Bi-Center Technical Paper

Specific Design Process associated with simulation tools improve PDC bi-center application definition, and delivered solution in directional environment


Bi-centre bit performance in directional applications usually presents performance challenges in terms of efficiency versus power availability and dynamic issues. In most instances the bi-centre bit selection and/or development compromises overall rate of penetration (ROP) for steerability. Extensive statistical analysis combined with drilling simulations (numerical) revealed the importance in the overall performance of a highly efficient bit during the sliding time.

This paper will discuss a field proven design process and technology used to enhance bi-centre bit performance in challenging applications such as directional drilling. After years of extensive development and modeling of cutting structures, including the drilling of simulated wells combined with full scale bit laboratory tests, a process combining cutting structure, rock type and application objectives has been developed. This process, which models and simulates bit behavior during the drilling process, is based upon "bridgeable” software. Analysis using different cutting structures with various parameters in line with drilling objectives and combined with Varel's rock analytics software is used to predict and analyze bit behavior in term of directional tendencies and ROP.

This paper will also discuss the use of this process and the bit developed for a 5 5/8” in Saudi Arabia application. Offset PDC bits averaged 200 $/ft including hole opening cost the solution as a result of the modeling and simulated drilling resulted in an average of 113 $/ft in the same application.

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