低渗透油藏CO2混相驱油机制及影响因素

摘要

依据CO2降低原油黏度以及CO2在原油中的传质扩散混相机制,建立考虑吸附现象的低渗透油藏CO2混相驱油数学模型,模拟CO2混相驱油过程.采用Barakat-Clark有限差分格式对模型进行数值求解,分析Peclet数、注入压力、孔隙度、原油黏度等因素对CO2在流出端的浓度分布以及降黏效果的影响.结果表明:Peclet数越小、注入压力和孔隙度越大,CO2突破流出端的时间越早,同时改变油藏原油黏度的时间越早;初始原油黏度越大,CO2降低原油黏度的效果越明显.%According to the miscible mechanisms including CO2 reducing crude oil viscosity and mass transfer and diffusion of CO2 in crude oil, a mathematical model for CO2 miscible displacement with adsorption in low permeability reservoir was built.The process of CO2 miscible displacement was modeled.This model was solved numerically by Barakat-Clark finite difference scheme.The effects of Peclet number, injection gas pressure, porosity, crude oil viscosity on CO2 effluent concentration profile and viscosity break effect were analyzed.The results show that the decrease of Peclet number and the increase of injection gas pressure and porosity speed up CO2 breakthrough and the change of crude oil viscosity.In addition, the increase of crude oil viscosity makes the effect of CO2 reducing crude oil viscosity more obvious.