低渗油藏水驱后CO2驱潜力评价及注入参数优化

杨红 余华贵 黄春霞 王伟 赵永攀 王维波

延长石油（集团）有限责任公司研究院，陕西 西安 710075

Research Institute of Yanchang Petroleum Group Co. Ltd., Xi′an 710075, China

延长油田乔家洼区块属于典型的低孔、特低渗油藏。针对该区块基质致密和非均质性严重造成注水开发效果差的问题，通过开展CO2室内驱油实验，在水驱基础上分别对连续气驱和气水交替驱驱油潜力进行评价，并对气水交替驱流体注入速度、段塞尺寸及气水比等注入参数进行优化；同时，对区块采用水驱、优化井网后水驱、利用优化的CO2驱注入参数开展气驱和注气5 a后转气水交替驱4种开发方案进行数值模拟产量预测。实验结果表明：CO2驱在目标区块高含水后有着较大驱油潜力，连续气驱和气水交替驱分别在水驱基础上可提高采收率8.43，20.95百分点；最佳注入速度、最佳注入段塞尺寸和最佳气水比分别为0.727　mＬ/min，0.10 PV，1∶1。数值模拟结果表明，连续气驱和注气5 a后转气水交替驱，在开发15 a末，在水驱基础上分别可以提高采收率13.81，12.98百分点。

Qiaojiaowa block in Yanchang Oilfield belongs to low porosity and extra low permeability reservoir. Due to dense matrix and serious heterogeneity, the waterflooding development effect is poor in this block. Aimed at this problem, CO2 indoor flooding experiment is carried out to evaluate the potentials of CO2 flooding and WAG based on waterflooding and optimize the injection parameters such as injecting velocity, slug size and the ratio of gas and water. At the same time, numerical simulation is used to predict production for waterflooding based on well optimized, CO2 flooding and WAG drive after injecting CO2 for 5 years. Experimental results show that there is a large potential in target block for CO2 flooding after waterflooding. The EOR of CO2 flooding and WAG drive is improved 8.43% and 20.95% compared with waterflooding. The best injection velocity, injection slug size and gas?鄄water ratio are respectively 0.727 ml/min, 0.10 PV and 1∶1. Simulation results show that the EOR of CO2 flooding and WAG drive after injecting CO2 for 5 years and after developing for 15 years is improved 13.81% and 12.98% compared with waterflooding. 

10.6056/dkyqt201502024