水力裂缝形态对煤层气藏动用程度影响规律

doi:10.7657/XJPG20260208

摘要/Abstract

摘要：

针对煤层气藏压裂后的多尺度和复杂应变耦合渗流特征，基于FVM建立气藏数值模型。利用EDFM表征裂缝系统，耦合基质蠕变、解吸附膨胀和割理压缩作用下的渗透率，并考虑其非均质分布。利用生产数据验证模型准确性，开展裂缝形态对动用程度影响规律研究，结果表明：水力压裂增大泄压面积，提高动用程度，加快煤层整体解吸附速率，近井形成的裂缝网络提供高渗通道；尤其针对低—中阶煤层，极限体积压裂，显著提高单井产能，延长生产周期。

关键词: 煤层气藏, 多尺度渗流, 有限体积法, 各向异性渗透率, 嵌入式离散裂缝

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

中图分类号:

TE371

李文杰, 王虎, 吴云利, 仲劼, 张涛, 赵志红. 水力裂缝形态对煤层气藏动用程度影响规律[J]. 新疆石油地质, 2026, 47(2): 192-200.

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.

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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