Use of a Decision Tree To Select the Mud System for the Oso Field, Nigeria

Far too often, the basis for selection of a mud system is the ``latest, greatest`` technology or personal preference rather than sound cost-effective analysis. The use of risk-vs.-cost decision analysis improves mud selection and makes it a proper business decision. Several mud systems usually are available to drill and well and, with good decision analysis, the cost-effectiveness of each alternative becomes apparent. This paper describes how the drilling team used structured decision analysis to evaluate and select the best mud system for the project. First, Monte Carlo simulations forecast the range of possible results with each alternative. The simulations provide most-likely values for the variables in the decision tree, including reasonable ranges for sensitivity analyses. This paper presents and discusses the simulations, the decision tree, and the sensitivity analyses.