CA1173822A

CA1173822A - Apparatus for drilling straight portion of a deviated hole

Info

Publication number: CA1173822A
Application number: CA000386214A
Authority: CA
Inventors: William C. Lyons; Scot L. Scurlock; Edward A. Zublin
Original assignee: Texas Eastern Drilling Systems Inc
Current assignee: Texas Eastern Drilling Systems Inc
Priority date: 1980-09-19
Filing date: 1981-09-18
Publication date: 1984-09-04
Also published as: MX153594A; US4343369A

Abstract

APPARATUS FOR DRILLING STRAIGHT
PORTION OF A DEVIATED HOLE

Abstract of the Disclosure A guide for drilling a straight section of a bore hole de-flected from the vertical. The apparatus comprises either a normally straight or a curved-straight tubular member which has a plurality of generally circumferential cuts disposed along the length of the guide. The cuts allow the guide to be bent sufficiently to enter and traverse a short radius curve and then return to its normal configuration for guiding the drilling of the straight portion of the deflected bore hole. A clutch mechanism disposed in the drill guide permits engagement of the guide by the drill string for orientation of the guide.

Description

sackground of ~he Inv~ntion 1~ Field of the Invention The invention relates to an apparatus for drilling a de-viated bore hole and ~or drilling a ~traight section of bore hole which may be horizontal or at any angle from the terminu~
of a small radius curved bore hole.

2.... Prior Art There have been many effort~ to devalop apparatu~ ~or suc-ce~3~ully drilling small radiu~ deviated well bores. Prominent among tho~e working in thi~ ld wa~ Zublin/ to who~l many patent~ have i~sued. Typical o~ hl~ e~fort~ in this ~ield is U.S. Paten~ No. 2,631,820, which teache~ the use of a curved drill guide to maintain a curved drill course in ~p~te of radlal ~orces working again3t the drill gulde. Included in the u~e of the dr~ll guide is a heavy duty ~lexible drill plpe ag taugh~ ln U.S. Patent No~ 2,515,366.
Zublin again directed his attention to a curved drill guide in U.S. Patent No. 2,644,270. In addition, this patent teaches the use o$ a rib, attached to the outside of the drill ~ ~73~2~
guide, to help stabilize the guide while rotating the ~lexible drill pipe of U.5. 2,515t366. The patentee used two or more ribs attached to the bottom end of the drill guide, as shown in the drawings, in order to limit the curvature of the well bore.
Otherwise, ~here was a ~endency to form a U-~haped well bore.
In ~.S. Patent No. 2,669,430, the patentee taught an appa-ratus for drilling devitated well bores utilizing a number of straight tubular drill guide sections. These so-called "straight" drill guide sections were stacked on the sectional drill collars, end to endr and designed so that the drill guide sections were rotatable relative to each other. Used in con-junction with a whipstock, they imparted flexibility to the drill string on making the curved drill path but became rigid for lateral drilling.
Another Zublin patent, U.S. 2,672,321, disclose~ a clutch mechanism useful with the curved drill guide of U.S. 2,515,366.
The drill guide and clutch mechanism carried the drill string weight during drilling operations. In practice, the bearings of this clutch were not able to withstand the thrust loads required in normal drilling operations.
Other art in this field is representea in the following U.S. Patents:
~,336,338 2,63~,097 2,3~4,277 ~,~80,358 2,402,003 2,684,581 2,515,365 __ the Invention It is a primary object to provide a drill guide or use in drilling laterally extended well bores.
A fuxther object is to provide an improved orientation clutch assembly to be used in conjunction with said drill guide.

