孔隙型生物礁灰岩油藏水驱剩余油赋存特征

Storage characteristics of residual oil in water drive of porous bioclastic limestone reservoir

汪周华 赵华臻 朱光亚 李茜瑶 郭平 方全堂1

西南石油大学油气藏地质及开发工程国家重点实验室，四川 成都 610500 中国石化胜利油田分公司滨南采油厂，山东 滨州 256600 中国石油勘探开发研究院，北京 100083

State Key Laboratory for Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China Binnan Oil Production Plant, Shengli Oilfield Company, SINOPEC, Binzhou 256600, China Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, China

H油田Mishrif组储层以生屑灰岩为主，主要发育粒间（溶）孔、铸模孔及体腔孔，属于孔隙型生物礁碳酸盐岩油藏，目前以注水开发为主。文中基于微CT扫描技术，针对不同物性的岩心开展了孔隙结构特征、原始状态及水驱后的油相分布特征测试。结果表明：干岩心孔径占比呈反J形（中孔低渗岩心）、正态（高孔低渗岩心）分布特征，孔径大于50 μm的孔体积占比大于90%以上；孔径小于50 μm的油相孔径占比超过80%，孔径大于50 μm的油相体积占比超过85%；水驱后剩余油以分散状态赋存，孔径大于50 μm的油相体积占比减少，孔径小于50 μm的油相体积占比增加。后期开发应提高小孔隙中原油的动用程度，不同物性储层水驱后剩余油分布特征研究结果可为后期挖潜增效方式的选择提供依据。

The Mishrif Formation of H oilfield is mainly composed of bioclastic limestone, mainly developed with intergranular (solution) pores, mold pores and cavity pores. The formatin belongs to porous reef limestone reservoir, and now it is mainly developed by water injection. Based on micro CT scanning technology, the pore structure characteristics, original oil facies and residual oil distribution characteristics after waterflooding were tested. The results show that the pore size distribution of dry core is anti-J?-type distribution characteristic for medium porosity and low permeability reservoir, and normal distribution characteristic for high porosity and low permeability reservoir. The pore volume of pore size greater than 50 μm is more than 90%. The core CT scanning results after saturated crude oil show that the diameter less than 50 μm accounts for more than 80%, and the volume larger than 50 μm accounts for more than 85%. After water flooding, the residual oil in the core is scattered. The total volume fraction of oil drop with diameter larger than 50 μm decreases, and the total volume fraction of oil drop with diameter less than 50 μm increases. In the later stage, the producing degree of crude oil in small pores should be increased, and the distribution characteristics of remaining oil in different physical reservoirs after waterflooding provides basis for the selection of potential tapping and efficiency increasing methods.

10.6056/dkyqt202103020