Drilling for Oil and Gas, Ceramics Make the Difference

A PetroCeram (R) thrust bearing employing advanced ceramics has been developed using hydrodynamic technology which minimizes wear and significantly decreases bearing frictional losses. With the thrust bearing acting as one of the primary sources of power loss in the motor, this reduction in frictional losses greatly increases available power to the bit meanwhile reducing the burden on the rig required to achieve similar drilling Rates of Penetration (ROP). In addition, downhole bearing longevity and reliability is increased resulting in a significant reduction in costly premature motor pulls. The use of mud motors is common in directional drilling for oil and gas where thrust bearings are exposed to severe operating conditions including high shock loads, misalignment, and abrasive lubrication. This paper covers the use of a hydrodynamic tilt-pad thrust bearing design which was optimized to operate in downhole motor environments. This patented bearing was tested and compared to conventional ball bearings and polycrystalline diamond compact bearings. Hydrodynamic bearings provide a fluid film that separates the relative moving parts and eliminates the wear mechanism conventional bearings experience. The fluid film also significantly reduces frictional loss which directly leads to more torque available to the drill bit. Theoretical evaluation, lab testing, and field trials were performed to study the possible advantages of load, power efficiency and endurance that may be attained using a hydrodynamic design. In partnering with Ryan Energy Technologies to test this design downhole, a motor incorporating this bearing successfully completed drilling of both the curved and lateral portions of the hole, saving the oil and gas company: Pioneer Drilling Company, three days of rig time. Similar tests confirmed that at motor speeds, a fluid film layer is developed resulting in insignificant wear and low frictional losses.