摘要
中国致密砂岩油气和页岩油气储层中普遍发育近水平层理缝,层理缝是致密砂岩和页岩储层的重要储集空间和渗流通道,影响着致密砂岩和页岩中油气的富集、单井产能和开发效果。岩心、岩石薄片和扫描电镜的系统对比分析表明,致密砂岩和页岩中的层理缝具有相似的发育特征,其层理缝呈顺层理面发育,具有随微层面弯曲、断续、尖灭、分叉和转折等形态。与构造裂缝相比,层理缝的发育程度高,但规模相对较小、横向连续性和连通性相对较差,部分层理缝中可见方解石、石英、泥质或沥青充填。层理缝在地质成因上可分为压溶型、收缩型和异常高压型3种基本类型。其中,致密砂岩储层的层理缝主要在沉积成岩过程中由压实压溶作用和收缩作用形成,而页岩层理缝的形成主要与压实压溶作用、收缩作用和异常高压作用有关。层理缝的发育程度受纹层类型、纹层数量与厚度、TOC含量、黄铁矿含量等因素影响,凝灰岩中层理缝的发育程度还与刚性玻屑含量密切相关。溶蚀作用和构造抬升-剥蚀作用虽然不是影响层理缝形成的主要机理,但对于层理缝的开度、规模、横向连续性与连通性及其发育程度有着重要影响。
Nearly horizontal bedding fractures are commonly developed in the oil and gas reservoirs of tight sandstone and shale in China.As the important reservoir space and seepage passage for tight sandstone and shale reservoirs,bedding fractures affect the enrichment,individual well deliverability and development effect of oil and gas in tight sandstone and shale.According to the systematical comparative analysis of cores,thin sections and scanning electron microscopic images,the bedding fractures in tight sandstone and shale have similar development characteristics,which are developed along bedding plane,and present the morphologies such as bending,intermittent,pinching out,branching and turning along with microlayer.Compared with tectonic fractures,the bedding fractures are highly developed,but are characterized with relatively small scale and relatively poor lateral continuity and connectivity,and some of them are filled with calcite,quartz,argillaceous or asphalt.In terms of geologic origin,the bedding fractures can be divided into three basic types,i.e.,pressolution,shrinkage and abnormal high-pressure types.Specifically,the bedding fractures in tight sandstone reservoirs are mainly formed under compaction and pressolution and shrinkage in the sedimentary diagenetic process,while the formation of shale bedding fractures is primarily related to compaction and pressolution,shrinkage and abnormal high pressure.The development of bedding fractures is affected by factors such as laminated type,laminated number,laminated thickness,TOC content and pyrite content,while that of bedding fractures in tuff is also closely related to the content of rigid vitric fragments.Although dissolution and tectonic uplift and denudation are not the main mechanisms affecting the formation of bedding fractures,they have a great impact on the aperture,scale,lateral continuity and connectivity and development degree of bedding fractures.
作者
曾联波
吕文雅
徐翔
田鹤
陆诗磊
张洺菁
Zeng Lianbo;Lü Wenya;Xu Xiang;Tian He;Lu Silei;Zhang Mingjing(State Key Laboratory of Petroleum Resource and Prospecting,Beijing 102249,China;College of Geosciences,China University of Petroleum,Beijing 102249,China)
出处
《石油学报》
EI
CAS
CSCD
北大核心
2022年第2期180-191,共12页
Acta Petrolei Sinica
基金
国家自然科学基金石油化工联合基金重点项目(U1663203)
国家科技重大专项(2017ZX05049006)资助。
关键词
层理缝
发育特征
成因机理
油气意义
致密砂岩
页岩
bedding fracture
development characteristic
formation mechanism
hydrocarbon significance
tight sandstone
shale
