System and method for controlled directional drilling

Claim 2

An improved system for controlled directional and straight drilling of a borehole wherein the entire drillstring is rotatable from the surface, including a bottomhole assembly comprised of a drill bit connected to the output shaft of a downhole motor for independent rotation from the drillstring, said motor connected at its uphole end to the drillstring, the improvement in the bottomhole assembly, comprising: a first, concentric stabilizer, having a preselected diameter slightly smaller than the diameter of the borehole, mounted between the drill bit and motor at a preselected distance from the bit around the output shaft of said downhole motor, said shaft being concentrically located therein; a .[.heat.]. .Iadd.bent .Iaddend.motor housing connected to the downhole end of said downhole motor that has a bend from its geometric center at a predetermined angle α at its downhole end, thereby offsetting the centerline of said first stabilizer and the centerline of the drill bit face from the borehole centerline by said angle α; a second concentric stabilizer, having a preselected diameter slightly smaller than the diameter of the borehole, mounted at a preselected distance from said first concentric stabilizer on the drillstring, said drillstring being concentrically located therein; and a third concentric stabilizer, having a preselected diameter slightly smaller than the diameter of the borehole, mounted at a preselected distance from said second concentric stabilizer on the drillstring, said drillstring being concentrically located therein; wherein the angle α of the bend in the motor housing, and the diameter and placement of the concentric stabilizers are determined by the desired path of the borehole to be drilled, said system drilling a curved borehole when only the downhole motor is activated, and drilling a straight borehole when the downhole motor is activated and both the drillstring and downhole motor housing are rotated.

Claim 3

The system for controlled directional and straight drilling of a borehole of claim 1 further comprising a bearing housing connected between the drill bit and the downhole end of said downhole motor housing, the drive shaft of said downhole motor being concentrically located therein and connected to drive said drill bit, said first concentric stabilizer being mounted on said bearing housing at a distance less than five feet from the face of the drill bit.

Claim 4

The system for controlled directional and straight drilling of a borehole of claim 2 wherein the bend angle α of the downhole motor housing is one degree or less.

Claim 5

The system for controlled directional and straight drilling of a borehole of claim 1 further comprising a fourth concentric stabilizer located a preselected distance on the drillstring from the third stabilizer.

Claim 6

The system for controlled directional and straight drilling of a borehole of claim 1, wherein the bend angle α of the downhole motor housing is about one-quarter of one degree.

Claim 7

The system for controlled directional and straight drilling of a borehole of claim 1, wherein the bend angle α of the downhole motor housing is about one-half of one degree.

Claim 8

The system for controlled directional and straight drilling of a borehole of claim 1, wherein the bend angle α of the downhole motor housing is about three-quarters of one degree.

Claim 9

The system for controlled directional and straight drilling of a borehole of claim 5, or claim 6, or claim 7, wherein said first concentric stabilizer is placed at four and one-quarter feet from the face of the drill bit.

Claim 10

The system for controlled directional and straight drilling of a borehole of claim 8, wherein said second concentric stabilizer is placed at thirty-one feet from said first concentric stabilizer.

Claim 11

The system for controlled directional and straight drilling of a borehole of claim 9, wherein said third concentric stabilizer is placed at forty-five feet from said second concentric stabilizer.

Claim 12

The system for controlled directional and straight drilling of a borehole of claim 9, wherein said third concentric stabilizer is placed thirty-five feet from said second concentric stabilizer.

Claim 13

The system for controlled directional and straight drilling of a borehole of claim 1, wherein said first concentric stabilizer is placed at four and one-quarter feet from the face of the drill bit.

Claim 14

The system for controlled directional and straight drilling of a borehole of claim 12, wherein said second concentric stabilizer is placed at thirty-one feet from said first concentric stabilizer.

Claim 15

The system for controlled directional and straight drilling of a borehole of claim 13, wherein said third concentric stabilizer is placed at forty-five feet from said second concentric stabilizer.

Claim 16

The system for controlled directional and straight drilling of a borehole of claim 13, wherein said third concentric stabilizer is placed at thirty-five feet from said second concentric stabilizer.

Claim 17

The system for controlled directional and straight drilling of a borehole of claim 14 or claim 15, wherein said first, second and third concentric stabilizers are 0.032 inches smaller than the borehole.

Claim 18

The system for controlled directional and straight drilling of a borehole of claim 14 or claim 15, wherein said first concentric stabilizer is 0.157 inches smaller than the borehole and said second and third stabilizers are 0.032 inches smaller than the borehole.

Claim 19

The system for controlled directional and straight drilling of a borehole of claim 14 or claim 15, wherein said first concentric stabilizer is 0.282 inches smaller than the borehole and said second and third stabilizers are 0.032 inches smaller than the borehole.

Claim 22

An improved steerable system for controlled directional and straight drilling of a borehole wherein the entire drillstring is rotatable from the surface, including a bottomhole assembly comprised of a drill bit connected to the output shaft of a downhole motor for independent rotation from the drillstring, said downhole motor connected at its uphole end to the drillstring, the improvement in the bottomhole assembly comprising: a concentric stabilizer, having a preselected diameter slightly smaller than the diameter of the borehole, mounted at a preselected distance from the drill bit, the output shaft of said downhole motor being concentrically located within the concentric stabilizer; and a bent housing connected above said concentric stabilizer and having a bend from its geometric center at a predetermined bend angle α, thereby offsetting the centerline of said concentric stabilizer and the centerline of the drill bit face from the borehole centerline by said predetermined bend angle α; wherein the predetermined bend angle α of the bend in the bent housing, and the diameter and placement of the concentric stabilizer are determined by the desired path of the borehole to be drilled, said system drilling a curved borehole when only the downhole motor is activated, and drilling a straight borehole when the downhole motor is activated and the drillstring is rotated. .Iaddend. .Iadd.

