油层孔隙结构与剩余油分布实验研究

Experimental Study on Pore Structure and Remaining Oil Distribution of Reservoir

大庆油田LSX油层是开发的主力油层,随着油田进入高含水后期,剩余油分布越来越零散,需要认识储层微观非均质性、剩余油分布及水驱油特征。利用地质及动态资料,对储层砂体发育规模和储层性质、裂缝发育特征、驱替特征、微观孔隙结构以及油水分布规律等开展了模拟实验与分析,明确了不同储层微观剩余油分布及水驱油特征,定量表征孔隙结构分布,并对成果进行了验证。研究表明,LSX油层以原生粒间孔和片状、弯片状喉道为主,划分5类孔隙结构类型,以Ⅱ类、Ⅲ类、Ⅳ类为主,孔隙结构中等偏差;剩余油分布受孔隙结构控制,微观剩余油二维分布主要以角隅状、喉道状为主,三维分布以多孔状和孤立状为主;驱油效率受孔隙结构影响,从Ⅰ类到Ⅴ类驱油效率逐渐变差,不同孔隙结构储层与开发特征具有较好的对应关系。

LSX reservoir is the major one for development in Daqing Oilfield. The oilfield has entered into the later high water cut stage,and the remaining oil distribution is more and more scattered.It is necessary to understand the microscopic heterogeneity of reservoir,distribution of remaining oil and the characteristics of water flooding.Based on the geological and dynamic data,the simulation experiments and analyses were carried out on the development scale of sandbody and properties of the reservoirs,fracture development characteristics,displacement characteristics,microcosmic pore structure and oil-water distribution law,and the microscopic remaining oil distribution and the characteristics of water flooding in different reservoirs were clarified.The pore structure distribution was quantitatively characterized,and the results were validated.The results show that LSX reservoir has primary intergranular pore,and platelike and bowed platelike throat mainly,and there are five types of pore structure with the majority of type Ⅱ, Ⅲ,and Ⅳ,and the pore structure is medium to poor.The remaining oil distribution is controlled by the pore structure,and the two-dimensional microscopic remaining oil distribution is mainly angle-shaped and throat-shaped,and the three-dimensional distribution is mainly porous and solitary.The displacement efficiency is affected by the pore structure,which is gradually getting worse from type I to type V,and the reservoirs with different pore structures have a good corresponding relation with the development characteristics.