Search

Gas injection is a well-known method for enhancing oil recovery (EOR). The utilization of greenhouse gases, such as carbon dioxide (CO2) or flue gas, offers the dual advantage of reducing greenhouse gas emissions while potentially enhancing the sweep efficiency in oil recovery. Nevertheless, one of the notable challenges encountered when using these gases is the precipitation and deposition of asphaltenes, leading to formation damage and a decrease in reservoir permeability, particularly in the case of light oil reservoirs. In this study, CO2 and flue gas were injected into an elongated core sample comprising four individual core plugs under reservoir conditions to displace the light live oil. The recovery factor and asphaltene deposition along the core holder were assessed and compared as two crucial parameters within the gas injection scenario. Our results indicate a significantly higher recovery factor of 86% achieved with CO2 injection compared to 36% with flue gas injection, attributable to differences in their interfacial tension and miscibility. However, the CO2 injection method exhibits more pronounced formation damage. Individual assessment of each core plug reveals that permeability impairment is most acute in the initial two core plugs, situated closer to the injection face of the extended core. These findings enhance our understanding of the mechanisms contributing to permeability impairment resulting from asphaltene deposition during CO2 and flue gas injection for EOR. [ABSTRACT FROM AUTHOR]

In the current investigation, feasibility study has been done for miscible selective simultaneous water alternating gas (MSSWAG) injection compared with immiscible and miscible water alternating gas (IWAG and MWAG) injection in one of the Iranian reservoirs which has been subject to water flooding for several years and the recovery factor (RF) for water flooding is about 23% of the original oil in place. Through IWAG injection, the effect of gas types comprising lean and rich has been investigated which led to increase the recovery factor to 29% for rich and 28% for lean gas. Moreover, miscible injection results show that the recovery factor for rich MWAG with optimized injection pore volume led to 41.74% which shows 12% greater values than the value for immiscible one. Also, sensitivity analysis represents that under rich MWAG injection with 1:2 WAG ratio and 100-day injection period, recovery factor has improved by 7% and reached 48.55%. In continuation to the study with emphasis on the advantages of miscibility, rich MSSWAG with RF: 54.73% has led to increase the recovery factor by 6% compared to rich MWAG with RF: 48.55% (being the best scenario in this study based on simulation results). Finally, considering the economic aspects, the net present value for rich MWAG and rich MSSWAG is significantly increased by approximately average 31% relative to water flooding. [ABSTRACT FROM AUTHOR]