Probability-Derived Risk-Model: Lowers Costs through Reduction in Backup Tool Requirements, Improves Return on Capital Employed for the Contractor, and Reduces Scope 1 CO2 Emissions

Abstract

A review of the utilization of Drilling Equipment highlighted an opportunity to lower operational cost for the Operator, reduce Capital Employed for the Service Company, and reduce industry Scope 1 CO2 emissions. The Operator and the Oilfield Services Company set the objective of developing a risk-based probability model that could be used to assess the positive and negative financial impacts of reducing, or perhaps entirely removing, the need for backup drilling tools in the historically risk-averse UK North Sea. The scope of the analysis was to be a drilling campaign on a single rig contracted by the Operator (Rig A). The last three years of Drilling tool reliability data from North Sea operations, as recorded by the Drilling Service Provider, were used as an input. To assess the probability of failure, a Binomial Model was developed to create a Binomial Distribution for each tool, before determining the probability of failure of a given drilling string. The method calculates the probability of having 0 to X failures for a selected Drilling tool/string for a given number of runs. Three Binomial Models were developed to analyze the effect of "Easy", "Moderate" and "Challenging" drilling environments on drilling tool reliability. A financial risk model was developed that balanced the probability-weighted cost of failure for the Operator against the lower costs resulting from reduced tool provision by the Service Provider. In order to better estimate the risks and financial impacts on the project, Sensitivity Analysis was performed on the financial risk model using the three Binomial Models. Scope 1 CO2 emission reductions result from fewer logistical movements and diminished backup tool manufacturing requirements. As a result of the analysis, it was shown that recent improvements in tool reliability support a reduction in backup Drilling tools for the majority of North Sea drilling scenarios, meeting the objective of reducing well construction cost while lowering carbon footprint. Open discussions, focused on maximizing economic hydrocarbon recovery, reducing costs for the Operator, improving Return on Capital Employed for the Oilfield Services Provider and reducing Scope 1 CO2 emissions, resulted in a commercial model that could deliver a Win-Win scenario for all parties. It was observed that the approach was scalable, and would deliver further benefit from a broader workscope, generating "network" benefits when applied to a cluster of rigs, and/or an entire play/basin. In addition, the risk model can be applied to alternative industry scenarios where strong reliability data exist.