The well construction fluid (WCF) used in a particular operation influences the overall cost of the well construction both during and after the construction phase. The fluid can also be associated with a certain Cost at Risk potential, as unwanted incidents involving fluids may lead to consequences that carry costs. These costs can be related to the fluid's hazard level. The cost and risk related data requirements that support informed WCF choice decisions include direct fluid costs, but also cost items related to operational deployment and production stream treatment. Health, safety and environment (HSE) direct and indirect costs through risk and liability potential also form an important input into the decision making process. Identifying the most cost effective fluid that carries least risk potential may therefore significantly enhance overall well economics.

To compare overall fluid costs, the different fluid pricing models, overall operational costs and HSE related risk potential must be evaluated and summed in the same format. The Activity Based Costing (ABC) approach provides a valid framework for allocating indirect operational costs to each well construction activity and evaluating the overall operational expenditure per well. However, such overarching cost comparisons for WCF choice appear to be rare. This is considered partially attributable to a lack of a simple yet overarching cost and risk assessment tool. This paper presents the management advantages achievable from using a novel, decision supporting software tool for collating and analysing all charges related to the deployment of WCF.

The tool utilises operator, location and operation-specific data in a format that supports data collation across different asset team departments and budgets. This enables systematic, fast, repeatable yet operation-specific assessment and allows management to base decisions on the overall cost and HSE risk associated with the assessed WCF alternatives. The tool has been initially set up to compare high-density completion brines. It provides management with a clear overview of the overall financial implications and comparative HSE risks and advantages related to fluid choice. The approach is currently being adopted by a major oil company and integrated into their fluid decisions-analysis software.

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