Thru Tubing Gaslift Installation Techniques in Dual Completion for Production Optimization and Improved Recovery in Brown Field Reservoirs

There are several non-rig well intervention methods used in the oil industry to resuscitate dead wells back to production. One of such methods implemented for non-gaslift wells (or previously gas lifted wells with shallow mandrel depths) is the installation of Thru Tubing Gas Lift (TTGL) equipment at a pre-determined depth on the walls of the tubing. Most TTGL assemblies are usually fitted with one orifice valve to provide single-point injection. As a result of the single-point injection, well performance might be impacted overtime as reservoir pressure depletes and produced fluid composition changes. In such cases, deepening of injection point is required to restore the wells to production and ensure maximum oil recovery. However, these TTGL installation techniques are especially delicate to implement in wells with dual completions due to the execution complexities introduce by the presence of the adjacent tubing string, existing or adjacent perforations and injection points in the tubing. Dual oil producers, Wells X19B and Y22C were completed with dual completions without gas lift equipment in ED and ET field offshore Nigeria respectively. Well X19BL had TTGL installed about 8 years after it began production but, started to cycle gas through the TTGL point and was shut-in to curtail unwanted gas production to the surface facility. Well Y22CL and Wells Y22CU quit production on natural flow due to low well head pressure that resulted from decline in reservoir pressure Rig based interventions was uneconomic owing to the fact the remaining reserves were marginal. This paper discusses the techniques, challenges and operational learnings from the first-time application of TTGL deepening and TTGL installation in both dual strings despite complexities from well architecture and previous TTGL installation