Abstract

The Nelson N-20 production restoration project was created to restore >1,500bopd after the well was shut in in May 2018 due to excessive sand production from a failed open hole standalone sand screen completion. The aim was to perforate ~490ft of the horizontal reservoir section and install a 1900ft screen assembly inside the completion. To deploy the guns and screens a live well deployment system was considered however ruled out due to the high project costs. As the well is sub-hydrostatic, the low head method of well control was utilized, managing a column of fluid subsurface, rather than at surface. This enabled the guns and screens to be deployed safely and cost effectively. As this was the first time Shell UK would carry out this operation without a functioning drilling package, a sharp focus was put on the planning stage to ensure success. Technical assurance on the well control aspects of the operation from across the wider Shell company and across the industry gave the team confidence to proceed. The operation was executed in June 2019, unfortunately encountering a liner damage in the reservoir section during the well clean up stage and resultantly were only able to perforate 138ft and deploy a 1,571ft screen assembly. However, the operation was completed safely, with technical success and proves that the low head method can be used for intervention activities of this sort and can simplify and take cost out of complex operations.

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