Center for Integrative Petroleum Research, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia.
Petroleum Engineering Dept., King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia.
Molecules. 2020 Jul 26;25(15):3385. doi: 10.3390/molecules25153385.
Laboratory measurements of capillary pressure () and the electrical resistivity index () of reservoir rocks are used to calibrate well logging tools and to determine reservoir fluid distribution. Significant studies on the methods and factors affecting these measurements in rocks containing oil, gas, and water are adequately reported in the literature. However, with the advent of chemical enhanced oil recovery (EOR) methods, surfactants are mixed with injection fluids to generate foam to enhance the gas injection process. Foam is a complex and non-Newtonian fluid whose behavior in porous media is different from conventional reservoir fluids. As a result, the effect of foam on and the reliability of using known rock models such as the Archie equation to fit experimental resistivity data in rocks containing foam are yet to be ascertained. In this study, we investigated the effect of foam on the behavior of both and curves in sandstone and carbonate rocks using both porous plate and two-pole resistivity methods at ambient temperature. Our results consistently showed that for a given water saturation (), the of a rock increases in the presence of foam than without foam. We found that, below a critical , the resistivity of a rock containing foam continues to rise rapidly. We argue, based on knowledge of foam behavior in porous media, that this critical represents the regime where the foam texture begins to become finer, and it is dependent on the properties of the rock and the foam. Nonetheless, the Archie model fits the experimental data of the rocks but with resulting saturation exponents that are higher than conventional gas-water rock systems. The degree of variation in the saturation exponents between the two fluid systems also depends on the rock and fluid properties. A theory is presented to explain this phenomenon. We also found that foam affects the saturation exponent in a similar way as oil-wet rocks in the sense that they decrease the cross-sectional area of water available in the pores for current flow. Foam appears to have competing and opposite effects caused by the presence of clay, micropores, and conducting minerals, which tend to lower the saturation exponent at low . Finally, the curve is consistently lower in foam than without foam for the same .
实验室测量毛管压力 () 和储层岩石的电阻率指数 () 可用于校准测井工具并确定储层流体分布。关于含油、气、水岩石中这些测量方法和影响因素的重要研究在文献中已有充分报道。然而，随着化学强化采油 (EOR) 方法的出现，表面活性剂与注入流体混合生成泡沫以增强注气过程。泡沫是一种复杂的非牛顿流体，其在多孔介质中的行为与常规储层流体不同。因此，泡沫对 和使用已知岩石模型（如 Archie 方程）拟合含泡沫岩石实验电阻率数据的可靠性的影响尚待确定。在这项研究中，我们使用多孔板和两极电阻率方法在环境温度下研究了泡沫对砂岩和碳酸盐岩中 和 曲线行为的影响。我们的结果一致表明，对于给定的水饱和度 ()，岩石的 在存在泡沫的情况下比没有泡沫时增加。我们发现，在临界 值以下，含泡沫岩石的电阻率继续快速上升。我们根据泡沫在多孔介质中的行为知识认为，这个临界 值代表泡沫结构开始变得更细的区域，并且取决于岩石和泡沫的性质。尽管如此，Archie 模型仍适用于岩石的实验数据，但得到的饱和度指数高于常规的气-水岩石系统。这两个流体系统之间饱和度指数的变化程度也取决于岩石和流体的性质。提出了一个理论来解释这种现象。我们还发现，泡沫对饱和度指数的影响与油润湿岩石类似，因为它们减小了当前流动中可用的孔隙中水的横截面积。泡沫似乎由于粘土、微孔和导电矿物的存在而产生相互竞争和相反的效果，这倾向于在低 时降低饱和度指数。最后，对于相同的 ，泡沫中的 曲线始终低于没有泡沫的情况。
