A Semianalytical Model for Simulating Fluid Flow in Naturally Fractured Reservoirs With Nonhomogeneous Vugs and Fractures
- Yonghui Wu (China University of Petroleum, Beijing) | Linsong Cheng (China University of Petroleum, Beijing) | Shijun Huang (China University of Petroleum, Beijing) | Sidong Fang (Sinopec Petroleum Exploration and Production Research Institute, Beijing) | Pin Jia (China University of Petroleum, Beijing) | Suran Wang (China University of Petroleum, Beijing)
- Document ID
- Society of Petroleum Engineers
- SPE Journal
- Publication Date
- February 2019
- Document Type
- Journal Paper
- 334 - 348
- 2019.Society of Petroleum Engineers
- Semi-analytical model, Multi-scaled fractures and vugs, Discrete fracture and vug model, Heterogeneity, Carbonate reservoirs
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- 235 since 2007
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Carbonate reservoirs comprise fractures, vugs, and cavities. Vugs have a large contribution to reserves of oil and gas, and the fractures provide effective paths for fluid flow in the reservoir. The triple-porosity (TP) model is an effective conceptual method for capturing rock matrix and vugs and the microfractures connecting them. However, these fractures and vugs are always nonhomogeneous. Macrofractures and vugs cannot be handled with a continuum scheme because of their low density and high conductivity.
In this approach, the TP conceptual model is implemented to characterize rock matrix, microvugs, and fractures. To capture the heterogeneity of fractures and vugs, macrofractures and vugs are represented explicitly with the discontinuum model. The boundaries of macrovugs and macrofractures are discretized into several elements. The boundary-element method (BEM) is used to handle flow into macrofractures and vugs. The finite-difference method is applied to handle flow within macrofractures. The flow within macrovugs is assumed to be pseudosteady state.
With a simple discretization of the boundaries of macrovugs and macrofractures, the proposed model is shown to efficiently simulate the behavior of fractured carbonate reservoirs with heterogeneity. The computational accuracy is demonstrated using an analytical model and numerical simulation. On the basis of the proposed model, the effect of the heterogeneity of macrofractures and vugs on pressure-transient behavior is analyzed. The results show that macrofractures and vugs cannot be handled with triple-continuum models analytically. There will be several “dips” on the derivative of the pressure curve if macrovugs are discretely handled. Also, discretely handling the fractures and vugs will make the calculated dimensionless pressure and the derivative pressure lower than those calculated with the triple-continuum models. After increasing the porosity of macrovugs, the pressure and the derivative will go down in the flow regimes dominated by macrovugs. The conductivity of macrofractures has a great impact on almost all the flow regimes except for boundary-dominated flow. Finally, a field case is used to show the application of the proposed semianalytical model.
The novelty of the new model is its ability to model the transient behavior of carbonate reservoirs with nonhomogeneous fractures and vugs. Furthermore, it provides an efficient method for characterizing the heterogeneity of multiscaled fractures and vugs.
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Abdassah, D. and Ershaghis, I. 1986. Triple-Porosity System for Representing Naturally Fractured Reservoirs. SPE Form Eval 1 (2): 113–127. SPE-13409-PA. https://doi.org/10.2118/13409-PA.
Bai, M., Elsworth, D., and Roegiers, J. C. 1993. Multiporosity/Multipermeability Approach to the Simulation of Naturally Fractured Reservoirs. Water Resour. Res. 29 (29): 1621–1633. https://doi.org/10.1029/92WR02746.
Barenblatt, G. I., Zheltov, I. P., and Kochina, I. N. 1960. Basic Concepts in the Theory of Seepage of Homogeneous Liquids in Fissured Rocks. PMM. J. Appl. Math. Mech. 24 (5): 852–864. https://doi.org/10.1016/0021-8928(60)90107-6.
Camacho-Velazquez, R., Vasquez-Cruz, M., Castrejon-Aivar, R. et al. 2005. Pressure Transient and Decline-Curve Behavior in Naturally Fractured Vuggy Carbonate Reservoirs. SPE Res Eval & Eng 8 (2): 95–111. SPE-77689-PA. https://doi.org/10.2118/77689-PA.
Closemann, P. J. 1975. The Aquifer Model for Fissured Reservoirs. SPE J. 15 (5): 385–398. SPE-4434-PA. https://doi.org/10.2118/4434-PA.
De Swaan O., A. 1976. Analytical Solutions for Determining Naturally Fractured Reservoir Properties by Well Testing. SPE J. 16 (3): 117–122. SPE-5346-PA. https://doi.org/10.2118/5346-PA.
Idorenyin, E. H. and Shirif, E. 2017. Transient Response in Arbitrary-Shaped Composite Reservoirs. SPE Res Eval & Eng 20 (3): 752–764. SPE-184387-PA. https://doi.org/10.2118/184387-PA.
