中非地区B盆地下白垩统储层特征及其控制因素

Clastic reservoir characteristics and their controlling factors of the Lower Cretaceous in B Basin,central Africa region

目的分析中非地区B盆地下白垩统沉积环境、储层特征及其控制因素。方法利用沉积学、储层地质学理论及分析技术。结果B盆地中下白垩统碎屑岩储层大多形成在河流—三角洲、近岸水下扇等沉积环境中。碎屑岩储层岩性主要为中、细砂岩,不同地区、不同类型储层物性存在较大差异;物性最好的储层为河道、(扇)三角洲前缘水下分流河道及河口坝砂体。结论储层物性主要受压实作用、碳酸盐溶解与胶结作用及沉积环境四大因素控制,其中压实、溶蚀作用及胶结作用是主要控制因素,而沉积环境对物性的影响主要表现在控制原生孔隙的发育程度,并进一步控制溶蚀、胶结等成岩作用。

Aim To analyze sedimentary environment, the characteristics ot elastic reservoirs ana their controlling factors of the Lower Cretaceous in B Basin, central region. Methods Analyzing sedimentary environment, the characteristics of elastic reservoirs and their controlling factors of the Lower Cretaceous in B Basin, Central region based on sedimentology and reservoir geology theories and analyzing technique. Results The elastic reservoirs of the Lower Cretaceous are mostly formed in sedimentary environments as fluvial-Delta, sub-fans in B Basin, Central region. The elastic reservoir is mainly composed of medium-fine sandstones. The micro-facies of channel, sub-distributary channel and distributary mouth bar are relatively good reservoir. Conclusion The reservoir quality is controUed by four factors as foUows： compaction, carbonate dissolution, cementations and sedimentary environment. The main reservoir quality controlling factors are compaction, dissolution and cementations. The effect of sedimentary environment on reservoir quality manifests the development of primary pore, and its control on diagenesis such as dissolutions, cementations.