Variable stiffness fixed bend housing for directional drilling
First Claim
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1. An apparatus for controlling the direction of drilling a borehole by a drilling system, comprising:
- an outer housing having non-uniform stiffness, wherein the non-uniform stiffness of the outer housing is due to the outer housing comprising a plurality of materials, wherein each of the plurality of materials is confined to a corresponding angular range of the outer housing, and wherein the outer housing selectively bends in response to a weight applied to a drill bit of the drilling system;
an inner housing at least partially within and rotationally independent from the outer housing and having non-uniform stiffness; and
a drive shaft at least partially within the inner housing.
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Abstract
An example apparatus for controlling the direction of drilling a borehole includes an outer housing having non-uniform stiffness and an inner housing at least partially within and rotationally independent from the outer housing and having non-uniform stiffness, A drive shaft may be at least partially within the inner housing. At least one of the outer housing and the inner housing may include a tubular structure with at least one of multiple materials with different stiffness, and a portion with less structural material than another portion.
35 Citations
22 Claims
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1. An apparatus for controlling the direction of drilling a borehole by a drilling system, comprising:
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an outer housing having non-uniform stiffness, wherein the non-uniform stiffness of the outer housing is due to the outer housing comprising a plurality of materials, wherein each of the plurality of materials is confined to a corresponding angular range of the outer housing, and wherein the outer housing selectively bends in response to a weight applied to a drill bit of the drilling system; an inner housing at least partially within and rotationally independent from the outer housing and having non-uniform stiffness; and a drive shaft at least partially within the inner housing. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for controlling the direction of drilling a borehole, comprising:
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drilling the borehole in a first direction in a subterranean formation by a drilling system, wherein a non-uniform stiffness of a housing of the drilling system is due to the housing comprising a plurality of materials, wherein each of the plurality of materials is confined to a corresponding angular range of the housing, and; altering a stiffness characteristic of the non-uniform stiffness of the housing of the drilling system, wherein the housing selectively bends in response to a weight applied to a drill bit of the drilling system; drilling the borehole in a second direction in the subterranean formation by the drilling system, the second direction based, at least in part, on the altered stiffness characteristic of the housing. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A system for controlling the direction of drilling a borehole, comprising:
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a variable stiffness housing, wherein the variable stiffness of the housing is due to the housing comprising a plurality of materials, wherein each of the plurality of materials is confined to a corresponding angular range of the housing, and; a drive shaft at least partially within the variable stiffness housing; a downhole motor coupled to the drive shaft and the variable stiffness housing; and a drill bit coupled to the drive shaft, wherein the variable stiffness housing selectively bends in response to a weight applied to the drill bit of the drilling system. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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Specification