin of Canadian Petroleum Geology, 42(2), 1994, pp 137-154. Borehole imaging techniques based on microconductivity changes in the rock, such as employed by Schlumberger's