CA2044945C

CA2044945C - Adjustable bent housing

Info

Publication number: CA2044945C
Application number: CA002044945A
Authority: CA
Inventors: Kenneth Hugo Wenzel; Dean Foote
Original assignee: Vector Oil Tool Ltd
Current assignee: NOV Canada ULC
Priority date: 1991-06-19
Filing date: 1991-06-19
Publication date: 1997-11-25
Anticipated expiration: 2011-06-19
Also published as: CA2044945A1; US5343966A

Abstract

An adjustable bent housing consisting of three tubular members arranged in end to end relation. Each of the tubular members has an interior bore. A first tubular member has a first axis. A second tubular member has a second axis. A central tubular member is centrally disposed between the first tubular member and the second tubular member and has a third axis. An internal tubular member extends into and engages the interior bores of the three tubular members thereby maintaining the tubular members in end to end relation.

Description

20~9'~'3 The present invention relate~ to an ~d~ustable Ben-t ~ousing.

~ U~D OF ~E lNVL~ ON

sent subs are used when ear~h drilling with downhole motors. There are used to create a bend which results in the bore hole deviatin~ from vertical. In order to avoid having a plurality of bent subs on site, adjustable bents subs were developed in which the magnitude of the bend was adjustable.

There are presently two alternative ways of constructing an adjustable bent sub. One alternative construction is exemplified by United States Patent 4,077,657 which issued to Xurt H. Trzeciak. The Trzeciak adjustable bent sub has two tubular members in end to end relation. The two tubular members meet at a mating end formed with respect to a common mating pla~e which is at an angle to the axis of the part. Means is pxovided to loek the tubular member~ to each other at selected angular rotation of the ends with respect to each other. In other words, the angular adjustment is accomplished through angularly offset mating faces. Another alternative construction is exemplified by United Skates Patent 4,813,497 which issued to Kenneth Hugh Wenzel. The Wenzel patent has one tubular member which is telescopically received in a second tubular member. Each of the tubular 3D members is "bent" having a primary axis and a secondary axis. Angular adjustment is accomplished by relative rotation of the tubular membersO The tubular members may be rotated to offset the "bends" so the opposed ends of the tubular members are parallel or rotated to create a ~l lative bend.

As the art of horizontal and directional drilling evolved, it wa8 determined that the preferred placement of the adjustable bend housing was as elose to the drill bit, 2 ~

as possible. Drilling motors operate in an eccentric motion in response to mud pumped from on surface pumps.
The bearing assemblies are used to rotate the drill but in a concentric motion. A universal joint type of drive shaft connects the drilling motor and the bearing assem~ly and is used ~o convert the eccentric motion of the drilling motor to a concentri~ motion of the bearing assembly which rotates the drill bit. United States Patent 4,813r497 which issued to Kenneth Hugo Wenzel was the first adjustable bent housing which could ~e placed over the connecting drive shaft between the drilling motor and the bearinq assembly. The distinction be-tween an adjustable bent sub and an adjustable bent housing is the ability of the tool to accommodate a universal joint type of drive shaft through its central bore.

An adjustable bent housing is subjected to friction where it comes into contact with the side wall of the borehole. With each of the above descri~ed constructions of adjustable bent housing problems are encountered due to contact with the side wall of the borehole. The Wenzel design has one tubular member with an exterior neck portion on which a locking nut is positioned. ~his neck can break due to the force of friction when the bend of the adjustable bent housing comes into contact with the side wall of the borehole. The Trzeciak design would require significant modification before it could be used as a housing. Even with those modifications, having the entire adjustment occurring on one common plane requires more rotational clearance and therefore exacerbates the problem of friction against the sidewall of the borehole.

Some f~iction between the body of the adjustable bent housings and the sidewall of the borehole is unavoidable, therefore means must be found to strengthen the adjustable bent housing.

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SUM~aRY OF THE 1NV~ ON

What is required is an alternate construction of Adjustable Bent Housing that has greater strength than adjustable bent housings known in the p.rior art.

According to the present invention there is pro~ided an adjustable bent housing which is comprised of three tubular members arranged in end to end relation. Each of the tubular members has an interior bore. A first tubular member has a first axis. A second tubular member has a second axis. A central tubular member is centrally dispo~ed between the first tubular member and the second tubular member and has a third axis. The first axis and the ~econd axis are offset from the third axis. Adjustment is effected by rotaking at least one of the first tubular member and the second tubular member in order to alter the positioning of the first axis or the second axis relativs to the third axis. An internal tubular member extends into and engages the interior bores of the three tubular members thereby maint~; n; ng the tubular members in end to end ~ relation with the axes in a predetermined relative position.

