不同地层水矿化度下CO2驱油对岩石性质的影响

Influence on Rock Properties of CO2 Flooding Saturated Water with Different Salinity

刘丽 马映雪 皮彦夫 刘金鑫 柏明星

LIU Li MAYingxue PI Yanfu LIU Jinxin BAI Mingxing

为研究地层水矿化度对CO2驱油效率的影响，选用孔渗参数相近的贝雷岩心，利用岩心驱替法分别测试了 饱和0、6778、15000 mg/L 的3 种矿化度水条件下的CO2驱油效率，并利用CT扫描分析了CO2驱前后岩心的孔隙 度、渗透率渗和孔喉半径变化，分析矿化度对CO2驱油效率的影响机理。研究表明，随着岩心内水矿化度的增 大，CO2驱过程中产生的沉淀量增多，对孔喉的堵塞严重，孔隙半径和喉道半径不断减小，孔隙度和渗透率不断降 低，导致其最小混相压力减小，CO2驱油效率也略有降低。图10表1 参26

In order to study the effect of formation water salinity on the oil displacement efficiency of CO2 flooding，using Berea cores with similar porosity and permeability parameters，the core displacement method was used to test the CO2 displacement efficiency of saturated 0，6778 and 15000 mg/L water，the changes of porosity and permeability，the radius changes of pore and pore throat before and after CO2 flooding were analyzed by CT scanning. The influence mechanism of water salinity on CO2 displacement efficiency was analysed. The results showed that with the increase of the salinity of saturated water in the cores，the precipitation produced in the process of CO2 flooding increased，and the pores and throats were blocked seriously. The radius of pore and throat decreased，and the porosity and permeability decreased，resulting in the decrease of the minimum miscible pressure and the CO2 displacement efficiency. It shows that the salinity of formation water has an effect on the oil displacement efficiency of CO2 flooding.