Analysis of Hydraulic Fracture Network Morphology in Stimulated Coal Reservoirs with Pre-Existing Natural Fractures  

作　　者：Weiping Ouyang Luoyi Huang Jinghua Liu Hongzhong Zhang 

机构地区：[1]National Engineering Laboratory for Exploration and Development of Low-Permeability Oil and Gas Fields,CNPC Chuanqing Drilling Engineering Company Limited,Xi’an,710018,China [2]Changqing Downhole Technology Company,CNPC Chuanqing Drilling Engineering Company Limited,Xi’an,710018,China [3]School of Petroleum Engineering,Yangtze University,Wuhan,430100,China

出　　处：《Energy Engineering》2025年第4期1491-1509,共19页能源工程(英文)

基　　金：This study was supported by the Foundation of National Engineering Laboratory for Exploration and Development of Low-Permeability Oil and Gas Fields(2023-015).

摘　　要：Hydraulic fracturing is a crucial technique for efficient development of coal reservoirs.Coal rocks typically contain a high density of natural fractures,which serve as conduits for fracturing fluid.Upon injection,the fluid infiltrates these natural fractures and leaks out,resulting in complex fracture morphology.The prediction of hydraulic fracture network propagation for coal reservoirs has important practical significance for evaluating hydraulic fracturing.This study proposes a novel inversion method for predicting fracture networks in coal reservoirs,explicitly considering the distribution of natural fractures.The method incorporates three distinct natural fracture opening modes and employs a fractal probability function to constrain fracture propagationmorphology.Based on thismethod,the study compares hydraulic fracture networkmorphologies in coal reservoirs with andwithout the presence of natural fractures.Theresults showthatwhile both reservoir types exhibitmulti-branch fracture networks,reservoirs containing natural fractures demonstrate greater branching and a larger stimulated reservoir volume(SRV).Additionally,the study employs a fractal dimension calculation method to quantitatively describe the geometric distribution characteristics of fractures.The analysis reveals that the geometry and distribution of natural fractures,as well as reservoir geological parameters,significantly influence the fracture networkmorphology and fractal dimension.The contact angle between natural and hydraulic fractures affects propagation direction;specifically,when the contact angle isπ/2,the fractal dimension of the hydraulic fracture network is maximized.Moreover,smaller lengths and spacings of natural fracture led to higher fractal dimensions,which can significantly increase the SRV.The proposed method offers an effective tool for evaluating the hydraulic fracturing of coal reservoirs.

关 键 词：Coal reservoirs hydraulic fracturing natural fractures inversion and evaluation fracturing fluid flow fractal dimension 

分 类 号：P61[天文地球—矿床学]