三叠系长6油藏二氧化碳驱技术方案优选

Selection of CO_2 Displacement Scheme for Triassic Chang-6 Reservoir,Changqing Oilfield

针对长庆油田三叠系长6特低渗透油藏物性差、水驱开发采收率低、含水上升快等问题,研究CO2驱在该油藏中的应用。利用油藏数值模拟技术,分别对CO2水气交替驱(CO2-WAG)和CO2连续气驱的注采参数进行了优选,并在此基础上对比了这2种开发方式。得到了最优的技术方案:采用CO2-WAG驱技术,产油速度提高1.5倍,单井平均产油速度为3 m3/d,关井气油比为1×103m3/m3,单井注气速度为1×104m3/d,水气比为1,交替注入6个月。模拟结果表明,20 a预测期内,优选方案的采出程度比水驱增加了9.7%。优化CO2驱方案适合特低渗透油藏的开发。

In order to solve the problems such as poor physical properties,low recovery rate by water flooding and rapid increase of water cut in extra- low permeability reservoir of Chang- 6 in Triassic system of Changqing Oilfield,the application of CO2 into the reservoir has been studied. Numerical simulation of reservoir was used to select injection- production parameters for CO2- WAG and the CO2 gas displacement,and on this basis,these two types of development have been compared. The optimal technical plan has been acquired: As for development by CO2- WAG,oil production rate was increased by 1. 5 times,average oil production rate of single well was 3 m3/ d,shut- in gas / oil ratio was 1 × 103m3/ m3,gas injection rate per well was 1 × 104m3/ d,water / gas ratio was is 1,and alternating injection was made for 6 months. Simulation results showed that during the forecast period of 20 a,the degree of reserve recovery of optimal plan was increased by 9. 7% than water displacement. Optimized CO2 displacement plan is suitable for the development of extra- low permeability reservoir.