伊拉克M油田Asmari组B段混积岩储层特征及储层非均质性对开发的影响

Characteristics and heterogeneity of the diamictite reservoir in B Member of Asmari Formation in M oilfield,Iraq and their impacts on development

伊拉克M油田Asmari组B段发育一套厚度110~140 m的混积岩储层。通过对岩心、薄片、实测孔渗数据、测井曲线及实际生产数据等分析认为,含油储层主要为砂岩、灰岩、白云岩及其过渡类型岩石;砂岩储集空间主要为粒间孔,为中高孔、中高渗—特高渗储层;灰岩和白云岩主要储集空间为粒间和粒内溶孔以及晶间和晶内溶孔,储层物性变化比较大,为中低孔、低—高渗储层;B段沉积环境为三角洲前缘的分流河道微相和局限台地的潮坪、泻湖亚相,混积岩储层整体连通性好,非均质性强,不同类型储层产能差异大,砂岩储层产能好于碳酸盐岩储层及二者的过渡类型储层。因此搞清砂岩储层分布将是提高油田单井产能的关键;储层出水模式为边水沿高渗砂岩层突进,再横向和纵向侵入,可据此指导油田新井井位部署、射孔方案、措施选取等。本文研究成果对混积岩储层的开发具有借鉴意义。

One set of 110 ~ 140 m thick diamictite reservoir was developed in the B Member of the Asmari Formation in the M oilfield,Iraq. Based on the analysis on cores,thin sections,measured porosity and permeability,wireline logging curves and actual production data,it was revealed that the lithology of oil-bearing reservoirs is mainly sandstone,limestone,dolomite and transitional rocks. Within the sandstone,the storage space is mainly intergranular pores and the reservoir belongs to the reservoir with medium-high porosity,and medium,high and super-high permeability. Within the limestone and dolomite,the storage space is mainly intergranular and intragranular dissolution pores and intercrystalline and intracrystalline dissolution ones,and the reservoir has medium—low porosity and low—high permeability,with obvious physical property changes,The sedimentary setting of the B Member is distributary channel microfacies of the deltaic front,and tidal flat and lagoon subfacies of the restricted platform. In the B Member of the Asmari Formation,the diamictite reservoir has good connectivity and strong heterogeneity as a whole,and different reservoir types have large productivity variation. The productivity of the sandstone reservoir is higher than that of carbonate reservoir and transitional reservoir type. Therefore,the key to enhance single well productivity in this oilfield is to make clear of the distribution of the sandstone reservoir. In this reservoir,the edge water may advance along high-permeable sandstone layers,resulting in water breakthrough and then invade in lateral and vertical directions. It could provide guidance to the geometric arrangement of new wells,the perforation plan and the selection of measures. In this paper,the study has the reference significance for the development of the diamictite reservoir.