渤中凹陷西北缘东三段低渗透储层特征及控制因素

发布时间：2018-10-14 14:15

【摘要】：渤中凹陷西北缘东三段发育典型的扇三角洲砂砾岩储层,但对储层的成岩演化及控制因素认识不清。利用岩心、壁心、铸体薄片、扫描电镜、物性等资料,结合埋藏史及油气充注史,对东三段砂砾岩扇三角洲储层的成岩演化及其对储层物性的影响进行了研究。结果表明:研究区东三段储层类型宏观上以杂基支撑砾岩、颗粒支撑砾岩、含砾砂岩、中—粗砂岩为主,细砂岩次之;微观上以长石岩屑砂岩和岩屑长石砂岩为主,岩屑以火山岩岩屑为主,变质岩岩屑次之。该区储层具有典型的低渗透特征,储集空间以溶蚀粒间孔为主,原生粒间孔次之。储层的成岩环境经历了中性→酸性(大气淡水淋滤)→碱性→酸性→碱性→酸性→碱性的变化。大气淡水淋滤后持续的压实作用和碱性条件下的碳酸盐、黏土矿物等的胶结作用均是形成低渗的根本原因,而大气淡水的淋滤作用和酸性环境下的溶蚀作用均是形成次生孔隙的主要原因,距今7 Ma以来油气的持续充注作用有利于储层孔隙的保存,距今1.5 Ma以来有机酸脱羧作用形成的碱性流体环境易形成碳酸盐胶结和伊利石充填,是形成低渗透储层的最终原因。
[Abstract]:Typical fan delta sandy gravel reservoirs are developed in the eastern third member of the northwestern margin of Bozhong Sag, but the diagenetic evolution and controlling factors of the reservoirs are not well understood. The diagenetic evolution of sandstone fan delta reservoir and its influence on reservoir physical properties of the third member of the east formation are studied by using the core, wall core, casting thin section, scanning electron microscope, physical properties and other data, combined with burial history and oil and gas filling history. The results show that the reservoir types of the third member in the east of the study area are mainly supported conglomerate by complex base, conglomerate supported by grain, conglomerate sandstone, meso-coarse sandstone, fine sandstone, feldspathic sandstone and lithic feldspathic sandstone. Volcanic rocks are the main cuttings, metamorphic rocks followed by metamorphic rocks. The reservoir in this area is characterized by typical low permeability. The reservoir space is mainly composed of dissolved intergranular pores, followed by primary intergranular pores. The diagenetic environment of the reservoir has undergone the change of neutral acid (atmospheric fresh water leaching) alkalinity. The continuous compaction after atmospheric fresh water leaching and the cementation of carbonate and clay in alkaline conditions are the fundamental reasons for the formation of low permeability. The leaching of fresh water in the atmosphere and the dissolution in acidic environment are the main reasons for the formation of secondary pores. The continuous filling of oil and gas since 7 Ma is beneficial to the preservation of reservoir pores. The alkaline fluid environment formed by organic acid decarboxylation since 1. 5 Ma is easy to form carbonate cementation and Illite filling, which is the ultimate cause of formation of low permeability reservoir.
【作者单位】：中海石油(中国)有限公司天津分公司渤海石油研究院;
【基金】：“十三五”国家重大科技专项课题“渤海海域勘探新领域及关键技术研究”(编号:2016ZX05024003)资助
【分类号】：P618.13

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