Successful Preservation Methodology on Gas Lift Network Pipeline and Wells in Offshore Field Fields

Abstract

Abstract Operation philosophy at an offshore field is relying on gas lift wells as an artificial lift. The contribution of gas lift wells is essential to achieve the Maximum Sustainable Capacity (MSC). Gas lift system included high- pressure gas piping network system to supply the required gas volume from onshore gas plant, which connected to offshore gathering facilities to feed oil producer wells. Dry gas source obtained from onshore compression plant through 12" high- pressure gas line with 1,250 psi. The major challenge is to preserve the gas-piping network and gas lift wells at a safe manner and a cost-effective approach. An attempt was made to maintain a minimum pressure at value of 150 psi in order to minimize a risk related to pipeline collapse and to shipment collusion at offshore area. A new approach was utilized to bleed off the high-pressure gas network and casing annulus of gas lift wells from operating value of 1,250 psi to the required pressure value of 150 psi. This approach was managed thorough the gas lift pipeline network as loops in terms of pressure and pipeline connection. Each pipeline loop consists of four inter-connected lines ended by one gas lift well at wellhead jacket. The results showed a successful preservation approach to bleed-off high-pressure gas lift wells with connected pipelines occupied with large volume of dry gas at a cost effective and a safe manner. A self-elevating service vessel was utilized to perform the task with proper procedures and safety measurements. The production casings which were occupied with high volume of dry gas had been successfully bled down at an acceptable pressure to ensure well integrity. The approach covered 20 loops related to offshore gas lift network pipelines at safe and cost effective manner. The new technique added a great value on preservation methodology in term of the released high-pressure gas from gas lift network and producer wells to resolve issues related to air emission and hazard potential through the surface testing equipment with its burner. Challenges, methodology, risk assessment, work schedule, findings and lesson learned will be discussed in this paper.