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. Salvo made changes in the bit geometry and nozzle configuration that substantially increased its life and enhanced cuttings removal. “CFD helped us understand the problem and guided us as we iterated the design to an optimized solution,” said Vince Salvo, Design Engineer for Encore Bits.

Encore 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.

From the simulation results Salvo gained an understanding of the problem. This almost immediately gave him ideas on how to improve the flow performance of the design. He tried out these ideas, singly and in combination by first modifying the design in the familiar Pro/ENGINEER Wildfire CAD environment and then by simply pushing a button to re-run the embedded CFD simulation, in the fully-embedded Pro/ENGINEER environment available with FloEFD.Pro. With each design iteration, he gained additional insights that generated steady improvements.

“By altering the nozzle configuration and the blade shapes, we were able to achieve lower fluid velocities in critical positions while maintaining and somewhat increasing velocities in junk slot areas,” Salvo said. These changes resulted in a bit that has better cleaning and cooling ability while also improving the wear characteristics. Decreasing erosion also helps us prolong the life of this bit giving us better profitability over the product lifecycle. This project clearly demonstrates that FloEFD.Pro offers the potential for huge advancements to companies whose products involve fluid flow.”

For more information about FloEFD.Pro, send an e-mail to info-mechanical@mentor.com or visit www.mentor.com/mechanical

CAPTION: Encore Bits solves drill bit erosion problems with Mentor Graphics FloEFD.Pro