浅层稠油油藏CO_2吞吐控水增油机理研究

Mechanism Study on Water Control and Enhanced Oil Recovery by CO_2 Huff-puff for Shallow Heavy Oil Reservoir

针对低稠油油藏和稠油油藏注水开发中后期含水上升快、原油采收率的低等问题,开展了CO2吞吐控水增油的室内物理模拟实验和单井CO2吞吐控水增油的数值模拟。为了研究CO2吞吐控水增油的机理及可行性,在室内分别开展了CO2与地层原油/地层水配伍性实验和CO2吞吐控水增油长岩芯实验。CO2与地层原油/地层水配伍性实验结果表明:CO2对原油有增容膨胀和降黏作用;一定温度下,随着压力的降低,饱和CO2的地层水的体积膨胀,CO2在地层水中的溶解度降低,CO2吞吐过程中,地层水遇到狭小孔隙受阻,产生贾敏效应,控制水的产出。长岩芯实验也表明,CO2吞吐有明显的控水增油的作用。单井CO2吞吐控水增油的数值模拟结果同样证实了CO2吞吐具有良好的控水增油显著。

To solve the problems of rapidly increase water cut and low oil recovery in the later water-flooding of low heavy oil and heavy oil reservoirs,we conducted laboratory physical simulation experiments and single well numerical simulation of CO2 huff and puff in water control and oil enhancement. To find out the mechanism and feasibility,CO2 and reservoir oil/water compatibility experiment and long core experiment of CO2 huff and puff are carried out respectively. The former has shown that CO2 has capacity expansion and viscosity reduction effects on the heavy oil. At a certain temperature,as the pressure decreases, the volume of reservoir water saturated with CO2 expands and the solubility of CO2 in reservoir water declines which indicates that in CO2 huff and puff,water is trapped by the small core thus causing Jamine Effect,and preventing the water from being produced. The long core experiment has also shown that CO2 huff and puff has a significant effect on controlling the water and enhancing the oil recovery. This has also been demonstrated by single well numerical simulation of CO2 huff and puff.