Claim 23

An improved steerable system for controlled directional and straight drilling of a borehole wherein the entire drillstring is rotatable from the surface, including a bottomhole assembly comprised of a drill bit connected to the output shaft of a downhole motor for independent rotation from the drillstring, said downhole motor connected at its uphole end to the drillstring, the improvement in the bottomhole assembly comprising: a concentric stabilizer, having a preselected diameter slightly smaller than the diameter of the borehole, mounted at a preselected distance from the drill bit, the output shaft of said downhole motor being concentrically located within the concentric stabilizer; and a bent housing connected above said concentric stabilizer and having a bend from its geometric center at a predetermined bend angle α, thereby offsetting the centerline of said concentric stabilizer and the centerline of the drill bit face from the borehole centerline by said predetermined bend angle α; wherein the predetermined bend angle α of the bend in the bent housing, and the diameter and placement of the concentric stabilizer are determined by the desired path of the borehole to be drilled, said system drilling a curved borehole when only the downhole motor is activated, and drilling a straight borehole when the downhole motor is activated and the drillstring is rotated. .Iaddend. .Iadd.

Claim 26

motor and selectively rotating the drillstring. .Iaddend. .Iadd.23. An improved system for controlled directional and straight drilling of a borehole wherein the entire drillstring is rotatable from the surface, including a bottomhole assembly comprised of a drill bit connected to the output shaft of a downhole motor for independent rotation from the drillstring, said downhole motor connected at its uphole end to the drillstring, the improvement int he bottomhole assembly comprising: a first concentric stabilizer, having a preselected diameter slightly smaller than the diameter of the borehole, mounted at a preselected distance from the drill bit, the output shaft of said downhole motor being concentrically located within the first concentric stabilizer; a bent housing connected above said first concentric stabilizer and having a bend from its geometric center at a predetermined bend angle α, thereby offsetting the centerline of said first concentric stabilizer and the centerline of the drill bit face from the borehole centerline by said predetermined bend angle α; and a second concentric stabilizer, having a preselected diameter slightly smaller than the diameter of the borehole, mounted at a preselected distance above said first concentric stabilizer; wherein the predetermined bend angle α of the bend in the bent housing, and the diameter and placement of the concentric stabilizers are determined by the desired path of the borehole to be drilled, said system drilling a curved borehole when only the downhole motor is activated, and drilling a straight borehole when the downhole motor is activated and the

Claim 27

motor and selectively rotating the drillstring. .Iaddend. .Iadd.23. An improved system for controlled directional and straight drilling of a borehole wherein the entire drillstring is rotatable from the surface, including a bottomhole assembly comprised of a drill bit connected to the output shaft of a downhole motor for independent rotation from the drillstring, said downhole motor connected at its uphole end to the drillstring, the improvement int he bottomhole assembly comprising: a first concentric stabilizer, having a preselected diameter slightly smaller than the diameter of the borehole, mounted at a preselected distance from the drill bit, the output shaft of said downhole motor being concentrically located within the first concentric stabilizer; a bent housing connected above said first concentric stabilizer and having a bend from its geometric center at a predetermined bend angle α, thereby offsetting the centerline of said first concentric stabilizer and the centerline of the drill bit face from the borehole centerline by said predetermined bend angle α; and a second concentric stabilizer, having a preselected diameter slightly smaller than the diameter of the borehole, mounted at a preselected distance above said first concentric stabilizer; wherein the predetermined bend angle α of the bend in the bent housing, and the diameter and placement of the concentric stabilizers are determined by the desired path of the borehole to be drilled, said system drilling a curved borehole when only the downhole motor is activated, and drilling a straight borehole when the downhole motor is activated and the

Claim 28

drillstring is rotated. .Iaddend. .Iadd.24. A method for controlled directional and straight drilling of a borehole, according to a predetermined well plan, utilizing a bottomhole assembly connected to a drillstring comprising a drill bit connected for independent rotation from said drillstring to the output shaft of a downhole motor having its uphole end connected to the drillstring, comprising the steps of: 1. selecting the placement and diameter of two concentric stabilizers as follows, the first concentric stabilizer being placed close to the face of the drill bit and having a slightly smaller diameter than the borehole, the output shaft of said downhole motor being concentrically located within the first concentric stabilizer, and the second concentric stabilizer being placed a predetermined distance above the first concentric stabilizer and having a slightly smaller diameter than the borehole; 2. selecting a predetermined weight on the drill bit; whereby the assembled concentrically stabilized bottomhole assembly with the weight on the drill bit exhibits a certain build angle or drop angle characteristic; 3. selecting bend angle;

Claim 29

drillstring is rotated. .Iaddend. .Iadd.24. A method for controlled directional and straight drilling of a borehole, according to a predetermined well plan, utilizing a bottomhole assembly connected to a drillstring comprising a drill bit connected for independent rotation from said drillstring to the output shaft of a downhole motor having its uphole end connected to the drillstring, comprising the steps of: 1. selecting the placement and diameter of two concentric stabilizers as follows, the first concentric stabilizer being placed close to the face of the drill bit and having a slightly smaller diameter than the borehole, the output shaft of said downhole motor being concentrically located within the first concentric stabilizer, and the second concentric stabilizer being placed a predetermined distance above the first concentric stabilizer and having a slightly smaller diameter than the borehole; 2. selecting a predetermined weight on the drill bit; whereby the assembled concentrically stabilized bottomhole assembly with the weight on the drill bit exhibits a certain build angle or drop angle characteristic; 3. selecting bend angle;

