ABSTRACT

Decision analysis (DA) methods were used to analyze the costs vs. benefits for MWD wireline replacement programs on two 6-well platform projects in the Gulf of Mexico. The DA on the first project indicated a cost savings between $0 - $50,000 per well could be expected, with a median probability of saving $21,000. The wells were drilled with MWD replacing wireline with total cost savings of over $240,000 for the project. The DA on the second project indi cated that there was virtually a 100% chance of not realizing any cost savings, and that we could incur additional costs of up to $70,000 per well with a median probability of an additional $29,000 cost per well. It was decided to not use MWD to replace wireline on this project, which turned out to be a prudent decision as drill pipe was stuck in several of the wells and a bottom hole assembly (BHA) was lost in one well.

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The common cost analysis on MWD wireline replacement is usually a simple comparison of invoice costs and anticipated rig time savings. While this type of method may yield useful information regarding cost benefits, it can be misleading as it does not take into account all of the risks and diverse factors that need be considered to evaluate the economic benefits of running MWD.

Decision analysis (DA) programs are capable of incorporating variable costs, risks, and diverse factors in evaluating the possible economic benefits of running MWD. They accomplish this by performing a Monte-Carlo simulation on a range of possible outcomes and their associated costs. Comparison of one set of outcomes and associated costs (wireline logging) to another set of outcomes and costs (MWD replacement) is then possible. Since risk is incorporated into this type of analysis, a more accurate picture can be obtained regarding the possible economic benefits of MWD wireline replacement.

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