Advanced Sealed Bearing Assembly for Positive Displacement Motors used in Micro-borehole Drilling

The DOE has identified a need for a sealed bearing assembly (SBA) so that positive displacement motors (PDMs) for microhole oil drilling can be used at high differential pressures. Current off-the-shelf small PDMs are not designed for open hole drilling; rather, they are used primarily for scale removal and drill-out of cement inside tubing ¿ short run operations at standard differential pressures. This project will develop a highly durable, low cost, low maintenance, long life (in excess of 1000 hours), advanced Sealed Bearing Assembly (SBA) capable of operating under high differential pressures. In Phase I, a three-dimensional Finite Element Analysis and a large matrix of laboratory tests were used to evaluate several concepts for next generation, micro-hole size, hydrodynamic rotary seals. A hydrodynamic thrust-bearing concept was extended to bidirectional, low cost designs, which also were evaluated by laboratory testing. The results confirmed the feasibility of a long-life high-differential-pressure SBA for micro-hole PDMs. In Phase II, concepts for enhanced lubrication seals and ¿bi-directional floating¿ hydrodynamic thrust bearings will be further developed and implemented in different SBA for microhole PDMs. Commercial Applications and other Benefits as described by the awardee: The advanced Sealed Bearing Assembly, which will be designed to mate with any of the new PDMs being developed to meet DOE goals, should significantly reduce the cost of drilling and exploration. The new hydrodynamic rotary seal and bearing designs also should find use in extending the life of high-speed drilling motors (turbodrill, electrodrill), rotary steerable/directional tools, and Integrated Rotary Percussion Motors, which are being developed by others for micro-hole applications.