改变微观水驱液流方向提高剩余油采收率试验研究

为了弄清特高含水油藏微观剩余油类型及提高剩余油的动用效果,进行了微观水驱油特征试验研究.在分析剩余油的几何特征和建立孔喉特征分析方法的基础上,进行了剩余油分类.采用微观可视化驱替试验、图像识别与统计等方法,定量分析了改变液流方向对微观剩余油的影响.试验结果分析表明:不改变液流方向的水驱剩余油饱和度为20.90%;改变液流方向后,继续水驱后剩余油饱和度降为9.69%;改变液流方向后原油采收率可提高11.2百分点.研究表明,改变液流方向后,随着注水量增加,分支状和连片型剩余油饱和度呈指数递减,油膜状、柱状和滴状剩余油饱和度先增大后减小,符合二次多项式函数关系.研究结果为水驱提高剩余油采出程度提供了理论基础. 

Experimental Study on Microscopic Water-Flooding to EOR of Remaining Oil through Changing Flow Di rection

To understand the type of remaining oil and the efficiency of enhanced oil recovery (EOR) in super-high water-cut oil reservoirs, experiments were conducted on the characteristic of oil displacement by water in micro-model. Based on analytical methods of geometric characterization of remaining oil and pore throats, remaining oil was classified. Moreover, flow direction effects on microscopic remaining oil were identified by using visible waterflooding test in micro-model, image recognition, statistical calculation technology, and other methods. Results showed that final oil saturation is 20.90% when flow direction remain unchanged. Nevertheless, it drops to 9.69% in continuous waterflooding if flow direction is changed, which could be raised by 11.2 percent of oil recovery. The research indicated that, the saturation of contiguous and branched remaining oil declines in exponential function, while the saturation of droplet, columnar or oil film remaining oil increases then declines in quadratic polynomial function with water injection after flow direction change. The research provides a theoretical basis for improving the recovery of remaining oil through waterflooding.