Investigation of Hydrogen Sulfide Oil Pollution Source: Asmari Oil Reservoir of Marun Oil Field in the Southwest of Iran

Marun oil field is located in the southwest of Iran and consists of two oil reservoirs named Asmari and Bangestan. Asmari oil reservoir has been producing sweet oil and gas since 1964, but for the first time a high amount of hydrogen sulfide gas was observed in one well of this reservoir in 1980. Moreover, the Bangestan oil reservoir is located deeper than the Asmari oil reservoir and has been producing sour oil and gas since 1972. This paper represents the conducted study on the determination of hydrogen sulfide oil pollution sources in the Asmari oil reservoir. There are two hypotheses for sources of hydrogen sulfide oil pollution in the Asmari oil reservoir; first, hydrogen sulfide gas migration from Bangestan oil reservoir and second, sour gas injection migration. Data of well souring history, hydrogen sulfide gas concentration of wells, volume of gas injection and RFT analysis were used to investigate these hypotheses. The results showed a similar trend of gas injection volume and hydrogen sulfide gas concentration of wells, which decreased over time. Also, the results demonstrated that the migration of gas injection is a source and cause of spreading of hydrogen sulfide gas in the Asmari oil reservoir.