Integrated transmitter surveying while boring entrenching powering device for the continuation of a guided bore hole

Information

  • Patent Grant
  • 6749030
  • Patent Number
    6,749,030
  • Date Filed
    Friday, December 21, 2001
    23 years ago
  • Date Issued
    Tuesday, June 15, 2004
    20 years ago
Abstract
A bottom hole assembly for horizontal directional drilling that improves the accuracy of surveying while boring by enabling the progress of the bore to be monitored and tracked with the aid of a sonde. In one embodiment the sonde is received in the wall of a housing area of a mud motor surrounding the bearing mandrel, in another embodiment the sonde is carried in the wall of a collar surrounding the bearing mandrel housing, and in an additional embodiment the sonde is carried in an adapter between the bearing mandrel and the bit.
Description




BACKGROUND OF THE INVENTION




The invention relates to horizontal directional drilling and, in particular, to improvements in bottom hole assemblies for such drilling techniques.




PRIOR ART




Horizontal directional drilling methods are well known and can offer many advantages over traditional open trench digging operations. There remains a need for greater precision in monitoring and guiding the course of the hole as it is being bored. This need is particularly acute in utility easements and like corridors where pre-existing lines are located often without precision in their placement and “as built” records.




As used herein, the terms “sonde” and “monitoring/tracking device” are used interchangeably to mean a device known in the trenchless boring industry as a surveying device for the monitoring and tracking of a bore hole. The term “boring device” refers to equipment such as a rock tricone drill bit, a poly-diamond-crystalline (PDC) bit, or any other device known in the art to drill or lengthen a bore hole. Finally, the terms “entrenching powering device” and “mud motor” are used interchangeably for a device generally known in the art used to rotate a boring device, without turning the drill pipe/drill string, by some type of drilling rig to continue a hole or bore.




Known horizontal directional drilling bottom hole assemblies typically include a sonde that transmits electromagnetic signals indicating the pitch (from horizontal), the clock (roll about a horizontal axis clockwise or counterclockwise from a reference of say 12 o'clock), and the depth of the sonde. The sonde also enables a person sweeping the corridor with a receiver or detector to locate the horizontal or lateral position of the sonde in the specified corridor.




Because of limitations of current tooling, the transmitter/guidance system or sonde is ordinarily located a considerable distance away from the boring device when an entrenching powering device is used. The sonde may only be as close as about 20 feet and as far as about 50 feet from the boring device. This is due to the fact that an entrenching powering device has generally not been designed to integrate a sonde. The distance between the sonde and the boring device is a major concern for drillers in the utility business, especially when they encounter a job with very restrictive parameters in terms of drilling path.




The sonde transmits a signal that indicates where the sonde is located which can be 20 feet+behind the boring device. This type of drilling has been described as driving a car forward, from the back seat looking out the rear window. A driller only “sees” where he has already drilled, not where he is currently drilling. This becomes a major problem if the boring device veers off course and begins boring outside a designated corridor. The operator will not know there is a potential problem until the boring device is 20 feet+off course. If the driller waits longer to see if the boring device steers back on course, the boring device may continue even further off course. This causes a risk that the driller may destroy cable lines, gas lines, or the like and if such destruction occurs it is not only expensive but dangerous as well.




SUMMARY OF THE INVENTION




The invention provides an improved bottom hole assembly for horizontal directional drilling in which the sonde is carried ahead of the power section of the entrenching powering device or mud motor. In a presently preferred embodiment, the sonde is located in a pocket formed in the wall of a housing of the entrenching powering device that surrounds a bearing mandrel or bit driving shaft. More specifically, the sonde receiving pocket is nestled axially between thrust bearings supporting the mandrel and a flex shaft transmission that couples the power section to the mandrel. This forward location of the sonde greatly improves the accuracy of surveying while boring the hole so as to facilitate placement of the hole and ultimate line in the intended path.




The disclosed mounting arrangement for the sonde readily allows the sonde to be adjusted for a proper clock orientation and is somewhat resilient to limit vibrational forces transmitted to the sonde during operation.




Other mounting structures for the sonde are disclosed. Each of these structures offers improved boring accuracy over prior art constructions by enabling the sonde to be positioned relatively close to the boring device.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a side elevational view of a bottom hole assembly and a portion of a trailing drill string;





FIGS. 2A through 2D

is a longitudinal cross sectional view of a mud motor constructed in accordance with the invention;





FIG. 3

is a fragmentary perspective exploded view of a portion of the mud motor and the sonde;





FIG. 4

is a transverse cross sectional view of the mud motor taken in the plane


4





4


indicated in

FIG. 2B

;





FIG. 5

is a side view, partially in section, of a second embodiment of the invention; and





FIG. 6

is a side view, partially in section, of a third embodiment of the invention.











