Modelling and Simulation of Foam Assisted Water-Alternating-Gas Injection in Naturally Fractured Carbonate Reservoirs
本研究使用CMG对三种不同的提高采收率方法进行了碳酸盐岩心浸润实验结果的数值模拟，以研究增强碳酸盐岩缝洞储层气体入侵区的油藏开采效果。研究使用了在伊朗低温碳酸盐岩核心上进行的二次和三次采油条件下的二氧化碳注入、间歇气体注入（WAG）和泡沫辅助间歇气体注入（FAWAG）的实验结果。
通过使用CMG，得出了岩心的相对渗透率曲线和适应泡沫参数。然后，将这些发现用于先导试验模型，该模型由一个四分之一的五点式图案和一个扇形模型组成，其中一个双五点设定被用作主要的油藏开采方法。此外，所有这些模型首先通过原油和原生水饱和，其次通过占40%的甲烷组成的现有气体侵入区进行模拟。发现在泡沫辅助采油过程中，对于气体入侵的裂缝储层开采是非常有用的，可以使先导试验模型的采收率惊人地提高20%，扇形模型的采收率提高了2%以上。通过调整注入水和气的比例，可以将采收率提高到在三次采油阶段的1 PVI后增加7%以上。
Abstract
In this research, carbonate core flooding experimental results of three different EOR methods were replicated numerically using CMG to study the enhancement of oil recovery in the gas invaded zone of carbonate fractured reservoirs. Experimental results for carbon dioxide injection, Water-alternating-gas injection [WAG], and foam-assisted water-alternating-gas injection [FAWAG] that were conducted in Iranian low-temperature fractured carbonate cores under both secondary and tertiary recovery conditions were used for this purpose.
From these experiments, the relative permeability curves of the cores and the fitting foam parameters were derived using CMG. These findings were then used in a pilot model, that consists of a quarter five-spot pattern, and in a sector model where a double five-spot setup was used as the primary method of oil extraction. Additionally, all these models were first simulated, having been saturated by live-oil and connate water and secondly with a present gas invaded zone of 40% consisting out of methane. The foam-assisted recovery process was found to be a very useful aid in the recovery of gas invaded fractured reservoirs increasing the recovery factor in the pilot model by an astonishing twenty percent and in the sector model by more than two percent. By tuning the ratio of injected water and gas the recovery can be raised to as far as 7% additional recovery after 1 PVI for a tertiary stage.
