A system for connecting a drill bit and pipe puller to a drill string. The system includes a downhole tool having an internal cavity and a through-hole in its wall. A coupler may be slidingly received in the cavity and connected using one or more fasteners which interconnect a groove in the coupler to the wall of the downhole tool. Fasteners used may be screws or bolts interconnecting the wall of the tool with radial holes in the coupler. Alternatively, bolts may interconnect the wall with a circumferential groove on the coupler. A drill bit may be threaded into the coupler. The coupler allows drill bits and other tools to be connected and disconnected from a downhole tool without unthreading the drill bit.

Adjustment of the angle of a bent sub or other steering feature in a drill string relative to a reference angle of a downhole sensor is facilitated by a rotatable coupling between the bent sub and the sensor. The rotatable coupling may be rotated to align the high side with a reference indicium and locked at the set angle. Rows of ceramic balls retained in circumferential channels may be provided to permit rotation while carrying tensile and compressional forces. Calibration of the sensor is facilitated and opportunities for certain measurement errors are eliminated. An embodiment provides a mechanism for locking the rotatable coupling at a desired angle. The embodiment comprises a ring with teeth that engage a downhole portion of the coupling and depressions that engage an uphole portion of the coupling.

Adjustment of the angle of a bent sub or other steering feature in a drill string relative to a reference angle of a downhole sensor is facilitated by a rotatable coupling between the bent sub and the sensor. The rotatable coupling may be rotated to align the high side with a reference indicium and locked at the set angle. Rows of ceramic balls retained in circumferential channels may be provided to permit rotation while carrying tensile and compressional forces. Calibration of the sensor is facilitated and opportunities for certain measurement errors are eliminated. An embodiment provides a mechanism for locking the rotatable coupling at a desired angle. The embodiment comprises a ring with teeth that engage a downhole portion of the coupling and depressions that engage an uphole portion of the coupling.

A pipe connection includes a pin having circumferentially extending external grooves. A box has an annular base with deflectable fingers extending upward from the base. Each of the fingers has circumferentially extending internal grooves on an inner side and an external thread on an outer side. A collar has an internal thread on an inner side. A radial dimension from the axis to the internal thread crest decreases from turn to turn of the internal thread in a downward direction. The box and the pin are movable from a stab-in position to a locked position in response to rotation of the collar. In the locked position, the external thread crests are in engagement with the internal thread crests, and the internal grooves are in full engagement with the external grooves.

A pipe connection includes a pin having circumferentially extending external grooves. A box has an annular base with deflectable fingers extending upward from the base. Each of the fingers has circumferentially extending internal grooves on an inner side and an external thread on an outer side. A collar has an internal thread on an inner side. A radial dimension from the axis to the internal thread crest decreases from turn to turn of the internal thread in a downward direction. The box and the pin are movable from a stab-in position to a locked position in response to rotation of the collar. In the locked position, the external thread crests are in engagement with the internal thread crests, and the internal grooves are in full engagement with the external grooves.

A spindle assembly for connecting a drill string to a rotational drive for use in a horizontal directional drilling operation. The assembly comprises a saver sub attached to the rotational drive, and a drive chuck for connection to the drill string. The drive chuck and saver sub form a torque-transmitting connection by engaging through a seat in the saver sub and an engagement point on the drive chuck. Dowel pins may be used to rotationally lock and provide the engagement between the saver sub and the drive chuck. A collar may thread to the saver sub and cause an interference fit by engaging the drive chuck at a shoulder.

A spindle assembly for connecting a drill string to a rotational drive for use in a horizontal directional drilling operation. The assembly comprises a saver sub attached to the rotational drive, and a drive chuck for connection to the drill string. The drive chuck and saver sub form a torque-transmitting connection by engaging through a seat in the saver sub and an engagement point on the drive chuck. Dowel pins may be used to rotationally lock and provide the engagement between the saver sub and the drive chuck. A collar may thread to the saver sub and cause an interference fit by engaging the drive chuck at a shoulder.

An interference apparatus is provided for a motor shaft transmission assembly. The interference apparatus may include split-ring shells and a retaining device. The interference apparatus may be mounted to an intermediate sleeve of the motor shaft transmission assembly. The interference apparatus is configured to prevent the loss of certain motor shaft transmission assembly components downhole in the event of a failure of the motor transmission due to dynamic loads.

An apparatus for perforating a subterranean formation comprises a first perforating gun (33b) having a box end (112) having a nose, a second perforating gun (33a) having a pin end (118) having a shoulder (124); and an alignment assembly. The alignment assembly includes internal threads formed on the box end, external threads formed on the pin end, and an alignment member (120) positioned between the box end nose and the pin end shoulder. The internal threads and the external threads are specified to form an angular alignment between the first perforating gun and the second perforating gun within a first specified angular tolerance. The alignment member has at least one characteristic selected to vary the angular alignment within the first specified angular tolerance without degrading a locking force connecting the first perforating gun to the second perforating gun.

An apparatus for perforating a subterranean formation comprises a first perforating gun (33b) having a box end (112) having a nose, a second perforating gun (33a) having a pin end (118) having a shoulder (124); and an alignment assembly. The alignment assembly includes internal threads formed on the box end, external threads formed on the pin end, and an alignment member (120) positioned between the box end nose and the pin end shoulder. The internal threads and the external threads are specified to form an angular alignment between the first perforating gun and the second perforating gun within a first specified angular tolerance. The alignment member has at least one characteristic selected to vary the angular alignment within the first specified angular tolerance without degrading a locking force connecting the first perforating gun to the second perforating gun.