~ 173~2 Summary of the Inventi:on -According to one aspect of th~ i.nve.ntion, there is provided a fle~ible, resi:lient drill ~uïde, connectable at its upper end to a rotary drïll strïng and at its lower end to a rotary drill bit, for guïding the dïrection of drilling a well bore deflected from the vertical, saïd drill ~uide comprising: an inner flex-ible segmented tubular drïve member for transmitting rotational forces and drilling fluid between said drill string and said drill bit; and an outer flexible, resilient, -tubular member for exerting directional drilling forces on said drill bit, said outer tubular member having disposed along at least a major portion of its length a plurality of non-connected shaped cuts extending therethrough and around a portion of the circum-ference thereof, but not severing said outer tubular member, and, said outer tubular member in an unstressed condition being normally curved through a portion of its length and normally straight through a portion of its length.
According to another aspect of the invention, there is provided an apparatus for guiding the direction of drilling a well bore deflected from the vertical comprising: a flexible, resilient tubular member which is normally straight in an unstressed state for a portion of its length and is normally curved in an unstressed state for a portion of its length, said tubular member having disposed along at least a major portion Oe i~s length a plurality oE non-connected, shaped cuts, said plurality of non-connected shaped cuts each comprising first and second circumEerentially spaced-apart port.ions generally parallel to the longi~udinal axis of said tubular member, said fi.rst and second portions ~eing interconnected by a sinuous third portion o~ substantially greater length than either of said first and second portions, a flexible drive member

3 ~3 2 2 rotatable within said tub.ular member and connectable to a drill string, said drlve membe.r being the torque bearing member, said flexible drive member being longitudinally movable with.in said tubular member~ dog means carried on said tu~ular member and on said flexible drive member, engageable upon upward movement of said flexihle drive member in relation to said tubular member, and which, when engaged, permits the tubular member to be moved for angular orientatï.on.
According to a further aspect of the invention, there is provided a flexible, resilient drill guide, connectable at its upper end to a rotary drill string and at its lower end -to a rotary drill bit, for guiding the direction of drilling a well bore deflected from the vertical, said drill guide comprising:
an inner flexible seymented tubular drive member for trans-mitting rotational forces and drilling fluid between said rotary drill string and said rotary bit; and an outer flexible, resilient, tu~ular member for exerting direction drilling forces on said drill bit, said outer tubular member in an unstressed state being straight for at least approximately one-third of its length and having disposed along at least a major portion of its length a plurality of nonconnected shaped cuts e~tending -there-through and around a major portion of the circumference thereof, but not severing said outer tubular member; a first plurality of stabili.zer fins positioned on the outer su.rface o:E said outer tubular member adjacent one end thereof :Eor retarding rotation of said tubular member while guiding the direction of drilling of sa.id drill bit; and, a second plurality oE stabilizer fins ~ositioned on the outer surface of said outer tubular member intermediate the ends thereof.
Descrlption of the Drawings FIGURF, 1 is a schematic representation of one embodiment -3a-~L17382~
of the flexible drill guide of the inventionJ depicted extending downward in a well bore;
FIGURE 2A-C is a plan sectional view of the cIutch mech- ~:
anism used with the flexible drill guide of the invention;
FIGURE 3 is a schematic representation of a flexible drill guide having a normally curved configuration;
FIGURE 3A is a schematic representation of one embodiment ,~ ' -3b-,~ :

