Production Restoration Through Innovative Sourcing of Lift Gas - Jacket X Case Study

Abstract

Gas lift is one of the most common and economical methods of artificial lift deployed in mature oil fields in the Niger Delta. Availability of lift gas on the oil production jacket or platform is a critical enabler for gas lift initiation. Most mature fields do not have the luxury of gas lift supply on its jackets either because gas 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, these wells stopped production one after the other due to low tubing head pressure (LTHP) because of increasing watercut and declining reservoir pressure. The wells were producing at a combined rate of over 1,000 barrels of oil per day (BOPD) prior to stopping production. Well diagnostic and preliminary Nodal Analysis revealed the need to place the wells on gas lift to improve the vertical lift performance. However, this could not be executed as jacket X was not on the field gas lift flowline network. Without conventional lift gas on Jacket X, it was imperative to source for the most economic means of getting gas on the jacket. This paper highlights 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 Asset Management reviewed and mapped out low cost strategy to restore production of the shut-in wells. Since most of these wells stopped production due to LTHP, improving vertical lift performance became the critical success factor. To address this issue economically, the asset team developed an ingenious method of sourcing the required lift gas on the same Jacket X through rigless well intervention on one of the existing idle wellbores. The innovative approach deployed involved identification of gas bearing reservoir in one of the idle wellbores, cement squeeze operations to provide zonal isolation, oriented perforation of identified gas reservoir, topside modification of existing wellhead configuration and eventual supply of lift gas to the casing 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 gas restored to production. Significant cost savings were realized during the execution of this project through the application of rigless interventions which eliminated the requirement of laying new flowlines to deliver required lift gas to Jacket X. Finally, this paper will share some of the challenges, lesson learned, and best practices adopted while executing this project.