DESCRIPTION OF THE PREFERRED EMBODIMENTS




With reference particularly to

FIGS. 1

,


2


A-


2


D,


5


and


6


, parts towards the left are sometimes hereafter referred to as forward parts in the sense of the drilling direction, it being understood that in such figures, the drilling direction is to the left; the rearward or trailing end of such parts, conversely, is shown to the right. The forward direction can be equated with a downward direction and the rearward direction can be equated with an upper direction where drilling is vertical.




Referring now to

FIG. 1

, a bottom hole assembly


10


comprises a boring device or bit


11


and an entrenching powering device or mud motor


12


having its forward end carrying the bit


11


. A drill string


13


is coupled to a trailing end


14


of the mud motor


12


in a conventional fashion.




The mud motor


12


, as shown in

FIGS. 2A-2D

includes a hollow cylindrical bearing mandrel


18


having a central through bore


19


. The bit


11


is coupled to a bit box


21


formed in the forward end of the bearing mandrel


18


. Thus, the bearing mandrel


18


is enabled to drive the bit


11


in rotation and to transmit thrust from the drill string


13


.




Adjacent its forward end


22


, the bearing mandrel


18


is rotationally supported in a lower tubular cylindrical housing


23


by a set of radial bearings


24


. A conical shoulder


28


of the bearing mandrel


18


is received in a conical bore


29


of a radial ring


31


. A radial face of the ring


31


is arranged to abut an adjacent one of the set of radial bearings


24


. Male threads


36


of the lower or forward housing


23


couple with female threads


38


in a forward end


39


of an elongated hollow circular outer housing


41


.




Sets of thrust bearings


44


,


46


are assembled on a carrier nut


47


at opposite sides of an annular flange


48


. The carrier nut


47


is threaded onto an externally threaded part


49


of the bearing mandrel


18


. The carrier nut


47


is locked in position on the bearing mandrel


18


by set screws


51


spaced about the periphery of the flange


48


.




Sleeve bearings


53


, of suitable self-lubricating material such as the material marketed under the registered trademark DU® are received in counterbores


54


formed in the outer housing


41


and serve to rotationally support the mid and trailing length of the bearing mandrel


18


. A longitudinal bore


56


in the surrounding outer housing


41


provides clearance for the main length of the bearing mandrel


18


.




An annular piston


59


floats on a rearward part of the mandrel


18


in a counterbore


61


in the outer housing


41


. The piston


59


retains lubricant in the annular zones of the bearings


53


,


44


and


46


. A circular bearing adapter


62


is threaded onto the rear end of the bearing mandrel


18


. A plurality of holes


63


distributed about the circumference of the adapter


62


are angularly drilled or otherwise formed in the adapter to provide mud flow from its exterior to a central bore


64


of the adapter. As shown, the central bore


64


communicates directly with the bore


19


of the bearing mandrel


18


. The bearing adapter


62


is radially supported for rotation in a sleeve-type marine bearing


66


assembled in a counter bore


67


in a rear portion of the outer housing


41


. Ports


68


allow flow of mud through the marine bearing


66


for cooling purposes.




A flex shaft


71


rotationally couples a rotor adapter


72


to the bearing adapter


62


. At each end of the flex shaft


71


is a constant velocity universal joint


73


comprising a series of circumferentially spaced balls


74


seated in dimples in the flex shaft and in axially extending grooves in a skirt portion


76


of the bearing adapter


62


or skirt portion


77


of the rotor adapter


72


. Each coupling or universal joint


73


also includes a ball


78


on the axis of the flex shaft and a ball seat


79


received in the respective bearing adapter


62


or rotor adapter


72


. Each universal joint


73


includes a bonnet


81


threaded into each of the skirts


76


or


77


to retain the joints or couplings


73


in assembly. Cylindrical elastomeric sleeves


82


are disposed within each of the bonnets


81


to retain grease in the area of the balls


74


,


78


and to exclude contamination from this area. A cylindrical tubular flex housing


84


surrounds the flex shaft


71


and is fixed to the rear end of the outer housing


41


by threading it into the latter at a joint


86


. The flex housing


84


is bent at a mid plane


87


such that the central axis at its rear end is out of alignment with its central axis at its forward end by a small angle of, for example, 2°. At its rearward end, the flex housing


84


is fixed to the stator or housing


88


of a power section


89


of the mud motor


12


by a threaded joint


91


. The stator


88


is a hollow internally fluted member in which operates an externally fluted rotor


92


. The power section


89


formed by the stator


88


and rotor


92


are of generally known construction and operation. The rotor adapter


72


is threaded into the forward end of the rotor


92


to rotationally couple these members together. The drill string


13


is threaded on the rear end of the stator with or without the use of an adapter. The flex shaft


71


converts the rotational and orbital motion of the rotor


92


into plain rotation of the bearing mandrel


18


.




