INJECTION OF HIGH-SULFUR GAS FOR RESERVOIR PRESSURE MAINTENANCE AT OIL AND GAS CONDENSATE FIELDS OF THE REPUBLIC OF KAZAKHSTAN

Abstract

Abstract. The paper addresses the technological and geological–physical aspects of injecting high-sulfur associated gas into productive formations of oil and gas condensate fields in order to maintain reservoir pressure, utilize acid gases, and improve the efficiency of reservoir development [10; 12; 14]. The prerequisites for the large-scale implementation of this technology at the major fields of the Republic of Kazakhstan—Karachaganak, Tengiz, and Kashagan—are analyzed, including the shortage of sour gas processing capacities, restrictions on pollutant emissions, and the need to increase hydrocarbon recovery factors [15–18; 20]. The key industrial safety, environmental, and techno-economic factors determining the selection of gas injection as a priority reservoir stimulation and pressure maintenance agent are identified, along with the requirements for well integrity, casing string stability, and corrosion resistance of equipment when operating in aggressive environments [14; 19]. Using the Karachaganak field as an example, the application of the cycling process is considered as a practical method for increasing liquid hydrocarbon recovery from gas condensate reservoirs, reducing in-reservoir condensate losses, and stabilizing the reservoir energy state [7; 8; 16]. It is shown that high-sulfur gas injection is an important element of the reservoir pressure maintenance system and rational subsurface management; however, it requires further optimization of injection regimes, taking into account geological heterogeneity of reservoirs, porosity–permeability characteristics of rocks, phase behavior of fluids, and long-term risks associated with possible gas migration and technogenic impacts on the reservoir system [3; 6; 9; 13].