Drill-Bit Catalog and Bit Index: a New Method for Bit Performance Evaluation

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe paper analyzes the application of a new method for the evaluation of bit performances. At present, the most utilized methods for bit performance evaluation are mainly based on the cost-per-foot. This approach is definitely a good reference system, but it represents only a mere economic calculation, and is not well suited for keeping into account drilling difficulties due to formation variability and directional drilling conditions. The objective of the research is both the analysis of a new drilling model for bit performance evaluation, known as Bit Index (BI), and the investigation of the possibility of BI to establish sound guidelines for the development of a mathematical tool able to help during well planning, well drilling and post-well analysis. The model was tested by mining data from the Drill-Bit Catalog (DBC) prepared at the Exploration & Production Division of Eni Group (Italy). The DBC is a database that contains both parameters for the geotechnical/geomechanical characterization of the formations and bit record/performance data. Within the DBC, three wells have been identified, recently drilled in Southern Italy. These wells have been used for the comparison and evaluation of bit performances through the BI methodology. Main results allowed to identify the bits (labeled with IADC code) that drilled with the best performances in the above three wells. The proposed model, although in its early stage of development, proved to be economic and reliable. The quality of bit performance analysis obtained with this model seems also more effective than the traditional "quick look" analysis, performed on the bit records or on the pure evaluation of the cost-per-foot.