川北地区飞仙关组储层特征及其主控因素

Reservoir Characteristics and Control Factor of Feixianguan Formation in Northern Sichuan

采用宏观和微观相结合的方法,对川北地区飞仙关组鲕粒滩储层的研究表明,其储集岩类型主要有鲕粒白云岩和鲕粒灰岩,储集空间以次生孔隙为主,储集物性较差,多为低孔、低渗的裂缝-孔隙型和孔隙-裂缝型储层。研究区飞仙关组储层是海平面下降形成的一套产物,储层的发育及演化受到沉积作用和成岩作用的共同控制。二叠纪长兴组生物礁古地貌高地和龙门山岛链的形成,为飞仙关组的沉积提供了高能沉积环境,而相对海平面的下降促进了高能滩体的形成,位于台地边缘的高能鲕粒滩体是储层发育的有利部位;混合水白云化作用和埋藏溶解作用为次生孔隙的形成提供了有利条件,改善了储层的储集性能。

Research on oolitic beach reservoir of Feixianguan Formation in northern Sichuan,with a combination of macro and micro methods,shows that the main reservoir rocks are oolitic dolomite and oolitic limestone,reservoir space is dominated by secondary pores and the reservoir property is relatively poor appearing as fracture-pore type and pore-fracture type with low porosity and low permeability.Reservoir of Feixianguan Formation in the study area was formed by eustatic sea level fall.Development and evolution of the reservoir were controlled by deposition and diagenesis.The generation of ancient highland of Permian Changxing reef and Longmenshan island chain provided Feixianguan Formation with high energy sedimentary condition.Relative sea level fall promoted the formation of high-energy beach,and the high energy oolitic beach on platform margin is the advantageous part for reservoir development.On the other hand,secondary pores,which markedly promoted the reservoir properties,were produced by mixing zone dolomitization and burial dissolution.