伊朗Zagros盆地西南部白垩系Sarvak组碳酸盐岩储层特征

Carbonate reservoir characteristics of the Creataceous Sarvak Formation in southwestern Zagros Basin,Iran

为了阐明伊朗Zagros盆地西南部白垩系Sarvak组碳酸盐岩储层特征,利用岩心、薄片、录井、试油及测井资料,通过储层岩性类型、储集空间、物性、电性特征及孔隙发育的影响因素分析,指出Zagros盆地西南部白垩系Sarvak组碳酸盐岩储层岩性类型有白垩质灰岩、云质灰岩、颗粒灰岩,储集空间类型多,主要为次生溶孔、铸模孔,其中颗粒灰岩的物性最好,白垩质灰岩中白垩质主要为浮游有孔虫,孔隙较发育,一般随物性增加,含油性级别升高。成岩作用对储层物性影响也较大,起建设性的成岩作用有溶蚀作用、白云化作用、生物扰动及压溶产生缝合线、缝合面。泥粒灰岩、粒泥灰岩在这些成岩作用的影响下,物性有较大改善。储层孔隙发育微观上主要受控于岩相、成岩作用,平面上还和构造位置及沉积环境有关,位于构造高部位的台地浅滩微相往往物性较好。利用垂向上测井响应及平面上小层物性分布特征,明确了物性较好、含油丰度较高的层段,为寻找高产有利储层提供了依据。

In order to reveal the characteristics of the Cretaceous Sarvak Formation carbonate reservoir in the southwestern Zagros Basin,a comprehensive study was carried out by integrating the core,thin section,production test and well log data. Analyses of the reservoir rock types,reservoir space,physical property,electrical property and the factors influencing pore development show that the lithology types of the Sarvak reservoir includes chalky limestone,dolomitic limestone and grainstone. And the reservoir spaces are dominated by secondary dissolved pores and mold pores. The physical property of grainstone is the best. The chalk in chalky limestone is mainly planktonic foraminifera which have well-developed porosity. Generally,the oil-bearing property enhances with the improvement of physical property. The diagenesis also have great impact on reservoir＇s physical property,and the constructive diagenesis include dissolution,dolomitization,biological disturbance,stylolites of pressolution origin. The physical property of packstone and wackestone are greatly improved under the influences of these constructive diageneses. Microscopically,the development of reservoir＇s pore is mainly controlled by facies and diagenesis. Laterally,it is also related to tectonic location and sedimentary environment. The physical property of platform shoal microfacies on structural high is commonly better. The vertical logging response and the areal distribution of physical property of sublayers can be used to identify zones with better physical property and oil-bearing abundance,thus providing a basis for highly productive reservoirs.