Surface Jet Pump Application in Maximizing Recovery from Offshore Gas Field

Platform Z is an unmanned platform at the SC gas reservoir located offshore Sarawak, Malaysia. As production matures, multiple wells experience reduced production as the depleted flowing tubing head pressure has minimal differential pressure to overcome the export header pressure. Eventually, these wells ceased to produce due to backpressure when a new infill well penetrating deeper reservoir is introduced. Sustaining production from depleting reservoirs while producing from deeper and higher pressure reservoirs has been notoriously difficult. Although multiple solutions exists, investment cost and tool simplicity remain as a challenge. Installation of a surface jet pump (resembling gas ejector) capitalizes the high-pressure infill well hydrocarbon fluid (as motive) to draw production from the idling wells which can no longer overcome the export header pressure. The high-pressure motive hydrocarbon passes through a dedicated nozzle within the surface jet pump (SJP) to create a high velocity and low-pressure condition to allow entrainment of hydrocarbon fluid from the low pressure well(s). This paper describes the engineering study, installation and operation of the surface jet pump at Platform Z in maximizing production from idle wells. The Surface Jet Pump (SJP) was successfully installed and has enabled the two depleting low-pressure wells (previously ceased to flow) to continue producing despite having the well flowing tubing head pressure lower than the export header pressure without reducing production of the new infill well. SJP is a significant cost-effective and energy-efficient method for production enhancement to fully deplete gas field by lowering down the well back pressure as the high-pressure motive fluid passes through the SJP internal nozzle. Although the efficiency of SJP is limited when compared to traditional compressors/pumps, it still has major advantages in terms of power consumption and maintenance as it requires neither external power supply nor moving parts that eliminate the need for frequent inspection or maintenance. The simple design makes SJP a pivotal technology in unlocking remaining reserves in all gas fields without requiring major modification to the existing facility.