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吐哈盆地台北凹陷中侏罗统三间房组沉积时 ,凹陷北部因地形较陡 ,发育扇三角洲 ;凹陷南部因地形较缓 ,发育辫状河三角洲。分流河道沉积的碎屑岩复合体在扇三角洲和辫状河三角洲沉积中非常发育 ,是其沉积主体。三间房组碎屑岩的成岩作用主要为机械压实作用、胶结作用和溶解作用。凹陷北部扇三角洲前缘碎屑岩体以机械压实作用为其主要特征 ,溶蚀作用微弱 ,碎屑岩体在强烈的机械压实作用改造下 ,原生粒间孔大部分消失 ,成为低孔低渗的致密储集体 ;凹陷南部辫状河三角洲以自生矿物的胶结作用和不稳定组分的溶解作用为特征 ,由于刚性物质含量较高 ,因而虽经机械压实作用 ,但却保留了较多的残余粒间孔 ,碎屑岩体在溶蚀作用的改造下 ,成为物性良好的储集体。
During deposition of the Sanjianfang Formation of the Middle Jurassic in the Taipei depression of the Turpan-Hami basin, the northern part of the depression was characterized by a steep terrain with fan delta. In the southern part of the depression, braided river delta was developed due to the slow terrain. The clastic rock complex of distributary channel sedimentation is well developed in fan delta and braided river delta deposits and is the main body of sedimentary. The diagenesis of the Sanfangfang clastic rocks is mainly mechanical compaction, cementation and dissolution. In the north of the depression, the fan delta front clastic rocks are characterized by mechanical compaction and weak dissolution. Under the action of strong mechanical compaction, most of the original intergranular pores disappear and become low porosity and low porosity Tight reservoirs. The braided delta in the south of the depression is characterized by the cementation of authigenic minerals and the dissolution of unstable components. Due to the high content of rigid materials, it retained more mechanical compaction Of the remaining intergranular pores, clastic rock body in the dissolution of the transformation, a good reservoir of physical properties.