Well Test Model and Analytical Method of Finite Conductivity Vertical Fracture Bilinear Flow of Low-Speed Non-darcy Flow
For low-permeability reservoirs, non-Darcy flow is not considered in the current bilinear flow model of vertical fractures, and then, the effect of trigger pressure gradient on bottom pressure is also not considered, which makes difference between the test analysis result and the actual value. Therefore, a new bilinear flow model for finite conductivity vertical fractures with trigger pressure gradient is set up and the typical curve is drawn by studying the non-Darcy seepage law. Finally, the new solution of bottom pressure is obtained. And the influences of flow conductivity, the effect of wellbore storage, the skin effect, trigger pressure gradient, and the effect of boundary distance on typical curves have been analyzed. The researched results show that trigger pressure gradient has greater effect on the typical curve in the later stage. The higher the trigger pressure gradient is, the faster the boundary responses is and the more upward the curve of the later stage is, which even leads the radial fluid flow to disappear. The case study shows that the presented new model not only uses pressure data of a low-permeability reservoir efficiently and increases the accuracy of well test results, but also provides a reliable reference for the dynamic analysis of field fracture wells.
KeywordsLow-permeability reservoirs Vertical fractures Bilinear flow model Trigger pressure gradient Typical curves
This study was supported by provincial key laboratory item of Education Department of Shaanxi Provincial Government “Study on EOR technology for low-permeability reservoir by gas injection (nitrogen and carbon dioxide)” (No.09JS036).
- 2.Cinco LH, Samaniego VF (1977) Effect of wellbore storage and damage on the transient pressure behavior of vertically fractured wells.In: SPE 6752Google Scholar
- 4.Barker BJ, Ramey HJ (1978) Transient flow to finite conductivity vertical fractures. SPE 7489Google Scholar
- 5.Cinco LH, Samaniego VF (1978) Transient pressure analysis for fractured wells. SPE 7490Google Scholar
- 6.Li F, Zhou Z (1998) Research on the finite conductivity vertical fractured wells of heterogeneous reservoir. Explor Technol 19(3):10–14Google Scholar
- 7.Deng Y, Liu C (2002) The typical line solution and finite difference solution of two-phase non-Darcy elliptic seepage flow and computational method of development bidding. Pet Explor Dev 2Google Scholar
- 8.Deng Y, Liu C (2003) The pressure analysis of nonlinear seepage flow of low permeability reservoir produced with vertical fracture wells. Pet Explor Dev 30(1):81–83Google Scholar
- 9.Liu P, Wang X (2004) Dynamic analysis of bottom pressure of finite conductivity vertical fracture wells of three-area composite system, well test 2Google Scholar
- 10.Yan T, Jia Y (2005) Well testing model of low-speed non-Darcy vertical fracture. Nat Gas Ind 25(2):130–132Google Scholar
- 11.Fu C, Yin H (2008) Dynamic pressure analysis of vertical fracture wells of composite system. J Daqing Pet Univ 32(2)Google Scholar
- 12.Wong DW, Harrington AG (1986) Application of the pressure-derivative function in the pressure-transient testing of fractured wells. SPE 00013056Google Scholar
- 13.Azari M, Wooden WO, Coble LE (1990) Complete set of laplace transforms for finite-conductivity vertical fractures under bilinear and trilinear flow. SPE 20556Google Scholar