Multiphase Flow Diagnostics for Evaluating Gas Shut-Off Performance to Minimize Carbon Footprint

Abstract

Abstract This paper discusses the results of a flow diagnostics survey conducted to evaluate the performance of a Gas Shut-Off (GSO) campaign in Field A. The field faced challenges associated with a high Gas-Oil-Ratio (GOR) production, leading to excessive carbon emissions, reduced field production efficiency, and elevated carbon-per-barrel rates. Additionally, the presence of excess gas not only consumed valuable pipeline ullage but also caused transportation and flow assurance issues. Total field gas production had already exceeded the limit of surface processing facilities, which meant the Operator had to choke back production. Managing and processing excess gas in Field A requires substantial effort and capital expenditure for surface infrastructure and facilities. The GSO campaign involved the installation of a 200 ft long 2-7/8 in. tubing straddle to effectively isolate the zones with the highest gas contribution. The identified well, DW#2, was a 7 in. × 4-1/2 in. cemented monobore across several commingled oil and gas-bearing zones. The well consists of five (5) clastic reservoir zones, each with multiple layers, all of which are perforated over an extensive interval exceeding 1,500 ft. This configuration poses significant challenges in accurately determining production allocation, addressing flow assurance issues, understanding reservoir connectivity, monitoring well performance, and forecasting total field production. In addition, the high degree of complexity meant that standard production logging methods could not accurately characterize flow or confidently distinguish the main gas-contributing layers. Through the flow diagnostics survey, the paper evaluates the success of the GSO campaign in mitigating the high GOR production challenges and improving the field's performance. This paper aims to contribute to the broader understanding of managing excessive gas production in complex reservoir systems while striving to achieve enhanced field productivity and environmental responsibility.