鄂西荆门地区志留系龙马溪组古构造应力场研究及裂缝预测  

Paleotectonic Stress Field and Fracture Prediction of Silurian Longmaxi Formation in Jingmen Area, Western Hubei

作　　者：张斗中 陈孔全[2] 汤济广[1] 庹秀松 马帅 ZHANG Douzhong;CHEN Kongquan;TANG Jiguang;TUO Xiusong;MA Shuai(School of Geosciences,Yangtze University,Wuhan,Hubei 430100;Cooperative Innovation Center of Unconventional Oil and Gas,Yangtze University,Wuhan,Hubei 430100)

机构地区：[1]长江大学地球科学学院,湖北武汉430100 [2]长江大学非常规油气省部共建协同创新中心,湖北武汉430100

出　　处：《地球学报》2024年第2期217-231,共15页Acta Geoscientica Sinica

基　　金：中国石化科技部项目“南川-武隆地区精细构造解析与页岩气保存评价”(编号:P21087-6)资助。

摘　　要：鄂西地区志留系龙马溪组页岩储层发育,由于页岩低孔低渗的特性,构造裂缝成为了页岩气运移和聚集的主控因素。本文以鄂西荆门地区志留系龙马溪组页岩为例,基于地震资料、岩石力学实验、野外实测资料,利用有限元数值模拟技术、岩石破裂准则,解析古构造应力场分布规律,预测构造裂缝分布特征。结果表明,荆门地区发育的构造裂缝主要以中燕山晚期形成的NNW向和NE向共轭剪切缝为主,其次为中燕山早期形成的NNE向和NEE向共轭剪切缝。构造裂缝的分布受断层、岩石物理参数和构造应力的影响较大,Ⅲ级裂缝发育区和断层区域综合破裂系数均大于1.1,构造裂缝最为发育,页岩气保存效果最差;Ⅱ级裂缝发育区综合破裂系数在1.0~1.1之间,为页岩气保存效果较好区域;Ⅰ级裂缝发育区综合裂缝破裂系数在0.85~1.0之间,处于“破而不裂”的状态,为页岩气最优保存区。The Silurian Longmaxi Formation shale reservoir in western Hubei is developed.Owing to the low porosity and low permeability of shale,tectonic fractures have become the main controlling factors of shale gas transport and accumulation.Taking the Silurian Longmaxi Formation shale in Jingmen area of western Hubei as an example,based on seismic data,rock mechanics experiment and field measurement data,finite element numerical simulations and rock fracture criteria are used to analyze the distribution law of the paleotectonic stress field and predict the distribution characteristics of tectonic fractures.The results show that the structural fractures developed in the Jingmen area are mainly NNW-trending and NE-trending conjugate shear fractures formed in late Middle Yanshan,followed by NNE-trending and Nee-trending conjugate shear fractures formed in early Middle Yanshan.The distribution of tectonic fractures is significantly affected by faults,petrophysical parameters,and tectonic stress.The fracture coefficients of gradeⅢfracture and fault zones are both greater than 1.1,indicating that the structural fractures are highly developed and that the shale gas preservation effect is minimal.The comprehensive fracture coefficient of gradeⅡfracture development area is between 1.0–1.1,indicating good shale gas preservation.The comprehensive fracture coefficient of the gradeⅠfracture development area is within 0.85–1.0,which is in the state of“fractured but not fractured”and is the best shale gas preservation area.

关 键 词：荆门地区 龙马溪组 数值模拟 构造应力场 裂缝预测 

分 类 号：P618.13[天文地球—矿床学]