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EP-4353943-B1 - DRILL STRING JOINT FOR HORIZONTAL DIRECTIONAL DRILLING SYSTEM

EP4353943B1EP 4353943 B1EP4353943 B1EP 4353943B1EP-4353943-B1

Inventors

  • SMITH, JACOB RICHARD

Dates

Publication Date
20260506
Application Date
20210720

Claims (15)

  1. A drill string coupler (128) for establishing a joint between drill string components at a head end of a drill string of a horizontal directional drilling system, the coupler (128) comprising: a first coupling portion (134A) adapted for insertion into a first bore along a central axial direction; a second coupling portion (134B) having a conical tapered surface adapted for insertion into a second bore smaller than the first bore, wherein the second coupling portion (134B) is provided along an axial span (L B ) that is offset from an axial span (L A ) of the first coupling portion (134A); a plurality of cross apertures (170) formed through the first coupling portion (134A) to receive a corresponding plurality of cross pins (140); and a torque connection structure provided at an axial position between the respective axial spans (L A , L B ) of the first and second connection portions (134A, 134B).
  2. The drill string coupler (128) of claim 1, further comprising a third coupling portion provided at an end opposite an end of the coupler (128) defining the second coupling portion (134B), the third coupling portion provided in an axial span that is offset from the respective axial spans (L A , L B ) of the first and second connection portions (134A, 134B).
  3. The drill string coupler (128) of claim 1, wherein the axial position of the torque connection structure is completely discrete and not overlapping with the first and second axial spans (L A , L B ) such that separate axial sections are provided for carrying the bending loads, the torque loads, and the axial pullback loads, respectively.
  4. The drill string coupler (128) of claim 1, wherein the torque connection structure is established by a plurality of receptacles (162) configured to receive torque connection pins (166) at least partially outside an outer profile defined by the first coupling portion (134A).
  5. The drill string coupler (128) of claim 1, wherein the torque connection structure (444) is established by a non-circular or polygonal cross-section profile of an intermediate coupling portion (136C) between the first and second coupling portions (134A, 134B).
  6. The drill string coupler (128) of claim 1, wherein the torque connection structure includes a plurality of torque pins (166) press fit to respective bores (168) in a shoulder surface (138) defined between the first coupling portion (134A) and the second coupling portion (134B).
  7. The drill string coupler (128) of claim 6, wherein the plurality of torque pins (166) define a torque pin length, and an engagement length of the second coupling portion (134B) is at least three times the torque pin length.
  8. The drill string coupler (128) of claim 7, wherein an engagement length of the second coupling portion (134B) is at least four times the torque pin length.
  9. The drill string coupler (128) of claim 6, wherein the plurality of torque pins (166) comprises more than four torque pins (166).
  10. The drill string coupler (128) of claim 1, wherein each one of the plurality of cross apertures (170) has a circular cross-section.
  11. The drill string coupler (128) of claim 1, wherein each one of the plurality of cross apertures (170) has a non-circular cross-section that is circumferentially elongated.
  12. The drill string coupler (128) of claim 1, further comprising an O-ring (150) at a distal end of the second coupling portion (134B).
  13. The drill string coupler (128) of claim 1, wherein the plurality of cross apertures (170) extend through the coupler (128) perpendicular to the central axial direction.
  14. The drill string coupler (128) of claim 1, wherein the torque connection structure comprises machined splines or teeth, the drill string coupler (128) further comprising an O-ring (150) positioned along the first coupling portion (134A) between the torque connection structure and the plurality of cross apertures (170).
  15. The drill string coupler (128) of claim 1, wherein the second coupling portion (134B) has a draft angle of 5 degrees or less to form the conical tapered surface.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application clauses the benefit of priority to co-pending U.S. Provisional Patent Application No. 63/057,562, filed July 28, 2020. BACKGROUND The invention relates to horizontal directional drilling (HDD) systems that include a series of drill rods joined end to end to form a drill string that is propelled though the ground by means of powerful hydraulic systems on a HDD machine, having the capacity to rotate while simultaneously pushing or pulling the drill string, as discussed in U.S. Patent 6,766,869, among numerous others. A spade, bit or head configured for boring is disposed at the end of the drill string and may include an ejection nozzle for water or mud to assist in boring. In order to enable steering of the drill underground the drill head has an asymmetric element that deflects the direction of the bore when it is propelled forward in one way, while the direction of the bore is not deflected when it is propelled forward in a different way. For instance, one common drill head incudes a flat plate bit that cuts a straight, undeflected, bore hole when it is propelled forward while at the same time it is rotated. It cuts a deflected bore hole when it is propelled forward without being rotated. While cutting a deflected bore hole the components of the drill head deflect to accommodate the deflected bore path, the components are thus subjected to bending loads. To control the direction, tool location information is tracked by a sonde attached to the cutting tool, the sonde including a sensor and transmitting device. During forward operation of the drill string by the HDD system, the drill head and sonde housing are attached to the front end of a drill string by a starter rod that includes a joint to which the sonde housing connects while the HDD machine pushes the drill string. Following emergence of the drill head at a terminal end of the drilling operation, the sonde housing is decoupled from the starter rod so that a back reamer can be connected to that joint and then the hole can be enlarged by a reamer as the HDD machine pulls the drill string back in the opposite direction. Some early solutions for this joint include a large slip-on torque collar specially adapted to carry torque loads between two threaded members of the joint, both of which have external hex portions that fit within a hex bore of the torque collar as is described in US 20130084131. The torque collar isolates the threaded joint from torque so that the threads effectively transfer only longitudinal pushing/pulling forces in the drill string. However, in attempts to obviate the assembly/disassembly requirements of extra collars, more recent designs include various versions of "collar-less" couplings, in which there is no extra collar component that slips over the joining drill string elements to carry the torque. Rather, as shown in EP3587729A1, drill string members may be connected for torque transmission by a spline structure while longitudinal forces are borne by pins that extend through mated portions of the drill string members adjacent the spline structure. Although collar-less joint designs have shown some limited efficacy, the durability and expected life span of such joints trails collared designs substantially when subjected to the combined effects of axial force, torque, and bending loads experienced during real world operation of a HDD drill string, or in laboratory testing simulating the same. Thus, a need exists for a more durable, yet simple, drill string connection joint. DE10359880 discloses a system having a bending unit including connection sides for a boring rod and a drilling tool, respectively, such that the bending unit is arranged between the drilling tool and the boring rod. The bending unit has a tube section whose length is approximately equal to one-fourth or one-third of the overall length of the boring rod. The bending unit exhibits one half of a quick coupler that connects the tool and rod. An independent claim is also included for a method of horizontal directional boring. SUMMARY In one aspect, the invention provides a drill string coupler for establishing a joint between drill string components, according to claim 1. Preferred features of the invention are set out in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view of a horizontal directional drilling operation.Fig. 2 is a side elevation view of a HDD drill head coupled with a drill string starter rod by a collar-less joint, according to one embodiment of the present disclosure.Fig. 2A is a side elevation view of the collar-less joint of Fig. 2 with a HDD reamer coupled to the drill string rather than the drill head.Fig. 3 is a perspective partial section view of the joint of Fig. 2 where a portion of the drill string starter rod is cut away.Fig. 4 is a side elevation view of the drill string starter rod for use in making the joint of Figs. 2-3.Fig. 4A is a perspective v