氮气泡沫驱气体窜流特征实验研究

Experimental study on gas channeling problem of N_2 foam flooding

在泡沫驱提高油田采收率的过程中容易发生气体窜流现象。为了界定气窜时机和程度,提出产气率上升指数I_g;通过物理模拟实验,研究起泡剂浓度、注入方式、注入速度以及含油饱和度等参数对氮气泡沫驱气窜现象的影响。结果表明:表面活性剂可以增强液膜的强度,液膜排液作用降低了气窜现象的发生;使用泡沫发生器产生的泡沫质量优于段塞注入以及气液共注等方式,且不易发生气窜;注入速度越小,越容易发生气窜现象,但是注入速度超过一定值以后,泡沫的封堵能力趋于稳定;I_g=0.5为临界气窜点,超过临界气窜点,即发生气窜。

The gas channeling problem happens often during the foam flooding for enhancing oil recovery. In order to define the gas channeling opportunity and degree,the index number of gas production rate Ig was proposed. The influences of surfactant concentration,injection manner,injection rate and oil saturation on the N2 foam flooding were investigated through physical simulation experiments. The results show that the high foam surfactant concentration can cause a high strength of liq-uid film,in which the function of liquid film flowing can reduce the chance of gas channeling. Compared with the slug injection and gas/liquid injection,the foam from generator has a better quality and has less chance of gas channeling. It is also found that low velocity of injection causes the gas channeling easily. However, when the velocity is above the certain value, the blockage ability of foam becomes stable. The Ig value of 0. 5 is defined as the critical gas channeling point,above which the gas channeling will happen.