苏里格气田东区马五段4亚段1小层与5亚段白云岩储层对比研究

A Comparative Study on Dolomite Reservoirs in the East of Sulige Gasfield

鄂尔多斯盆地苏里格气田东区下古生界中奥陶统马家沟组五段4亚段1小层(O2m4(1)5)和5亚段(O2m55)分别为上、中组合中主力产气层,但两者在储层规模、储集性能上却相差较大。对比发现,O2m4(1)5储层厚度稳定,分布在局限蒸发环境含膏云坪微相中,岩石类型主要为泥粉晶含硬石膏结核白云岩和泥粉晶白云岩,孔隙空间为膏模孔、裂缝;O2m55储层在平面上呈珠串状分布,在云坪及颗粒滩微相分布较厚,岩石类型主要为粗粉晶白云岩和颗粒白云岩,储集空间为晶间孔和少量的裂缝。白云岩成因及成岩作用的差异造成了2个层位储层的差异。

The O2m4(1)5and O2m55of middle Ordovician Majiagou Formation in the east of Sulige Gasfield were the main gas reservoirs in upper and middle assemblage.But they were quite different in reservoir size and reservoir characteristics.It was found out by comparison that the reservoir thickness of O2m4(1)5was stable,and it was distributed in the gypsum contained dolomite flat microfacies with limited evaporation environment.The main types of rocks were powder crystal argillaceous dolomite with anhydrite concretion and powder crystal argillaceous dolomite,while the main types of pore space were gypsum mould pore and cracks.However,the reservoir thickness of O2m55was beadedly distributed in the plane,it was relatively thick in dolomite flat and grain beach microfacies.The main types of rocks were coarse powder crystal dolomite and grain dolomite,while the main types of pore space were intercrystalline pore and a small amount of cracks.The difference of the origin of dolomite and diagenesis causes the difference in reservoirs among these two formations.