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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 the history of thermal history-burial, the evolution history of organic matter and the history of the accumulation of organic matter, petrographic, fluid inclusions and diagenetic mineral assemblages of carbon and oxygen isotopes, laser scanning confocal microscopy, cast thin films, cathodoluminescence and SEM This paper studied the densification mechanism, the evolution of diagenetic fluids and the matching between tight and accumulative history of the low permeability tight sandstone reservoirs in the Huagang Formation in the northern part of the central anticlinal zone of the Westlake Sag of the East China Sea.The main diagenesis of the low permeability and tight reservoirs Sequences: Early calcite cementation - Effective compaction - (Pressing) Quartz augmentation - Organic acid dissolution (associated authigenic quartz and kaolinite) - Kaolinite Erie Petrochemical - Montmorillonite illite - Ferrous calcite cements - Lower heat flux (associated with authigenic quartz and calcite cementation) - Hydrocarbon charging. The results show that the most important factor is the low porosity and low permeability of the reservoir. Lack of mudstone thin films, autolysis of autolysis and feldspar dissolution and quartz carried by exogenous heat flux make quartz more abnormally developed and carbonate feldspar filled with feldspar, which is important for low porosity of reservoir Factor, respectively, the proportion of the reduced hole were about 10% and 7%, respectively.Many authigenic illite “bridge ” plug pore throat is an important factor in low permeability.The above factors combined to create a low porosity and low porosity The infiltration of tight sandstone reservoirs, the recovered porosity evolution history and the history of hydrocarbon accumulation show that the low-permeability tight sandstone reservoirs in this area are of the “first-densified and later-formed” type.