Application of oil in situ combustion for the catalytic methane conversion in the porous medium of the gas reservoir

Abstract

Catalytic methane conversion (CMC) could be realized in situ in gas reservoirs. Through this process, a new environment-friendly energy carrier - hydrogen-can be generated inside the hydrocarbon field's porous medium. This method can become a new low-carbon, cost-effective method for hydrogen production. For this purpose, the catalyst has to be delivered into the reservoir, and the temperature inside the active zone of the reservoir has to be raised. The effective way to increase the temperature directly inside the reservoir is by injection of air and combustion of saturating liquid hydrocarbons. This research investigates the CMC process at conditions achieved in the reservoir due to oil in situ combustion (ISC). Numerical and physical modeling of in situ hydrogen generation from methane was performed using forward wet ISC of oil to heat the reservoir. The results of the unique experiment on a crushed oil-saturated core-packed model with different inlet flow rates of air, steam, and methane in the combustion tube (CT) are presented in the current study. The experiment consisted of four parts with different regimes and operational parameters: forward ISC of oil, steam methane reforming (SMR) at 450 °C and 8.9 MPa, SMR at 550 °C and 8.9 MPa, SMR at 550 °C and 2.3 MPa. The combination of these processes has led to the generation of hydrogen and methane conversion rates of up to 40% (during the combustion stage). Comparatively, low hydrogen yield was observed within the experiment, possibly due to the secondary reactions. However, irreversible reduction of oil viscosity, density, sulfur, and asphaltenes content was achieved within the experiment. The influence of catalyst and generated hydrogen on oil quality is one of the additional positive effects of in situ hydrogen generation. The numerical simulation of the experiment was performed for further study of the optimal hydrogen generation conditions. The proposed kinetic model consisted of ISC reactions and hydrogen generation reactions. The primary purpose of this experiment was to validate the principle study of the possibility of in situ hydrogen generation and simulate the processes in the core model physically and numerically.