Abstract: A stator for a positive displacement motor including an external tube. The external tube includes an outer surface and an inner surface, and the inner surface includes at least two radially inwardly projecting lobes extending helically along a length of the external tube. A liner is positioned adjacent the inner surface, and the liner conforms to the radially inwardly projecting lobes formed on the inner surface and to the helical shape of the inner surface. A thickness of the liner is at a maximum at the at least two radially inwardly projecting lobes.

Abstract: A stator for a positive displacement motor including an external tube. The external tube includes an outer surface and an inner surface, and the inner surface includes at least two radially inwardly projecting lobes extending helically along a length of the external tube. A liner is positioned adjacent the inner surface, and the liner conforms to the radially inwardly projecting lobes formed on the inner surface and to the helical shape of the inner surface. A thickness of the liner is at a maximum at the at least two radially inwardly projecting lobes.

Abstract: A drilling motor includes a non-elastomeric stator and rotor which are dimensioned for negative or zero interference. The amount of negative interference between the rotor and the stator is determined by the largest solid particle expected to pass through the motor. The negative interference or gap between the rotor and the stator is preferably at least two times the greatest particle size. According to the invention, stators are made by machining or casting stainless steel and are fabricated in sections having lengths of 20 to 40 centimeters. The sections are indexed so that each section may be properly aligned with another. The sections are aligned and welded together to form a motor stator of conventional length.

Abstract: A near bit offset stabilizer for use with a bent sub or bent motor housing is presented wherein a mechanism is provided to correctly orient and lock the stabilizer in a desired position in alignment with the bend angle in the bent sub or bent motor housing. This alignment and locking mechanism comprises a ring nut having a series of radial slots on its lower end; and the provision of a series of corresponding radial slots on the upper end of the stabilizer. The corresponding slots permit mutual interlocking between the ring nut and stabilizer for locking the stabilizer in any one of a plurality of radial positions. A scribe line or other indicia on the stabilizer permits visual alignment with the bend in the bent sub or bent motor housing in the drill string above. Finally, a second nut locks the stabilizer in the selected radial position.

Abstract: In situations where it is necessary to directionally drill boreholes from the surface in a substantially horizontal attitude, such as for pipeline river crossings, the precise directional parameters of drilling become critical. A system of tools for efficiently accommodating the precise directional steering of the drilling includes a continuous electrical communications path within a drill string, which path provides steering data at the surface for controlling the drilling operation. A side entry sub is positioned in the tool string at its upper end. A cable system is employed in each pipe section placed in the string and includes provisions for breaking and making connections with the cable without withdrawing the cable from the pipe string. A steering tool is fixedly positioned in the drill pipe near the drill bit and is not normally withdrawn from the hole except with the drill bit.