Claim 30

placing the bend angle above the drill bit on the uphole end of said first concentric stabilizer; whereby said first concentric stabilizer and said bend angle exhibit a certain build angle characteristic, the concentrically stabilized bottomhole assembly with the weight on the drill bit and the bend angle combining to form an interacting bottomhole assembly having a certain build angle or drop angle characteristic uniquely suited to the well plan; and 5. steering said unique bottomhole assembly by: (a) turning the drillstring to point the drill bit in the desired direction the borehole should follow and activating the downhole motor while keeping the drillstring stationary when it is desired to drill along a curved path, as determined by the bend angle and first concentric stabilizer combination; (b) rotating the drillstring while activating the downhole motor to turn the drill bit when it is desired to drill along a straight path. .Iaddend. .Iadd.25. A method for controlled directional and straight drilling of a borehole, according to a predetermined well plan, utilizing a bottomhole assembly connected to a drillstring comprising a drill bit connected for independent rotation from said drillstring to the output shaft of a downhole motor having its uphole end connected to the drillstring, comprising the steps of: 1. selecting the placement and diameter of two concentric stabilizers as follow, the first concentric stabilizer being placed close to the face of the drill bit and having a slightly smaller diameter than the borehole, the output shaft of said downhole motor being concentrically located within the first concentric stabilizer, and the second concentric stabilizer being placed a predetermined distance above the first concentric stabilizer and having a slightly smaller diameter than the borehole; 2. selecting a predetermined weight on the drill bit; whereby the assembled concentrically stabilized bottomhole assembly with the weight on the drill bit exhibits a certain build angle or drop angle characteristic; 3. selecting bend angle; 4. placing the bend angle above the drill bit on the uphole end of said first concentric stabilizer; whereby said first concentric stabilizer and said bend angle exhibit a certain build angle characteristic, the concentrically stabilized bottomhole assembly with the weight on the drill bit and the bend angle combining to form an interacting bottomhole assembly having a certain build angle or drop angle characteristic uniquely suited to the well plan; and 5. steering said unique bottomhole assembly by activating the downhole

Claim 31

placing the bend angle above the drill bit on the uphole end of said first concentric stabilizer; whereby said first concentric stabilizer and said bend angle exhibit a certain build angle characteristic, the concentrically stabilized bottomhole assembly with the weight on the drill bit and the bend angle combining to form an interacting bottomhole assembly having a certain build angle or drop angle characteristic uniquely suited to the well plan; and 5. steering said unique bottomhole assembly by: (a) turning the drillstring to point the drill bit in the desired direction the borehole should follow and activating the downhole motor while keeping the drillstring stationary when it is desired to drill along a curved path, as determined by the bend angle and first concentric stabilizer combination; (b) rotating the drillstring while activating the downhole motor to turn the drill bit when it is desired to drill along a straight path. .Iaddend. .Iadd.25. A method for controlled directional and straight drilling of a borehole, according to a predetermined well plan, utilizing a bottomhole assembly connected to a drillstring comprising a drill bit connected for independent rotation from said drillstring to the output shaft of a downhole motor having its uphole end connected to the drillstring, comprising the steps of: 1. selecting the placement and diameter of two concentric stabilizers as follow, the first concentric stabilizer being placed close to the face of the drill bit and having a slightly smaller diameter than the borehole, the output shaft of said downhole motor being concentrically located within the first concentric stabilizer, and the second concentric stabilizer being placed a predetermined distance above the first concentric stabilizer and having a slightly smaller diameter than the borehole; 2. selecting a predetermined weight on the drill bit; whereby the assembled concentrically stabilized bottomhole assembly with the weight on the drill bit exhibits a certain build angle or drop angle characteristic; 3. selecting bend angle; 4. placing the bend angle above the drill bit on the uphole end of said first concentric stabilizer; whereby said first concentric stabilizer and said bend angle exhibit a certain build angle characteristic, the concentrically stabilized bottomhole assembly with the weight on the drill bit and the bend angle combining to form an interacting bottomhole assembly having a certain build angle or drop angle characteristic uniquely suited to the well plan; and 5. steering said unique bottomhole assembly by activating the downhole

Claim 32

motor and selectively rotating the drillstring. .Iaddend. .Iadd.26. An improved steerable system for controlled directional and straight drilling of a borehole wherein the entire drillstring is rotatable from the surface, including a bottomhole assembly comprised of a drill bit connected to the output shaft of a downhole motor for independent rotation from the drillstring, said downhole motor connected at its uphole end to the drillstring, the improvement in the bottomhole assembly comprising: a concentric stabilizer, having a preselected diameter slightly smaller than the diameter of the borehole, mounted at a preselected distance from the drill bit, the output shaft of said downhole motor being concentrically located within the concentric stabilizer; and a bent housing connected above said concentric stabilizer and having a bend from its geometric center at a predetermined bend angle α, said bend angle α being oriented in substantially a single direction from the borehole centerline, thereby offsetting the centerline of said concentric stabilizer and the centerline of the drill bit face from the borehole centerline by said predetermined bend angle α; wherein the predetermined bend angle α of the bend in the bent housing, and the diameter and placement of the concentric stabilizer are determined by the desired path of the borehole to be drilled, said system drilling a curved borehole when only the downhole motor is activated, and drilling a straight borehole when the downhole motor is activated and the

