US Patent 7942213 Using hydrostatic bearings for downhole applications

Hydrostatic bearings are used for drill string stabilization and bottom hole assembly steering. The hydrostatic bearings utilize an existing mud flow as the bearing fluid. For steering, the bearings may be used between movable kick pads and the formation to reduce friction. Alternatively, differential hydrostatic bearing pressure may be utilized to steer. Multi-modal (non-linear and linear) steering may be provided by selectively applying equal and unequal hydrostatic bearing pressures. The bearings can be made more tolerant of imperfections in the formation by utilizing multiple pressure pockets.