陇东地区HQ区块东部长8致密砂岩储集层成岩相划分

Diagenetic Facies Division of Chang 8 Tight Sandstone Reservoirs in Eastern HQ Block,Longdong Area

为确定鄂尔多斯盆地陇东地区HQ区块东部长8致密砂岩储集层成岩相及其演化规律,综合铸体薄片、岩石物性、岩心、测井等资料,在划分单砂层岩心成岩相和测井相后,采用优势相法,对研究区长8含油层系成岩相进行分类,筛选出对油气勘探有利的成岩相,预测其有利成岩相带展布。依据成岩作用的影响,可将目的层成岩相划分为5类:剩余粒间孔与长石溶蚀相、绿泥石胶结剩余粒间孔相、绿泥石与伊利石强胶结相、自生碳酸盐胶结相和黏土杂基压实相。剩余粒间孔与长石溶蚀相为研究区最利于油气储集的成岩相类型,有利成岩相总体上呈条带状展布,连续性较好,分布面积较大,研究区中部是有利成岩相带的主要发育区。

To determine the diagenetic facies and their evolution patterns of the Chang 8 tight sandstone reservoir in the eastern part of the HQ block in the Longdong area of the Ordos basin,the diagenetic facies and logging facies of the cores from individual sand layers were di⁃vided by using the data of cast thin section,rock property,coring,and logging.Then,the diagenetic facies of the Chang 8 reservoir were classified with the dominant facies method,the favorable diagenetic facies for oil and gas exploration were determined,and the distribution zones of favorable diagenetic facies were predicted.Considering the diagenetic influences,the diagenetic facies of target layers can be clas⁃sified into five categories:facies of residual intergranular pores and feldspar dissolution,facies of chlorite⁃cemented residual intergranular pores,strongly chlorite⁃illite cementation facies,authigenic carbonate cementation facies,and clay matrix compaction facies.The facies of residual intergranular pores and feldspar dissolution is the most favorable for hydrocarbon accumulation in the study area.Generally,the fa⁃vorable diagenetic facies distribute as strips with good continuity and in large areas.The central and east⁃central parts of the study area are the main development zones for favorable diagenetic facies belts.