The two most common challenges on the oil and gas production today are the flowing production under natural pressure depletion and the surface facility capacity limitation. Ujung Pangkah field is no exception regarding finding a method to overcome this problem. It compelled to embolden many strategies to ensure the continuity of oil and gas production. Production enhancement initiatives were delivered through both Subsurface and Surface sides.
SAKA Energi Indonesia, as the operator of Pangkah PSC, proved that Surface Modification approach increased the oil and gas production. Historically, gas lift injection dependency in all production wells force a continuous operation of Gas Lift Compressor (GLC) unit to supply gas lift. However, GLC as a production backbone is no longer sustainable, it has reached its maximum limit and unable to fulfil the gas lift rate requirement for all wells. Furthermore, the changing flowing conditions – low gas feeding - from wells are relatable to most of the critical surface equipment.
Considering all the challenges faced in Ujung Pangkah field, SAKA developed initiatives on MP Compressor and GLC configuration by performing compressors restaging. The equipment modifications started out with restaging the MP Compressor (MPC) that led to MP Separator operating pressure reduction – from 22 barg down to 16 barg. Pressure changes on MP Separator also directly affected the GLC system since it works on the same pipeline header. Technical assessment analysis for other corresponding equipment were performed to verify if each of the equipment's operating boundary could accommodate lower pressure at the facility.
Compressor restaging has direct and indirect impacts. The direct impacts are decrease in suction pressure, increase in gas lift rates, and decrease in flowing of suction pressure due to the pressure at wellhead. The indirect impact is production gain from wells by lowering the wellhead pressure. Particularly in the pressure depletion case, this initiative could extend the lifetime of the wells. Production gain was quantified after compressor restaging and pressure system lower to 16 barg. The gain from this method was 3 MMscfd and ~400 BOPD.