浅薄层稠油蒸汽驱中后期过渡注汽方式优化——以春风油田排612区块为例

Optimization of transitional steam injection mode in mid-late stage of steam flooding for shallow thin heavy oil reservoirs:A case study of Block Pai 612,Chunfeng Oilfield

为解决稠油油藏开发过程中,连续汽驱转间歇汽驱过渡期出现的热利用率不高、蒸汽带不饱满等问题,基于油藏工程理论,采用数值模拟的方法对蒸汽驱中后期的过渡注汽方式进行对比计算。结果表明,脉冲注汽和变速注汽相较于连续注汽的热利用率更高,可有效驱替残余油。根据新疆春风油田排612区块实际地质情况,建立数值模型,对蒸汽驱生产前期的部分高汽窜井进行控关调控,研究中后期2种过渡注汽方式的最佳注汽参数,得到脉冲注汽的周期为注汽5 d停注1 d、注汽速度100 m^(3)/d时开发效果最好,变速注汽的变速时间50 d、每个变速周期的注汽速度分别为50、80、110 m^(3)/d时区块开发效果最佳,对比后得出变速注汽为目标区块过渡注汽方式的最优选择。该方式不仅可有效改善储层动用程度,同时能有效恢复底层压力,为后续间歇注汽提供能量,从而进一步提高目标区块采出程度。

Some problems,such as low heat utilization rate and unsaturated steam chamber,often occur during the transition from continuous to intermittent steam flooding of heavy oil reservoirs.Based on the reservoir engineering theory,the transitional steam injection modes in the mid-late stage of steam flooding were compared by way of numerical simulation.The results show that the pulse steam injection and rate-variable steam injection deliver higher heat utilization rates than continuous steam injection and effectively displace residual oil.As per the geological conditions of Block Pai 612 in the Chunfeng Oilfield,a numerical model was built for control of the shut-in of some high steam channeling wells in the early stage of steam flooding.The optimal steam injection parameters of two transitional steam injection modes in the mid-late stage were clarified.For the pulse steam injection,the best performance is achieved when the injection is performed at 100 m~3/d for 5 d and suspended for 1 d.For the rate-variable steam injection,the best performance is realized when the rate-variable injection interval is 50 d at 50,80 and 110 m~3/d,respectively.The comparison suggests that the rate-variable steam injection is the optimal transitional steam injection option for the target block.This mode can effectively improve the recovery of reserves and restore the formation pressure to provide energy for subsequent intermittent steam injection and further enhance the recovery efficiency of the target block.