Improved Characterization and Modeling of Capillary Transition Zones in Carbonate Reservoirs
- Shehadeh K. Masalmeh (Shell Abu Dhabi BV) | Issa M. Abu-Shiekah (Shell Intl. E&P) | Xudong Jing (Shell Intl. E&P)
- Document ID
- Society of Petroleum Engineers
- SPE Reservoir Evaluation & Engineering
- Publication Date
- April 2007
- Document Type
- Journal Paper
- 191 - 204
- 2007. Society of Petroleum Engineers
- 5.5.8 History Matching, 5.1 Reservoir Characterisation, 1.2.3 Rock properties, 5.6.1 Open hole/cased hole log analysis, 3.3.6 Integrated Modeling, 5.3.1 Flow in Porous Media, 5.2.1 Phase Behavior and PVT Measurements, 1.6.9 Coring, Fishing, 5.1.5 Geologic Modeling, 5.1.1 Exploration, Development, Structural Geology, 5.2 Reservoir Fluid Dynamics, 5.6.2 Core Analysis, 5.7.2 Recovery Factors, 5.5.2 Core Analysis, 5.6.9 Production Forecasting, 5.3.4 Reduction of Residual Oil Saturation, 5.8.7 Carbonate Reservoir, 5.4.1 Waterflooding, 5.5 Reservoir Simulation, 5.6.4 Drillstem/Well Testing
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An oil/water capillary transition zone often contains a sizable portion of a field's initial oil in place, especially for those carbonate reservoirs with low matrix permeability. The field-development plan and ultimate recovery may be influenced heavily by how much oil can be recovered from the transition zone. This in turn depends on a number of geological and petrophysical properties that influence the distribution of initial oil saturation (Sor) against depth, and on the rock and fluid interactions that control the residual oil saturation (Sor), capillary pressure, and relative permeability characteristics as a function of initial oil saturation.
Because of the general lack of relevant experimental data and the insufficient physical understanding of the characteristics of the transition zone, modeling both the static and dynamic properties of carbonate fields with large transition zones remains an ongoing challenge. In this paper, we first review the transition-zone definition and the current limitations in modeling transition zones. We describe the methodology recently developed, based on extensive experimental measurements and numerical simulation, for modeling both static and dynamic properties in capillary transition zones. We then address how to calculate initial-oil-saturation distribution in the carbonate fields by reconciling log and core data and taking into account the effect of reservoir wettability and its impact on petrophysical interpretations. The effects of relative permeability and imbibition capillary pressure curves on oil recovery in heterogeneous reservoirs with large transition zones are assessed. It is shown that a proper description of relative permeability and capillary pressure curves including hysteresis, based on experimental special-core-analysis (SCAL) data, has a significant impact on the field-performance predictions, especially for heterogeneous reservoirs with transition zones.
The reservoir interval from the oil/water contact (OWC) to a level at which water saturation reaches irreducible is referred to as the capillary transition zone. Fig. 1 illustrates a typical capillary transition zone in a homogeneous reservoir interval within which both the oil and water phases are mobile. The balance of capillary and buoyancy forces controls this so-called capillary transition zone during the primary-drainage process of oil migrating into an initially water-filled reservoir trap.
Because the water-filled rock is originally water-wet, a certain threshold pressure must be reached before the capillary pressure in the largest pore can be overcome and the oil can start to enter the pore. Hence, the largest pore throat determines the minimum capillary rise above the free-water level (FWL). As shown schematically in Fig. 2, close to the OWC, the oil/water pressure differential (i.e., capillary pressure) is small; therefore, only the large pores can be filled with oil. As the distance above the OWC increases, an increasing proportion of smaller pores are entered by oil owing to the increasing capillary pressure with height above the FWL. The height of the transition zone and its saturation distribution is determined by the range and distribution of pore sizes within the rock, as well as the interfacial-force and density difference between the two immiscible fluids.
|File Size||2 MB||Number of Pages||14|
Archie, G.E. 1942. The ElectricalResistivity Log as an Aid in Determining Some Reservoir Characteristics.Trans., AIME 146: 54.
Brooks, R.H. and Corey, A.T. 1966.Properties of Porous Media Affecting Fluid Flow. J. of the Irrigation andDrainage Div., Proc. of ASCE 92 (IR2):61-88.
Christiansen, R.L., Heymans, M.J., andKumar, A. 1999. Transition Zone Characterization with Appropriate Rock FluidProperty Measurements. Paper SCA-9939 presented at the International Symposiumof the Society of Core Analysts, Golden, Colorado, 1-4 August.
Eigestad, G.T. and Larsen, J.A. 2000. Numerical Modelling of CapillaryTransition Zones. Paper SPE 64374 presented at the SPE Asia Pacific Oil andGas Conference and Exhibition, Brisbane, Australia, 16-18 October. DOI:10.2118/64374-MS.
Fanchi, J.R., Christiansen, R.L., andHeymans, M.J. 2002. Estimating OilReserves of Fields With Oil/Water Transition Zones. SPEREE 5(4): 311-316. SPE-79210-PA. DOI: 10.2118/79210-PA.
