西南石油大学学报(自然科学版) ›› 2019, Vol. 41 ›› Issue (6): 1-12.DOI: 10.11885/j.issn.1674-5086.2019.09.16.13

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Linear Coupling Seepage Model for Fractured Horizontal Wells in Shale Gas Reservoir

ZHANG Liehui1, CUI Qianchen1, XIE Jun2, ZHENG Jian3, LI Chengyong4   

  1. 1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China;
    2. Southwest Oil and Gas Field Company, PetroChina, Chengdu, Sichuan 610051, China;
    3. Sichuan Changning Natural Gas Development Company Limited, Chengdu, Sichuan 610051, China;
    4. College of Energy, Chengdu University of Technology, Chengdu, Sichuan 610059, China
  • Received:2019-09-16 Online:2019-12-10 Published:2019-12-10

Abstract: In order to study the effects of threshold pressure gradient at low-velocity gas flow in shale matrix on well test curves, and to overcome the difficulties of coupling of flow mechanism of shale gas, a new cylindrical triple-porosity shale matrix model was proposed. Combined with the five-region flow model, a new linear seepage model characterizing flow process of multifractured horizontal wells was established. Laplace transformation and Green function were employed to solve the model, and the Stehfest numerical inversion algorithm was applied to plot dimensionless pseudo-pressure curves and conduct sensitivity analysis. The results show that pressure response curves of the new model could be divided into 7 periods and the threshold pressure gradient conspicuously affects the middle and later periods. The lager the threshold pressure gradient is, the larger seepage resistance is, and the higher pseudo-pressure and its derivative are. The smaller the matrix permeability is, the more difficult it is for transition flow from matrix to fractures, and the later the boundary control flow occurs.

Key words: shale gas, fractured horizontal well, triple-porosity shale matrix, threshold pressure gradient, pressure response

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