, ~ :11 '7 3 8 ~J .~
of a flexible drill guide having a normally partially curved configuration.
FIGURE 4A-C is a plan, partially cut away view of the flexible drill guide of FIGURE 3, illustrating the configura-tion of the stabilizer shoes attached thereto and the cuts made therein to impart flexibility;
FIGURE 5 iS a cross-sectional view on the line 5-5 of FIGURE 4A showing the positioning of the stabilizer fins at-tached to the upper end of the flexible drill guide;
FIGURE 6 is a cross-sectional view on the line 6-6 of FIGURE 4C showing the positioning of the stabilizer fins at-tached to the lower end of the fle~ible drill guide;
FIGUR~ 7 is a laid out section of the flexible drill guide of FIG~RE 3, showing the cut made therein;
FIGURE 8 is a laid out section of the flexible drill guide of FIGURE 9, showing the cut made therein;
FIGURE 9 is a schematic representation of one embodiment of a flexible drill guide embodiment having a normally par-tially curved configuration;
FIGURE lOA-C is a plan view of the flexible drill guide of FIGURE 9, showing the fin axrangement therein;
FIGURE 11 is a schematic representation of the flexible drill guide embodiment having a normally straight coniguration but which i~ bendable through a relatively short radius? and FIGURE 12~-C iS a plan view o the ~lexible drill guide o~
FIGU~ howing the ~in arrangement therein.
~etailed ~escriptio ~ odiments Re~erring to FIGU~E 1, there i8 illustrated schema~ically one embodiment o~ the flexible drill guide 10 po~itioned in a vertical well bore 12, being lowered to commence drilling a bore hole deviated ~rom the perpendiculax. The drill guide 10 surrounds and is carried by a ~ectionalr flexible drill stem 14 :~ ~7382,~
which is reerred to hexeinafter as a drive pipe. The drill guide 10 illustrated in FIGURE 1 is referred ko as a "normally curved" drill guide.
The basic geometric configuration of the normally curved drill guide 10 has been known for a number of years. Typical of these is the curved drill guide 10 of FIGURE 1 of ~.S.
2,631,820. In utilizing the normally curved drill guide 10 of the present invention, the operator lowers the drill guide to virtually any point in a previously drilled well bore 12 and~
selecting the proper azimuth, commence to drill a deviated hole using the drill bit 18 attached to the end 64 of an interiorly disposed drive pipe 14 and clutch member 37. The normally curved drill guide 10 carries stabilizer fins 22, 24 a~d 26 which act to prevent rotation of the drill guide 10 while the drill bit 18 is being operatedO It has been found that the number and placement of the stabilizer fins is a critical factor in maintaining the proper drill path and azimuth. These will be discussed in more detail hereinafter.
It has now been discovered that for drilling the straight portion of a deviated hole, after the curve has been drilled with the normally curved drill guide 10 o~ FIGURE 1 (shown schematically in FIGURE 3~, a flexible drill guide having at least a portion of its leng~h normally straight, as illustrated in F~GU~S 3~r 9 and 11, ~hould be used. It i~ pre~erred that at l~a~t a portion o~ its straight ~ection should be on the bit end o the flexible drill guide, rrhus~ in FIGVRE 3A there is illustrated an embodiment of the flexible drill guide 10' o~ the invention wherein the straight portion Y' thereo~ comprises about one-third of the length of the drill guide 10'. However, this is just an ap-proximation and is not criticalO What is important is that at least some part of the bit end llb of the drill guide be essen-, 2 tially straightr compared to the normally curved portion Z' ofthe drill guide 10'.
Another embodiment of the invention is illustrated in FIGURE 9, wherein a greater portion of the flexible drill guide 80 is essentially straight. These are the lengths X and Y, while the portion Z is curved. In this embodiment, approxi-mately two-thirds of the drill guide 80 is straight. Again, this proportion is a rough approximation, and is not critical.

The normally curved-straight drill guides 10' and 80, as illustrated in FIGURES 3A and 9~ should be used for entering a deviated hole which has been kicked off from the side of an open well bore. The normally ~traight drill guide 82 shown in FIGURE 11 is a variation of the drill guide of FIG~RE 3A and 9, and would be used when the deviated hole is kicked off from the bottom of a vertical hole or when some other device is used to insert the normally s~raight drill guide into a side track.
The normally straight 82 and curved-straight 10' and 80 drill guides of FIGURES 11, 3A and 9, respectively, are prefer-ably each constructed from single pieces of annealed ~teel tubing. Each drill guide receives a series of special cuts 100 (and 106). Th~ cuts are illustrated in FIGURES 7 and 8, intemplate form ~howing relative dimensions of the radial and longitudlnal portions of the cuts.
~ he cu~ 100 are spaced at e~entially equal dl~tances apart along the length of the drill guides 80 and 82. The cuts 100 are made radially across ~he guide and intersec~ a longi-tudinal cut 102 ha~ing ends 104 and 104'. The radial cut 100 is made at an angle to the plane of the drill guide 80. This permit~ the drill pipe 80 to be bent somewhat and the cut sur~aces are able to act as bearing surfaces.
It has been found that either the short cut 20 of FIGURE
7, or the longer cut 100 of FIGURE 8 may be used with the .~ 173~22 straiyht drill guide 82 and the curved-straight drill guide 80.
Alternatively, there may be used a combination of short and long cuts, as illustrated in FIGURE 9, with the longer cuts lO0 used in the curved portion of the guide 80~
The cuts lO0, of the nor~ally straight 82 and the curved-straight 80 drill guides are placed at a predetermined distance from one another to provide the needed flexibility for the guides 80 and 82 to traverse both the horizontal and curved sections of the deviated hole.
As previously ~entioned, the stabilizer fins are used to maintain the desired angle of declination and azimuth while drilling the straight portion of the deviated hole using the normally straight drill guide 82 and the curved-straight drill guide 80. Referring to FIGURE 9, the drill guide 80 has an upper set of fins 90 and a lower set of fins 92 placed thereon.
Also, there are pre~erably two sets of fins 88 and 91 pla¢ed at intermediate locations along the iength of the drill guide B0.
Preferably, the upper set of intermediate fins 91 should be placed just above the curved portion Z of the drill guide 80~
It is preferred ~hat the lower intermediate fins 88 be placed just below the ~urved portion Z of the drill guide 80. ~ow-e~er, the positions of these intermediate fins 88 and 91 are not cri~ical and can be varied for particular drilling re-quirement~
For the purpo~e of position for khe upper 90 a~d lower 92 in~ on the curved-straight drill guide 80, the direction of aurvature side ~hall be re~erred to as the "face" ~ide o~ the drill guide 80. ~e~erring to FIGURES 9 and lOA~C, it will be ~een that the upper fin~ 90 are preferably positioned to pro-vide a~ least one fin 90" on the side opposite the face side ofthe drill guide 80. The lower fins 92 are preferably placed on ' .