25Although beneficial result may be obtained through the use of the adjustable bent housing as described above, there is an engagement between the internal tubular member and the interior bore of the three tubular members that is to preferred over the use of internal retaining nuts as is known in the art. In this preferred embodiment the internal tllbular member has an external surface, a first end and a second end. Spline extend r~ lly outwardly from the external surface of the internal tubular member intermediate the first end and the second end and threads are positioned on the external surface adjacent the first end and the second end. The ~irst tubular member has a first end face and an interior bore. I'he interior bore o~

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the first tubular member has interior threads adjacent the first end face such that the first tubular member is adapted to threadedly engage the first end of the interior tubular memberO The second tubular member has a second end face and an interior bore. The interior bore of the second tubular has interior threads adjacent the second end face such that the second tubular member is adapted to threadedly engage the second end of the interior tubular member. The central tubular member has an interior bore, a first end and a second end. The central tubular member telescopically receives the interior tubular member and is A~;~lly moveable between the first end and the second end of the interior tubular member. The interior bore of the central tubular member has spline extending r~;ally inwardly, such that the spline mate with spline on the exterior surface of the interior tubular memher to no~-rotatably couple the interior tubular member with the - central tubular member. At least one of the ends of the central tubular member has a mating clutch engagement with at lea~t one of the first end of the first tubular member and the second end of the second tubular member.

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BRI~F DE8CRIPTION OF TH~ DRaWIN~
These and other features of the invention will become more apparent from the following description in which reference is made to the appended drawings, wherein:
FIGURE la is a simplified diagrammatic representation of a prior art mode of adju~tm~nt as exempli~ied by Trzeciak in a straight orientation.
FIGURE lb is a simplified diagrammatic representation of a prior art mode of adjustment as exemplified by Trzeciak in a bent orientation.
FIGURE 2a i~ a ~implified diagran~atic representation of a prior art mode of adjustment as exemplified hy Wenzel in a straight orientation.

2~ 3 FI~UR~ 2b is a simpli~ied diagral~na-tic representatio of a prior art mode of adjustment as exemplified by Wenzel in a ben-t orientation.
FTGURE 3a is a simpli~ied diagrammatic representation of the present invention in a straight orientation.
FI~U~ 3b is a simplified diagrammatic repr2sentation of the present invention in a bent orientation.
FI~URE 4 is a longitudina] section view of an a~justable bent housing constructed in accordance with the teachings o~ the present inven-tion.

D~ATT~ DESCRIPTION OF T~E P~r~n~ EMBODIM~NT

The preferred embodiment, an Adjustable Bent Housing, generally identified by refer nce numeral 30, will now be descrlbed with reference to FI~URES 3a, 3b, and 4. Prior to describing the invention the Prior Art will be described as illustrated in FIGU~E~ la, lb, 2a, and 2b.

FIGUR~S la and lb are simplified versions of the mode of adjustment taught by Trzeciak. The essence of the teachings of Trzeciak is that by cutting a single length of pipe 10 at an angle two tubular members 12 and 14 are created. Tubular members 12 and 14 have end faces 16 and 18, respectively, which mate on a common plane 20. For the purposes of illustration the relative rotational positioning of tu~ular members 12 and 14 are designated by the notation A-B. When tubular members 12 and 14 are maintained in one orientation th~ overall re~ult is that pipe 10 is straight as illustrated in FI&URE la. When tubular member 12 i8 rotated 180 degrees the overall result is that pipe 10 is l'bent" as illustrated in FIGUR~ lb.

FIGURES 2a and 2b are simplified versions of the mode 35 of adjustment taught by Wenzel. The essence of the teaching~ of Wenzel is that by telescopically mating two tubular members 22 and 24 which are already angularly 2 ~

offset, a "bend" can be created which is adjustable by relative rotation O r tubular members 22 and 24. In FIGU~E
2a and 2b the bend has been exaggera-ted. Each of tubular members 22 and 24 is "bent", having a primary axis 26 and a secondary axis 28. Angular ad~ustment is accomplished by relative rotation of tubular members 22 and 24, which is designated by the notation A B. In FIGUR~ 2a, tubular members 22 and 24 have been rotated to offset the ~bends~
so the primary axes 26 of tubular memhers 22 and 24 are parallel. In FI~URE 2b, tubular members 22 and 24 have been rotated 180 degrees t~ create a cumulative bend.

