Steerable drilling system and method
First Claim
1. A bottom hole assembly for drilling a deviated borehole, the bottom hole assembly comprising:
- one of a positive displacement motor and a rotary steerable device having a housing, the housing having an upper central axis;
a rotary shaft having a portion with a lower central axis, the portion being offset with respect to the housing so as to result in an intersection of the upper central axis and the lower central axis;
the housing containing at least a portion of the rotary shaft;
a bit powered by the rotary shaft, the bit having a bit face defining a bit full cutting diameter; and
a gauge section spaced above the bit face, a top of the gauge section having a diameter which is substantially the bit full cutting diameter;
wherein an axial spacing between the bit full cutting diameter and the top of the gauge section is at least 75% of the bit full cutting diameter; and
wherein an axial spacing along the lower central axis between the intersection and the bit face is less than twelve times the bit full cutting diameter.
1 Assignment
0 Petitions
Accused Products
Abstract
A bottom hole assembly 10 for drilling a deviated borehole includes a positive displacement motor (PDM) 12 or a rotary steerable device (RSD) 110 having a substantially uniform diameter motor housing outer surface without stabilizers extending radially therefrom. In a PDM application, the motor housing 14 may have a fixed bend therein between an upper power section 16 and a lower bearing section 18. The long gauge bit 20 powered by the motor 10 may have a bit face 22 with cutters 28 thereon and a gauge section 24 having a uniform diameter cylindrical surface 26. The gauge section 24 preferably has an axial length at least 75% of the bit diameter. The axial spacing between the bit face and the bend of the motor housing preferably is less than twelve times the bit diameter. According to the method of the present invention, the bit may be rotated at a speed of less than 350 rpm by the PDM and/or rotation of the RSD from the surface.
80 Citations
70 Claims
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1. A bottom hole assembly for drilling a deviated borehole, the bottom hole assembly comprising:
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one of a positive displacement motor and a rotary steerable device having a housing, the housing having an upper central axis; a rotary shaft having a portion with a lower central axis, the portion being offset with respect to the housing so as to result in an intersection of the upper central axis and the lower central axis; the housing containing at least a portion of the rotary shaft; a bit powered by the rotary shaft, the bit having a bit face defining a bit full cutting diameter; and a gauge section spaced above the bit face, a top of the gauge section having a diameter which is substantially the bit full cutting diameter; wherein an axial spacing between the bit full cutting diameter and the top of the gauge section is at least 75% of the bit full cutting diameter; and wherein an axial spacing along the lower central axis between the intersection and the bit face is less than twelve times the bit full cutting diameter. - View Dependent Claims (2, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 56)
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3. A method of drilling a deviated borehole utilizing a bottom hole assembly including one of a positive displacement motor and a rotary steerable device having a housing, the housing having an upper central axis, a rotary shaft having a portion with a lower central axis, the portion being offset with respect to the housing so as to result in an intersection of the upper central axis and the lower central axis, the housing containing a portion of the rotary shaft, the bottom hole assembly further including a bit rotated by the rotary shaft and having a bit face defining a bit full cutting diameter, the method comprising:
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providing an axial spacing between the intersection and the bit face of less than twelve times the bit full cutting diameter; and providing a gauge section rotatably fixed to the bit and spaced above the bit face, the gauge section having a top with a diameter which is substantially the bit full cutting diameter, where an axial spacing between the top of the gauge section and the location of the bit full cutting diameter is at least 75% of the bit full cutting diameter. - View Dependent Claims (4, 5, 6, 7, 46, 47, 48, 49, 50, 51, 52, 57)
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8. A bottom hole assembly for drilling a borehole with a bit having a bit face defining a bit full cutting diameter, comprising:
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a positive displacement motor with an output shaft, and a power section central axis offset by a bend from a lower bearing section central axis; the bit coupled to the output shaft; a gauge section above the bit face, such that an axial distance from a bit full cutting diameter to a top of the gauge section having a diameter which is substantially the bit full cutting diameter is at least 75% of the bit full cutting diameter; and an axial distance between the bend and the bit full cutting diameter being less than twelve times the bit full cutting diameter. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 58)
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21. A method, comprising:
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drilling a deviated borehole using a bottom hole assembly having a positive displacement motor, said positive displacement motor having an output shaft, the positive displacement motor having a power section central axis offset by a bend from a lower bearing section central axis; using a bit coupled to the output shaft to drill the deviated borehole, the bit having a bit face, the bit face having a bit full cutting diameter; and using a gauge section above the bit face, such that an axial distance from the bit full cutting diameter to a top of the gauge section having a diameter which is substantially the bit full cutting diameter is at least 75% of the bit full cutting diameter, and the distance from the bend to the bit full cutting diameter is less than twelve times the bit full cutting diameter. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 53, 54)
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29. A borehole drilled with a bit having a bit face defining a bit full cutting diameter, the borehole formed by the method comprising:
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rotating a drill shaft within a motor housing, the drill shaft having a lower shaft axis of rotation offset at a selected bend angle from an upper axis of rotation by a bend; coupling the drill shaft with the bit and with a gauge section above the bit face, the gauge section having an axial length between the bit full cutting diameter to a top of the gauge section having a diameter which is substantially the bit full cutting diameter is greater than or equal to 75 percent of the bit full cutting diameter; and spacing the bend from the bit face less than or equal to 12 times the bit full cutting diameter. - View Dependent Claims (30, 31, 32, 33, 59)
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55. A bottom hole assembly for drilling a deviated borehole, the bottom hole assembly comprising:
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a rotary steerable device having a housing, the housing having an upper central axis; a rotary shaft having a portion with a lower central axis, the portion capable of being offset with respect to the housing so as to result in an intersection of the upper central axis and the lower central axis; the housing containing at least a portion of the rotary shaft, the rotary shaft being rotatable with respect to the housing from the surface while the rotary steerable device steers the deviated borehole; a bit powered by the rotary shaft, the bit having a bit face defining a bit full cutting diameter; and a gauge section spaced above the bit face; wherein an axial spacing between the bit full cutting diameter and a top of the gauge section which is substantially the bit full cutting diameter is at least 75% of the bit full cutting diameter. - View Dependent Claims (60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70)
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Specification