致密砂岩储层物性的主控因素分析

以鄂尔多斯盆地上古生界下石盒子组盒二段储层为例,综合利用岩心、测井以及各种分析化验资料,通过储层沉积学、岩石学和成岩作用的研究,详细探讨了该区致密砂岩储层物性的主控因素.研究结果表明,盒二段储层属于辫状河流相沉积体系,沉积微相在宏观上控制了储层物性的空间分布,其中辫状河主河道微相物性最好;在砂岩的岩矿组成中,随石英含量的增加,长石、岩屑等含量的减少,储层物性变好;研究区经历了较强的成岩作用,其中压实作用、胶结作用对储层原始孔隙起到破坏作用,导致储层致密,低孔低渗,但溶蚀作用可以在一定程度上改善储层的储集性能,次生孔隙发育带的识别将是致密砂岩气藏勘探的一个重要方向.

Analysis of main control factors of the physical property of tight sandstone reservoir

Taking He-2 member of lower Shihezi formation in upper Paleozoic,Ordos Basin as an example,the factors of controlling the physical property of the tight sandstone reservoir are discussed in detail by comprehensively studying on the sedimentology,lithology and diageneses of the reservoir based on core,well logging data.It is shown that He-2 reservoir belongs to braided river sedimentary system.The distribution of microfacies controls the spatial distribution of reservoir property,the main river channel microfacies of the braided river has the best reservoir property.From the components of the sandstone,the reservoir physical property tends to be getting better with the increase of the quartz content and the decrease of the feldspar and detritus contents.The reservoir experienced intensive diageneses,of which compaction and cementation have damage action on the preservation of original intergranular pore,and hence they reduce the porosity and permeability of the reservoir and make the sandstone reservoir tight.But corrosion can improve the physical property of the reservoir in certain extent.From the study results above,it is held that the recognition of secondary pore development zones can guide the exploration of tight sandstone gas reservoir.