榆林大型气田石英砂岩储集层特征及成因

Origin and characteristics of quartz-sandstone reservoir of the Yulin gas field, Ordos Basin

鄂尔多斯盆地中东部的榆林气田是以上古生界山西组山2段石英砂岩为主要储集层的大型气田。山2段石英砂岩属致密储集层,孔隙度和渗透率呈明显的正相关关系,孔隙类型以粒间孔为主,具有排驱压力和中值压力低、粗孔喉、孔隙结构较为均匀的特点,形成于水动力较强的沉积环境,是碎屑成分在较长距离的搬运过程中经过化学分解、机械分选作用而形成的。

Yulin gas field is one of the large gas fields in the middle-east part of the Ordos Basin. Its reservoir strata, mainly tight quartz-sandstone of the Shan-2 Member of the Shanxi Formation, show a positive correlation between porosity and permeability, with mainly intergranular porosity, low drainage and median pressures, coarse pore throats, and a homogeneous pore structure, suggesting a high water-energy depositional environment. Chemical weathering and mechanical sorting through long distance transportation may have played an important role in forming the reservoir characteristics of the quartz-sandstone.