超稠油水平井CO_2与降黏剂辅助蒸汽吞吐技术

CO_2 and viscosity breaker assisted steam huff and puff technology for horizontal wells in a super-heavy oil reservoir

为了改善超稠油油藏蒸汽吞吐开采效果,通过室内驱油实验研究水平井CO2与降黏剂辅助蒸汽驱驱油效率,利用数值模拟方法研究水平井CO2与降黏剂辅助蒸汽吞吐的降黏机理。研究证实:CO2与降黏剂辅助蒸汽驱驱油效率(80.8%)明显高于常规蒸汽驱驱油效率(65.4%);水平井CO2与降黏剂辅助蒸汽吞吐技术实现了降黏剂、CO2与蒸汽协同降黏作用的滚动接替,从而有效降低了注汽压力,扩大了蒸汽波及范围即扩大了降黏区域,提高了产油速度。根据温度分布和降黏机理的不同可将降黏区分成4个复合降黏区,即蒸汽复合降黏区、热水复合降黏区、低温水复合降黏区和CO2-降黏剂复合降黏区。矿场应用表明,水平井CO2与降黏剂辅助蒸汽吞吐技术在深部薄层超稠油油藏、深部厚层超稠油油藏和浅部薄层超稠油油藏开发过程中取得了显著的降黏增油效果。

In order to improve the recovery effect of steam huff and puff in a super-heavy oil reservoir,the displacement efficiency of CO2 and viscosity breaker assisted steam flooding was studied through in-lab displacement experiments.The viscosity reduction mechanism of CO2 and viscosity breaker assisted steam huff and puff for horizontal wells was realized by numerical simulation.The results show that the displacement efficiency of CO2 and viscosity breaker assisted steam flooding（80.8%） is higher than that of steam flooding（65.4%）.The CO2 and viscosity breaker assisted steam huff and puff technology for horizontal wells realizes the rolling replacement of viscosity reduction of viscosity breaker,CO2 and steam,thus effectively reducing the steam injection pressure,expanding the steam sweep area,i.e.,expanding the viscosity reduction region and improving oil production rate.The viscosity region can be divided into four compound viscosity reduction areas according to temperature distribution and viscosity reduction mechanism.They are steam compound viscosity reduction region,hot water compound viscosity reduction region,low temperature water compound viscosity reduction region,and CO2-viscosity breaker compound viscosity reduction region.Field tests show that the CO2 and viscosity breaker assisted steam huff and puff technology for horizontal wells is effective in reducing viscosity and improving production of super-heavy oil reservoirs with deep and thin layers,deep and heavy layers,shallow and thin layers.