Abstract

Thrust bearings used in mud lubricated drilling motors have to handle high loads, abrasive drilling mud, and large impacts, all of which reduce bearing life. In bent housing motors used for directional drilling, these adverse operating conditions are amplified and generally result in severely shortened bearing life and reliability. When drilling the lateral section with a bent housing motor a shorter "bit-to-bend" length is a great advantage because it reduces the loads on many of the motor components. Through the use of a resiliently-mounted stacked ceramic bearing design, the thrust bearing length can be reduced while retaining the capability to handle the increasing thrust and impact loads and withstand the erosion from abrasive drilling muds, thus increasing life expectancy and reliability.

The patented ceramic stack bearing has been designed to replace ball and PDC bearings in mud lubricated drilling motors. Although the bearing can be used in any drilling motor, a significant advantage is realized from using the shorter bearing design for short bit-to-bend motors. The increasing demand for short bit-to-bend motors has led manufacturers to reduce the length of their bearing section, and thus the life and load capacity of the thrust bearing. A shorter conventional thrust bearing stack means the load is carried by fewer bearing components and thus the load-per-bearing stage is increased, reducing the life expectancy of the bearing and, in turn, limiting the drilling hours a motor can continuously operate.

With the increasing number of directional wells being drilled, short bit-to-bend motors have become more desireable; more drilling companies are requesting them and more motor manufacturers are designing them. Using the improved bearing technology, combined with short bit-to-bend mud motors, directional drillers are able to drill curved and lateral sections of wells with one motor. This eliminates tripping out of the well to change the motor / BHA (Bottom Hole Assembly). Deep wells in the Eagleford formation have saved days of drilling time by operating motors in excess of 280 hours continuously with this resiliently mounted ceramic thrust bearing assembly.

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