New Plug and Abandonment Solution, Improving the Well Economy and Reduction of the CO2 Footprint on NCS Wells

Abstract Due to new environmental and cost challenges in the oil and gas industry, operators are looking for solutions to save costs and reduce their CO2 footprint. The main objective of this project was to find a solution to save time in the plug and abandonment (P&A) operation and reduce the CO2 footprint in a manner that can be applied in future P&A operations in the Norwegian Waters. The first step was to perform a detailed engineering analysis of the new solution, comparing it with the standard P&A technique. Technical requirements, associated costs, additional risks, equipment, NORSOK D010 requirements and blend designs were considered. After this analysis, the decision was made to go for the new P&A solution. This implied placing one long cement plug in one go (1425m) using a sacrificial drill pipe and a disconnect tool. The cement plug was tailored to achieve competent slurry properties for the job, such as fluid loss (FL), free fluid (FF), thickening time (TT), wait on cement (WOC), etc. Pre-job laboratory tests were conducted to assess the suitability of this blend for the new technique. The project was then planned, and the proper tools, equipment, and slurry design were selected for the job. A detailed cost analysis compared a conventional P&A method, which implied placing 5 – 6 plugs, versus the new method of placing one long plug in one go with a sacrificial pipe and a disconnect tool. The HSE aspects were evaluated, significantly reducing rig time, slop generation, CO2 footprint and people's exposure in the red zone. The job was performed as planned, observing normal circulation throughout the whole cement job and a clear indication of the dart landing and the tool release. The well barrier was verified by tagging and pressure test after WOC confirmed hard cement and isolation at the theoretical top of the cement. This new P&A method has been used for five jobs in Norway in the last two years. No issues have been recorded. The tool was disconnected as planned, confirming its reliability. Substantial rig time savings and HSE improvements have been achieved on all jobs so far. Improved HSE and reduced CO2 emissions can be achieved with this new P&A method. The paper will also show the advantage of the tool compared with conventional P&A methods and how important this can be for both environmental improvements and cost reductions.