摘要
致密砂岩储层微观孔隙结构对CO2驱油特征有重大影响。基于铸体薄片分析、扫描电镜、高压压汞和核磁共振测试等实验结果,建立了姬塬油田长8油层组微观孔隙结构分类标准,并选取每种类型储层有代表性的岩心样品开展不同驱替压力下的CO2驱油实验,辅以核磁共振T2谱,对3种类型孔隙结构储层在不同驱替压力下大、小孔隙中的原油动用特征进行了研究,详细分析了储层物性、孔隙结构和黏土矿物对CO2驱油效率的影响。结果表明:研究区长8油层组的孔隙结构可以划分为Ⅰ、Ⅱ、Ⅲ类,3种类型孔隙结构对应的储集空间和渗流能力依次下降。Ⅱ类储层CO2混相驱油效率最大,Ⅲ类储层CO2非混相驱油效率最大;不同孔径孔喉中原油的动用特征随驱替压力和储层孔隙结构类型的不同而存在较大差异。CO2非混相驱油效率与岩石渗透率、孔喉半径、分选系数和黏土矿物含量存在较好的相关性,而CO2混相驱油效率的高低与孔隙结构参数和黏土矿物含量有关。Ⅱ类储层作为未来主要挖潜层位更适合开展注CO2驱。
The microscopic pore structures of tight sandstone reservoirs have a significant impact on the CO2 flooding characteristics.Based on the experimental results from thin section analysis,SEM,high-pressure mercury injection and NMR testing,this paper establishes a classification standard for the microscopic pore structures of the Chang 8 oil-bearing formation in Jiyuan oilfield,carries out CO2 flooding experiment under different displacement pressures using the representative core samples of each type of reservoir,and in combination with NMR T2 spectroscopy,studies the displacement characteristics of crude oil in macro and small pores under various displacement pressures in reservoirs of 3 types of pore structures,and detailedly analyzes the effect of reservoir physical property,pore structure and clay minerals on CO2 flooding efficiency.The results show that the pore structure of Chang 8 reservoir in the study area can be divided into type I,ⅡandⅢ.The reservoir space and percolation ability corresponding to the three types of pore structures decrease successively.TypeⅡreservoir has the largest miscible CO2 flooding efficiency,and typeⅢreservoir has the largest immiscible CO2 flooding efficiency;the displacement characteristics of crude oil in pore throats with different pore sizes vary greatly with different displacement pressure and various types of reservoir pore structures.Immiscible CO2 flooding efficiency has a good correlation with rock permeability,pore throat radius,sorting coefficient and clay mineral content,while the level of miscible CO2 flooding efficiency is related to pore structure parameters and clay mineral content.As the main production potential tapping horizon in the future,typeⅡreservoir is more suitable for CO2 flooding.These achievements provide a method and basis for the reasonable and efficient CO2 flooding of Chang 8 reservoir in Jiyuan oilfield.
作者
黄兴
倪军
李响
薛俊杰
柏明星
周彤
Huang Xing;Ni Jun;Li Xiang;Xue Junjie;Bai Mingxing;Zhou Tong(School of Petroleum Engineering,Xi'an Shiyou University,Shaanxi Xi'an 710065,China;Research Institute of Shaanxi Yanchang Petroleum(Group)Co.,Ltd.,Shaanxi Xi'an 710075,China;School of Petroleum Engineering,The University of Tulsa,Tulsa,OK 74104,USA;School of Petroleum Engineering,Northeast Petroleum University,Heilongjiang Daqing 163318,China;Sinopec Petroleum Exploration and Production Research Institute,Beijing 100083,China)
出处
《石油学报》
EI
CAS
CSCD
北大核心
2020年第7期853-864,共12页
Acta Petrolei Sinica
基金
国家自然科学基金项目(No.51774236,No.51974254,No.51774095)
中国石油科技创新基金项目(2019D-5007-0204)
陕西省自然科学基础研究计划项目(2019JQ-823)
国家科技重大专项(2017ZX05049-003-005)
陕西高校青年创新团队项目资助。
关键词
致密砂岩
微观孔隙结构
核磁共振
CO2驱
驱油效率
tight sandstone
microscopic pore structure
nuclear magnetic resonance
CO2 flooding
oil displacement efficiency