塔河油田奥陶系一间房组礁滩相储层特征及成因机制新认识

塔河油田中奥陶统一间房组发育的礁滩相主要位于台地内部坡折带以北,储层的储集空间主要为粒内溶孔、铸模孔.储层具有独特的测井特征,纵向上发育于层序的高水位体系域,且多套储层的发育受高水位体系域的高频层序控制;横向上,储层分布于台地内部坡折带以北的4个滩体区域,且滩体中心控制着储层的优势发育.一间房组储层的孔隙度、渗透率均较低,其储渗空间具有非均质性.岩芯、薄片、荧光薄片、电子探针及阴极发光的综合分析结果表明,储层的形成受多种地质作用叠加的控制:同生期大气水溶蚀作用是储层形成的主要因素;岩溶作用对储层有一定的改善作用;构造作用是形成有效储层的关键因素.

A New Know of Characteristics and Genesis of Reef and Bank Facies Reservoirs in Ordovician Yijianfang Formation in Tahe Oilfield

The reef and bank facies,widely developed in Middle Ordovician Yijianfang Formation in Tahe oilfield,lies in the north of break of slope in the platform.The reservoir spaces are dominated by intragranular solution pores and cast solution pores.The reservoir not only has a particular log character,but also vertically develops the high system tract of sequence,while the multi-reservoir is controlled by high frequency sequence of the high system tract.On the plane,the reservoir is distributed in four beaches of the northern break of the slope in the platform,with the center of beach controlling reservoir's advantage development.Also the porosity and permeability are both lower in Yijianfang Formation.In addition,the permeable-storage spaces are heterogeneous in the reservoir intervals.The integrated study of cores,slices,fluorescence and electronic probe leads to the conclusion that reservoir's mechanism results from the superimposition of many geologic activities.It is found that the dissolution of syngenesis meteoric water is primarily responsible for the reservoir formation while tectonic fracture is key factor.The unconformable interface of sequence may have improved the reservoir,but the effect is quite limited.