Compositional Modeling of Dimethyl Ether–CO2 Mixed Solvent for Enhanced Oil Recovery
二甲醚（DME）是壳牌公司首次引入的化学溶剂，用于提高石油采收率（EOR）。本研究旨在探讨在注入二氧化碳和二甲醚混合溶剂时，使用最小混相压力（MMP）和粘度重力数来提高采收率。向二氧化碳气水交替（WAG）过程中添加DME可以降低MMP和粘性重力数。MMP的降低导致在更低压力下达到混相条件，这有利于油膨胀和粘度降低，从而提高油的流动性。此外，粘度重力数的降低增加了驱替效率26.6%。通过一系列多相、多组分模拟进行的数值研究。在DME含量为25%时，与仅注入二氧化碳相比，MMP降低了30.1%，粘度重力数降低了66.4%。结果表明，与仅使用二氧化碳相比，同时注入DME和二氧化碳的最大石油采收率提高了31%。
CMG软件应用情况：
在本研究中，使用了CMG（计算机模拟溶剂集团公司）开发的GEM组分模拟器进行数值模拟。该模拟器用于分析根据DME摩尔分数变化的驱替效率。研究中设计了一个二维均质剖面油藏模型，并根据文献获得了油藏属性。模拟的总注入过程进行了12年：3年的二次水驱，6年的WAG（1:1.5 WAG比例），以及3年的水驱以产出剩余的DME。
Abstract
Dimethyl ether (DME) is a compound first introduced by Shell as a chemical solvent for enhanced oil recovery (EOR). This study aims to investigate the efficiency of EOR using the minimum miscible pressure (MMP) and viscous gravity number when a mixed solvent of CO2 and DME is injected. Adding DME to the CO2 water-alternating-gas process reduces the MMP and viscous gravity number. Reduction in MMP results in miscible conditions at lower pressures, which has a favorable effect on oil swelling and viscosity reduction, leading to improved mobility of the oil. In addition, the viscous gravity number decreases, increasing the sweep efficiency by 26.6%. Numerical studies were conducted through a series of multi-phase, multi-component simulations. At a DME content of 25%, the MMP decreased by 30.1% and the viscous gravity number decreased by 66.4% compared with the injection of CO2 only. As a result, the maximum oil recovery rate increased by 31% with simultaneous injection of DME and CO2 compared with only using CO2.
Keywords: dimethyl ether (DME); water alternating gas (WAG); enhanced oil recovery (EOR); chemical solvent; miscible gas
作者单位：
韩国首尔汉阳大学（Hanyang University）地球资源与环境工程学院
