黄骅坳陷北大港潜山中生界碎屑岩储层特征及成因机理

为了弄清黄骅坳陷北大港潜山中生界碎屑岩储层的成因机理,综合应用目的层段的岩心、X射线衍射、铸体薄片、扫描电镜及测录井等资料,结合地层的埋藏演化史,系统分析了北大港地区中生界碎屑岩储层特征及成因机制。结果表明:①研究区中生界碎屑岩岩石类型较多,但以长石岩屑砂岩、岩屑石英砂岩和岩屑砂岩为主。②研究区中生界碎屑岩储层发育有原生孔隙、次生溶蚀孔隙和微裂缝等储集空间类型,但以次生溶蚀孔隙为主,原生孔隙和微裂缝所占比例较小;储层物性特征以低孔-低渗、低孔-特低渗为主,高孔-高渗储层段发育的比例较小,多数储层为低渗小孔喉储层。③储层发育受沉积、成岩和构造作用共同控制,成岩过程中的压实、胶结、溶蚀及油气充注对储层发育均有影响,其中溶蚀作用对储集空间发育的影响较大;从对储层发育的控制程度来看,岩石颗粒的分选性强于岩性,成岩压实作用强于胶结作用;构造作用形成的斜坡、不整合面及断裂不仅为溶蚀作用的发生提供了场所,也为溶蚀流体的流动提供了通道。该研究成果为黄骅坳陷北大港潜山地区有利勘探目标区的优选提供了地质依据。

Characteristics and genetic mechanism of Mesozoic clastic reservoirs in Beidagang buried hill,Huanghua Depression

The characteristics and genetic mechanism of Mesozoic clastic reservoirs in Beidagang buried hill,Huanghua Depression were systematically analyzed by combining the data of core,X-ray diffraction,casting thin section,scanning electron microscope and logging with the burial evolution history of the strata.The results show that:(1)There are many types of Mesozoic clastic rocks in the study area,but they are mainly feldspathic lithic sandstone,lithic quartz sandstone and lithic sandstone.(2)The Mesozoic clastic reservoirs in the study area are composed of primary pores,secondary dissolved pores and micro-fractures,dominated by secondary dissolved pores.The reservoir properties are characterized by low porosity and low to extra low permeability.(3)Reservoir development is influenced by sedimentary,diagenetic and tectonic processes.Compaction,cementation,dissolution and oil and gas charging in diagenetic process all have effects on reservoir development,among which dissolution has the greatest impact on the development of reservoir space.From the control degree of reservoir development,the sorting of rock particles is stronger than lithology,and compaction is stronger than cementation.The slope,unconformity surface and fault caused by tectonic action not only provide the place for the dissolution,but also provide channel for the flow of the dissolution fluid.The research results provide a geological basis for the optimization of favorable exploration target areas in Beidagang buried hill area of Huanghua Depression.