The aim of this paper is to solve the problems that the existing method of critical production of gas cap reservoir is only suitable for single-phase flow, and the method of critical production of gas cap reservoir under water-flooding is still blank. In this paper, the relationships between dynamic and static equilibrium, plane radial flow theory, oil-water infiltration method and three-dimensional seepage field decomposition theory, were applied to study a calculation method for critical production of directional wells and horizontal wells. Furthermore, the effects of different factors on critical output were studied, such as horizontal permeability, ratio of horizontal permeability to vertical permeability, length of horizontal section, effective thickness, viscosity of crude oil and water content etc. Results show that the critical production increases with the increment of the horizontal permeability, the ratio of the vertical permeability to the horizontal permeability, the reservoir thickness and the horizontal well length; when the viscosity of crude oil is small, the critical production decreases first and then increases with the increase of water content; when the viscosity of crude oil is high, the critical production increases continuously with the increase of water content. This study could provide theoretical and technical guidance for changing of the working system of oil wells. It can avoid gas channeling and improve the development effect.
Muskat, M. and Wycokoff, R.D. (1935) An Approximate Theory of Water-Coning in Oil Production. Transactions of the AIME, 114, 144-163. https://doi.org/10.2118/935144-G
Mayer, H.I. and Garder, A.O. (1954) Mechanics of Two Immiscible Fluids in Porous Media. Journal of Applied Physics, 25, 1400-1406. https://doi.org/10.1063/1.1721576
Wheatley, M.J. (1985) An Approximate Theory of Oil/Water Coning. SPE Annual Technical Conference and Exhibition, Las Vegas, 22-26 September 1985, SPE-14210. https://doi.org/10.2118/14210-MS
Chaperon, I. (1986) Theoretical Study of Coning toward Horizontal and Vertical Well in Anisotropic Formations: Subcritical and Critical Rates. SPE Annual Technical Conference and Exhibition, New Orleans, 5-8 October 1986, SPE-15377.
B., Guo and Lee, R.L. (1992) Determination of the Maximum Water-free Production Rate of a Horizontal Well with Water-Oil-Interface Cresting. SPE Rocky Mountain Regional Meeting, Casper, 18-21 May 1992, SPE-24324.
Fan, Z.F. and Lin, Z.F. (1994) A Study of Critical Rate of a Horizontal Well in a Reservoir with Bottom-Water Drive. Petroleum Exploration and Development, 21, 65-70.
Zhou, D.Y., Jiang, T.W., Zhao, J.Z., et al. (1995) The Uncertainty and Prediction of Critical Output of Horizontal Wells in Bottom Water Reservoir. Drilling & Production Technology, 28, 33-36.
Li, C.L., Yang, B.X. and Cheng, L.S. (2004) A Method to Determine the Optimum Perforation Place and Height in a Vertical Well of Gas-Water Coning Reservoir. China Offshore Oil and Gas, 16, 105-106.
Rao, Z., Wu, F. and Li, X.P. (2006) The Method of Ascertaining the Horizontal Well’s Reasonable Position in Gas-Cap Reservoir. Journal of Southwest Petroleum Institute, 28, 7+42-44.
Lv, A.M. and Yao, J. (2007) Study on Optimal Vertical Position of Horizontal Well in Gas-Cap Reservoir. Oil Drilling & Production Technology, 29, 98-99.
Wang, D.L., Ling, J.J., Zheng, S.J., et al. (2008) Study on Optimum Vertical Location of Horizontal Wells in Reservoir with Bottom Water and Gas Cap. Fault-Block Oil and Gas Field, 15, 76-79.
Yao, K., Chen, S.Y., Jiang, H.Q., et al. (2009) Research and Application of Critical Productivity in Water-Driving Development Horizontal Well Reservoirs. Petroleum Geology and Recovery efficiency, 16, 77-80.
Chen, Y.Q. (2010) New Methods to Predict Critical Production Rates in Horizontal Wells with Water and Gas Coning. China Offshore Oil and Gas, 22, 22-26.
Tu, B., Han, J. and Sun, J. (2014) A Calculation Method of Critical Production for Oil Wells in Thick Reservoirs with Bottom Water. Petroleum Drilling Techniques, 42, 107-110.
Yuan, L., Li, X.P. and Liu, P.P. (2015) New Method for Determining Critical Rate of Horizontal Well in Gas Cap and Bottom Water Reservoirs. Lithologic Reservoirs, 27, 122-126.
Yuan, L., Li, X.P. and Yan, Y.C. (2015) New Method for Determination of Horizontal Well Critical Output in Bottom-Water Reservoir. Natural Gas and Oil, 33, 65-68.
Zhang, Y., Tang, L.D., Xu, Y.D., et al. (2017) Research on Critical Production of Heavy Oil Reservoir with Bottom Water. Natural Gas and Oil, 35, 72-75.