the drill guide 80 to provide at least one fin 92 on the side opposite the face side of the drill guide 80.
All four sets of fins 90, 90', 90" and 91, 91', 91" and 92, 92', 92" and 88 ~rest not shown in FIGURE 10~-C) are pre-ferably placed around the circumference o~ the drill guide 80 to provide a configuration essentially as shown in FIGURE 6.
With regard to the fins of the normally straight drill guide, shown in FIGURE 11, reference is made to FIGURE 12A-C.
For purpose of explanation, the cut side of the drill guide 82 shall be referred to as the face side. It has been unexpect-edly found that the best stabilization results are achieved by placing at least one fin 94 on the face side of the upper end of the normally straight d A ll guide 82~ A plurality of fins 94l and 94" ~hould be spaced about the circumference of the upper end of the drill guide 82, essentially as shown in FIGU~E
6.
At the lower, drill bit end of the normally straight drill guide 82, at least one fin 98" should preferably be placed on the side opposite the face side of the drill guide 82. A
plurality of additional fins 98 and 98' are spaced circumfer-entially around the lower end of the drill guide, essentially as shown in FIGURE 6.
While the normally curved drill guide 10 configuration is known in the art, ik has bee.n unexpectedly ~ound that the addi-tion ther0to o~ ~tabilizer ~ins 22 and 26, as shown in li'IGURES
3~ S, 6 and 4A-C, provide ~tabilization to the normall~ curved drill guide 10 previou~ly unattainable. The upper end ins 22 and 22' are placed around the c~rcum~erence o~ the upper end o~
the drill guide in the manner shown in FIG~RE 5, pre~erably placed opposite each other.
On the lower end of the normally curved drill guide 10 are a similar series of circumferentially placed fins 26, 26' and _ ~ _ , 3 8 ~ ~ ~
26". However, one fin 26 is preferably placed on the cut side of the drill guide 10. The remaining fins 26' and 26" are spaced equidistantly apart around the circumference of the drill guides' 10 lower end.
At essentially ~he longitudinal mid point of the drill guide 10 there are placed a third series of fins 24, 24' and 24~ spaced equidistantly around the circumference of the drill guide 10. As with the lower fins 26, 26' and 26", one fin 24 is preferably placed on the cut side of the drill guide 10.

As previously mentioned, use of the normally straight 82, curved-straight 80 or curved straight 10' drill guide permits drilling o~ an essentially straight deviated hole after tra-versing the kickoff portion of the well. The drilling is accomplished by rotation of the drill bit 18 attached to the clutch mechanism 37, which in turn is attached to a plurality of connected drive pipe 14. Drilling fluid is conducted to the drill bit 18 through the normal drill pipe (not shown) con-nected to the upper terminus of the drive pipe 14.
Since the drive pipe 14 is segmented, suitable pressure resistant tubing 16 traverses the interior of the drive pipe 14 and terminates at the end of the drive pipe 14 connected to the upper end sub 32 of the clutch mechanism 27 in a manner ko be more fully described hereinafter. It i~ preferred to utilize a rein~orced elastomer in constructing the drilling 1uid tubing 16. The elastomer sho~ld preferably be capable o~ withstanding the kemperature encountered in drllling to extended depths and be resi~ant ~o drilling chemicals and hydrocarbons. ~uch elastomers are typically, neoprene, ethylene-propylene-diene type terpolymers~ ethylene-propylene copolymers, SBR alone or blended with other elastomers, natural rubber and the like, either alone or suitably blended with other materials.
~he lowermost end of the elastomer tubing 16 i~ securedly _g_ :` :

