Abstract

The Kaji-Semoga fields in South Sumatra, Indonesia, are mature, waterflooded oil fields with ESP's in more than half the wells. To minimize oil deferment due to down-hole ESP problems, an ESP-gas lift hybrid was implemented in 2009. The idea was to install gas lift as a backup so the well could be kept on production, albeit at reduced rate, until the ESP could be serviced or replaced. During the period 2011-2012, 97 wells had the hybrid lift system installed and ESP problems occurred 23 times in these wells. The availability of the ESP-gas lift hybrid minimized oil deferment and allowed approximately 24,000 bbls of oil to be produced while waiting for the ESP to be serviced or replaced.

However, the previous hybrid design used just a single gas lift valve as an unloader and injection point. Performance analysis of the previous design showed that the gas lift performance could be optimized if the injection point was, on average, about 300 feet deeper. But that would be too deep for unloading, so the gas lift hybrid system was redesigned by incorporating two gas lift valves, one a shallower unloading valve and the other a deeper injection valve.

Between April 2013 and March 2014, twenty-four wells had the redesigned ESP-gas lift hybrid installed. Performance analysis of the design was conducted at KS-XXX well when it had an ESP down-hole problem. After the redesigned gas lift was activated, it increased drawdown by 121 psi compared to the previous design, kept the liquid lifting to 57% of ESP production rate (compared to 25% of ESP production rate with the previous gas lift hybrid design) and minimized oil deferment leading to 540 bbls of additional oil production in this one instance. Analysis of the overall performance of the redesigned ESP-gas lift hybrid is onging, but results are similarly good.

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