Referring particularly to

FIGS. 3 and 4

, the outer housing


41


is formed with a pocket or elongated recess


101


rearward of the thrust bearing units


44


,


46


. The pocket


101


is milled or otherwise cut out of the wall of the outer housing


41


with an included angle of 90° in the plane of

FIG. 4

transverse to the longitudinal axis of the housing


41


. Surrounding the pocket


101


is a relatively shallow seat or recess


102


similarly cut into the wall of the housing


41


. When viewed in the plane of

FIG. 4

, this seat has a cylindrical arcuate surface area


103


concentric with the axis of the housing


41


and radially extending surfaces


104


.




An elastomeric sarcophagus


106


of polyurethane or other suitable material has exterior surfaces generally conforming to the surfaces of the pocket


101


. The sarcophagus


106


is configured with a round bottom slot


107


for receiving a sonde


108


. More specifically, the slot


107


is proportioned to receive a standard commercially available sonde of a size which, for example, can be 1¼″ diameter by 19″ long. It is understood that the sarcophagus may be configured with a slot to fit sondes of other standard sizes such as 1″ diameter by 8″ long or a secondary sarcophagus may be provided to increase the effective size of a smaller sonde to that of the larger size. An arcuate cover plate


109


of steel or other suitable material is proportioned to fit into the area of the seat


102


to cover and otherwise protect the sonde


108


from damage during drilling operations. The cover


109


is proportioned, when installed in the seat


102


, to provide an outer cylindrical surface


111


that lies on the same radius as that of the outer cylindrical surface of the housing


41


surrounding the pocket or slot


101


. The cover


109


, is provided with a plurality of longitudinal through slots


112


, to allow passage of electromagnetic signals transmitted from the sonde


108


. The slots


112


are filled with non-metallic material such as epoxy to exclude contaminates from passing into the pocket


101


or otherwise reaching the sonde


108


. Additionally, for purposes of allowing the sonde to transmit signals over a wide angle, the body of the housing


41


is drilled with holes


113


which are filled with epoxy or other non-metallic sealant. A shallow groove


114


is cut in a generally rectangular pattern in the surface


103


around the pocket


101


to receive an O-ring seal


116


.




The round bottom slot or groove


107


in the sarcophagus is dimensioned to provide a friction fit with the sonde


108


. This permits the sonde


108


to be rotated or rolled on its longitudinal axis to “clock” it by registering its angular orientation relative to the plane of the bend in the flex housing


84


as is known in the art.




The cover or plate


109


is retained in position over the sonde


108


by a plurality of screws


117


assembled through holes


118


in the cover and aligned with threaded holes


119


formed in the outer housing


41


. The screw holes


118


,


119


are distributed around the periphery of the cover


109


. The O-ring


116


seals against the inside surface of the cover


109


to exclude contaminates from entering the pocket


101


during drilling operations.




The sarcophagus


106


is proportioned so that it is compressed by the cover


109


around the sonde


108


when the screws


117


draw the cover tight against the seat surface


103


. This compression of the sarcophagus


106


increases its grip on the sonde


108


so that the sonde is locked in its adjusted “clocked” position. The elastomeric property of the sarcophagus


106


, besides enabling it to resiliently grip the sonde when compressed by the cover


109


, can serve to cushion the sonde


108


from excessive shock forces during drilling operation.




Other resilient mounting structures for the sonde


108


are contemplated. For example, the sonde


108


can be retained in the pocket


101


by resilient steel straps arranged to overlie the sonde as it lies in the pocket


101


. The straps can be retained in place by suitable screws or other elements.




When the mud motor


12


is operated, mud or water passing between the stator


88


and rotor


92


travels through the transmission and bearing sections of the mud motor bounded by the flex housing


84


, outer housing


41


, and lower housing


23


and is delivered to the bit


11


. More specifically, the mud flows through the annulus between the flex shaft


71


and an inner bore


120


of the flex housing


84


. From this annulus, the mud enters the central bore


64


of the bearing adapter through the angularly drilled holes


63


. The mud flows from this bore


64


through the axial bore


19


in the bearing mandrel


18


.




