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Drilling assembly

Drilling assembly description/claims

This application claims the priority of U.S. Provisional Application No. 60/899,531 filed on Feb. 5, 2007, the disclosure of which is incorporated herein by reference for all purposes.

1. Field of the Invention

The present invention relates to drilling earth boreholes and, more particularly, to an assembly for effecting directional drilling of earth boreholes using either coiled tubing rigs or jointed pipe rigs.

2. Description of Prior Art

Directional drilling is widely used in the oil and gas industry whether the drilling be accomplished using coiled tubing rigs or conventional, jointed pipe rigs. As is well known to those skilled in the art, a typical directional drilling system has a drill bit at its bottom end which is rotated by a drill motor, commonly referred to as a “mud motor.” In addition to the drill bit and the mud motor, a typical directional drilling assembly can include an orienting or steering tool, an MWD or LWD tool, drill collars, and a bent sub which can comprise a portion of the housing of the mud motor.

Typically, prior art directional drilling assemblies have comprised a single mud motor, the mud motor supplying, as well known to those skilled in the art, the power to rotate the drill bit.

In one aspect, the present invention provides an assembly for use in drilling an earth borehole employing a drill string including a drill bit. The assembly can include a first downhole motor having an upper end and a lower end, a first rotor and a first stator, the lower end of the first downhole motor being proximal and operatively connected to the drill bit.

There is also a second downhole motor having an upper end and a lower end, a second rotor and a second stator, the second rotor having a passageway there through and being distal the drill bit. There is a bypass valve operatively connected to the upper end of the second downhole motor, the bypass valve including a valve element which is selectively movable from a first position wherein a drilling fluid flowing through the drill string can flow through the passageway in the second rotor to a second position wherein the drilling fluid is prevented from flowing through the passageway in the second rotor.

In another aspect of the present invention, there is a orienter subassembly forming part of the drill string which can include a bent housing separate from or forming part of the first motor. The second downhole motor, in conjunction with the bypass valve, can be used to induce or stop rotation of at least a portion of the orienter subassembly as required.

FIG. 1 is a schematic view of one embodiment of the assembly of the present invention.

FIG. 2 is a schematic, elevational view of a bypass valve used in conjunction with the first or lower motor; and

FIG. 3 is a cross-sectional view taken along the lines 3-3 of FIG. 2.