基于LBM的海上低渗油藏水驱后烃气驱动用机理及提采效果研究  

Mobilization mechanisms and enhanced oil recovery of hydrocarbon gas injection in offshore low-permeability reservoirs after water flooding based on LBM

作　　者：李南 谭先红 杨仁锋 张利军 吴峻川 刘帅 刘云帆 李蕾[3] LI Nan;TAN Xianhong;YANG Renfeng;ZHANG Lijun;WU Junchuan;LIU Shuai;LIU Yunfan;LI Lei(National Key Laboratory of Offshore Oil and Gas Exploitation,Beijing 102209,China;CNOOC Research Institute Ltd.,Beijing 100028,China;China University of Petroleum(East China),Qingdao,Shandong 266580,China)

机构地区：[1]海洋油气高效开发全国重点实验室,北京102209 [2]中海油研究总院有限责任公司,北京100028 [3]中国石油大学(华东),山东青岛266580

出　　处：《中国海上油气》2024年第6期80-91,共12页China Offshore Oil and Gas

基　　金：中海石油(中国)有限公司重大科技专项“海上油藏气驱提高采收率技术(编号:KJGG2021-0505)”;中海石油(中国)有限公司重大科技专项“海上低渗及潜山油气田有效开发技术(编号:KJGG2021-0702)”部分研究成果。

摘　　要：海上低渗油藏水驱后孔隙中仍存在大量剩余油,采用烃气驱可进一步提高采收率,但动用机理尚不明确。以南海北部湾海域涠洲12-1油田为研究对象,根据铸体薄片实验结果抽提孔隙特征,利用格子玻尔兹曼微观孔隙尺度模拟方法,开展了水驱后烃气驱微观模拟,探究水驱后剩余油分布特征、烃气驱对剩余油的动用机理及不同气驱方式对驱油效果的影响。结果表明:水驱后孔隙中剩余油主要以并联孔道、膜状、盲端孔隙、小孔喉盲端孔隙等形式赋存;注入烃气可通过溶解萃取、原油膨胀、改善流道等动用剩余油,提高波及系数;烃气与原油混相时,气体突破时间延后25.29%,波及系数提高24.87%;不同注气方式中水气交替驱替效果最好,注入水可有效封堵高渗通道,提升注入气利用率,以1:1的水气段塞时注入气利用率可提升41.43%。该研究对海上低渗油藏水驱后烃气驱开发具有理论指导意义。In offshore low-permeability reservoirs,a significant amount of residual oil remains trapped in the pore spaces after water flooding.Hydrocarbon gas injection offers a potential method to enhance oil recovery,but its mobilization mechanisms remain unclear.This study focuses on the WZ12-1 Oilfield in the Beibu Gulf of the South China Sea.Based on pore characteristics extracted from cast thin section experiments,microscopic simulations of hydrocarbon gas injection after water flooding were conducted using the lattice Boltzmann method(LBM).The study investigated the distribution characteristics of residual oil,the mechanisms of mobilization by hydrocarbon gas injection,and the effects of different gas injection methods on oil displacement efficiency.Results indicate that residual oil after water flooding primarily exists in parallel channels,as membrane-like oil,in dead-end pores,and in micropore throats.Hydrocarbon gas injection can mobilize residual oil through dissolution and extraction,oil expansion,and improved flow pathways,thereby increasing sweep efficiency.When hydrocarbon gas and crude oil achieve miscibility,the gas breakthrough time is delayed by 25.29%,and the sweep efficiency improves by 24.87%.Among various gas injection methods,water-alternating-gas(WAG)injection proved most effective,as water injection effectively blocked high-permeability channels,improving gas utilization efficiency.A 1:1 WAG ratio increased gas utilization by 41.43%.This research provides theoretical guidance for the development of hydrocarbon gas injection in offshore low-permeability reservoirs after water flooding.

关 键 词：LBM 海上低渗油藏 孔隙尺度 混相程度 烃气驱 

分 类 号：TE341[石油与天然气工程—油气田开发工程]