1Institute of Mechanics, Chinese Academy of Sciences
2PetroChina Research Institute of Petroleum Exploration & Development, Beijing, China
For the characteristics of horizontal fractures in shallow low-permeability oil layers after hydraulic fracturing in multilayer reservoirs, horizontal fractures are taken equivalent to an elliptical cylinder with the reservoir thickness using the equivalent permeability model; then, upon the elliptic seepage theory, the seepage field which has led by a vertical well with horizontal fractures is divided into two parts: (1)radial flow from the external formation to the equivalent area of horizontal fracture and (2) elliptic flow in the equivalent area of horizontal fracture. The loss of pressure caused by threshold pressure gradient, material balance in the reservoir, and multi-well pressure superposition principle are synthesized to calculate the performance. Finally, separate-layer multi-stage horizontal fractured well performance is deduced by summing the performance of high-permeability oil layers and fractured thin low-permeability oil layers. Low-permeability thin oil layers in Xing Shu-Gang oilfield are taken as practical cases, and the well space limits and economic reservoir thickness limits are calculated by the performance model; the relationship among recovery and productivity intensity, and the ratio of thin low-permeability oil layers thickness to the total thickness are also discussed.
Ren L., Zhao J. Zh., Hu Y. Q. et al., “Affecting Factor Analysis of Productivity for Horizontal Fractured Wells,” Journal of Southwest Petroleum University (Science & Technology Edition), 2010, 32, 77-78.
Zhang G. S., Tang G. C., Wang X. Y. et al., “A New Productive Method of Horizontal Fracture Wells in Hydraulic Fracturing,” Journal of Oil and Gas Technology, 2009, 31, 121-124.
Yang Y., Li X. F., Lu W. et al., “Application and Derivation of Vertical Well Deliverability Equation for Shallow Layer and Low Permeability Reservoirs with Horizontal Fracture,” Science Technology and Engineering, 2013, 13, 7015-7020.
McDaniel B. W., “Review of Current Fracture Stimulation Techniques for Best Economics in Multilayer, Lower-permeability Reservoirs,” SPE 98025, 2005.
Prats M., Aime M., Hazebroek P., and Strickler W. R., “Effect of Vertical Fractures on Reservoir Behavior-compressible-fluid Case,” SPE 98, 1962.
Friehauf K. E., Suri A., and Sharma M. M., “A Simple and Accurate Model for Well Productivity for Hydraulically Fractured Wells,” SPE Production & Operations, 2010, 25, 453-460.
Deng Y. E. and Liu C. Q., “Analysis of Pressure of Nonlinear Flow through Low-permeability Reservoir with Vertically Fractured Well Producing,” Petroleum Exploration and Development, 2003, 30, 81-83.
W. S. and Ertekin T., “Performance Comparison of Vertical and Horizontal Hydraulic Fractures and Horizontal Boreholes in Low Permeability Reservoirs: A Numerical Study,” SPE 16407, 1987.