Downhole tool
AssigneeSmith International, Inc.
InventorsAndrew McPherson Downie, Edward Docherty Scott, Roy Powell
Life of this patent
Estimating the term…
Abstract
A downhole tool including a selectively releasable joint, a downhole drilling assembly including the downhole tool, and a corresponding method. In one embodiment of the invention, a downhole drilling assembly includes a downhole tool having a first body and a second body mounted for relative rotation; a joint part for use in forming a selectively releasable joint between the second body and a part of the assembly coupled to the second body; and one or more locking member(s) for locking the first and second bodies relative to one another against relative rotation so as to allow a release force to be applied through the first body to release the releasable joint and allow the tool to be separated from the part of the assembly.
Claims26
A downhole tool for use in a downhole tool assembly, the tool comprising:
- a first body and a second body, the bodies being mounted for relative rotation;
- a joint part adapted to form a selectively releasable joint between the second body and a part of the assembly couplable to the second body;
- and
- locking means for locking the first and second bodies relative to one another against relative rotation;
- whereby, in use, locking said bodies relative to one another facilitates application of a release force through the first body to the releasable joint to release said joint so as to thereby separate the tool from said part of the assembly, wherein the joint comprises a threaded male pin and a co-operating threaded female box, and wherein the threads on the pin and box of the joint are configured such that:
- 1
- <
- joint
-
-
- coefficient
-
-
- of
-
-
- friction
- tan
-
-
- (
- helix
-
-
- angle
- )
- >
- 3
- where the tangent of the helix angle (α) is determined by:
- tan
-
- (
- α
- )
- =
- lead
- 2
-
- Π
-
-
- r
- m
- where rm is the thread mean radius.
A downhole tool assembly, the assembly including a downhole tool, the tool comprising:
- a first body and a second body, the bodies being mounted for relative rotation;
- a joint part forming a selectively releasable joint between the second body and a part of the assembly coupled to the second body;
- and locking means for locking the first and second bodies relative to one another against relative rotation;
- whereby locking the bodies relative to one another facilitates application of a release force through the first body to the releasable joint to release the releasable joint to thereby separate the tool from the part of the assembly, wherein the selectively releasable joint is configured to release at a release force which is less than the force applied to make up the joint.
A downhole drilling assembly comprising:
- a drill bit;
- a downhole drilling motor having a motor body for coupling to tubing of the assembly and a rotatable drive shaft for coupling to the drill bit;
- a selectively releasable joint located between the drilling motor and the drill bit;
- and locking means for locking the drive shaft relative to the motor body;
- whereby locking the drive shaft relative to the motor body facilitates application of a release force through the assembly tubing and the motor body to the releasable joint to release the releasable joint to thereby separate the drill bit from a remainder of the drilling assembly, wherein the selectively releasable joint is configured to release at a release force which is less than the force applied to make up the joint for drilling operations.
A method of selectively releasing a drill bit of a downhole drilling assembly from a remainder of the assembly, the method comprising the steps of:
- providing the drilling assembly with a selectively releasable joint between a drilling motor of the assembly and the drill bit, and a locking means for locking a rotatable drill bit drive shaft of the drilling motor relative to a body of the motor;
- activating the locking means to lock the drive shaft against rotation with respect to the motor body;
- applying a rotational release force through tubing of the assembly and the motor body to release the releasable joint and separate the drilling motor from the drill bit;
- and recovering the remainder of the drilling assembly to surface, wherein the step of applying a rotational release force further comprises applying a release torque to generate the release force, and wherein the release torque is less than the torque required to make up the drilling assembly.
Dependencies are inferred from the claim text.