征沙村地区三工河组低渗透砂岩储层孔隙结构研究

低渗透砂岩储层孔隙结构复杂,制约了该类型油藏的高效勘探开发,一直是地质学者研究的关键问题。以准噶尔盆地征沙村地区侏罗系三工河组低渗透砂岩储层为研究对象,利用岩石薄片、铸体薄片、扫描电镜、X射线衍射等微观测试方法,结合常规压汞、恒速压汞及核磁共振等岩石物理分析手段,系统地对孔隙结构进行了综合研究。结果表明:该区低渗透砂岩储层的岩石类型以长石岩屑砂岩为主,储集空间主要为残余粒间孔和粒间溶孔;喉道半径的差别是造成渗透率级差的主要控制因素;核磁共振横向弛豫时间T_2的分布与孔隙半径有较好的对应性,可以有效评价可动流体孔隙特征。研究对本地区的勘探开发具有积极作用,可以应用到其他相似低渗透砂岩油气藏评价中。

Study on pore structure of low-permeability sandstone reservoirs of the Sangonghe formation of Zhengshacun region

Pore structure of low permeability sandstone reservoir is complex, which restricts efficient exploration and development of this type of reservoir. It has been a key problem in the study of geological scholars.For the low-permeability sandstone reservoirs of the member 2 of Sangonghe formation of Jurassic in Zhengshacun region, Junggar Basin, the fine characterization of their microscopic features was studied by means of analyzing plenty of data from thin section, casting thin section, SEM, X-ray diffraction, mercury injection ,constant-rate mercury injection, and nuclear magnetic resonance (NMR). Results show that (1) they are mainly composed of both feldspathic lithic sandstone; (2) their reservoir space includes residual intergranular pores and intergranular dissolved pores; (3) the throat radius difference is is the key factor for permeability differences; (4) the transverse relaxation time T2 distribution and pore radius have good correspondence, and range of pore throat of movable fluid can be obtained by NMR tests. This study has positive effect on the pore structure of low permeability sandstone reservoir and the exploration and development of the local area, and can be applied to other similar low permeability sandstone reservoirs.