Field Study: Impact of Risk Mitigation Systems and Solutions on the Fluid Sampling Success Rate and E&P Project Economics of a Large North Sea Field Development Project

This paper documents the outcome of an eight-year field study that confirmed how the consistent use of innovative conveyance methods and technologies significantly improved the success rate of fluid sampling programs while reducing the overall cost of the E&P projects in long-reach challenging wells part of the largest development project undertaken in the last 25 years in the UK, North Sea sector. The formation properties encountered by these wells along their trajectories, including long deviated sections, posed massive challenges to the acquisition of critical formation evaluation (FE) data, core samples and representative formation fluid-samples required in these wells. In the early stages of this field development, the most significant risks encountered were differential sticking of the wireline-conveyed sampling tools and differential sticking of the wireline in very permeable reservoir rocks. The direct consequence of a stuck sampling tool is the need to fish the sampling tool first and then recover the required fluid samples using pipe-assisted wireline conveyance methods, a sequence that typically takes five additional days. The additional cost to the Project Partners is $4.0 million, based on five days rig spread costs plus the deferred production revenue losses resulting from the five-day production delay of all development wells not yet drilled/completed from the same installation. During the first eight fluid sampling operations in the development phase of this field the fishing rate was as high as 25%. The development and adoption of modern methods and technologies to manage the conveyance risks identified when performing coaxial packer sampling in 2012 resulted in no wireline fishing jobs (0% fishing rate) and no pipe conveyed logging (PCL) operations required (0% PCL rate) on these UK North Sea projects.