Iwere, F. O., Moreno, J. E., Apaydin, O. G. et al. 2002. Vug Characterization and Pore Volume Compressibility for Numerical Simulation of Vuggy and Fractured Carbonate Reservoirs. Presented at the SPE International Petroleum Conference and Exhibition, Mexico, 10–12 February. SPE-74341-MS. https://doi.org/10.2118/74341-MS.
Kang, Z., Wu, Y. S., Li, J. et al. 2006. Modeling Multiphase Flow in Naturally Fractured Vuggy Petroleum Reservoirs. Presented at the SPE Annual Technical Conference and Exhibition, San Antonio, Texas, 24–27 September. SPE-102356-MS. https://doi.org/10.2118/102356-MS.
Karimi-Fard, M., Durlofsky, L. J., and Aziz, K. 2004. An Efficient Discrete-Fracture Model Applicable for General-Purpose Reservoir Simulators. SPE J. 9 (2): 227–236. SPE-88812-PA. https://doi.org/10.2118/88812-PA.
Kazemi, H. 1969. Pressure Transient Analysis of Naturally Fractured Reservoir With Uniform Fracture Distribution. SPE J. 9 (4): 451–462. SPE-2156-PA. https://doi.org/10.2118/2156-PA.
Liu, J. C., Bodvarsson, G. S., and Wu, Y. S. 2003. Analysis of Pressure Behavior in Fractured Lithophysical Reservoirs. J. Contam. Hydrol. 62–63 (1): 189–211. https://doi.org/10.1016/S0169-7722(02)00169-9.
Popov, P., Qin, G., Bi, L. et al. 2007. Multiscale Methods for Modeling Fluid Flow Through Naturally Fractured Carbonate Karst Reservoirs. SPE Res Eval & Eng 12 (2): 218–231. SPE-105378-PA. https://doi.org/10.2118/105378-PA.
Pruess, K. and Narasimhan, T. 1985. A Practical Method for Modeling Fluid and Heat Flow in Fractured Porous Media. SPE J. 25 (1): 14–26. SPE-10509-PA. https://doi.org/10.2118/10509-PA.
Serra, K. V., Reynolds, A. C., and Raghavan, R. 1983. New Pressure Transient Analysis Method for Naturally Fractured Reservoirs. J Pet Technol 35 (12): 2271–2283. SPE-10780-PA. https://doi.org/10.2118/10780-PA.
Stehfest, H. 1970. Algorithm 368: Numerical Inversion of Laplace Transforms. ACM Commun. 13 (1): 47–49. https://doi.org/10.1145/361953.3611969.
van Everdingen, A. F. and Hurst, W. 1949. The Application of the Laplace Transformation Flow Problem in Reservoirs. J Pet Technol 1 (12): 305–324. SPE-949305-G. https://doi.org/10.2118/949305-G.
Warren, J. E. and Root, P. J. 1963. The Behavior of Naturally Fractured Reservoirs. SPE J. 3 (3): 245–255. SPE-426-PA. https://doi.org/10.2118/426-PA.
Wu, Y. S., Qin, G., Ewing, R. E. et al. 2006. A Multiple-Continuum Approach for Modeling Multiphase Flow in Naturally Fractured Vuggy Petroleum Reservoirs. Presented at the SPE International Oil & Gas Conference and Exhibition, Beijing, 5–7 December. SPE-104173-MS. https://doi.org/10.2118/104173-MS.
Wu, Y. S., Ehlig-Economides, C. A., Qin, G. et al. 2007. A Triple-Continuum Pressure-Transient Model for a Naturally Fractured Vuggy Reservoir. Presented at the SPE Annual Technical Conference and Exhibition, Anaheim, California, 11–14 November. SPE-110044-MS. https://doi.org/10.2118/110044-MS.
Wu, Y. S., Di, Y., Kang, Z. et al. 2011. A Multiple-Continuum Model for Simulating Single-Phase and Multiphase Flow in Naturally Fractured Vuggy Reservoirs. J. Petrol. Sci. & Eng. 78 (1): 13–22. https://doi.org/10.1016/j.petrol.2011.05.004.
Yao, J., Huang, Z., Li, Y. et al. 2010. Discrete Fracture-Vug Network Model for Modeling Fluid Flow in Fractured Vuggy Porous Media. Presented at the International Oil and Gas Conference and Exhibition, Beijing, 8–10 June. SPE-130287-MS. https://doi.org/10.2118/130287-MS.
Yong, L., Li, B., Qi, W. et al. 2017. Different Equivalent Simulation Methods for Fractured-Vuggy Carbonate Gas Condensate Reservoirs. Presented at the International Oil and Gas Conference and Exhibition, Beijing, 8–10 June. SPE-130287-MS. https://doi.org/10.2118/130287-MS.
Zhang, N., Sun, Q., Wang, Y. et al. 2017. Multiscale Coupling of Triple-Continuum Model and Discrete Fracture Network for Carbonate Reservoir Simulation. Presented at the SPE Reservoir Characterization and Simulation Conference and Exhibition, Abu Dhabi, 8–10 May. SPE-186063-MS. https://doi.org/10.2118/186063-MS.