Adaptive Strategy in Execution of Crown Plug Retrieval at the First Deepwater Subsea Workover Campaign

Abstract

A thorough planning and preparation is very critical to ensure a successful deep-water subsea workover campaign particularly the first one in the country. A reliable back-up plan played important role in this subsea operation where the hydraulic stroking tool with the support of other downhole robotic tools, that once a contingency became the main procedure due to the successful crown plug retrieval when the conventional solutions failed. This paper will present the planning, process, execution and lesson learned during the operations. Wireline intervention has always been prepared for various activities in recent subsea workover campaign including being the contingency of crown plug retrieval. The conventional way to retrieve crown plugs is using slick line jarring. If this method is not successful due to certain causes and equipment limitation due to water depth (ranging between 400 and 1500 meters), a hydraulic electric stroking tool will be run to pull out the crown plugs. This new advanced electric line stroking tool is a proven and reliable solution to remove the plugs that can apply axial force up to 100,000 klbs using bi-directional hydraulic ram. In addition to the stroking tool, a detail procedure was developed involving cleaning the landing string prior RIH and deploy suction tool on the top of crown plugs to make sure that GS pulling tool run with stroker able to latch on to the crown plug. In this campaign, at the first well from three wells workover campaign, the slick line was deployed first. On the first and second attempt, after more than 25 times, the GS pulling tool failed to latch. It was believed the crown plug fish neck was full of debris. The suction tool was run to clean out the debris subsequently after confirming the crown plug was clean, the stroking tool was run and pulled out the upper crown plug in one stroke. The lower crown plug was also successfully retrieved with the same method. From being the contingency, now deploying the electric line stroking tool continued to the second and third wells as main activity with improved operational procedure by capturing the lessons learned from each well. The operator would have added more rig days for rigging up and down the coil tubing unit to retrieve the crown plugs. This emphasizing how significant to have a very well-planned contingency solutions and being agile to overcome the challenges in the deep-water.