低渗致密砂岩储层的致密化机理与成岩流体演化——以东海西湖凹陷中央背斜带北部花港组为例  

Densification mechanism and diagenesis fluid evolution of low-porosity and low-permeability tight sandstone reservoir:An example from Huagang formation in the northern of the central anticlinal zone in Xihu depression,East China Sea

作　　者：苏奥[1,2] 陈红汉[1] 王存武 李倩[4] 李培军[1] SU Ao CHEN Honghan WANG Cunwu LI Qian LI Peijun(Key Lab of Tectonics and Petroleum Resource of Ministry of Education, China University of Geosciences, Wuhan, Hubei 430074, China Geophysical Research Institute, BGP, CNPC, Zhuozhou, Hebei 072750, China CNOOC Research Institute, Beijing 100027, China Institute of SINOPEC Offshore Oil ＆ Gas Company, Shanghai 200120,China)

机构地区：[1]中国地质大学(武汉)构造与油气资源教育部重点实验室,湖北武汉430074 [2]中国石油东方地球物理公司研究院,河北涿州072750 [3]中海油研究总院,北京100027 [4]中国石化上海海洋油气分公司研究院,上海200120

出　　处：《中国矿业大学学报》2016年第5期972-981,1029,共11页Journal of China University of Mining & Technology

基　　金：国家重大科技专项(2011ZX05023-004-010)

摘　　要：基于热史-埋藏史、有机质成熟度演化史和成藏史,应用岩相学、流体包裹体、成岩矿物的碳氧同位素组成、激光共聚焦扫描显微镜、铸体薄片、阴极发光、扫描电镜等手段对东海西湖凹陷中央背斜带北部花港组低渗致密砂岩储层的致密化机理、成岩流体演化和致密史与成藏史的匹配关系进行了研究.认为低渗致密储层的主要成岩序列:早期方解石胶结—有效压实作用—(压溶)石英加大—有机酸溶蚀(伴生自生石英和高岭石)—高岭石的伊利石化—蒙脱石的伊利石化—含铁方解石胶结—下部热流(伴生自生石英和方解石胶结)—烃类充注.研究结果表明:强压实作用是储层低孔低渗最为主要的因素,它对减孔量的比重约占83%.绿泥石薄膜缺乏,压溶、长石溶蚀生成的自生石英和外源热流携带的石英使得石英加大异常发育以及碳酸盐胶结充填长石溶孔,是储层低孔的重要因素,对减孔比重分别约为10%和7%.大量自生伊利石"搭桥式"堵塞孔喉是低渗的重要因素.以上各种因素叠加造就了该区花港组低孔低渗致密砂岩储层.恢复的孔隙度演化史与成藏史显示,该区低渗致密砂岩储层为"先致密后成藏"类型.Based on burial-thermal, organic matter evolution and accumulation history, this paper reveals densification mechanism, diagenesis fluid evolution and matching relation between densification and accumulation history of low-porosity and low-permeability tight sandstone reservoir of Huagang formation in the north of the central anticlinal zone in Xihu depression, East China Sea, by using microphysiography, fluid inclusion, stable carbon isotope composition of diagenetic mineral, laser scanning confocal microscope, casting thin section, cathode luminescence and scanning electron microscope. It is revealed that diagenetic sequence in tight sandstone reservoir include： early calcite cementation, effective compaction, （pressure solution） secondary overgrowth of quartz, corrosion of organic acid（associated authigenic quartz and kaolinite）, kaolinite illitization, montmorillonite illitization, iron calcite cementation, heat flow（associated authigenic quartz and calcite cementation）, and hydrocarbon charging. The forced compaction effect is the most important factor of low porosity and low-permeability reservoir, whose contribution to porosity decrement is about 83%. Lack of chlorite thin film, ab- normal secondary overgrowth of quartz as a result of pressure solution, feldspar corrosion and heat flow from external source, as well as carbonate cementation filling feldspar dissolved pore are important factors for low-porosity of reservoir, and their contribution values are 10% and 7% respectively. A large number of aulhigenic illite blocking pore throat whh＂bypass type＂ is a key factor for low-permeability. The mutual effects of all above factors give rise to the lowporosity and low-permeability tight sandstone reservoir of Huagang formation. According to the recovered history of porosity evolution and accumulation, the low permeability tight sand- stone reservoir is a type of densification before the hydrocarbon accumulation.

关 键 词：低渗致密储层 成岩 致密化 流体 西湖凹陷 

分 类 号：TE122[石油与天然气工程—油气勘探]