Claim 33

motor and selectively rotating the drillstring. .Iaddend. .Iadd.26. An improved steerable system for controlled directional and straight drilling of a borehole wherein the entire drillstring is rotatable from the surface, including a bottomhole assembly comprised of a drill bit connected to the output shaft of a downhole motor for independent rotation from the drillstring, said downhole motor connected at its uphole end to the drillstring, the improvement in the bottomhole assembly comprising: a concentric stabilizer, having a preselected diameter slightly smaller than the diameter of the borehole, mounted at a preselected distance from the drill bit, the output shaft of said downhole motor being concentrically located within the concentric stabilizer; and a bent housing connected above said concentric stabilizer and having a bend from its geometric center at a predetermined bend angle α, said bend angle α being oriented in substantially a single direction from the borehole centerline, thereby offsetting the centerline of said concentric stabilizer and the centerline of the drill bit face from the borehole centerline by said predetermined bend angle α; wherein the predetermined bend angle α of the bend in the bent housing, and the diameter and placement of the concentric stabilizer are determined by the desired path of the borehole to be drilled, said system drilling a curved borehole when only the downhole motor is activated, and drilling a straight borehole when the downhole motor is activated and the

Claim 34

drillstring is rotated. .Iaddend. .Iadd.27. A method for controlled directional and straight drilling of a borehole, according to a predetermined well plan, utilizing a bottomhole assembly connected to a drillstring comprising a drill bit connected for independent rotation from said drillstring to the output shaft of a downhole motor having its uphole end connected to the drillstring, comprising the steps of: 1. selecting the placement and diameter of a concentric stabilizer, the concentric stabilizer being placed close to the face of the drill bit and having a slightly smaller diameter than the borehole, the output shaft of said downhole motor being concentrically located within the concentric stabilizer; 2. selecting a predetermined weight on the drill bit; whereby the assembled concentrically stabilized bottomhole assembly with the weight on the drill bit exhibits a certain build angle or drop angle characteristic; 3. selecting bend angle oriented in substantially a single direction from the centerline of the borehole; 4. placing the bend angle above the drill bit on the uphole end of said concentric stabilizer; whereby said concentric stabilizer and said bend angle exhibit a certain build angle characteristic, the concentrically stabilized bottomhole assembly with the weight on the drill bit and the bend angle combining to form an interacting bottomhole assembly having a certain build angle or drop angle characteristic uniquely suited to the well plan; and 5. steering said unique bottomhole assembly by: (a) turning the drillstring to point the drill bit in the desired direction the borehole should follow and activating the downhole motor while keeping the drillstring stationary when it is desired to drill along a curved path, as determined by the bend angle and concentric stabilizer combination; (b) rotating the drillstring while activating the downhole motor to turn the drill bit when it is desired to drill along a straight path. .Iaddend.

Claim 35

drillstring is rotated. .Iaddend. .Iadd.27. A method for controlled directional and straight drilling of a borehole, according to a predetermined well plan, utilizing a bottomhole assembly connected to a drillstring comprising a drill bit connected for independent rotation from said drillstring to the output shaft of a downhole motor having its uphole end connected to the drillstring, comprising the steps of: 1. selecting the placement and diameter of a concentric stabilizer, the concentric stabilizer being placed close to the face of the drill bit and having a slightly smaller diameter than the borehole, the output shaft of said downhole motor being concentrically located within the concentric stabilizer; 2. selecting a predetermined weight on the drill bit; whereby the assembled concentrically stabilized bottomhole assembly with the weight on the drill bit exhibits a certain build angle or drop angle characteristic; 3. selecting bend angle oriented in substantially a single direction from the centerline of the borehole; 4. placing the bend angle above the drill bit on the uphole end of said concentric stabilizer; whereby said concentric stabilizer and said bend angle exhibit a certain build angle characteristic, the concentrically stabilized bottomhole assembly with the weight on the drill bit and the bend angle combining to form an interacting bottomhole assembly having a certain build angle or drop angle characteristic uniquely suited to the well plan; and 5. steering said unique bottomhole assembly by: (a) turning the drillstring to point the drill bit in the desired direction the borehole should follow and activating the downhole motor while keeping the drillstring stationary when it is desired to drill along a curved path, as determined by the bend angle and concentric stabilizer combination; (b) rotating the drillstring while activating the downhole motor to turn the drill bit when it is desired to drill along a straight path. .Iaddend.

