Kaji-Semoga (KS) field, a mature field located in South-Sumatra, requires more efficient production operation to reduce production lifting cost. Since 2008, KS field has been experiencing gas shortage due to the decline in associate gas production. As a result, some of the gas lifted producer wells need to be converted to another type of Artificial Lift (AL). After various studies and trials, it was concluded that ESP (Electrical Submersible Pump) was the most suitable alternative. Currently, the AL system is dominated by ESP with total deployment 140 of 190 producing wells, contributing 70% to the field's overall oil production, i.e. a total of 9,500 BOPD. Furthermore, KS field purchases gas as fuel for the electricity system, which is mainly consumed by AL. Therefore, efforts have been made to evaluate and obtain significant cost reduction in power consumption of ESP through power efficiency assessment and feasibility of new technology implementation.
Power efficiency assessment for ESP application becomes a promising attempt to reduce ESP power consumption. Components which mostly affect the power consumptions are pumps and motors. With this understanding, technology selection of ESP has been carefully determined to obtain significant result in power efficiency. Permanent Magnet Motor (PMM) is one of the ESP technologies that offers higher efficiency, higher power factor, greater power density and wider operating speed compared to conventional induction motor (IM). Short term field trial PMM ESP application has been conducted. Field-testing procedures and measurements on power consumption are presented both for PMM and existing IM at identical condition (head generated, motor rating, pump type & fluid rate). It yielded conclusive result that PMM has higher power efficiency. Thus, a wider application is justified and expected to have substantial energy savings and cost reductions.
Currently, PMM is utilized at 20% of ESP wells in KS field. Field observation of these PMM-ESP units revealed power efficiency improvements by as much as 10-30% compared to IM ESP units. This improvement has led to the reduction of fuel gas consumption, which we have estimated to potentially save the company almost $ 750,000 per year in power generation expenditure. In the future, all IM ESP are planned to be replaced by PMM to gain higher cost reduction.