Abstract

Optimization of mature fields in maximizing the hydrocarbon recovery has been a major concern for exploration and production companies including PETRONAS Carigali Sdn. Bhd (PCSB). CC is a brown field, situated in south central region of the DD Province of the Sarawak Basin. Since CC field has marginal reserves, an effort to enhance the production was initiated with the objective of economically boosting the remaining reserves. The proven Low Pressure System (LPS) that is widely implemented across Petronas operating fields has benefited CC in optimizing the production by lowering the existing surface back pressure. However, the challenges faced in implementing the system in CC are platform surface constraint and unmanned-operation-at-night philosophy.

Through further optimization on the existing LPS design and the estimated production from LPS well candidates, Compact Low Pressure System (CLPS) was born. The smaller package is lighter compared to existing system and has more flexibility and mobility. The separator process can cater up to 4000 bopd with approximately 4.0 MMscf/d of gas disengagement. This package consists of three major equipments compacted in one skid, which are shut down valve (SDV) for emergency purposes, vertical separator (V-100) for liquid storage and flow rate measurement, and transfer pump for pumping back the liquid to the main production line. The total dry weight of this skid is approximately 9.8 tonnes with smaller foot print of 8.3 m2. Preliminary well candidates were chosen mainly based on well status (idle well/string were given higher priority), water cut and sand control equipment in place. Then, a network model was generated using Integrated Production Modeling (IPM) software to simulate several operating scenarios and choose the best candidates. To-date, the additional oil gained from the selected 5 wells is approximately 400–600 bopd. With this achievement, CLPS has shown the capability of improving the production by overcoming the surface back pressure impact and solving space constraint issues for wells located in small wellhead platforms.

Field Background

CC field is an offshore oilfield located in East Malaysia which has been producing for 30 years since 1979. The current field watercut is around 40% and total oil production is estimated at 12,000 BOPD. The key challenges in this field is to sustain the production rate to above economic level through various production enhancement inititives including infill drilling. For existing wells, various issues such as high watercut, flow assurance, sand production and sub optimal gas-lift injections in dual-strings has been the main causes of production deferral. Numerous well interventions activities such as gas-lift valve change out for gas-lift optimisation, water shut-off, additional perforations for new zones and well stimulations were planned to maximise oil production. Due to reservoir pressure decline limited water injection pilot using portable system is also currently on-going with the aim to further maximise oil recovery from the field. In the longer term a full field water injection system is planned.

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