Claim 36

.Iadd.28. A method for controlled directional and straight drilling of a borehole, according to a predetermined well plan, utilizing a bottomhole assembly connected to a drillstring comprising a drill bit connected for independent rotation from said drillstring to the output shaft of a downhole motor having its uphole end connected to the drillstring, comprising the steps of: 1. selecting the placement and diameter of a concentric stabilizer, the concentric stabilizer being placed close to the face of the drill bit and having a slightly smaller diameter than the borehole, the output shaft of said downhole motor being concentrically located within the concentric stabilizer; 2. selecting a predetermined weight on the drill bit; whereby the assembled concentrically stabilized bottomhole assembly with the weight on the drill bit exhibits a certain build angle or drop angle characteristic; 3. selecting bend angle oriented in substantially a single direction from the centerline of the borehole; 4. placing the bend angle above the drill bit on the uphole end of said concentric stabilizer; whereby said concentric stabilizer and said bend angle exhibit a certain build angle characteristic, the concentrically stabilized bottomhole assembly with the weight on the drill bit and the bend angle combining to form an interacting bottomhole assembly having a certain build angle or drop angle characteristic uniquely suited to the well plan; and 5. steering said unique bottomhole assembly by activating the downhole

Claim 37

.Iadd.28. A method for controlled directional and straight drilling of a borehole, according to a predetermined well plan, utilizing a bottomhole assembly connected to a drillstring comprising a drill bit connected for independent rotation from said drillstring to the output shaft of a downhole motor having its uphole end connected to the drillstring, comprising the steps of: 1. selecting the placement and diameter of a concentric stabilizer, the concentric stabilizer being placed close to the face of the drill bit and having a slightly smaller diameter than the borehole, the output shaft of said downhole motor being concentrically located within the concentric stabilizer; 2. selecting a predetermined weight on the drill bit; whereby the assembled concentrically stabilized bottomhole assembly with the weight on the drill bit exhibits a certain build angle or drop angle characteristic; 3. selecting bend angle oriented in substantially a single direction from the centerline of the borehole; 4. placing the bend angle above the drill bit on the uphole end of said concentric stabilizer; whereby said concentric stabilizer and said bend angle exhibit a certain build angle characteristic, the concentrically stabilized bottomhole assembly with the weight on the drill bit and the bend angle combining to form an interacting bottomhole assembly having a certain build angle or drop angle characteristic uniquely suited to the well plan; and 5. steering said unique bottomhole assembly by activating the downhole

Claim 38

motor and selectively rotating the drillstring. .Iaddend. .Iadd.29. An improved system for controlled directional and straight drilling of a borehole wherein the entire drillstring is rotatable from the surface, including a bottomhole assembly comprised of a drill bit connected to the output shaft of a downhole motor for independent rotation from the drillstring, said downhole motor connected at its uphole end to the drillstring, the improvement in the bottomhole assembly comprising: a first concentric stabilizer, having a preselected diameter slightly smaller than the diameter of the borehole, mounted at a preselected distance from the drill bit, the output shaft of said downhole motor being concentrically located within the first concentric stabilizer; a bent housing connected above said first concentric stabilizer and having a bend from its geometric center at a predetermined bend angle α, said bend angle α being oriented in substantially a single direction from the borehole centerline, thereby offsetting the centerline of said first concentric stabilizer and the centerline of the drill bit face from the borehole centerline by said predetermined bend angle α; and a second concentric stabilizer, having a preselected diameter slightly smaller than the diameter of the borehole, mounted at a preselected distance above said first concentric stabilizer; wherein the predetermined bend angle α of the bend in the bent housing, and the diameter and placement of the concentric stabilizers are determined by the desired path of the borehole to be drilled, said system drilling a curved borehole when only the downhole motor is activated, and drilling straight borehole when the downhole motor is activated and the

Claim 39

motor and selectively rotating the drillstring. .Iaddend. .Iadd.29. An improved system for controlled directional and straight drilling of a borehole wherein the entire drillstring is rotatable from the surface, including a bottomhole assembly comprised of a drill bit connected to the output shaft of a downhole motor for independent rotation from the drillstring, said downhole motor connected at its uphole end to the drillstring, the improvement in the bottomhole assembly comprising: a first concentric stabilizer, having a preselected diameter slightly smaller than the diameter of the borehole, mounted at a preselected distance from the drill bit, the output shaft of said downhole motor being concentrically located within the first concentric stabilizer; a bent housing connected above said first concentric stabilizer and having a bend from its geometric center at a predetermined bend angle α, said bend angle α being oriented in substantially a single direction from the borehole centerline, thereby offsetting the centerline of said first concentric stabilizer and the centerline of the drill bit face from the borehole centerline by said predetermined bend angle α; and a second concentric stabilizer, having a preselected diameter slightly smaller than the diameter of the borehole, mounted at a preselected distance above said first concentric stabilizer; wherein the predetermined bend angle α of the bend in the bent housing, and the diameter and placement of the concentric stabilizers are determined by the desired path of the borehole to be drilled, said system drilling a curved borehole when only the downhole motor is activated, and drilling straight borehole when the downhole motor is activated and the

