An Experimental Investigation of WAG Injection in a Carbonate Reservoir and Prediction of the Recovery Factor Using Genetic Programming

Mirosław Wojnicki, Jan Lubaś, Mateusz Gawroński, Sławomir Szuflita, Jerzy Kuśnierczyk and Marcin Warnecki
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Mirosław Wojnicki: Oil and Gas Institute—National Research Institute, 31-503 Krakow, Poland
Jan Lubaś: Oil and Gas Institute—National Research Institute, 31-503 Krakow, Poland
Mateusz Gawroński: Department of Robotics and Mechatronics, AGH University of Science and Technology, 30-059 Krakow, Poland
Sławomir Szuflita: Oil and Gas Institute—National Research Institute, 31-503 Krakow, Poland
Jerzy Kuśnierczyk: Oil and Gas Institute—National Research Institute, 31-503 Krakow, Poland
Marcin Warnecki: Oil and Gas Institute—National Research Institute, 31-503 Krakow, Poland

Energies, 2022, vol. 15, issue 6, 1-23

Abstract: Production from mature oil fields is gradually declining, and new discoveries are not sufficient to meet the growing demand for oil products. Hence, enhanced oil recovery is emerging as an essential link in the global oil industry. This paper aims to recognize the possibility of increasing oil recovery from Polish carbonate reservoirs by the water alternating gas injection process (WAG) using various types of gases, including CO 2 , acid gas (a mixture of CO 2 and H 2 S of 70/30% vol/vol) and high-nitrogen natural gases occurring in the Polish Lowlands. A series of 17 core flooding experiments were performed under the temperature of 126 °C, and at pressures of 270 and 170 bar on composite carbonate cores consisting of four dolomite core plugs. Original reservoir rock and fluids were used. A set of slim tube tests was conducted to determine the miscibility conditions of the injected fluids with reservoir oil. The WAG process was compared to continuous gas injection (CGI) and continuous water injection (CWI) and was proven to be more effective. CO 2 WAG injection resulted in a recovery factor (RF) of up to 82%, where the high nitrogen natural gas WAG injection was less effective with the highest recovery of 70%. Based on the core flooding results and through implementing a genetic programming algorithm, a mathematical model was developed to estimate recovery factors using variables specific to a given WAG scheme.

Keywords: enhanced oil recovery; WAG; carbonate reservoir; CO 2; acid gas; high-nitrogen natural gas; water alternating gas; EOR; recovery factor; genetic programming (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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