Production Restoration Through Innovative Sourcing of Lift Gas - Jacket XCase Study

摘要

Gas lift is one of the most common and economical methods of artificial lift deployed in mature oil fieldsin the Niger Delta. Availability of lift gas on the oil production jacket or platform is a critical enabler forgas lift initiation. Most mature fields do not have the luxury of gas lift supply on its jackets either becausegas flowlines were not laid at inception or the gas flowlines are out-of-service due to integrity issues. Jacket X had four active oil well streams producing on natural flow at inception. In early 2017, thesewells stopped production one after the other due to low tubing head pressure (LTHP) because of increasingwatercut and declining reservoir pressure. The wells were producing at a combined rate of over 1,000barrels of oil per day (BOPD) prior to stopping production. Well diagnostic and preliminary Nodal Analysisrevealed the need to place the wells on gas lift to improve the vertical lift performance. However, this couldnot be executed as jacket X was not on the field gas lift flowline network. Without conventional lift gas onJacket X, it was imperative to source for the most economic means of getting gas on the jacket. This paperhighlights the processes and methodology of sourcing lift gas through an existing idle wellbore. During the bi-anual field review, the team of Operations personnel, Facilities Engineering and AssetManagement reviewed and mapped out low cost strategy to restore production of the shut-in wells. Sincemost of these wells stopped production due to LTHP, improving vertical lift performance became the criticalsuccess factor. To address this issue economically, the asset team developed an ingenious method of sourcingthe required lift gas on the same Jacket X through rigless well intervention on one of the existing idlewellbores. The innovative approach deployed involved identification of gas bearing reservoir in one of theidle wellbores, cement squeeze operations to provide zonal isolation, oriented perforation of identified gasreservoir, topside modification of existing wellhead configuration and eventual supply of lift gas to thecasing of the shut-in wells. Utilizing the lift gas, the wells were placed on gas lift with 1,100 barrels of oil and 3.5 MMScfd of gasrestored to production. Significant cost savings were realized during the execution of this project throughthe application of rigless interventions which eliminated the requirement of laying new flowlines to deliverrequired lift gas to Jacket X. Finally, this paper will share some of the challenges, lesson learned, and best practices adopted whileexecuting this project.