Claim 40

drillstring is rotated. .Iaddend. .Iadd.30. A method for controlled directional and straight drilling of a borehole, according to a predetermined well plan, utilizing a bottomhole assembly connected to a drillstring comprising a drill bit connected for independent rotation from said drillstring to the output shaft of a downhole motor having its uphole end connected to the drillstring, comprising the steps of: 1. selecting the placement and diameter of two concentric stabilizers as follows, the first concentric stabilizer being placed close to the face of the drill bit and having a slightly smaller diameter than the borehole, the output shaft of said downhole motor being concentrically located within the first concentric stabilizer, and the second concentric stabilizer being placed a predetermined distance above the first concentric stabilizer and having a slightly smaller diameter than the borehole; 2. selecting a predetermined weight on the drill bit; whereby the assembled concentrically stabilized bottomhole assembly with the weight on the drill bit exhibits a certain build angle or drop angle characteristic; 3. selecting bend angle oriented in substantially a single direction from the centerline of the borehole; 4. placing the bend angle above the drill bit on the uphole end of said first concentric stabilizer; whereby said first concentric stabilizer and said bend angle exhibit a certain build angle characteristic, the concentrically stabilized bottomhole assembly with the weight on the drill bit and the bend angle combining to form an interacting bottomhole assembly having a certain build angle or drop angle characteristic uniquely suited to the well plan; and 5. steering said unique bottomhole assembly by: (a) turning the drillstring to point the drill bit in the desired direction the borehole should follow and activating the downhole motor while keeping the drillstring stationary when it is desired to drill along a curved path, as determined by the bend angle and first concentric stabilizer combination; (b) rotating the drillstring while activating the downhole motor to turn the drill bit when it is desired to drill along a straight path. .Iaddend. .Iadd.31. A method for controlled directional and straight drilling of a borehole, according to a predetermined well plan, utilizing a bottomhole assembly connected to a drillstring comprising a drill bit connected for independent rotation from said drillstring to the output shaft of a downhole motor having its uphole end connected to the drillstring, comprising the steps of: 1. selecting the placement and diameter of two concentric stabilizers as follows, the first concentric stabilizer being placed close to the face of the drill bit and having a slightly smaller diameter than the borehole, the output shaft of said downhole motor being concentrically located within the first concentric stabilizer, and the second concentric stabilizer being placed a predetermined distance above the first concentric stabilizer and having a slightly smaller diameter than the borehole; 2. selecting a predetermined weight on the drill bit; whereby the assembled concentrically stabilized bottomhole assembly with the weight on the drill bit exhibits a certain build angle or drop angle characteristic;

Claim 41

drillstring is rotated. .Iaddend. .Iadd.30. A method for controlled directional and straight drilling of a borehole, according to a predetermined well plan, utilizing a bottomhole assembly connected to a drillstring comprising a drill bit connected for independent rotation from said drillstring to the output shaft of a downhole motor having its uphole end connected to the drillstring, comprising the steps of: 1. selecting the placement and diameter of two concentric stabilizers as follows, the first concentric stabilizer being placed close to the face of the drill bit and having a slightly smaller diameter than the borehole, the output shaft of said downhole motor being concentrically located within the first concentric stabilizer, and the second concentric stabilizer being placed a predetermined distance above the first concentric stabilizer and having a slightly smaller diameter than the borehole; 2. selecting a predetermined weight on the drill bit; whereby the assembled concentrically stabilized bottomhole assembly with the weight on the drill bit exhibits a certain build angle or drop angle characteristic; 3. selecting bend angle oriented in substantially a single direction from the centerline of the borehole; 4. placing the bend angle above the drill bit on the uphole end of said first concentric stabilizer; whereby said first concentric stabilizer and said bend angle exhibit a certain build angle characteristic, the concentrically stabilized bottomhole assembly with the weight on the drill bit and the bend angle combining to form an interacting bottomhole assembly having a certain build angle or drop angle characteristic uniquely suited to the well plan; and 5. steering said unique bottomhole assembly by: (a) turning the drillstring to point the drill bit in the desired direction the borehole should follow and activating the downhole motor while keeping the drillstring stationary when it is desired to drill along a curved path, as determined by the bend angle and first concentric stabilizer combination; (b) rotating the drillstring while activating the downhole motor to turn the drill bit when it is desired to drill along a straight path. .Iaddend. .Iadd.31. A method for controlled directional and straight drilling of a borehole, according to a predetermined well plan, utilizing a bottomhole assembly connected to a drillstring comprising a drill bit connected for independent rotation from said drillstring to the output shaft of a downhole motor having its uphole end connected to the drillstring, comprising the steps of: 1. selecting the placement and diameter of two concentric stabilizers as follows, the first concentric stabilizer being placed close to the face of the drill bit and having a slightly smaller diameter than the borehole, the output shaft of said downhole motor being concentrically located within the first concentric stabilizer, and the second concentric stabilizer being placed a predetermined distance above the first concentric stabilizer and having a slightly smaller diameter than the borehole; 2. selecting a predetermined weight on the drill bit; whereby the assembled concentrically stabilized bottomhole assembly with the weight on the drill bit exhibits a certain build angle or drop angle characteristic;

Claim 42

selecting bend angle oriented in substantially a single direction from the centerline of the borehole; 4. placing the bend angle above the drill bit on the uphole end of said first concentric stabilizer; whereby said first concentric stabilizer and said bend angle exhibit a certain build angle characteristic, the concentrically stabilized bottomhole assembly with the weight on the drill bit and the bend angle combining to form an interacting bottomhole assembly having a certain build angle or drop angle characteristic uniquely suited to the well plan; and 5. steering said unique bottomhole assembly by activating the downhole

Claim 43

selecting bend angle oriented in substantially a single direction from the centerline of the borehole; 4. placing the bend angle above the drill bit on the uphole end of said first concentric stabilizer; whereby said first concentric stabilizer and said bend angle exhibit a certain build angle characteristic, the concentrically stabilized bottomhole assembly with the weight on the drill bit and the bend angle combining to form an interacting bottomhole assembly having a certain build angle or drop angle characteristic uniquely suited to the well plan; and 5. steering said unique bottomhole assembly by activating the downhole

