基于微观渗流特征的水驱后残余油动用机理研究  

Mechanism of residual oil mobilization after water flooding based on microscopic flow characteristics

作　　者：杨庭宝 钟会影[1] 夏惠芬[1] 赵欣[2] YANG Tingbao;ZHONG Huiying;XIA Huifen;ZHAO Xin(Key Laboratory for Enhanced Oil&Gas Recovery of the Ministry of Education,Northeast Petroleum University,Daqing,Heilongjiang 163318,China;Research Institute of Exploration and Development,Daqing Oilfield of CNPC,Daqing,Heilongjiang 163712,China)

机构地区：[1]东北石油大学提高油气采收率教育部重点实验室,黑龙江大庆163318 [2]中国石油大庆油田有限责任公司勘探开发研究院,黑龙江大庆163712

出　　处：《油气藏评价与开发》2020年第6期46-52,共7页Petroleum Reservoir Evaluation and Development

基　　金：中国博士后科学基金“考虑诱导裂缝闭合的黏弹性聚合物驱压力降落特征研究”(2019M661250)。

摘　　要：为摸清水驱后残余油的形成机理及分布情况并挖掘残余油潜力,基于N-S方程建立了并联孔隙微观模型,运用相场法追踪驱替过程中的相界面,研究不同壁面润湿条件下的水驱后残余油分布特征,并通过聚合物驱改善流度比、表面活性剂改变界面张力或发生润湿反转等方法挖潜水驱后残余油,研究流度比及界面张力等参数对水驱后并联孔隙内残余油微观流动规律的影响。结果表明,当岩石表面表现为亲水时,水驱后残余油主要滞留在并联孔隙的大孔道内,通过聚合物驱改善流度比可以将孔道内的残余油有效动用,表现为残余油被整体驱动。当岩石壁面为亲油时,水驱后残余油主要滞留在并联孔隙的壁面以及小孔道内,改善流度比对小孔道内形成的残余油很难达到动用的目的,但通过表活剂改变润湿性后,残余油被拉伸成油滴并聚并,最终降低残余油饱和度;流度比或界面张力越小,驱油效率越高。该研究揭示了并联孔隙内水驱后残余油分布及动用机理,为水驱油藏有效开发提供了重要的理论依据。In order to find out the formation mechanism and distribution of residual oil after water flooding and tap the potential of residual oil,a parallel pore micro model has been established based on N-S equation.Phase field method has been used to track the phase interface in the process of water flooding.The distribution characteristics of residual oil after water flooding under different wall wetting conditions have been studied.The residual oil after water flooding has been exploited by mobility ratio improved by polymer flooding,interfacial tension changed by surfactant or wettability inversion occurred.And the effects of different mobility ratio and interfacial tension on the micro flow of residual oil in parallel pores after water flooding have been studied.The results show that when the rock surface is water-wet,the residual oil mainly stays in the large pore channels in parallel pores after water flooding.The polymer flooding improving the mobility ratio can effectively displace the residual oil in the pore channels,entirely.When the rock surface is oil-wet,the residual oil after water flooding mainly stays in the wall of parallel pores and small channels.It is difficult to displace the residual oil in the small pore by improving the mobility ratio.However,after changing wettability by surfactant,the residual oil is stretched into oil droplets and congregated,and finally the residual oil saturation is reduced.The lower the mobility ratio or interfacial tension,the higher the oil displacement efficiency.This study reveals the distribution and displacement mechanism of residual oil in parallel pores after water flooding,and provides an important theoretical basis for the effective exploitation of reservoirs by water flooding.

关 键 词：相场 N-S方程 孔隙尺度 润湿性 残余油 

分 类 号：TE357[石油与天然气工程—油气田开发工程]