From the foregoing description, it can be seen that the disclosed arrangement in which the sonde is received in the wall of a main housing part, namely the outer housing


41


, the sonde can be disposed quite close to the bit


11


with minimal hardware and without complexity. As seen, the flow of mud from the power section


89


to the bit


11


is unrestricted and the diameter of the transmission section is not unnecessarily enlarged beyond that which is already required for the necessary bearings and other componentry. By locating the sonde


108


close to the bit


11


, much greater accuracy in monitoring and tracking the progress of the boring process over that possible with the prior art is achieved.




Operation of the mud motor to steer the pipe string along its desired path will be evident to those skilled in the art. Typically, to adjust the direction of the bore, the drill string is rotated to point the bit in the direction of the needed adjustment. The orientation of the bit is transmitted to a surface receiver by the sonde. The drill string is held against rotation while the mud motor rotates the bit and the drill string is thrust forward to redirect the direction of the bore. The disclosed mud motor provides a unique function that is enabled by the provision of the forward set of thrust bearings


44


. These bearings


44


allow the mud motor to operate to rotate the bit


11


when the drill string is being pulled out of the hole so that during this withdrawal process the hole is conveniently reamed or enlarged with a hole opening device.





FIGS. 5 and 6

illustrate additional embodiments of the invention. Parts like those described in connection with the embodiment of

FIGS. 1-4

are designated with the same numerals. In

FIG. 5

, a tubular cylindrical collar


126


housing the sonde


108


is assembled around a housing


127


that corresponds to the outer housing


41


of the embodiment of

FIGS. 1-4

. The collar


126


is formed of steel or other suitable material. The collar


126


is fixed longitudinally and angularly relative to the housing


127


by set screws


128


threaded into the wall of the collar


126


and received in blind holes


129


drilled in the wall of the housing


127


. The sonde


108


is received in the sarcophagus


106


and protected by the cover


109


as previously described. Various other techniques, besides the set screws


128


, can be used to fix the collar


126


on the housing


127


. The collar


127


can be threaded onto the housing


127


where the housing, for example, is provided with external threads and a stop shoulder. Another technique is to weld the collar


126


to the housing


127


. If desired or necessary, the sonde


108


can be assembled in a hole aligned with the axis of the collar


126


and open at one end. The opening can be plugged with a suitable closure during use.





FIG. 6

illustrates another embodiment of the invention. A coupler


131


is disposed between the bearing mandrel


18


and the bit


11


. The coupler


131


has external threads mated with the bit box


21


and internal threads receiving the bit


11


. The coupler


131


is formed with the pocket


101


for receiving the sonde


108


. The coupler


131


has a central bore for conveying mud from the bearing mandrel


18


to the bit


11


. If desired, an axially oriented hole can be used instead of the open face pocket


101


to receive the sonde


108


and the hole can be plugged by a suitable closure. Still further, if it is desired to locate the sonde


108


at the center of the coupler


131


, water corsets or passages can be drilled or otherwise formed axially through the coupler and circumferentially spaced about the sonde to allow mud to pass through the coupler.




While the invention has been shown and described with respect to particular embodiments thereof, this is for the purpose of illustration rather than limitation, and other variations and modifications of the specific embodiments herein shown and described will be apparent to those skilled in the art all within the intended spirit and scope of the invention. Accordingly, the patent is not to be limited in scope and effect to the specific embodiments herein shown and described nor in any other way that is inconsistent with the extent to which the progress in the art has been advanced by the invention.



