Evaluation of Two Risk Analysis Tools for Planning of Offshore Well Constructions in D&W Equinor With Focus on Uncertainty and Reusability

Abstract

The Petroleum Safety Authority (PSA) recently introduced a new definition of risk that emphasizes uncertainty as a main component of risk. Offshore well construction carry major accident potential and risk analyses in line with the new definition are expected. Equinor (former Statoil) is a company that annually drill about 150 offshore wells. This stresses the need for consistent reuse of applicable parts of previous risk analyses. Drilling & Well (D&W) is responsible for planning and construction of wells in Equinor. The purpose of the work presented in this thesis is to discuss and evaluate selected well construction risk analysis tools used by D&W Equinor. Familiarization with Equinor’s management system and well construction process DW600 was necessary to properly conduct the evaluation. Among the tools in DW600, focus was on the Concept Risk Analysis Checklist and Risk Analysis Logsheet. The evaluation was based on a discussion of pros and cons of selected elements. Finally, the tools were compared with respect to a set of criteria and improvements was suggested. The evaluation showed that both tools are easy to use, efficient and tailored for use by engineers. Both tools provide a detailed risk picture that, if presented correctly, allow for description of the major accident potential in offshore well constructions. In terms of uncertainty, both tools contain elements that indirectly reflect parts of the uncertainty dimension but they lack direct measures. When reflecting uncertainty, it is important to specify: uncertainty about what? The checklist manages to reflect uncertainties about activities by describing a term called manageability for all risk conditions. The risk description format used in the logsheet reflects uncertainties about the risk picture by including causes, consequences, and existing safeguards for all risks elements. In terms of reusability, the checklist tool uses a field specific template to ensure applicable reuse of main features in the risk picture for specific wells in a field perspective. The logsheet tool is designed for a more detailed analysis context, starting from scratch with “blank sheets”. It is therefore unfortunate that, despite the numerous downsides of reusing risk analyses in this tool, experience shows that previously conducted risk analyses are uncritically reused. Based on the evaluation, two important suggestions are to include more direct measures of uncertainty such as strength of knowledge (SoK) and to create a generic risk template to allow proper reuse in the logsheet. Looking at recent changes, the tools are developing in the right direction.