Unique Electric Line Deployed Mechanical Cutting, Milling and Pulling Solution Successfully Applied in a Complex Fishing Operation, Regaining Access to a Critical Well

An offshore injection well in an operating field situated in the Norwegian Continental Shelf was being used for secure dumping of old drill water and well debris, this being a critical resource in support of field operations. During a routine check of the functionality of the well's downhole safety valve (DHSV) it failed its seal test. A flow tube exercise tool was run to try and resolve the situation, however it proceeded to get stuck within the DHSV, preventing the valve functionality, blocking access to the well and hence rendering the well unusable until a solution was found. The customer utilised all usual means to fish the exercise tool, with numerous slickline and e-line runs to jar and pull the fish proving unsuccessful. An assortment of high strength fishing tools were also used, including a high strength stroker providing as high as 100 Klbs force. This too was unsuccessful, proving brute force was not the solution. A detailed analysis of the situation was carried out to determine the probable cause, the extent of the challenges faced, and the appropriate solution options available. A thorough recovery plan was then devised based on a number of key steps and processes to be executed, with a decision tree created to aid operational progress. Steps included a means of determining the exact position of the core of the exercise tool. Bespoke tooling was also designed and tested to provide the securing, cutting and milling of several internal components of the exercise tool to enable it to be pulled free from the valve. These e-line deployed solutions were highly innovative, providing extremely effective, precise, and controlled capabilities resulting in the flow tube exercise tool retrieval, in turn enabling further intervention operations and a subsequent re-completion to be carried out. As a result of the processes and solutions devised to recover the stuck exercise tool from this well, a new method for securely exercising DHSV flow tubes using strokers has been devised and applied as an alternate method by the operator.