超稠油油藏HDCS开采技术优化

针对胜利油田广9区块超稠油油藏HDCS开采过程中存在的问题,通过油藏数值模拟分析了HDCS的降黏作用机理,优化了HDCS吞吐各周期降黏剂、CO_2与蒸汽的注入量,提出HDCS吞吐后期开采方式应转为HNS吞吐。研究结果证实:降黏剂、CO_2与蒸汽先后注入地层具有滚动接替、协同降黏作用,降黏剂的作用范围主要集中在近井地带0~2.4 m,CO_2的受效半径大于降黏剂,约为6.4 m,蒸汽的作用范围最大,受效半径约为11.2 m。从经济角度出发,HDCS吞吐4周期时,应停止注入降黏剂,转入HCS开发;吞吐7周期时,停止注入CO_2,转入蒸汽吞吐开发。HDCS吞吐8周期后,近井地带温度逐渐升高,原油黏度大幅度降低,地层能量逐渐衰竭,产油量下降较快。通过优化得出,HDCS吞吐8周期后转HNS吞吐4周期的总产油量最高。

Optimization of CO2 and viscosity breaker assisted steam huff and puff technology for horizontal wells in super-heavy oil reservoir

This study aims to improve the recovery effect of CO2 and viscosity breaker assisted steam huff and puff technology for horizontal wells(HDCS) in consideration of the current development situation of extra-heavy oil reservoir in the Guang 9 Block of Shengli Oilfield.The viscosity reduction mechanism of HDCS was studied through numerical simulation,and the injection volumes of viscosity reducer,CO2 and steam were optimized.It is suggested to transform from HDCS to HNS after 8 cycles of HDCS huff and puff for the exploitation.The results show that the injections of viscosity breaker,CO2 and steam have a collaborative viscosity reduction in formation,and the effective viscosity reduction area of viscosity breaker is mainly near the wellbore with a 0-2.4 m radius,the effective viscosity reduction radius of CO2,6.4 m,while the steam has the most extensive operation radius of 11.2 m.Considering the premise of economic factor,the injection of viscosity reducer should be stopped after 4 cycles of HDCS huff and puff,while the injection of CO2 should be stopped after 7 stimulation cycles.After 8 cycles of HDCS huff and puff,the oil production decreases rapidly due to the exhaustion of formation energy and the low viscosity of crude oil.The exploitation method is suggested to transform from HDCS to HNS after 8 cycles of HDCS huff and puff.