鄂尔多斯盆地南部马家沟组成岩作用特征

The Diagenesis Characteristics of Ordovician Majiagou Reservoir in Southern Part of Ordos Basin

通过对研究区16口钻井15条剖面数百片岩石薄片的详细鉴定,结合沉积史和区域地质特征,综合分析了主要目的层马家沟组的成岩作用类型及其特征。马家沟组储层的岩石类型主要为石灰岩和白云岩。石灰岩类型多样,主要有泥晶—微晶灰岩、微晶—亮晶颗粒灰岩及云斑灰岩等;白云岩以泥晶—微晶白云岩为主。主要的建设性成岩作用为白云石化作用和溶蚀作用;不利的成岩作用主要有重结晶、压实压溶、去白云石化、膏化等作用。在此基础上,进一步分析了鄂尔多斯盆地南部的成岩作用演化序列。

Based on data of conventional identification of several hundreds thin-sections from 16 wells in the southern part of Ordos Basin,the types and characteristics of the diagenesis of Ordovician Majiagou Formation reservoir are analyzed in combination with the depositional history and regional geological characteristics of the research region.It is conclude that the Majiagou reservoir rocks predominantly consist of limestone and dolostone.The limestone commonly are micritic limestone,microlitic and sparry grainstone and dolomite-stained limestone.The dolostone mainly are dolomicrite.Dolomitization,dissolution are the main constructive ones while recrystallization,compaction,pressolution,dedolomitisation and gypsification are the main destructive diagenesis in Majiagou reservoir.In addition,the evolutionary sequence of diagenesis in this region is discussed.