Influence of Hydraulic Fracture Morphology on the Producing Degree of CBM Reservoir

doi:10.7657/XJPG20260208

Abstract

Abstract:

To investigate the multi-scale and complex strain-coupled seepage characteristics of coalbed methane (CBM) reservoirs after fracturing, a numerical model for gas reservoirs was established based on finite volume method (FVM). Using the embedded discrete fracture method (EDFM), the fracture system was characterized, coupling with the permeability under matrix creep, desorption swelling, and cleat compression, and considering the nonhomogeneous permeability distribution. The model was validated on production data and then used to identify the influence of hydraulic fracture morphology on the producing degree of CBM reservoirs. The results show that hydraulic fracturing increases the drainage area, enhancing the producing degree and accelerating the overall desorption rate of coal seams. The fracture network formed near the wellbore provides a high-permeability pathway system. Especially in low- to medium-rank coal seams, the ultimate volume fracturing technology significantly increases the production capacity of a single well and prolongs its production period.

Key words: CBM reservoir, multi-scale seepage, finite volume method, anisotropic permeability, embedded discrete fracture

CLC Number:

TE371

LI Wenjie, WANG Hu, WU Yunli, ZHONG Jie, ZHANG Tao, ZHAO Zhihong. Influence of Hydraulic Fracture Morphology on the Producing Degree of CBM Reservoir[J]. Xinjiang Petroleum Geology, 2026, 47(2): 192-200.

Figures/Tables 10

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参数	取值	参数	取值
物理边界/（m×m×m）	600×600×20	网格参数/（m×m×m）	3×3×20
储集层压力/MPa	20	井底流压/MPa	2
甲烷密度/（kg·m^-3）	0.76	煤层密度/（kg·m^-3）	1 350
甲烷黏度/（mPa·s）	0.001 8	Biot系数	0.9
基质压缩系数/（MPa^-1）	0.003 5	裂缝压缩系数/（MPa^-1）	0.010 0
裂缝初始渗透率/mD	1 000	基质孔隙度	0.072
裂缝孔隙度	0.900	割理初始开度/m	6×10^-5
基质渗透率标准差	0.1	基质渗透率级差	0.02
朗格缪尔压力/MPa	2.4	朗格缪尔应变	0.03
杨氏模量/GPa	1.79	泊松比	0.28
基质-割理连接系数	0.7	甲烷体积系数	12