Claims
  • 1. An apparatus comprising a mud motor having a tubular outer housing, said tubular outer housing having a through bore substantially along a longitudinal axis thereof and an interior surface and an exterior surface, said tubular outer housing of said mud motor comprising a receiving pocket in the exterior surface sized to receive a sonde, and a cover plate removably attached to the outer housing over the receiving pocket, wherein the cover plate further includes at least one slot to allow the passage of electromagnetic signals from the sonde, said slot including a filling of non-metallic material.
  • 2. Apparatus of claim 1, further comprising a shock resistant holder for the sonde shaped to be received in the receiving pocket, said cover plate functioning to hold the sonde and shock resistant holder in place.
  • 3. Apparatus of claim 2, further comprising a sonde placed in the shock resistant holder.
  • 4. Apparatus of claim 1, said slot being oriented in a longitudinal direction relative to the longitudinal axis of the tubular outer housing.
  • 5. Apparatus comprising a mud motor having a tubular outer housing having an exterior diameter, said tubular outer housing further including a cavity therein shaped to hold a mount for a sonde within the exterior diameter of the housing, a lip formed around the cavity, and a removable cover plate set in the lip, said mount comprising an elastomeric sarcophagus shared to hold said sonde.
  • 6. Apparatus of claim 5, further comprising a sonde set in the elastomeric sarcophagus.
  • 7. Apparatus comprising a mud motor having a tubular outer housing, said tubular outer housing having a through bore substantially along a longitudinal axis thereof, an interior surface and an exterior surface, said tubular outer housing comprising a collar having an interior surface and an exterior surface removably attached at the inner surface of the collar to the outer surface of the tubular outer housing, a receiving pocket in the exterior surface of the collar shaped to receive a sonde, a shock resistant holder for the sonde shaped to set in the receiving pocket, and a cover plate, removably attached to the collar over the receiving pocket, functioning to hold the sonde and shock resistant holder in place.
  • 8. Apparatus for well drilling comprising a mud motor having a bit box, a bearing mandrel and a coupler disposed therebetween, said coupler comprising a through bore substantially along a longitudinal axis of the coupler, said coupler having an interior surface and an exterior surface, a receiving pocket in the exterior surface shaped to receive a sonde, and a cover plate removably attached to the coupler over the receiving pocket, wherein the cover plate further includes at least one slot to allow the passage of electromagnetic signals from the sonde, said slot including a filling of non-metallic material.
  • 9. Apparatus of claim 8, further comprising a shock resistant holder for the sonde shaped to set in the receiving pocket, said cover plate functioning to hold the sonde and shock resistant holder in place.
  • 10. In an entrenching powering device having an exterior wall of a housing, an improvement comprising a sonde mounted in a pocket formed in the housing, the exterior wall having at least one slot therein to allow the passage of electromagnetic signals from the sonde, said slot including a filling of non-metallic material.
  • 11. The entrenching powering device of claim 10, further comprising a shock resistant holder set in the pocket, said sonde being mounted in said shock resistant holder.
  • 12. The entrenching powering device of claim 10, further comprising a removable cover mounted over the pocket, said slot being provided in said removable cover.
Parent Case Info

This application claims the priority of U.S. Provisional Application No. 60/174,487, filed Jan. 4, 2000 and U.S. Provisional Application No. 60/203,040, filed May 9, 2000. This application is a divisional of U.S. patent application Ser. No. 09/617,189 filed on Jul. 14, 2000 now U.S. Pat. No. 6,349,778.

US Referenced Citations (37)
Number Name Date Kind
4241796 Green et al. Dec 1980 A
4733733 Bradley et al. Mar 1988 A
4779852 Wassell Oct 1988 A
4821563 Maron Apr 1989 A
4828050 Hashimoto May 1989 A
4907658 Stangl et al. Mar 1990 A
5096001 Buytaert et al. Mar 1992 A
5148880 Lee et al. Sep 1992 A
5186256 Downs Feb 1993 A
5242026 Deken et al. Sep 1993 A
5253721 Lee Oct 1993 A
5269383 Forrest Dec 1993 A
5311951 Kyte et al. May 1994 A
5325714 Lende et al. Jul 1994 A
5341887 Deken et al. Aug 1994 A
5382760 Staron et al. Jan 1995 A
5392868 Deken et al. Feb 1995 A
5456106 Harvey et al. Oct 1995 A
5469736 Moake Nov 1995 A
5560437 Dickel et al. Oct 1996 A
5589775 Kuckes Dec 1996 A
5602541 Comeau et al. Feb 1997 A
5646611 Dailey et al. Jul 1997 A
5678643 Robbins et al. Oct 1997 A
5679894 Kruger et al. Oct 1997 A
5680906 Andrieux et al. Oct 1997 A
5725061 Van Steenwyk et al. Mar 1998 A
RE35790 Pustanyk et al. May 1998 E
5798488 Beresford et al. Aug 1998 A
5812068 Wisler et al. Sep 1998 A
5877996 Krokstad et al. Mar 1999 A
5924499 Birchak et al. Jul 1999 A
5931240 Cox Aug 1999 A
5934391 Cox Aug 1999 A
5950743 Cox Sep 1999 A
6050350 Morris et al. Apr 2000 A
6487901 Keyes Dec 2002 B1
Foreign Referenced Citations (1)
Number Date Country
0 553 908 Aug 1993 EP
Provisional Applications (2)
Number Date Country
60/203040 May 2000 US
60/174487 Jan 2000 US