Design optimization of a pneumatic-powered drilling tool thrust assembly

The petroleum industry is dependent on developing more efficient means of drilling oil and gas wells. A prototype of a new design has been recently demonstrated which places the drilling power source (a pneumatic turbine) down-hole with the drilling bit. However, the thrust assembly shaft used to connect the power source to the bit was not optimally designed. Because of constraints placed on the geometry of the thrust assembly, severe stress raisers exist and these cannot be predicted by traditional analytical means. The conflicting requirements for increasing air flow through the internal passages in the thrust shaft while maintaining the torque-carrying capacity were studied to develop the guidelines for optimizing the thrust assembly.