SPE 63000
Visualisation of Oil Recovery by Water Alternating Gas (WAG) Injection Using High Pressure Micromodels - Water-Wet SystemAbstract
The use of WAG (water alternating gas) injection can
potentially lead to improved oil recovery compared to
injection of either gas or water alone, however the physical
process is not well understood. Using high pressure glass
micromodels, a series of WAG tests have been conducted
using equilibrated fluids, with high quality images of the oil
recovery processes operating during alternate WAG cycles
being recorded. The tests were conducted using both waterwet
and oil-wet micromodels. In this paper results of a typical
water-wet test is presented (results of the oil-wet and mixed
wet tests will be presented in a subsequent paper).
Water-wet micromodels were initially fully saturated with
water and then displaced with oil to establish the connate
water saturation. The micromodels were then flooded with
water to observe the process of establishing the waterflood
residual oil saturation (Sorw). Alternate cycles of gas and water
injection were then conducted to observe three-phase flow and
its associated oil recovery. The experiments were performed
within the capillary dominated flow regime.
The results highlighted the importance of corner filament
flow of water in the recovery process, with the initial
waterflood residual oil saturation being trapped mainly in the
centre of the majority of pore space surrounded by layers of
water, and not in only large pores. The successive WAG
cycles redistributed the oil in a way which resulted in
improved oil recovery, hence, the oil which otherwise would
not have been mobile under either gas or water injection alone
was mobilised and produced.
It was identified that a limited number of WAG cycles were
required to approach maximum oil recovery, after which
additional recovery was minimal. All recovery processes were
filmed and electronically stored using high resolution imaging,
with oil recovery at the end of each flooding cycle being
measured using image analysis techniques.
用高压微观模型水湿系统研究水气交替注的采收率摘要
相比单独的注入水和单独的注入气，水气交替注入的利用能很大程度上提高原油的采收率，但是实验过程不好理解。利用高压玻璃微模型加以平衡流体，一系列的水气交替注入实验已经实施，高质量高清晰的采油过程的图像已被应用到水气交替注入的过程中。此实验既用到了亲水性的微模型，又用到了亲油性的微模型。在这篇论文中出现了典型的亲水性实验。
奖水湿微米型用水全部浸湿，接着用油来代替原来的水来建立原始含水饱和度。然后这些微模型再被水充满来观察注水过程对残余油饱和度的影响。接着实施水和气交替循环注入来观察三相流和其对共生油的采收率。实验是在毛管流的水平下实施的。
实验结果强调了在采油的过程中拐弯处睡的线状流动的重要性。原先的注入水使残余油进入由地层水包围的主要的孔隙中间，不只是在大的孔隙中。相继的水汽交替注入循环使地层原油以一种最能提高采收率的方式再分布。因此，虽然不能在单一的注入气、注入水的方式下被驱替的原油，却能在此种方式下被驱替和采出。
在认识到辅助采收率的数值很少以后，水气交替注入循环的数量要求接近原油采收率的最大值，所有的采油过程将会用高分辨率的相机拍摄和保存下来。在注入循环的最后用成像分析技术计量出原油采收率。
[ 此贴被zhouxiang在2009-05-18 00:05重新编辑 ]
