塔里木盆地库车坳陷大北地区白垩系巴什基奇克组(K₁b_s)储层以岩屑砂岩为主，夹少量长石岩屑砂岩，其粒度以细—中粒为主，杂基为铁泥质和泥质（2%~10%），胶结物以方解石（3%~15%）为主,粘土矿物以伊利石、绿泥石和伊/蒙混层为主，不含高岭石，伊/蒙混层中的蒙皂石含量一般为15%~20%，主要的孔隙组合为溶蚀孔—残余原生粒间孔，占储集空间总量的50%~90%，其次为微孔隙及构造缝，总体属于低孔低渗—特低孔特低渗储层。综合分析了该储层的岩性特征、古构造背景和沉积环境后认为：阶段性地前陆逆冲推覆构造作用对沉积旋回性、水体盐度变化及物源区距离变化的控制至关重要;构造活跃期扇三角洲前缘环境下的差分选中—粗砂岩,近源快速堆积下的高岩屑含量、干旱咸湖下的高碳酸盐胶结、早成岩期相对深埋—后期持续快速深埋压实作用,是特低孔低渗储层的主要成因;高产能储层的发育是构造平缓期辫状河三角洲前缘环境下的好分选中—细砂岩、早期表生溶蚀及弱碳酸盐胶结作用、晚期构造破裂的复合作用、叠加效应的结果。

Reservoirs of the Cretaceous Bashijiqike Formation in the Dabei area of the Kuqa depression are dominantly lithic sandstone with a little feldspar-lithic sandstone, and mostly fine-middle grains, with 2%~10% iron-mud and mud, 3%~15% calcite cement. Clay minerals are mostly illite, chlorite, and illite-smectite (15%~20% smectite), and have no kaolinite. The main pore types are emposieu-primary pores (50%~90%), followed by micropore and tectoclase, and the reservoirs generally belong to low porosity-permeability and extra-low porosity and permeability. Comprehensively analyses show that episodic thrusting-overriding tectonism had an utmost importance in controlling the sediment cycle, alteration of water salt and distance from provenance. Origin mechanisms of extra-low porosity and permeability reservoirs are: poorly sorting middle-and coarse-stones formed in fan delta front during tectonically active time, high content debris formed by proximal and quick deposit, high carbonate cement formed in dry saline lake, relatively deep burial in early diagenesis and quick deep burial and compaction in later diagenesis. High productive reservoirs are the synergistic effect of well sorting fine-and middle-stones formed in braided river delta front during tectonically calm time, early regressive corrosion and poor carbonate cement, later tectonic disruption.