中东M油田Mishrif组碳酸盐岩储集层分类及主控因素

Classification and main controlling factors of carbonate reservoir of Mishrif Formation, M Oilfield in the Middle East

为揭示碳酸盐岩储层非均质性对开发生产的影响,以中东M油田白垩系Mishrif组生物碎屑灰岩为研究对象,基于岩心、铸体薄片、分析化验及生产测试等资料,通过地质成因—储层物性—生产动态相互标定,采用每米日产油和物性指标进行储层分类。结果表明:M油田白垩系Mishrif组储层划分为3类,Ⅰ类储层发育于高能浅滩,Ⅱ类储层发育于低能潟湖和高能浅滩,Ⅲ类储层主要发育于潟湖。储层特征受沉积作用和成岩作用综合控制,浅滩原始物性好,滩体顶部发生强溶蚀、弱胶结,储层孔渗同步提升,形成Ⅰ类储层;滩体下部以破坏性成岩作用为主,发生弱溶蚀、强胶结,降低储层物性,形成Ⅱ类储层。潟湖相岩石原始物性较低,沉积期生物扰动形成连通潜穴,为成岩流体提供运移通道,后期以建设性成岩作用为主,溶蚀作用和白云化作用在潜穴和基底形成大量铸模孔、晶间孔和生物体腔孔,有效改善岩石物性,形成Ⅱ类或Ⅲ类储层。该结果为中东厚层碳酸盐岩储层分类提供参考。

In order to reveal the effects of carbonate rock reservoir heterogeneity on development,taking the bioclastic limestone of the Cretaceous Mishrif Formation of the M Oilfield in the Middle East as an example,based on core,cast thin section,experimental data and production test,the reservoir was studied,according to the calibration of geological genesis,physical property and development performance characteristics,in combination with production per day per meter and physical property index.The result showed that the reservoir was divided into three types.TypeⅠwas mainly developed in the high-energy shoal.TypeⅡcould be developed both in low-energy lagoon and high-energy shoal while typeⅢwas mainly developed in the lagoon.It was considered that the characteristics of different reservoirs were mainly controlled by sedimentation and diagenesis.The rock in high-energy shoal usually had good primitive physical properties,but intensive dissolution and weak cementation occurred during the diagenetic period at the top of the shoal.The reservoir porosity and permeability improved when typeⅠdeveloped.However,in the lower part of the shoal,it was dominated by destructive diagenesis,which resulted in weak dissolution and strong cementation,reducing the physical properties of the reservoir forming the typeⅡ.Lagoon facies rocks had low original physical properties,and the formation of connected burrows in lagoon provided a migration channel for diagenetic fluids with subsequent constructive diagenesis.Dissolution and dolomitization formed a large number of moldic pore,intercrystalline pores and biological cavity in the burrow and the substrate,which effectively improved rock physical properties forming the typeⅡor typeⅢ.The new classification matched the geological understanding,revealing the reason of productivity difference between wells.The result could provide a reference basis for the classification of thick carbonate reservoirs in the Middle East.