Steerable underreaming bottom hole assembly and method
AssigneeHalliburton Energy Services, Inc.
InventorsChen-Kang D. Chen, William H. Smith, Jr.
Life of this patent
Estimating the term…
Abstract
A steerable bottom hole assembly may be used for drilling both a curved section and straight section of the borehole, with the bottom hole assembly including a reamer beneath the downhole motor 12. The bottom hole assembly includes a bit 30 having a bit face defining a bit diameter, and a gauge section 32 having a substantially uniform diameter cylindrical surface approximating the bit diameter and having an axially length of at least 75% of the bit diameter. The motor is preferably run slick without stabilizers for engaging the wall of the borehole.
Claims20
A steerable bottom hole assembly for drilling a borehole comprising:
- the downhole motor having a motor housing and a bend angle, a motor housing enclosing an output rotor offset at a selected bend angle from a central axis of an upper housing, the motor rotor powering a bit when sliding to drill a curved section of the borehole and the bottom hole assembly being rotated from the surface to build a straight section of the borehole;
- the bit having a bit face defining a bit diameter;
- a gauge section having a substantially uniform diameter cylindrical surface approximating the bit diameter, the gauge section having an axial length at least 75% of the bit diameter;
- and
- a reamer positioned between the down hole motor and the gauge section, the reamer including cutters for enlarging the borehole diameter substantially beyond the bit diameter.
A steerable bottom hole assembly for drilling a borehole comprising:
- a downhole motor having a motor housing and a bend angle, a motor housing enclosing an output rotor offset at a selected bend angle from a central axis of an upper housing, the motor rotor powering a bit when sliding to drill a curved section of the borehole and the bottom hole assembly being rotated from the surface to build a straight section of the borehole;
- the bit having a bit face defining a bit diameter;
- an axial spacing between the bend angle and the bit face being less than 15 times the bit diameter;
- a gauge section having a substantially uniform diameter cylindrical surface approximating the bit diameter, the gauge section having an axial length at least 75% of the bit diameter;
- and
- a reamer positioned between the down hole motor and the gauge section, the reamer including cutters for enlarging the borehole diameter substantially beyond the bit diameter.
A method of forming a subterranean borehole utilizing a steerable bottom hole assembly including a downhole motor having a motor housing and a bend angle, the motor housing enclosing an output rotor offset at a selected bend angle from a central axis of an upper housing, the method comprising:
- providing a bit having a bit face defining a bit diameter;
- providing a gauge section above the bit having a substantially uniform diameter cylindrical surface approximating the bit diameter, the gauge section having an axial length at least 75% of the bit diameter;
- providing a reamer between the downhole motor and the gauge section, the reamer including cutting cutters for enlarging the borehole diameter substantially beyond the bit diameter;
- powering the motor with fluid to rotate the bit while the motor housing is slid to drill a curved section of the borehole;
- and
- rotating the bottom hole assembly from the surface to build a straight section of the borehole.
Dependencies are inferred from the claim text.