3 8 ~, 2 connected to the lower terminus of the drive pipe 14 by suit-able clamping means 30, as shown in FIGURE 2A. The drive pipe 14 is connectable to the upper end sub 32 of the clutch mech-anism 37~
The clutch mechanism 37 is used in reorienting the drill guide 36 in order to change direction of drilling. As men-tioned previously, the drive pipe 14 is connected through the clutch 37 to the drill bit 66. The drill guide 36 does not rotate with the drive pipe 14 and drill bit 66.
With the drill guide 36 being rictionally engaged with the bore hole and the clutch mechanism 37 being freely rotat-able -~herei~, there i5 provided means for securing the clutch 37 to the drill guide 36 to permit rotation of the drill guide ~ -to a new direction.
Referring to FIGURE 2A-C9 there is shown the drill guide 36 of the invention, having connected thereto an upper clutch 34 and a bottom cap 60r Disposed within the bore 21 of the drill ~uide 36 is the clutch mechanism 37, which in¢ludes a top sub 32, connectable to the drive pipe 14, means 56 for con-ducting drilling fluid through the alutch mechanism 37, and abottom ~ub 64, connectable to a drill bit 66.
There is additionally provided a lower clutch dog 44 having a face 40 engageable with an opposing face 42 on the upper clutch 34. Resilient urging means 38 are po~itioned bstween the lower clutah dog 44 and the uppex clutch 34 to prevent engagement oi the oppo~ing aces 40 and 42 during normal drilling operations. As shown in FIG~RE 2B, the resil-ient uxging means illustrated is a ~pring member 38.
The spring 38 would be compressed during the period when the drill string would be pulled up, and friction would be restricting upward movement of the drill guide 36.

There is normally provided an inner drive pipe 74 con-3 ~3 2 2 nected within the drill guide 36~ The inner drive pipe 74 issegmented in the same manner as the drive pipe 14 to allow bending thereof to follow the contour of the drill guide 36 In order to condu~t drilling fluid through the bore 28 of the clutch mechanism 37, suitable conduit 56 is connected within ~he inner drive pipe 74, using suitable clamps 58 or other fa~tening means.
For assembly purposes, there is shown in FIGURE 2B a top sub adapter 54 connecting the inner drive pipe 74 to the top ~ub 32. In like manner, a bottom sub adapter 72 connects the lower end of the inner drive pipe 74 to the bottom sub 64. It should be recognized that other suitable means can be used to connect the inner drive pipe 74 to the top sub 32 and ~he bottom sub 64.
It i~ preferred that thare be provided a fluid sealing means 47 and 68 between the drill guide 36 and the clutch mechanism 37. As illustrated in FIGURES 2B and 2C, seals 47 and 48 are positioned on the bore surace of the top clutch 34 to seal again~t the outer surface of the top sub 32. In prac-tice, the seals 47 and 48 can be any suitable configuration andcan be placed on either the top clutch 34 or the top sub 32 of the clutch mechani~m 37.
Similar ~eals 67 and 68 are preferably provided to ~eal between the bore sur~ace o~ the botto~ aap 60 and the other ~ur~aae o~ the bottom sub.
When the drill stem is placed under a load as a conse-quenGe o~ placing weight on the drill bit 66, there is some compre~ion but essentiall~ no drilling weiyh~ placed on the inner drive pipe 74. However, compre~ion o~ the inner drive pipe 74 will normally cause ~ome ~hortening of the clutch mechanism 37. ~he drilling weight i9 carried by the drill guide 36. In order to prevent binding and friction between the :~ :173~2~ `
clutch mechanism 37 and the drill guide 36, there is provided means 46 and 62 for reducing friction. These means are illus- -trated as bearings 46 and 62.
Preferably, there are provided an upper set of bearings 46 positioned to ride between the top sub 32 and the top ~lutch 34 of the drill guide 36. A second, lower set of bearings 62 are positioned to ride between the bottom sub 64 of the clutch mechanism 37 and the bottom cap 60 of the drill guide 36.

