库车坳陷克拉苏构造带博孜段巴什基奇克组超深储层特征及成岩演化

Characteristics and diagenesis evolution of ultra-deep Bashijiqike Formation reservoir in Bozi Section of Kelasu structure belt,Kuqa Depression

库车坳陷克拉苏构造带博孜段巴什基奇克组储层成岩作用类型多样,成岩演化复杂。在岩心观察描述、多尺度显微分析及相关储层物性分析的基础上,系统研究了博孜段巴什基奇克组岩石学特征、储层特征及成岩作用特征,进一步建立了储层成岩演化序列。研究结果表明,研究层段的储层在埋藏后的发育演化过程中,先后主要经历了压实作用、胶结作用、溶解作用以及交代作用4种成岩作用。储层经历了较强的垂向和侧向压实作用。胶结物类型多样,主要为方解石、白云石和膏质,其次为石英和钠长石,常见自生赤铁矿,在博孜102井、博孜21井和博孜22井的局部层段还可见较多的方沸石胶结物。溶解作用的对象主要是长石颗粒、长英质岩屑和石英颗粒,博孜102井、博孜21井和博孜22井的局部层段还可见较多的方沸石胶结物被溶解,极少见碳酸盐胶结物发生溶解。储层中发育的交代作用主要有碳酸盐和膏质胶结物交代石英、长石和长英质岩屑等碎屑颗粒。博孜段巴什基奇克组储层经历了浅埋藏压实作用-大气水长石溶解/石英、钠长石胶结→第1期碳酸盐胶结/第1期膏质胶结/石英溶解→第2期碳酸盐胶结/第2期膏质胶结→方沸石溶解/长石溶解的成岩演化过程。

The types of diagenesis of Bashijiqike Formation reservoir in Bozi Section are diverse,and the diagenesis evolution is complex in Kelasu structural belt of Kuqa Depression.Based on the observation and description of cores,multiscale microscopic analysis,and related reservoir physical property analysis,the characteristics of petrology,reservoir and diagenesis of Bashijiqike Formation in Bozi Section were systematically studied,and the diagenetic evolution sequence of the reservoir was further established.The research showed that the reservoir mainly underwent four types of diagenesis,namely compaction,cementation,dissolution,and metasomatism,and strong vertical and lateral compaction during the development and evolution process of the reservoir in the study interval after its burial.There are various types of cement,mainly calcite,dolomite and gypsum,followed by quartz and albite,and autogenic hematite is common.In addition,analcime cement is also found in local intervals of wells Bozi102,Bozi21 and Bozi22.The most objects of dissolution are feldspar particles,felsic cuttings and quartz particles.Carbonate cements are also dissolved in partial intervals of wells Bozi102,Bozi21 and Bozi22,and very few carbonate cements are dissolved.The metasomatism developed in the reservoir mainly involves the replacement of quartz,feldspar,felsic rock debris and other debris particles with carbonate and gypsum cement.The basic diagenetic evolution process of Bashijiqik Formation reservoir in Bozi Section is early compaction→feldspar dissolution/quartz and albite cementation→carbonate cementation/first phase gypsum cementation/quartz dissolution in the first stage→carbonate cementation/second phase gypsum cementation in the second stage→analcime dissolution/feldspar dissolution.