摘要
深部煤层气的勘探开发不能简单套用浅部煤层气的勘探开发理论,原因之一在于深煤层地应力制约了煤层气的吸附/解析、渗流等过程,决定了煤层裂隙的有效性,并影响着水平井轨迹设计。因此,开展深部地应力变化规律研究对煤层气的勘探开发具有重要意义。本文以鄂尔多斯盆地大吉区块为例,利用阵列声波测井、微地震监测数据和岩心测试等资料,综合考虑深层煤岩微构造类型与产状、边界应力条件和顶底板岩石力学性质组合等因素,利用ANSYS有限元软件,建立微构造三维地质力学模型,全面分析了微构造的类型、产状和对煤层应力的控制机理。研究结果表明:煤层微构造越平缓,应力分布越均匀,反之应力越容易集中;煤层微构造产状对煤层应力的影响主要为:随着煤层微构造曲率的增大,挠曲处水平应力差会随之增大,且挠曲处周缘水平最小主应力也会越集中。由微构造类型与煤层力学性质、顶底板岩性、边界应力条件等因素交叉模拟得到,正向微构造下的煤层应力与泊松比呈正相关,与杨氏模量呈负相关,而负向微构造则相反。当顶板为灰岩时,煤层应力大小受微构造类型变化影响比顶板为砂岩时更显著。区域应力大小对深部煤层应力的影响相对较小。论文研究成果可为深部煤层地应力成因机制分析、煤层气高效开发和地质工程一体化实践提供有益的参考。
The theory of shallow coalbed methane(CBM)exploration and development cannot be directly applied to deep CBM partly due to the effect of in situ stress.In situ stress in deep coal beds restricts the process of CBM adsorption/desorption and seepage,determines the effectiveness of coalbed fissures,and affects the design of horizontal well trajectory.Thus the pattern of in situ-stress change in deep coal seams is of great significance to the exploration and development of CBM.In this paper,taking the Daji block in Ordos Basin as an example,using data from array acoustic logging,microseismic monitoring,and core testing,considering the microstructure types and attitude,boundary stress conditions,and combination of mechanical properties of top and bottom slabs,we established a three-dimensional geomechanical microstructural model of deep coal beds by using ANSYS finite element software to comprehensively analyze the control mechanism of microstructure types and attitute on in situ stress in deep coal beds.Results show that with smoother microstructure the stress distributes more uniformly;conversely,the stress concentrates more easily.The influence of the attitute of microstructure on in situ stress in coal seams is mainly as follows:as the curvature of the microstructure increases,the differential horizontal stress at the bending point increases,and the minimum principal stress increasingly concentrates around the bending point.According to cross-simulation between microstructure type and mechanical properties of coal seam,lithology of top/bottom slabs,and boundary stress conditions,in situ stress under positive curvature is positively correlated with Poisson’s ratio and negatively correlated with Young’s modulus,whereas the opposite is true under negative curvature.Compared to with sandstone top slab,the magnitute of in situ stress in coal seams with limestone top slab is more significantly affected by the change of microstructure type.The magnitude of the regional stress has relatively small influence on in situ
作者
唐志潭
刘敬寿
闫霞
冯延青
蒋恕
张滨鑫
张冠杰
付一鸣
TANG Zhitan;LIU Jingshou;YAN Xia;FENG Yanqing;JIANG Shu;ZHANG Binxin;ZHANG Guanjie;FU Yiming(Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education,China University of Geosciences(Wuhan),Wuhan 430074,China;School of Earth Resources,China University of Geosciences(Wuhan),Wuhan 430074,China;Zhonglian Coalbed Methane National Engineering Research Center Co.,Ltd,Beijing 100095,China;PetroChina Coalbed Methane Co.,Ltd,Beijing 100028,China)
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2024年第5期344-357,共14页
Earth Science Frontiers
基金
国家自然科学基金项目(42102156)
山东省自然科学基金项目(ZR2020QD035)
中国地质大学(武汉)“地大学者”人才岗位科研启动项目(2022046)。
关键词
微构造
地应力
深层煤岩
大吉区块
有限元模拟
microstructure
in situ stress
deep coal rock
Daji Block
finite element simulation
