摘要
页岩气、煤层气等非常规油气储层层理面较为发育,而不同地域层理面胶结程度具有差异性,揭示层理面强度对水力裂缝的影响机制,对理解水力压裂缝网形成演化具有重要意义。基于ABAQUS有限元软件,利用Python编程建立了含层理面的全局嵌入0厚度cohesive单元模型,基于该模型研究了层理面强度对水力裂缝扩展的影响,进一步结合MATLAB编程实现了压裂过程的声发射(AE)模拟,为精细化研究裂缝扩展过程提供了重要手段。通过分析数值模拟结果及声发射数据可知:水力裂缝的扩展路径由最大主应力和层理面共同决定,层理面强度决定了两者影响比重,层理面强度越弱,对水力裂缝的捕获能力则越强,裂缝扩展路径将由层理面主导,层理面强度适中时在层理面和地应力共同作用下可产生顺层-穿层交错复杂裂缝网络,压裂效果最佳。顺层破裂裂缝表现为低缝宽剪切裂缝,地应力作用下不易闭合,对支撑剂强度要求较低,穿层裂缝为大缝宽拉张裂缝,有利于支撑剂的运移填充。矿物非均质性可导致裂缝的非同步扩展,间接影响裂缝的复杂程度。水力压裂施工设计时可针对不同层理面强度储层,差异化压裂设计,从而实现非常规致密油气的高效开采。
The bedding planes of unconventional oil and gas reservoirs,such as shale gas and coalbed methane,are relatively developed.The existence of bedding planes directly interferes with the expansion of hydraulic fractures.Different regions have different cementation degrees.It is of great significance to reveal the influence mechanism of the bedding plane on hydraulic fractures for understanding the formation and evolution of the hydraulic fracturing network.Therefore,based on Python programming,the global embedded 0-thickness cohesive element model with a bedding plane is established.Based on the model,the influence of the bedding plane strength on hydraulic fracture propagation is studied.Furthermore,the acoustic emission(AE)simulation is realized by MATLAB programming,which provides an important means for the fine study of the fracture propagation process.According to the numerical simulation results and AE data,it can be known that the propagation path of hydraulic fractures is determined by the maximum principal stress and the bedding plane.The strength of the bedding plane determines the proportion of the two.The weaker the bedding plane strength,the stronger the ability to capture hydraulic fractures.At this time,the fracture propagation path is dominated by the bedding plane.When the bedding plane strength is moderate,the phenomenon of cross-layer fracture and bedding fracture alternately appears,which shows the characteristics of intermittent dislocation fracture.So the fracture network is complex.During hydraulic fracturing,the tensile fracture is the dominant fracture type,and it is manifested in cross-layer fracture.There is a large fracture width,which is conducive to proppant migration and filling.However,the shear fracture is mostly manifested as the bedding slip fracture with a small crack width.Moreover,mineral heterogeneity can cause the asynchronous propagation of fractures and indirectly affect the complexity of fractures.Therefore,the fracturing construction design can be differentiated for reservoirs with different bedding plane strengths,to realize the efficient exploitation of unconventional tight oil and gas.
作者
韩伟歌
彭皓睿
崔振东
朱正国
刘利
张康健
HAN Weige;PENG Haorui;CUI Zhendong;ZHU Zhengguo;LIU Li;ZHANG Kangjian(Key Laboratory of Roads and Railway Engineering Safety Control(Shijiazhuang Tiedao University),Ministry of Education,Shijiazhuang 050043,China;Hebei Province Technical Innovation Center of Safe and Effective Mining of Metal Mines,Shijiazhuang 050043,China;Key Laboratory of Shale Gas and Geoengineering,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Institutions of Earth Science,Chinese Academy of Sciences,Beijing 100029,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;China Railway 18 th Bureau Group Co.,Ltd.,Tianjin 300222,China)
出处
《工程地质学报》
CSCD
北大核心
2023年第6期2030-2040,共11页
Journal of Engineering Geology
基金
中国博士后科学基金资助项目(资助号:2022M712211)
国家自然科学基金专项项目(资助号:42141009)
国家自然科学基金面上项目(资助号:41972296)
河北省重点研发计划项目(资助号:22375416D)
中国铁建股份有限公司科技重大专项(资助号:2019-A05)
石家庄铁道大学土木工程学院自主科研课题(资助号:TMXN2208)。
关键词
黏性单元
水力压裂
层理面强度
MATLAB
声发射模拟
Cohesive element
Hydraulic fracturing
Bedding plane strength
MATLAB
Acoustic emission simulation