Claim 44

motor and selectively rotating the drillstring. .Iaddend. .Iadd.32. A component for a steerable bottomhole assembly for controlled drilling of a borehole, said component comprising: a downhole motor having a centerline, an uphole end and a downhole end and a motor housing substantially surrounding said downhole motor; said uphole end of said downhole motor including means for connecting said downhole motor to a drillstring; said downhole end of said downhole motor including means for connecting said downhole motor to a drill bit; said means for connecting said downhole motor to a drill bit including a bent housing and a bearing assembly; said bearing assembly including a bearing housing, and an output shaft with said output shaft being concentrically located within said bearing housing; a first concentric stabilizer, having a diameter slightly smaller than the diameter of the borehole and a centerline; said first concentric stabilizer being mounted at a distance below the bent housing; said output shaft of the bearing assembly being concentrically located within the first concentric stabilizer; said bent housing having a single bend in one direction located above the first concentric stabilizer and locate below the downhole motor at a bend angle α, thereby offsetting the centerline of said first concentric stabilizer from the centerline of said downhole motor by said bend angle α; a second concentric stabilizer, having a diameter slightly smaller than the diameter of the borehole and a centerline; said second concentric stabilizer being mounted above said first concentric stabilizer and said bent housing; said centerline of said second concentric stabilizer being offset from the centerline of the first concentric stabilizer by said bend angle α; said component for a steerable bottomhole assembly being adapted to aid in steering said bottomhole assembly when activating the downhole motor and selectively rotating the drillstring. .Iaddend. .Iadd.33. A component for a steerable bottomhole assembly for controlled drilling of a borehole, said component comprising: a downhole motor having a centerline, an uphole end and a downhole end and a motor housing substantially surrounding said downhole motor; said uphole end of said downhole motor including means for connecting said downhole motor to a drillstring; said downhole end of said downhole motor including means for connecting said downhole motor to a drill bit; said means for connecting said downhole motor to a drill bit including a bent housing and a bearing assembly; said bearing assembly including a bearing housing, and an output shaft with said output shaft being concentrically located within said bearing housing; a first concentric stabilizer, having a diameter slightly smaller than the diameter of the borehole and a centerline; said first concentric stabilizer being mounted at a distance below the bent housing; said output shaft of the bearing assembly being concentrically located within the first concentric stabilizer; said bent housing having a single bend in one direction located above the first concentric stabilizer and located below the downhole motor at a bend angle α, thereby offsetting the centerline of said first concentric stabilizer from the centerline of said downhole motor by said bend angle α; said component for a steerable bottomhole assembly being adapted to aid in steering said bottomhole assembly when activating the downhole motor and

Claim 45

motor and selectively rotating the drillstring. .Iaddend. .Iadd.32. A component for a steerable bottomhole assembly for controlled drilling of a borehole, said component comprising: a downhole motor having a centerline, an uphole end and a downhole end and a motor housing substantially surrounding said downhole motor; said uphole end of said downhole motor including means for connecting said downhole motor to a drillstring; said downhole end of said downhole motor including means for connecting said downhole motor to a drill bit; said means for connecting said downhole motor to a drill bit including a bent housing and a bearing assembly; said bearing assembly including a bearing housing, and an output shaft with said output shaft being concentrically located within said bearing housing; a first concentric stabilizer, having a diameter slightly smaller than the diameter of the borehole and a centerline; said first concentric stabilizer being mounted at a distance below the bent housing; said output shaft of the bearing assembly being concentrically located within the first concentric stabilizer; said bent housing having a single bend in one direction located above the first concentric stabilizer and locate below the downhole motor at a bend angle α, thereby offsetting the centerline of said first concentric stabilizer from the centerline of said downhole motor by said bend angle α; a second concentric stabilizer, having a diameter slightly smaller than the diameter of the borehole and a centerline; said second concentric stabilizer being mounted above said first concentric stabilizer and said bent housing; said centerline of said second concentric stabilizer being offset from the centerline of the first concentric stabilizer by said bend angle α; said component for a steerable bottomhole assembly being adapted to aid in steering said bottomhole assembly when activating the downhole motor and selectively rotating the drillstring. .Iaddend. .Iadd.33. A component for a steerable bottomhole assembly for controlled drilling of a borehole, said component comprising: a downhole motor having a centerline, an uphole end and a downhole end and a motor housing substantially surrounding said downhole motor; said uphole end of said downhole motor including means for connecting said downhole motor to a drillstring; said downhole end of said downhole motor including means for connecting said downhole motor to a drill bit; said means for connecting said downhole motor to a drill bit including a bent housing and a bearing assembly; said bearing assembly including a bearing housing, and an output shaft with said output shaft being concentrically located within said bearing housing; a first concentric stabilizer, having a diameter slightly smaller than the diameter of the borehole and a centerline; said first concentric stabilizer being mounted at a distance below the bent housing; said output shaft of the bearing assembly being concentrically located within the first concentric stabilizer; said bent housing having a single bend in one direction located above the first concentric stabilizer and located below the downhole motor at a bend angle α, thereby offsetting the centerline of said first concentric stabilizer from the centerline of said downhole motor by said bend angle α; said component for a steerable bottomhole assembly being adapted to aid in steering said bottomhole assembly when activating the downhole motor and

Claim 46

selectively rotating the drillstring. .Iaddend. .Iadd.34. The component for a steerable bottomhole assembly for controlled drilling of a borehole of claims 32 or 33 wherein said bent housing has a bend angle α of

