湖南桑植地区下志留统龙马溪组页岩孔缝特征及主控因素  

Pore and fracture characteristics and main controlling factors of Lower Silurian Longmaxi Formation shale in Sangzhi area of Hunan Province

作　　者：张成龙[1,2] 钱战宏[3] 张建东[3] 邹海燕 许姗姗[3] 蒋文博 付雷[1] 金晓琳[1] ZHANG Chenglong;QIAN Zhanhong;ZHANG Jiandong;ZOU Haiyan;XU Shanshan;JIANG Wenbo;FU Lei;JIN Xiaolin(Center for Hydrogeology and Environmental Geology,China Geological,Baoding 071051,China;Key Laboratory of Carbon Dioxide Geological Storage,China Geological Survey,Baoding 071051,China;Exploration and Development Research Institute,PetroChina Qinghai Oilfield Company,Dunhuang 736200,China)

机构地区：[1]中国地质调查局水文地质环境地质调查中心,河北保定071051 [2]中国地质调查局二氧化碳地质储存重点实验室,河北保定071051 [3]中国石油青海油田公司勘探开发研究院,甘肃敦煌736200

出　　处：《大庆石油地质与开发》2023年第2期13-21,共9页Petroleum Geology & Oilfield Development in Daqing

基　　金：国家科技重大专项“湖南省页岩气资源潜力评价”(1212011220802)。

摘　　要：桑植地区多口探井发现良好的页岩气显示,表明了龙马溪组海相地层具备勘探开发的价值,但整体勘探程度较低、孔缝类型划分标准不统一、孔缝影响因素需要系统归纳。为了开展桑植地区龙马溪组页岩孔缝的发育特征与主控因素研究,在文献调研的基础上,结合野外实勘、页岩露头、岩心观察、利用薄片及X-衍射、电镜扫描下天然裂缝特征参数分析,从宏观到微观,对页岩孔缝和影响因素进行了深入研究。研究结果表明:该页岩内部发育多种储集空间类型,孔隙类型划分为2大类7小类、裂缝类型划分为3大类6小类;页岩孔缝发育和分布受内外因共同影响和控制,构造因素是页岩裂缝发育的控制外因,脆性矿物的含量、有机碳含量、岩石力学性质等是影响裂缝发育的重要内因;其中多幕次挤压构造活动决定了研究区裂缝的性质与整体发育特征;脆性矿物含量、有机碳含量则与裂缝发育程度呈正相关;由于页岩的力学性质非均质性和各向异性,在构造活动下,呈现了与“S”形构造体系相关的NE―SW向方位期次配套裂缝。研究成果为桑植地区龙马溪组页岩气评价与勘探开发提供借鉴。Several exploratory wells in Sangzhi area got good shale gas shows, indicating the exploration and development potential of marine strata in Longmaxi Formation, but with overall low degree of exploration, non-standard-ized or non-unified classification criteria of pore and fracture types, and non-systematically summarized influencing factors of pores and fractures. In order to study the development characteristics and main controlling factors of shale fractures in Longmaxi Formation in Sangzhi area, based on literature review and natural fractures characteristics pa-rameters analysis through combining field investigation with outcrop, core observation, thin section, XRD and SEM, the shale pores and fractures and their influencing factors are studied from macro-to micro-scale. The results show several types of accumulation space in the shale, with pore types divided into 2 categories including 7 subcate-gories and fracture types divided into 3 categories including 6 subcategories. The development and distribution of shale pores and fractures are influenced and controlled by internal and external factors. Structural factors are exter-nal factors controlling shale fractures development, while brittle minerals content, organic carbon content and rock mechanical properties are important internal factors affecting shale fractures development. The properties and over-all development characteristics of fractures in the studied area are determined by multiple compressional tectonic ac-tivities, while brittle minerals content and organic carbon content are positively correlated with fractures develop-ment degree. Due to the heterogeneity and anisotropy of mechanical properties of shale and with structural activi-ties, there are NE-SW directional matching fractures associated with S-shape tectonic system. This research pro-vides evidence for shale gas exploration and development in Longmaxi Formation in Sangzhi area.

关 键 词：湖南桑植地区 黑色页岩 龙马溪组 储层 孔缝特征 主控因素 

分 类 号：TE122[石油与天然气工程—油气勘探]