LG is a marginal offshore field lying in the west coast of India. Well A and B in field LG were completed using 4 ½ - in and 3 ½ - in single-string multizone completion intersecting gas and oil-bearing zones. During the initial phase of its production, the wells only produced gas, until the oil-bearing sands were perforated, and the wells produced commingled gas and oil. These wells had been flowing naturally on self-drive and recently ceased to flow after showing gradual decline in their production. The diagnosis suggested a failure of Vertical Lift Performance (VLP) indicating a need to change the production technique and possibly a need for artificial lift in the wells to bring them online. The paper discusses an innovative and cost-effective approach involving the implementation of through-tubing mechanical straddle pack-off with gas lift assistance to bring the wells back to production and increasing the overall recovery from the field. A detailed analysis of the various techniques for bringing the well online was evaluated keeping in mind the associated cost and time for each method. The considerations lead to the plan of introducing gas lift as an artificial lift method for these wells. Wells A and B were not equipped with any gas lift mandrel for introducing artificial gas lift. Workover for these wells would result in higher cost, time & risk factors for the wells. The economic viability of such a workover was not justifiable given the incremental production anticipated. After performing a detailed technical and economic analysis, the decision was made to implement a through-tubing gas lift technique using a straddle packer conveyed on slickline across the circulation Sliding Sleeve Door (SSD). The straddle pack-off was to be introduced in the existing 4 ½ - in and 3 ½ - in production tubing with internally mounted gas lift mandrels/orifice valves. Detailed modelling was performed to determine the correct orifice size for different lift parameters. The operations in candidate wells A and B were successfully conducted and the surface setup for the gas lift was installed. The mechanical pack-off was set at the desired depths without any issue, and the gas was injected through the annulus leading to instantaneous production from the well. The total operations period was minimal as compared to the workover operations, far safer and more cost-effective for the production enhancement achieved. This paper describes the job design, technique implemented, and challenges overcome during the successful activation of a theoretically dead well to 1000 BOPD production, establishing the viability of through-tubing gas lifting. Learnings from the paper will help professionals plan for such well interventions involving the use of mechanical straddle pack off for gas lift operations.

The subject well is a recently drilled and completed in Cambay field offshore in West coast of India. After landing the completion, two mechanical plugs were installed to nipple down BOP and nipple up X-mas tree. The plugs were installed in a 3.875" tubing hanger profile and in a 3.813" SC-TRSSSV selective profile. The problem arose while retrieving the 3.813" selective plug with 4" GS tool after installation of X-mas tree. The slickline wire snapped while doing the jarring operations resulting in fish in the well with BHA and plug slipping down below the selective profile. The plug fell inside the well and got stuck at the 4.5" × 3.5" tubing crossover joint ~20m below the SC-TRSSSV depth. The fished slickline wire along with the slickline tool-string BHA was successfully retrieved from the well, however, the plug remained stuck at the 4.5" × 3.5" tubing cross-over and could not be fished out even after several conventional approaches with slickline. Solutions involving rig based retrieval and rig less coil tubing intervention and e-line robotic technology for retrieval of the plug were evaluated. Upon completion of a detailed feasibility study of available options, it was decided to conduct fishing of the plug with e-line based advanced robotic well intervention techniques such as eline miller, tractor and stroker. Unique milling bits were designed and customized for this operation. The milling operation involved multiple runs to target the removal of various parts of the struck lock mandrel. Upon successful milling operation, it was planned to retrieve the plug with slickline. Initial attempts to retrieve the plug by straight pull using 33k pulling capacity Eline Stroker were unsuccessful. Subsequently, milling was attempted with a combination of E-line tractor and Miller to drill thru the plug. The milling initially started as per the plan but after 3 inches of milling the bit got stalled and was eventually stuck inside the plug. The E-line BHA had to be released from the mechanical disconnect sub above the bit. A modified 2" UPT tool with E-line tractor-stroker was run to fish out the bit and plug which resulted in the plug getting released from the stuck position and moving upwards about 10-meter from the stuck depth. Once this was accomplished, plug and bit were successfully retrieved with slickline. The paper details the background of the stuck incident, selection methodology of fishing technique, fishing work plan and its successful execution. The paper also describes the operational difficulties encountered and the mitigation chosen while milling a plug with an electric line in the offshore environment.