鄂尔多斯盆地奥陶系马家沟组风化壳岩溶储层是盆地重要的储集类型,但后期成岩及埋藏期对溶蚀孔洞的充填,造成不同地区有效储层发育具有很大差异.对显微薄片观察及地球化学测试等研究表明,充填物主要以白云石、方解石、石英、石膏、硅质等为主,并常以组合形式出现,其中以白云石为主的充填最有利于孔洞的保存.孔洞充填主要经历了早表生期(风化壳期),浅埋藏期和深埋藏期三个阶段.认为孔洞充填主要受控于后期构造格局的转变.

Ordovician Majiagou paleokarst weathering crust is an important reservoir in Ordos Basin but filling in the early dissolved pores and caves during late diagenesis and burial caused the effective reservoirs to be anisotropic in different areas. On the base of a large numbers of data from microscope observation and geochemical analysis of cores, it is shown that the fillings in pore space are dolomite, calcite, quartz and anhydrite, or assorted of them, in which dolomite-dominating filling is sure to be the most favorable for porosity preservation. Three stages of pore-space filling are identified. It is deemed that the filling is mainly in control of late tectonic transformation in this region.