Encore Bits LLC solved a difficult erosion problem in an oilfield drill bit by using FloEFD computational fluid dynamics software (CFD) from Mentor Graphics Mechanical Analysis (formerly Flomerics) to improve flow around the bit. Changes were made to the bit geometry and nozzle configuration that substantially increased its life and enhanced cuttings removal.

Based in Houston, Texas, Encore specialises in the manufacture of PCD drill bits for the oil and gas industries. It developed the F5165D to provide a bit that can drill an entire section of a well with only one bit and be rebuilt several times to reduce the costs for both the operator and Encore. Early versions of the bit showed an erosion problem affecting the ability to rebuild the bit. Encore sets its rental rates based on being able to rebuild these bits and an erosion problem will result in a substantial decrease in the profit margin.

Obviously, the drilling process provides no way to discover what kind of flow pattern might be causing this problem. Very large drill bit producers use traditional CFD codes that cost in the region of $25,000 to lease on an annual basis. An even greater cost for most companies is the need to hire experts to run the codes.

But in the last few years a new generation of CFD software has been introduced that addresses all the major reasons for the relative lack of use of CFD software. Its use of native 3D CAD data, automatic gridding of the flow space, the managing of flow parameters as object-based features helps eliminate the need for engineers to understand the computational part of CFD. Instead, the software enables them to focus on the fluid dynamics of the product, which is already their responsibility to understand and master.

By altering the nozzle configuration and the blade shapes, Encore were able to achieve lower fluid velocities in critical positions while maintaining and somewhat increasing velocities in junk slot areas. These changes resulted in a bit that has better cleaning and cooling ability while also improving the wear characteristics. Decreasing erosion also helps prolong the life of the bit giving better profitability over the product lifecycle.

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