Experimental Study on Enhanced Oil Recovery: Utilizing CO2 Injection for Reservoir Revitalization

Abstract

Over the past decades, billions of dollars has been invested by the oil industry in researching and developing enhanced oil recovery (EOR) technologies to recover remaining oil. One of the most promising technologies developed is based on injecting CO2 into existing oil wells to produce ever-smaller amounts of crude oil. The latter, which is difficult to obtain, will react with carbon dioxide, at reservoir high pressures and temperatures, through a number of mechanisms, including interfacial tension (IFT) reduction, oil swelling, viscosity reduction and light hydrocarbon extraction. These mechanisms may play a more important role in enhancing oil recovery, based on whether the CO2 displacement is miscible or immiscible. Like for instance, in miscible condition, IFT reduction and oil viscosity reduction play more vital roles in CO2- EOR. Additionally, CO2 has the capability of invading zones not previously invaded by water, as well as releasing and reducing trapped oil to flow more freely into an old well and reviving its production.

In this study we focused on the miscible CO2 injection process as an effective and widely used method for improving oil recovery, and based on the characteristics of the Hassi Messaoud reservoir, We prepared corresponding synthetic cores with similar properties (clay sandstone from the upper Triassic), which we heated to a temperature of 70C⸰. In the realized experiment, we demonstrated the effectiveness of miscible CO2 injection applied to multiple samples by calculating the effective permeability of artificial cores through the falling tip permeability set and then using “oil/water and gas” constant pressure system and inject carbon dioxide under different conditions (pressure and temperature) to extract residual oil. Thus, experimental results show that residual oil from the Hassi Messaoud field can be extracted by injecting carbon dioxide at a pressure of 28 bar and at a temperature of 70C⸰ in the laboratory, increasing the remaining oil yield up to 10 % for low permeability and light oil tanks to conclude that carbon dioxide is one of the best methods for residual oil recovery.