鄂尔多斯盆地西缘逆冲带上古生界孔隙发育影响因素

对鄂尔多斯西缘逆冲带上古生界的岩心、薄片等资料进行了分析。从该区的构造、成岩作用、沉积相等方面分析了地层孔隙发育主要受构造和成岩等因素的影响,逆冲带的构造作用不仅使其产生许多裂缝,使孔隙度增加,而且构造抬升使地层承受的压力得到释放而减小,因而地层遭受的压实作用也相应减小。成岩作用所处阶段上提,从而使孔隙度、渗透率增加。在成岩作用中,受压实、压溶、胶结充填和溶蚀作用的影响较大。其中压实、压溶和胶结充填作用严重地损害了储层物性特征,使本区原生孔隙大大减少;而溶蚀作用从一定程度上使储层物性得到了改善,次生孔隙相对增多。另外,沉积微相决定了砂岩的分选性、粒度及杂基含量,进而影响了成岩作用及孔隙发育的演化特点。

Influence factors for development of the Upper Paleozoic pore in thrust belt of western Ordos Basin

The data of core and electron microscope thin sections acquired from the Upper Paleozoic thrust belt in the western Ordos Bain were analyzed. The structure, diagenesis, sedimentary microfacies and other factors in this area showed that the tectonic and diagenesis had great influences on the development of pores. The tectonic in thrust belt could make it create many cracks and increase porosity, and the tectonic uplifting could release and reduce the pressure on the strata. As a result, the compacting action on the strata was correspondingly reduced. The stage of the diagenesis went up, and porosity and permeability of strata increased. During the course of diagenesis, the compacting action, pressolution and consolidated filling destroyed the physical property of reservoir, which makes the primary pore of this area reduced greatly. To some extent, the chemical erosion made the physical property of reservoir getting better and increased the secondary pore relatively. In addition, the sedimentary microfacies determined the selection, grain size and the percentage of matrix in sand and then made an impact on diagenesis and evolution characteristics of porous development.