Managing Gas-Constrained Facility: Converting Oil Producer into Gas Injection Well

Abstract In accordance with Banyu Urip reservoir simulation for production outlook, produced gas is increasing over time causing the facility to become gas-constrained. With approximately 80% of the gas is being re-injected back for reservoir pressure maintenance, the existing Gas Injection (GI) capacity is limited by the backpressure which is close to the compressor pressure limit. Well conversion helps to resolve these challenges, subsequently allowing more gas production which translates to higher oil production. Repurposing the existing shut-in oil producers into gas injection wells require surface piping modification. The development of this project needs Surface and Subsurface team collaboration to acquire both hydraulic benefit and meet reservoir pressure maintenance requirement. It mainly consists of: Well selection criteria for shut-in oil producers Surface piping system modification concept and hydraulic calculation Gas injection wells operation and injectivity performance observation Address challenges from the converted wells (sulfur deposition, schmoo formation, injectivity loss) Subsurface selection criteria for conversion well candidate include ensuring all perforation intervals are already within gas zone by performing contact logging to evaluate the latest gas-oil contact. Selecting the appropriate gas supply route proved to be beneficial for gas injection wells operation and performance, as well as for the oil production. Injectivity data suggests that supplying gas injection from the gas lift manifold resulted in lower backpressure by 900 kPag, compared to flowing gas from gas injection manifold. Furthermore, two additional Gas Injection (GI) wells resulted in the significant reduction of compressor discharge pressure, allowing more gas to be re-injected back to the reservoir. It also provides more flexibility to perform one GI well preventive maintenance without continuous flaring. The project has successfully increased the gas injection capacity by approximately 30%, thus allowing higher produced gas to be handled by the system. It translates to additional oil production of 4,000 – 6,000 bbls/day while maintaining lower emission. This paper provides insight of successful effort in converting oil producer wells into gas injection wells with a proper measure and precautions for a gas-constrained facility. Simple modification of well conversion proved to be giving higher injection capacity and significantly impact the oil production.