Master of Science in Petroleum Engineering (MSPE)
Bit performance in deep shale when using water-based mud is typically poor. This study is part of a larger research project to improve that performance entitled "Automated Rig Controls for Improved Drilling Costs." The objective of the project is diagnosis of changes in drill bit performance to provide a logical basis for automating draw works control, maximizing bit performance, and reducing drilling costs. The specific goal of this study is a means to diagnose bit performance, specifically to identify bit balling and lithology changes, using real-time drilling data. The research began by identifying symptoms relating to specific causes of bit performance changes based on previously published research. Four published and six additional new potential parameters were identified for evaluation. Laboratory data was analyzed from both single cutter and full-scale tests to evaluate which diagnostic measures best indicated the causes of different or changing performance. Five of the diagnostic parameters were selected for further evaluation. An example set of field data was acquired that included both surface records of operational parameters and an electric log of the formations in a 2600 foot interval. Rate of penetration was estimated using Lubinski's method. Three published and two new diagnostic parameters were calculated for the entire interval. The sign, magnitude, and trend of these diagnostic parameters were compared to the changes evident in the data to establish the relationship between each diagnostic parameter, the lithology, and whether the bit was balled or drilling efficiently. As a result, a method for defining baseline values of each parameter, identifying lithology, and determining whether the severity of bit balling is constant, being reduced, or increasing is proposed and demonstrated. This method can potentially provide a basis for operational changes to improve bit performance, to help detect lithology changes, and to delineate bed boundaries more accurately.
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Aghassi, Arash, "Investigation of qualitative methods for diagnosis of poor bit performance using surface drilling parameters" (2003). LSU Master's Theses. 4031.
John Rogers Smith