鄂尔多斯盆地东南部山西组、下石盒子组储层特征及差异性对比

摘要

研究鄂尔多斯盆地东南部二叠系山西组、下石盒子组砂岩储层特征的差异性.通过野外观察、薄片鉴定、扫描电镜、物性分析等手段,对山西组、下石盒子组储层岩石学特征、物性特征、孔隙特征及成岩作用等进行对比分析.结果显示近源快速沉积以辫状河三角洲沉积环境为主的下石盒子组储层表现出更低的成分成熟度和结构成熟度,曲流河沉积环境下的山西组由于优质孔隙的比例更高、孔隙连通性更好的原因,储层表现出更好的物性特征;成岩时期,石英含量更高、酸性流体更为充足的山西期粒间孔和溶蚀孔发育得更好,高岭石和水云母中出现的晶间孔主要集中在下石盒子组出现.储层特征明显的差异性是物源、沉积环境和成岩作用等多种因素控制影响的结果,鄂尔多斯盆地东南部地区山西组较下石盒子组具有更优质的储层表现.%The characteristics of petrology,physical property,pore and diagenesis of Shanxi-Lower Shihezi Formation in the southeast Ordos Basin were compared and analyzed on the basis of field investigation,thin section observation,application of scanning electron microscopy and physical property analysis and other analytical methods,so as to understand the difference of sandstone reservoir characteristics.It shows that the sedimentary facies of the Lower Shihezi Formation are dominated by braided river delta sedimentary environment,with lower compositional maturity and structural maturity.The Shanxi Formation of meandering river sedimentary environment shows better physical properties due to higher porosity and better pore connectivity.During the diagenetic period,the quartz content in the rock is high and the intergranular pores and dissolved pores in Shanxi Period are well developed.Intergranular pores in the kaolinite and hydromica mainly occur in the lower Shihezi Formation.It is considered that the difference of reservoir characteristics is the result of controlling influence of sediment provenance,sedimentary environment and diagenesis.The Shanxi Formation has better reservoir performance than the Lower Shihezi Formation in the southeastern part of the Ordos Basin.