, , .

Claims

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

1. A flexible, resilient drill guide, connectable at its upper end to a rotary drill string and at its lower end to a rotary drill bit, for guiding the direction of drilling a well bore deflected from the vertical, said drill guide comprising:
an inner flexible segmented tubular drive member for trans-mitting rotational forces and drilling fluid between said drill string and said drill bit; and an outer flexible, resilient, tubular member for exerting directional drilling forces on said drill bit, said outer tubular member having disposed along at least a major portion of its length a plurality of non-connected shaped cuts extending therethrough and around a portion of the circum-ference thereof, but not severing said outer tubular member, and, said outer tubular member in an unstressed condition being normally curved through a portion of its length and normally straight through a portion of its length.

2. The drill guide according to claim 1 wherein the lower portion of said outer tubular member is normally straight.

3. The apparatus according to claim 1 wherein said shaped cuts comprise first and second circumferentially spaced-apart portions each generally parallel to the longitudinal axis of said outer tubular member, said first and second portions being inter-connected by a sinuous third portion of substantially greater length than either of said first and second portions.

4. The apparatus of claim 3, wherein a majority of said second plurality of stabilizer fins are secured to the side of said tubular member opposite said cuts.

5. The apparatus of claim 3, wherein said tubular member is essentially straight, while in the unstressed state, for about at least two-thirds of its length with the remaining length thereof being normally curved.

6. The apparatus. of claim 1, wherein said tubular member is essentially straight, while in an unstressed state, for about at least one-half of its total length with the remaining length thereof being normally curved.

7. The apparatus of claim 1, wherein said tubular member is essentially straight, while in an unstressed state, for about at least about two-thirds of its total length with the remaining length thereof being normally curved.

8. The apparatus of claim 1, wherein said tubular member is essentially straight, while in an unstressed state, for about one-third of its total length with the remaining length thereof being normally curved.

9. The apparatus of claim 6, wherein the cuts made in said curved portion of said tubular member are of greater length than the cuts made in the straight portion of the tubular member.

10. The apparatus of claim 9, including a plurality of stabilizer fins being secured to each end of said tubular member.

11. An apparatus for guiding the direction of drilling a well bore deflected from the vertical comprising:
a flexible, resilient tubular member which is normally straight in an unstressed state for a portion of its length and is normally curved in an unstressed state for a portion of its length, said tubular member having disposed along at least a major portion of its length a plurality of non connected, shaped cuts, said plurality of non-connected shaped cuts each comprising first and second circumferentially spaced-apart portions generally parallel to the longitudinal axis of said tubular member, said first and second portions being interconnected by a sinuous third portion of substantially greater length than either of said first and second portions, a flexible drive member rotatable within said tubular member and connectable to a drill string, said drive member being the torque bearing member, said flexible drive member being longitudinally movable within said tubular member, dog means carried on said tubular member and on said flexible drive member, engageable upon upward movement of said flexible drive member in relation to said tubular member, and which, when engaged, permits the tubular member to be moved for angular orientation.

12. A flexible, resilient drill guide, connectable at its upper end to a rotary drill string and at its lower end to a rotary drill bit, for guiding the direction of drilling a well bore deflected from the vertical, said drill guide comprising:
an inner flexible segmented tubular drive member for trans-mitting rotational forces and drilling fluid between said rotary drill string and said rotary bit; and an outer flexible, resilient, tubular member for exerting direction drilling forces on said drill bit, said outer tubular member in an unstressed state being straight for at least approximately one-third of its length and having disposed along at least a major portion of its length a plurality of nonconnected shaped cuts extending therethrough and around a major portion of the circumference thereof, but not severing said outer tubular member;
a first plurality of stabilizer fins positioned on the outer surface of said outer tubular member adjacent one end thereof for retarding rotation of said tubular member while guiding the direction of drilling of said drill bit; and a second plurality of stabilizer fins positioned on the outer surface of said outer tubular member intermediate the ends thereof.