塔西南阿克莫木气田白垩系克孜勒苏群砂岩储层特征及其控制因素

根据常规薄片、铸体薄片、常规物性和粒度分析,研究了塔西南阿克莫木气田克孜勒苏群砂岩储层的地质特征及其主控因素。结果表明,该套储层岩石类型以长石岩屑砂岩及岩屑砂岩为主;储层物性较差,为低孔、低渗储层;孔隙类型以次生孔隙为主,主要有粒内溶孔、粒间溶孔及微孔隙等;压汞曲线排驱压力较高,一般孔喉分选较差,总体具有小孔-细喉的孔隙结构特征。阿克莫木气田克孜勒苏群砂岩储层发育程度与碎屑颗粒的粒度粗细、岩屑含量以及成岩阶段的压实、胶结和溶蚀作用具有较强的相关性。辫状水道控制下的碎屑颗粒越粗,岩屑含量相对越高,溶蚀作用越强,储层就越发育;压实作用及成岩后期的碳酸盐岩、粘土类、硅质矿物的胶结作用不利于储层发育。

Characteristics and their controlling factors of Cretaceous Kezilesu Group sandstone reservoirs in Akmomu gas field, northwestern Tarim Basin

Characteristics of Kezilesu Group sandstone reservoirs and factors controlling their development are investigated based on the analysis of routine thin-sections,cast thin-sections,physical property and grain sizes.The results show that the reservoir rocks are dominanted by feldspathic litharenite and lithic sandstones with low porosity and permeability,and the pore types are mainly secondary pores including intragranular dissolved pores,intergranular dissolved pores and micropores.The mercury intrusion curve has high displacement pressure,indicating that the sorting of pore throats is poor and the pore structure feature in small pores and fine throats.The development of Kezilesu Group sandstone reservoirs in Akemomu gas field has strong correlation with grain sizes,debris content and diagenetic compaction,cementation and dissolution.For reservoir rocks were deposited under the control of braided rivers,their quality improves with grain size enlarging,debris content increasing and enhancing of dissolution.On the contrary,compaction and cementation of carbonate,clay and siliceous mineral formed during the post-diagenesis have adverse effects on reservoir rocks.