大港油田开发中后期稠油油藏CO2吞吐参数优化及实践

Optimization and practice of CO2 huff and puff parameters of heavy oil reservoir in the middle and late development stage in Dagang Oilfield

大港油田稠油油藏水驱开发中后期含水快速上升,开采效果变差。CO2吞吐技术是开发稠油油藏的有效方式,但高含水后期稠油吞吐的参数优化及现场效果亟待研究。利用大港油田某稠油油藏,开展注CO2增溶膨胀和降黏实验。基于实验和测井资料,建立单井数值模拟模型,模拟了储层参数和CO2注入参数,分析了CO2吞吐增油机理。基于理论研究结果在板桥地区和刘官庄地区进行了CO2吞吐矿场试验。研究结果显示:CO2控水增油机理主要为膨胀原油体积、降低原油黏度,黏度降低幅度可达到98%。注入量、注入速度、吞吐周期对CO2吞吐效果影响相对较大,建议单井CO2注入量在600~1000 t(0.22~0.37HCPV),注入速度在40~80 t/d,吞吐周期为3~4次。板桥及刘官庄地区共实施CO2吞吐12井次,平均单井增油3.4倍,综合含水率降低52.2%。因此,CO2吞吐是一种有效的控水增油技术,这对类似稠油油藏注水开采后期提高采收率具有重要的借鉴意义。

The water cut of heavy oil reservoir in Dagang Oilfield increased rapidly in the middle and late period of water flooding,and the production effect became worse.CO2 huff and puff technology is an effective method to develop heavy oil reservoirs.But the parameter optimization and field effect in the late stage of high water cut needed to be studied urgently.Therefore,the heavy oil reservoir in Dagang Oilfield was used to carry out the experiments of CO2 injection for solubilization and swelling with viscosity reduction.Based on the experiments and well logging data,a single-well numerical simulation model was established to simulate the reservoir parameters and CO2 injection parameters,and analyzed the CO2 oil stimulation mechanism.Based on the results of theoretical researches,the in-site CO2 huff and puff experiments were carried out in Banqiao and Liuguanzhuang.The research results show that the mechanism of water control and oil increase by CO2 is mainly to expand the volume of crude oil and reduce the viscosity of crude oil,and the viscosity can be reduced by up to 98%.The impact of injection volume,injection speed,and throughput cycle is relatively large on the CO2 throughput effect.It is recommended that the CO2 injection volume of a single well is 600~1000 t(0.22~0.37HCPV),the injection speed is 40~80 t/d,and the throughput runs 3~4 cycles.In Banqiao and Liuguanzhuang,CO2 huff and puff have been carried out 12 times on wells,with an average increase of 3.4 times of oil production per well and a 52.2%reduction of comprehensive water cut.Thus,CO2 huff and puff technology is an effective water-control and oil-increasing technology,which has important reference significance for improving oil recovery in the later stage of water injection in similar heavy oil reservoirs.