浅层油藏稠油热水/CO2驱油效率实验模拟研究

新疆油田九_6区齐古组浅层稠油油藏已进入蒸汽开采中后期,油藏开采经历了蒸汽吞吐、加密调整、蒸汽驱过程,采出程度为37%。现阶段单一蒸汽驱效果明显下降,地层亏空严重,蒸汽热利用效率低,吸汽不均,波及程度差异大,油水流度比大,采收率低。热水复合CO_2驱油充分利用热水热效应和发挥CO_2溶解降黏等作用,是提高原油采收率的有效方法。因此,针对九_6区稠油开展不同混合方式热水/CO_2驱油模拟实验,分别研究了纯热水驱、热水与CO_2混注、热水与CO_2段塞的驱油效率。结果表明,纯热水驱累积驱油效率为49.19%,热水/CO_2混注累积驱油效率最大为71.25%,段塞驱累积驱油效率高达85.96%。同时,分析了驱出原油及岩心残余油组分变化。

Experimental simulation study on displacement efficiency of heavy oil in shallow reservoir by hot water and carbon dioxide

The shallow heavy oil reservoirs of Qigu group in the Nine-six District of Xinjiang Oilfield have entered the late stage of steam mining. The exploitation of this heavy oil reservoir has experienced steam stimulation, encryption adjustment and steam flooding. The oil recovery factor was 37%. At present, the effect of single steam flooding has obviously decreased, along with serious formation deficit, low steam heat utilization efficiency, uneven gas inhaling, variant sweeping ability, large oil-water mobility ratio, and low oil recovery. Hot water combined CO₂ flooding is an effective way to enhance oil recovery by making full use of hot water heating effect and huge CO₂ dissolve in crude oil leading to viscosity reduction. In this paper, series of simulated flooding experiment of Nine-six district heavy oil by hot water and CO₂ in different injection ways including hot water flooding, hot water and CO₂ simultaneous injection, hot water and CO₂ slug injection were researched. The results show that the cumulative displacement efficiency(ED)of hot water flooding is 49.19%, the maximum cumulative ED of hot water and CO₂ simultaneous injection is 71.25%, and the maximum cumulative ED by hot water and CO₂ slug injection is 85.96%. The change of four-component of the produced oil and the residual oil in the core was analyzed.