库车坳陷克拉苏构造带致密砂岩气储层物性特征

 在库车坳陷克拉苏构造带大北地区地质研究的基础上,利用显微镜观测、激光共聚焦显微扫描、高压压汞分析及孔渗测试等方法,研究了致密砂岩气储层物性特征。结果表明,库车坳陷的致密砂岩气储层孔隙类型以槽型孔、溶蚀孔为主;致密砂岩气储层排驱压力一般在5 MPa以上,孔隙分选性差,孔喉半径较小;致密砂岩气储层孔隙度小于5%时,孔隙度与渗透率之间的相关性较差,表现为孔隙度低而渗透率高,推断是微裂缝的发育提高了砂岩的渗透率;致密砂岩气储层岩石类型以长石岩屑质石英砂岩为主,胶结作用以方解石胶结为主,裂缝改造作用明显。

Tight sandstone gas reservoir properties of Kelasu-structural belt in Kuqa-depression

Based on the geological research of Kelasu structural belt in Kuqa depression, we analyze tight sandstone gas reservoir properties of Dabei area by using microscope and laser scanning confocal microscope (LSCM) observation, mercury-injection capillary pressure (MICP) testing, and porosity and permeability testing. The results show the followings. The major pore types in tight sandstone gas reservoirs of Dabei area are slot pores and solution pores; Expulsion pressure of tight sandstone in the study area is generally above 5 MPa, with poor pore sorting and small pore throat radius; When the sandstone reservoir porosity is less than 5%, the correlation between porosity and permeability is weak, with small porosity and high permeability, which may be resulted from the contribution of micro-fractures in tight sandstone. The major rock type in Dabei gas field is feldspar lithic quartz sandstone, and it is dominated by calcite cementation. Besides, tight sandstone reservoir shows obvious fractures reconstruction.