Fleury, M. 2002. Resistivity in Carbonates: NewInsights. Paper SPE 77719 presented at the SPE Annual Technical Conferenceand Exhibition, San Antonio, Texas, 29 September-2 October. DOI:10.2118/77719-MS.
Ghedan, S.G., Thiebot, B.M., and Boyd,D.A. 2004. Modeling and Validationof Initial Water Saturation in the Transition Zone of Carbonate OilReservoirs. Paper SPE 88756 presented at the Abu Dhabi InternationalPetroleum Exhibition and Conference, Abu Dhabi, UAE, 10-13 October. DOI:10.2118/88756-MS.
Jing, X.D, Gillespie, A., and Trewin,B.M. 1993. Resistivity Index FromNon-Equilibrium Measurements Using Detailed In-Situ Saturation Monitoring.Paper SPE 26798 presented at the Offshore Europe Conference, Aberdeen, 7-10September. DOI: 10.2118/26798-MS.
Killough, J.E. 1976. Reservoir Simulation WithHistory-Dependent Saturation Functions. SPEJ 16 (1): 37-48;Trans., AIME, 261. SPE-5106-PA. DOI: 10.2118/5106-PA.
Kjosavik, A., Ringen, J.K., andSkjaeveland, S.M. 2002. RelativePermeability Correlation for Mixed-Wet Reservoirs. SPEJ 7(1): 49-58. SPE-77328-PA. DOI: 10.2118/77328-PA.
Kleppe, J., Delaplace, P., Lenormand, R.,Hamon, G., and Chaput, E. 1997. Representation of Capillary PressureHysteresis in Reservoir Simulation. Paper SPE 38899 presented at the SPEAnnual Technical Conference and Exhibition, San Antonio, Texas, 5-8 October.DOI: 10.2118/38899-MS.
Land, C.S. 1968. Calculation of Imbibition RelativePermeability for Two- and Three-Phase Flow From Rock Properties.SPEJ 8 (2): 149-156; Trans., AIME, 243.SPE-1942-PA. DOI: 10.2118/1942-PA.
Larsen, J.A., Thorsen, T., and Haaskjold,G. 2000. Capillary Transition Zones from a Core Analysis Perspective. Paper SCA2000-20 presented at the International Symposium of the Society of CoreAnalysts, Abu Dhabi, UAE, 18-22 October.
Masalmeh, S.K. 2000. High Oil Recoveries From TransitionZones. Paper SPE 87291 presented at the Abu Dhabi International PetroleumExhibition and Conference, Abu Dhabi, UAE, 13-15 October. DOI:10.2118/87291-MS.
Masalmeh, S.K. 2002. Studying the Effectof Wettability Heterogeneity on the Capillary Pressure Curves Using theCentrifuge Technique. J. Pet. Sci. & Eng. 33 (1-3):29-38.DOI: http://dx.doi.org/10.1016/S0920-4105(01)00173-5.
Masalmeh, S.K. 2003. The Effect ofWettability Heterogeneity on the Capillary Pressure and Relative Permeability.J. Pet. Sci. & Eng.39 (3-4): 399-408. DOI: http://dx.doi.org/10.1016/S0920-4105(03)00078-0.
Masalmeh, S.K. and Oedai, S. 2000. OilMobility in Transition Zone. Paper SCA 2000-02 presented at the InternationalSymposium of the Society of Core Analysts, Abu Dhabi, UAE, 18-22October.
Masalmeh, S.K., Jing, X.D., van Vark, V.,Christiansen, S., van der Weerd, H. and van Dorp, J. 2003. Impact of SCAL onCarbonate Reservoirs: How Capillary Forces Can Affect Field PerformancePredictions. Paper SCA 2003-36 presented at the International Symposium of theSociety of Core Analysts, Pau, France, 22-25 September.
Parker, A.R. and Rudd, J.M. 2000. Understanding and Modeling Water FreeProduction in Transition Zones: A Case Study. Paper SPE 59412 presented atthe SPE Asia Pacific Conference on Integrated Modelling for Asset Management,Yokohama, Japan, 25-26 April. DOI: 10.2118/59412-MS.
Sarwaruddin, M., Skauge, A., andTorstaeter, O. 2001. Fluid Distribution in Transition Zones. Paper SCA 2001-62presented at the International Symposium of the Society of Core Analysts,Edinburgh, U.K., 17-19 September.
Skjaeveland, S.M., Siqveland, L.M.,Kjosavik, A., Hammervold, W.L., and Virnovsky, G.A. 1998. Capillary Pressure Correlation forMixed-Wet Reservoirs. Paper SPE 39497 presented at the SPE India Oil andGas Conference and Exhibition, New Delhi, India, 17-19 February. DOI:10.2118/39497-MS.
van der Post, N., Masalmeh, S., Coenen,J., van der Gijp, K., and Maas, J. 2000. Relative Permeability, Hysteresis andI-Sw Measurements on a Carbonate Prospect. Paper SCA 2000-07 presented at theInternational Symposium of the Society of Core Analysts, Abu Dhabi, UAE, 18-22October.