Claim 47

one degree or less. .Iaddend. .Iadd.35. A component for a steerable bottomhole assembly for controlled drilling of a borehole, said component comprising: a downhole motor having a centerline, an uphole end, and a downhole end, and a motor housing substantially surrounding said downhole motor; said uphole end of said downhole motor including means for connecting said downhole motor to a drillstring; said downhole end of said downhole motor including means for connecting said downhole motor to a drill bit; said means for connecting said downhole motor to a drill bit including a bent housing and a bearing assembly; said bearing assembly including a bearing housing, and an output shaft with said output shaft being concentrically located within said bearing housing; means for stabilizing said component for a steerable bottomhole assembly; said means for stabilizing said component for a steerable bottomhole assembly consisting of a first concentric stabilizer having a diameter slightly smaller than the diameter of the borehole and a centerline, said first concentric stabilizer being mounted at a distance below the bent housing, said output shaft of said bearing assembly being concentrically located within the first concentric stabilizer; said bent housing having a single bend in one direction located above the first concentric stabilizer and located below the downhole motor at a bend angle α, thereby offsetting the centerline of said first concentric stabilizer from the centerline of said downhole motor by said bend angle α; said component for a steerable bottomhole assembly being adapted to aid in steering said bottomhole assembly when activating the downhole motor and

Claim 48

one degree or less. .Iaddend. .Iadd.35. A component for a steerable bottomhole assembly for controlled drilling of a borehole, said component comprising: a downhole motor having a centerline, an uphole end, and a downhole end, and a motor housing substantially surrounding said downhole motor; said uphole end of said downhole motor including means for connecting said downhole motor to a drillstring; said downhole end of said downhole motor including means for connecting said downhole motor to a drill bit; said means for connecting said downhole motor to a drill bit including a bent housing and a bearing assembly; said bearing assembly including a bearing housing, and an output shaft with said output shaft being concentrically located within said bearing housing; means for stabilizing said component for a steerable bottomhole assembly; said means for stabilizing said component for a steerable bottomhole assembly consisting of a first concentric stabilizer having a diameter slightly smaller than the diameter of the borehole and a centerline, said first concentric stabilizer being mounted at a distance below the bent housing, said output shaft of said bearing assembly being concentrically located within the first concentric stabilizer; said bent housing having a single bend in one direction located above the first concentric stabilizer and located below the downhole motor at a bend angle α, thereby offsetting the centerline of said first concentric stabilizer from the centerline of said downhole motor by said bend angle α; said component for a steerable bottomhole assembly being adapted to aid in steering said bottomhole assembly when activating the downhole motor and

Claim 49

selectively rotating the drillstring. .Iaddend. .Iadd.36. A component for a steerable bottomhole assembly for controlled drilling of a borehole, said component comprising: a downhole motor having a centerline, an uphole end, and a downhole end, and a motor housing substantially surrounding said downhole motor; said uphole end of said downhole motor including means for connecting said downhole motor to a drillstring; said downhole end of said downhole motor including means for connecting said downhole motor to a drill bit; said means for connecting said downhole motor to a drill bit including a bent housing and a bearing assembly; said bearing assembly including a bearing housing, and an output shaft with said output shaft being concentrically located within said bearing housing; means for stabilizing said component for a steerable bottomhole assembly; said means for stabilizing said component for a steerable bottomhole assembly consisting of a first concentric stabilizer having a diameter slightly smaller than the diameter of the borehole and a centerline, said first concentric stabilizer being mounted at a distance below the bent housing, said output shaft of said bearing assembly being concentrically located within the first concentric stabilizer, and a second concentric stabilizer having a diameter slightly smaller than the diameter of the borehole and a centerline, said second concentric stabilizer being mount above said first concentric stabilizer and said bent housing; said bent housing having a single bend in one direction located above the first concentric stabilizer and located below the downhole motor at a bend angle α, thereby offsetting the centerline of said first concentric stabilizer from the centerline of said downhole motor by said bend angle α; said centerline of said second concentric stabilizer being offset from the centerline of said first concentric stabilizer by said bend angle α; said component for a steerable bottomhole assembly being adapted to aid in steering said bottomhole assembly when activating the downhole motor and selectively rotating the drillstring. .Iaddend.

Claim 50

selectively rotating the drillstring. .Iaddend. .Iadd.36. A component for a steerable bottomhole assembly for controlled drilling of a borehole, said component comprising: a downhole motor having a centerline, an uphole end, and a downhole end, and a motor housing substantially surrounding said downhole motor; said uphole end of said downhole motor including means for connecting said downhole motor to a drillstring; said downhole end of said downhole motor including means for connecting said downhole motor to a drill bit; said means for connecting said downhole motor to a drill bit including a bent housing and a bearing assembly; said bearing assembly including a bearing housing, and an output shaft with said output shaft being concentrically located within said bearing housing; means for stabilizing said component for a steerable bottomhole assembly; said means for stabilizing said component for a steerable bottomhole assembly consisting of a first concentric stabilizer having a diameter slightly smaller than the diameter of the borehole and a centerline, said first concentric stabilizer being mounted at a distance below the bent housing, said output shaft of said bearing assembly being concentrically located within the first concentric stabilizer, and a second concentric stabilizer having a diameter slightly smaller than the diameter of the borehole and a centerline, said second concentric stabilizer being mount above said first concentric stabilizer and said bent housing; said bent housing having a single bend in one direction located above the first concentric stabilizer and located below the downhole motor at a bend angle α, thereby offsetting the centerline of said first concentric stabilizer from the centerline of said downhole motor by said bend angle α; said centerline of said second concentric stabilizer being offset from the centerline of said first concentric stabilizer by said bend angle α; said component for a steerable bottomhole assembly being adapted to aid in steering said bottomhole assembly when activating the downhole motor and selectively rotating the drillstring. .Iaddend.