The basic principlP behind adjustable bent housing 30 is illustrated in ~IGURES 3a and 3b. Adjustahle bent housing 30 consists of three tubular members, which will hereinafter be identified as ~irst tubular member 32, second tubular member 34, and central tubular member 36, arranged in end to end relation. First tubular member 32 has a first axis 38. Second tubular member 34 has a second axi~ 40. Central tubular member 36 is centrally disposed between first tubular member 32 and second tubular member 34 and has a third axis 42. First axi~ 38 and second axis 40 are not coaxial with third axis 42, but rather are of~set from third axis 42 by approxima-tely 1 1/2 degree~, thereby creating a "bend". Adjustment of the "bendi' is effected by rotating first tubular member 32, second tuhular member 34 or both in order to alter the positioning of firs-t axis 38 or second axis 40 relative to third axis 42. FIGURE 3a illustrates adjustable bent housin~ 30 in a straight position. FIGURE 3b illustrates adjustable bent housing 30 in a ben-t position.

The mode of maintaining tubular members 32, 34, and 36 in end to end relation with axes 38~ 40, and 42 in a predetermined relative position is not illustrated in FIGURES 3a and 3b. Referring to FI~UR~ 4, each of the tubular members 32, 34, and 36 has an interior bore 44, 46, . .
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and 48, respectively. Tubular members 32, 34, and 36 are held together by an internal tubular member 50 which extendg into and engages interior bores 44, 46, and 48 of tubular memb~rs 32, 34, and 36. There are a number of way~
of configur.ing adjustable bent housing 30 in accordance with the teachings of the invention. The pre~erred embodiment will now be described with reference to FI~U~
4.

Referring to FIGURE 4, internal tubular me~ber 50 has an external surface 52 / a first end 54 and a second end 56. Spline 58 extend radially outwardly from external surface 52 of internal tubular member 50 inte -~;ate first end 54 and second end 56. Threads 60 are positioned on external surface 52 adjacent first end 54. Threads 62 are positioned on external surface 52 adjacent and second end 56. First tubular member 32 has a first end face 64 and an opposed pin connection 66. Interior bore 44 of first tubular member 32 has interior threads 68 adjacent first end face 64 such that first tubular member 32 is adapted to threadedly engage threads 60 at first end 54 of interior tubular member 50. Second tubular member has a second end face 70 and an opposed pin connection 72. A portion of : second end face 70 has a projecting clutch profile 74.
Interior bore 46 o~ second tubular member 34 has interior threads 76 adjacent second end face 70 such that second tubulax member 34 is adapted to threadedly engage threads 62 at second end 56 of interior tubular mernber 50. Central tubular member 36 has a first end 78 and a second end 80~
Central tubular member 36 telescopically receives interior tubular member 50 and is axially moveable between first end 54 and second end 56 of interior -tubular member 50.
Interior hore 48 o~ central tubular member 36 has spline 82 exten~; ng radially inwardly, such that spline 82 mat~ with ~pline 58 on exterior surface 52 of interior tubular member : 50 to non-rotatably couple interior tubular member 50 with central tubular mernber 36. A portion of second end 80 o~

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2 ~A~ ~3 central tubular member 36 has a clutch profile 84 which matingly engages clutch profile portion 74 at second end 70 of second tubular member 34. Seals 86 along external surface 52 of internal tubular member 50 adjacent ends 54 and 56 to preclude the passage of drilling fluids into that portion of adjustable bent housing 30 where -threads 60 and 62 enga~e threads 68 and 76, respectively. Shoulders 88 project into interior bore 46 of second tubular member 34 the function of which will be hereinafter further described in relation to the operation of adjustable bent housing 30.

It was previously noted that first axis 38 and second axis 40 are offset from third axis 42. In the preferred embo~; ~nt illustrated in FIGURE 4 first axis 3~ has been offset from third axis 42 by machining first end 78 of central tubular member 36 at an angle of 1 1/2 degrees off being perpendicular to axis 42. This is illustrated in FIGUR~ 4 by a transverse axis, identified by reference numeral 77~ which is perpendicular to axis 42, as compared to a transverse axis line, identified by reference numeral 79, which is offset from axis 42 by 1 lt2 degrees. When first tubular membex 32 is placed in end to end relation with central tubular member 36, first end face 64 of first tubular member 32 engages first end 78 of central tubular member 36. First end 78 being offset by 1 1/2 degrees in the manner described results in first tubular member 32 being offset by 1 1/2 degrees. To accommodate this 1 1/2 degree offset, first end 54 of internal tubular men~er 50 which holds first tubular member 32 and central tubular member 36 together in end to end relation is also offset by 1 1/2 degrees in the area of threads 60. Second axis 40 is offset from third axis ~2 by machining the outer diameter of second tubular member 34 in an eccentric fashio~ so that it is offset from second end face 70 and interior bore 46 by 1 1/2 degrees. Therefore, when second tubular member 34 is in end to end relation with central tubular member 36 ' ~

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with s~cond end face 70 of second tubular member 34 engaging second end 80 of central tubular member 36 second : tubular membe~ 34 extends at an angle of 1 l/Z degrees and axis 40 is offset by 1 1/2 degrees.

