Effect of Capillary Pressure on Phase Behavior in Tight Rocks and Shales
- Bahareh Nojabaei (Pennsylvania State University) | Russell T. Johns (Pennsylvania State University) | Lifu Chu (Hess Corporation)
- Document ID
- Society of Petroleum Engineers
- SPE Reservoir Evaluation & Engineering
- Publication Date
- July 2013
- Document Type
- Journal Paper
- 281 - 289
- 2013. Society of Petroleum Engineers
- 5.1 Reservoir Characterisation, 5.2.1 Phase Behavior and PVT Measurements, 5.2 Reservoir Fluid Dynamics, 5.8.4 Shale Oil, 5.7 Reserves Evaluation, 5.5.8 History Matching
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Phase behavior is important in the calculation of hydrocarbons in place and in the flow of phases through the rocks. Pore sizes can be on the order of nanometers for shale and tight-rock formations. Such small pores can affect the phase behavior of in-situ oil and gas because of increased capillary pressure. Not accounting for increased capillary pressure in small pores can lead to inaccurate estimates of ultimate recovery, and of saturation pressures. In this paper, capillary pressure is coupled with phase equilibrium equations, and the resulting system of nonlinear fugacity equations is solved to present a comprehensive examination of the effect of small pores on saturation pressures and fluid densities. Binary mixtures of methane with heavier hydrocarbons and a real reservoir fluid from the Bakken shale are considered. The results show that accounting for the impact of small pore throats on pressure/volume/temperature (PVT) properties explains the inconsistent gas/oil-ratio (GOR) behavior, high flowing bottomhole pressures, and low gas-flow rate observed in the tight Bakken formation. The small pores decrease bubble-point pressures and either decrease or increase dew-point pressures, depending on which part of the two-phase envelope is examined. Large capillary pressure also decreases the oil density in situ, which affects the oil formation volume factor and ultimate reserves calculations. A good history match for wells in the middle Bakken formation is obtained only after considering a suppressed bubblepoint pressure. The results show that the change in saturation pressures, fluid densities, and viscosities is highly dependent on the values of interfacial tension (IFT) (capillary pressure) used in the calculations.
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Ayirala, S. C. and Rao, D. N. 2006. A New Parachor Model to Predict DynamicInterfacial Tension and Miscibility in Multicomponent Hydrocarbon Systems.J. Colloid Interf. Sci. 299 (1): 321-331. http://dx.doi.org/10.1016/j.jcis.2006.12.030.
Brusllovsky, A. L. 1992. Mathematical Simulation of Phase Behavior ofNatural Multicomponent Systems at High Pressure with an Equation of State.SPE Res Eng 7 (1): 117-122. http://dx.doi.org/10.2118/20180-PA.
Byrnes, A. P. 2003. Aspects of Permeability, Capillary Pressure, andRelative Permeability Properties and Distribution in Low-Permeability RocksImportant to Evaluation, Damage, and Stimulation. Proc., Rocky MountainAssociation of Geologists Petroleum Systems and Reservoirs of Southwest WyomingSymposium, Denver, Colorado, 19 September.
Carman, P. C. 1937. Fluid Flow Through Granular Beds. T. I. Chem.Eng.-Lond. 15: 150-166.
Du, L. and Chu, L. 2012. Understanding Anomalous Phase Behavior inUnconventional Oil Reservoirs. Paper SPE 161830 presented at SPE CanadianUnconventional Resources Conference, Calgary, Alberta, Canada, 30 October-1November. http://dx.doi.org/10.2118/161830-MS.
Evans, R., Marconi, U. M. B. and Tarazona, P. 1986. Fluids in Narrow Pores:Adsorption, Capillary Condensation, and Critical Points. J. Chem. Phys. 84 (4): 2376-2399. http://link.aip.org/link/doi/10.1063/1.450352.
Firincioglu, T., Ozkan E. and Ozgen, C. 2012. Thermodynamics of MultiphaseFlow in Unconventional Liquids-Rich Reservoirs Paper SPE 159869 presented atthe SPE Annual Technical Conference and Exhibition, San Antonio, Texas, 8-10October. http://dx.doi.org/10.2118/159869-MS.
Firoozabadi, A. 1999. Thermodynamics of Hydrocarbon Reservoirs. NewYork City, New York: McGraw-Hill.
Giovambattista, N., Rossky, P. J. and Debenedetti, G. 2006. Effect ofPressure on the Phase Behavior and Structure of Water Confined BetweenNanoscale Hydrophobic and Hydrophilic Plates. Phys. Rev. E 73 (4). http://dx.doi.org/10.1103/PhysRevE.73.041604.
Kozeny, J. 1927. Über Kapillare Leitung des Wassers im Boden.Sitzungsberichte der Akademie der Wissenschaften, Wien 136(2a): 271-306.
Kuila, U. and Prasad, M. 2011. Surface Area and Pore-Size Distribution inClays and Shales. Paper SPE 146869 presented at the SPE Annual TechnicalConference and Exhibition, Denver, Colorado, 30 October-2 November. http://dx.doi.org/10.2118/146869-MS.
Peng, D. Y., and Robinson, D. B. 1976. A New Two-Constant Equation of State.Ind. Eng. Chem. Fundamen. 15 (1): 59-64. http://dx.doi.org/10.1021/i160057a011.
Ping, G., Liangtian, S., Li, S., et al. 1996. A Theoretical Study of theEffect of Porous Media on the Dew Point Pressure of a Gas Condensate. Paper SPE35644 presented at SPE Gas Technology Symposium, Calgary, Alberta, Canada, 28April-1 May. http://dx.doi.org/10.2118/35644-MS.
Restagno, F., Bocquet, L. and Biben, T. 2000. Metastability and Nucleationin Capillary Condensation. Phys. Rev. Lett. 84 (11):2433-2436. http://dx.doi.org/10.1103/PhysRevLett.84.2433.
Sigmund, P. M., Dranchuk, P. M., Morrow, N. R., et al. 1973. RetrogradeCondensation in Porous Media. SPE J. 13 (2): 93-104. http://dx.doi.org/10.2118/3476-PA.
Zhilin, Q., Wang, S., Du, Z., et a. 2007a. A New Approach for Phase Behaviorand Well Productivity Studies in the Deep Gas-Condensate Reservoir with LowPermeability. Paper SPE 106750 presented at Production and OperationsSymposium, Oklahoma City, Oklahoma, 31 March-3 April. http://dx.doi.org/10.2118/106750-MS.
Zhilin, Q., Du, Z., Liang, B., et al. 2007b. Phase Behavior Study in theDeep Gas-Condensate Reservoir with Low Permeability. Paper SPE 107315 presentedat the EUROPEC/EAGE Conference and Exhibition, London, UK, 11-14 June. http://dx.doi.org/10.2118/107315-MS.