周口拗陷和通许隆起二叠纪砂岩中石英的二次增生

对周口和通许两地区 4口井砂岩的薄片观察、多种测试、分析 ,发现砂岩中石英的增生可分窄边型、宽边型和自形边型 3种 ,增生石英的发育情况与砂岩的类型、成分等密切相关 .宽边和自形边型增生石英形成的温度一般在 1 0 0℃～ 1 50℃ .硅质物来源主要是孔隙内原生孔隙水供给、成岩过程中泥层蒙脱石→伊利石转化供给、或长石的溶解作用供给 .成岩中晚期有机质向烃转化发生脱羧基作用 ,地下流体变为酸性 ,促进了长石颗粒的溶解 ,增加了硅物质供给 .通过研究该地区内砂岩石英的增生 ,对进一步分析区内砂岩的孔隙演化、次生孔隙形成、砂岩储层物性等具有重要意义

The two growth of quartz in sandstone of Permain system at Zhoukou depression and Tongxu uplift

Based on lots of indoor observation, tests and analyses by 4 wells in the two areas, it is discovered that authigenic quartz in sandstone can be divided into three kinds:narrow,width and fine crystal. Species and composition of sandstone are the main factors which controled the formation of authigenic quartz. Formation temperature of width and fine crystals authigenic quartz is generally at 100 ℃-150 ℃.The source of silila for quartz cement are mainly the flow of pore fluid water, transformation of clay minerals (M-I) in diganesis process, dissolution of feldspar.In intermedicate-late stage of diagenisis,organic transformed into hydrocarbon and caused the decarboxylation.The fluid of underground changed into acid. It facilitated dissolution of feldspar and added up silila for the authigenesis of quartz.