Abstract: Bearing assemblies for downhole tools include a compensator member operatively associated with a slidable member and a bearing member. The slidable member is movable longitudinally relative to the bearing member. Such movement of slidable member occurs when a force acts upwardly on the downhole tool. Thus, the slidable member facilitates absorption of the upward force acting on the downhole tool. During movement of the slidable member, the compensator member is moved from its expanded position to one of its plurality of compressed positions. As a result, the compensator member becomes biased or further biased toward the expanded position. After the upward force dissipates, the compensator member releases some of its stored energy to move from a compressed position toward the expanded position. Longitudinal movement of the slidable member facilitates maintaining engagement of the downhole tool in its working position so that interruptions of operations are minimized.

Abstract: In one aspect, an apparatus for forming a borehole is provided that in one embodiment may include a first milling device configured to rotate at a first rotational speed in a first direction, and a second milling device around the first milling device configured to rotate at a second rotational speed in a second direction, wherein the rotational first speed is greater than the second rotational speed. In another aspect, the first and the second milling devices may be configured to rotate in the same direction at different speeds.

Abstract: Bearing assemblies for downhole tools include a compensator member operatively associated with a slidable member and a bearing member. The slidable member is movable longitudinally relative to the bearing member. Such movement of slidable member occurs when a force acts upwardly on the downhole tool. Thus, the slidable member facilitates absorption of the upward force acting on the downhole tool. During movement of the slidable member, the compensator member is moved from its expanded position to one of its plurality of compressed positions. As a result, the compensator member becomes biased or further biased toward the expanded position. After the upward force dissipates, the compensator member releases some of its stored energy to move from a compressed position toward the expanded position. Longitudinal movement of the slidable member facilitates maintaining engagement of the downhole tool in its working position so that interruptions of operations are minimized.

Abstract: In one aspect, an apparatus for forming a borehole is provided that in one embodiment may include a first milling device configured to rotate at a first rotational speed in a first direction, and a second milling device around the first milling device configured to rotate at a second rotational speed in a second direction, wherein the rotational first speed is greater than the second rotational speed. In another aspect, the first and the second milling devices may be configured to rotate in the same direction at different speeds.