The use and operation of adjustable bent housing 30 will now be described with reference to FI~U~ES 3ar 3b, and 4. In order to adjust the bend in adjustable bent housing 30, first tubular member 32 is rotated while internal tubular member 50 is maintained stationary thereby resulting in threads 68 partially backing out of engagement with threads 60 at first end 54 of internal tubular member 50. The threads are backed off to permit central tubular member 36 to move axially along internal tubular member 50 : until clutch profile ~4 at second end 80 of central tubular memher 36 disengages clutch profile 74 at second end 70 of second tubular member 34. As long as clutch profiles 74 and 84 remain engaged second tubular member 34 aanrlot be :- 20 rotated, for second tubular member is locked to central tubular member 36. Central tubular member 36 is, in turn, non-rotatably coupled to internal tubular member 50 by the mating of radially inwardly extending spline 82 on interior bore 48 of central tubular member 36 with radially outwardly extending spline 58 on exterior surface 52 of interior tubular member 50. However, once the respective -clutch profiles have been disengaged second tubular member 34 can be rotated in relation to central tubular member 36.
The rotation of second tubular member 34 adjusts the 30relative positioning of axes 38l ~0 and 42. Depending upon : this relative positioning of the two 1 1/2 degree of~sets represant~d by axes 38 and 40 the result can be a tive "bend" of 3 degrees, a cancelling of the offsets for a "bend" of 0 degrees, or a range of positions inbetween. M~; thread engagement between threads 62 at second end 56 of internal tuhular member 50 and threads 76 adjacent second end face 70 of second tubular member 34 is , , :' i.~' : ' ., ' ' , ' ' , ': ' : . ' -- , , . ' -- 2 ~

desirable. To facilitate this shoulders 88 have been provided. In making an adjustment second tubular member 34 is first tightened onto second end 56 of internal tubular member 50 until second end 56 engages shoulders 88. Second tubular member 34 is then rotated, backward~ or left hand, until axes 38, 40, and 42 are in the desired position.
Then central tubular member 36 is slid axially along internal tubular member 50 un-til clutch profile 84 is back in engagement with clutch profile 74. This prevents further rotation of second tubular member 34 to maintain the adjustment. Then first tubular member is rotated to bring threads 68 into -~; engagement with threads 60 and tightly draw together second end face 70 with second end 80 and first end face 64 with first end 78 to maintain tubular members 32, 34, and 36 in end to end relation.
Seals 86 prevent drilling fluids from contaminating the threads or spline when adjustable bent housing 30 is being used downhole.

It will be apparent to one skilled in the art that the adjustable bent housing described i8 much improved in strength to the prior art adjustable bent housings. The adjustable bent housing is as stiff as the rest of the drilling motor and is stronger in tension than previous designs. ~he threaded connections used for adjustment can be tightened to the same torque as the rest of the connections in the motor, while ret~1 n; ng a positive in~;ng capacity. It will also be apparent to one skilled in the art that modifica-tions may be made to the described and illustrated embodiment without departing from the ; spirit and scope of the invention as defined by the claims.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An adjustable bent housing comprising:
a. three tubular members arranged in end to end relation, each of the tubular members having an interior bore, the tubular members comprising:
i. a first tubular member having a first axis, ii. a second tubular member having a second axis, iii. a central tubular member centrally disposed between the first tubular member and the second tubular member and having a third axis, the first axis and the second axis being offset from the third axis such that adjustment is effected by rotating at least one of the first tubular member and the second tubular member in order to alter the positioning of the first axis or the second axis relative to the third axis, b. an internal tubular member extending into and engaging the interior bores of the three tubular members thereby maintaining the tubular members in end to end relation with the axes in a predetermined relative position;
c. the internal tubular member having an external surface, a first end and a second end, a spline extending radially outwardly from the external surface intermediate the first end and the second end and threads on the external surface adjacent the first end and the second end, the threads at one of the first end and the second end being offset;
d. the first tubular member having a first end face and an interior bore, the interior bore having interior threads adjacent the first end face such that the first tubular member is adapted to threadedly engage the first end of the internal tubular member;
e. the second tubular member having a second end face and an interior bore, the interior bore having interior threads adjacent the second end face such that the second tubular member is adapted to threadedly engage the second end of the internal tubular member;
f. the central tubular member having an interior bore, a first end and a second end, the central tubular member telescopically receiving and being axially moveable between the first end and the second end of the internal tubular member, the interior bore having a spline extending radially inwardly, such that the spline mates with the spline on the exterior surface of the internal tubular member to non-rotatably couple the internal tubular member with the central tubular member, at least one of the ends of the central tubular member having a mating clutch engagement with at least one of the first end of the first tubular member and the second end of the second tubular member.