Baroid Technology, Inc.

Henk H Jelsma

A downhole centralizer is provided for positioning along a drill pipe string passing through a deviated well bore. A centralizer body is connected to an upper sub by a plurality of lobe-shaped connectors which permit angular deviation of the central axis of the upper sub with respect to the central axis of the centralizer body. The centralizer body is preferably connected to a lower sub by similar lobe-shaped connectors. The opposite ends of each of the upper and lower subs are threaded for fixed engagement with respective upper and lower pipe joints in the tubular string. A flexible flow conduit is positioned within a passageway through the centralizer body, and a pair of upper and lower sealing member are provided to maintain sealed engagement between the respective upper and lower subs and the flow conduit for transmission of fluid through the centralizer. The centralizer of the present invention may be reliably used to center the tubing string within the deviated portion of a borehole, thereby reducing torque lossed to the drill bit and wear on the drill string.

Flexible centralizer

A drill string includes an anchor type set down bit threadedly connected to the deflection section. Threadably coupled above the deflector section is a shear and retrieve sub having three equally spaced latch pin receptacles and three equally spaced shear pin holes. Above the shear and retrieve sub is a beveled guide section for receiving a retrieving setting tool having a tapered end sized to be inserted within the beveled guide section. The shear and retrieve section has three equally spaced latch pin mechanisms and three equally spaced shear pins. A pickup cross over sub is coupled into the top of the shear and retrieve sub and has an enlarged diameter ring which acts to limit the downward movement of the shear and retrieve section within the interior of the beveled guide and retrieving setting tool sections. A drill string operating from the earth's surface is coupled into the pickup cross-over sub which allows the entire assembly to be lowered into an earth borehole to a desired depth. By applying additional set down weight through the drill string, the shear pins are sheared and the deflector section remains at the desired depth in the borehole. In the retrieving mode, the retrieving setting tool is run back into the earth borehole on the drill string to latch with the shear and retrieve section to enable the retrieval of the deflector section.

Method and apparatus for setting and retrieving a deflection tool

A non-rotating drill string is formed from a plurality of independent, cylindrical sections pivotally connected together by a latch mechanism. The adjacent ends are partially beveled such that the sections can bend in a single direction. Means are disclosed for varying the effect of the beveled surfaces, thus controlling the angle of bend for a given one of the sections. A downhole mud motor (PDM) drives the drill bit through the use of a flexible drive shaft running through the center of a metal-lined, neoprene drilling fluid hose which runs through the interior of the independent cylindrical sections. The total curvature of the borehole drilled by the system equals the sum of the angles of bend between the individual sections.

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Spring, TX, United States of America

Henk H Jelsma