东营凹陷北部砂砾岩成岩作用及次生孔隙特征

CHARACTERISTIC OF DIAGENESIS AND SECONDARY POROSITY OF NORTHERN GLUTENITE IN NORTHERN DONGYING SAG

通过对大量岩石薄片、扫描电镜以及储层物性数据进行分析,研究了东营凹陷北部砂砾岩体的成岩作用和次生孔隙的发育特征。东营凹陷北部发育近岸水下扇、深水浊积扇等砂砾岩扇体,储层成分成熟度和结构成熟度均较低。砂砾岩储层在埋藏过程中经历了压实、胶结、溶蚀等多种成岩作用。压实作用以机械压实为主;胶结作用主要为碳酸盐胶结、石英次生加大和粘土矿物胶结;溶蚀作用以碳酸盐胶结物溶蚀为主,长石和灰岩岩屑的溶蚀次之。根据镜质体反射率、包裹体测温以及粘土矿物混层比的变化特征,确定砂砾岩体经历了早成岩A、早成岩B和中成岩A期,同期孔隙经历了由原生到次生的演化过程。北部砂砾岩体次生孔隙主要发育在1 650～2 450 m深度范围,与北部地区滨南、胜坨地区相比,利津地区次生孔隙相对不发育。

Based on the analysis of thin section,SEM and there servoir property data,the digenesis and characteristics of the development of the secondary porosity in the glutenite of northern Dongying Sag are studied.Glutenite fans such as nearshore subaqueous fan,deep water turbidite fan are developed in the northern part of Dongying Sag.They have a low maturity in composition and structure.Glutenite reservoir has experienced many kinds of diagenesis,suchas compaction,cementation,dissolution and soon.Mechanical compaction is the main compaction.Cementations are mainly carbonate cementation,quartz overgrowth and clay minerals cementation.Dissolution comprises carbonate cementation content dissolution,felds parparticles and limestone debris dissolutions.According to the characteristics of vitrinite reflectance,fluid inclusion thermometry,and clay minerals mixed-layer proportion,it is ascertained that the glutenite has experienced stage A and B of the early diagenesis,and stage A of the middle diagenesis.At the same time,the pores have experienced an evolutionary process from primary to secondary.In this area,secondary pore mainly develops in the range of 1 650～2 450m.Compared with Binnan and Shengtuo area,secondary porosity in Lijin is less developed.