Investigative Approaches to Troubleshooting and Remediating Sub-Optimal Gas Lift Performance in a Dual Completion Well

Abstract

Gas lift is said to be one of the most forgiving forms of artificial lift techniques because even a poorly designed gas lift system will lead to some production of fluids. As a result, the tendency exists for Production Engineers to pay little attention to designing and maintaining optimal gas lift systems. Some unique considerations are required for a dual gas lift system where both strings in a dual completion are on gas lift. Using a case study, this paper highlights key investigative questions and assessments to understand the individual well string performances, assess optimal contribution of both strings and optimal distribution of the injected gas. This paper focuses on the gas lift optimization on Well-AX SS which experienced production decline from about 1,000 BOPD to 40 BOPD. The highlights of the methods employed involved investigating for communication between strings, identifying the string with highest production potential, determining optimal gas lift valve depth, and ensuring no surface network bottleneck exists. With industry emphasis on low-cost oil, it has become critical to minimize the Operating Expense (OPEX) by ensuring optimal gas lift injection into wells. After investigation and assessment of the production potential and the gas lift injection status, the gas lift injection was redesigned, and optimal gas lift design recommended. The work-over executed involved isolating the source of communication, shutting in the completion with lower potential and optimizing the gas lift system of the more productive string. This work-over led to an increase in production of 850 BOPD. One of the key challenges to optimal gas lift is accurate gas measurement and understanding the split of gas between each string in a dual completion. Lessons learned from this assessment include obtaining robust and recent surveillance data for well performance assessment and thorough evaluation of production strings to ascertain the injection depth of gas lift gas.