CA1221085A - Earth drilling apparatus and method - Google Patents

Abstract

Abstract of the Disclosure Apparatus for forming a bore hole in an underground formation including a guide pipe with a fluid seal and a tube sealed with the seal and terminating in a drillhead with at least one fluid exit port. The tube moves out the exit end of the guide pipe into the formation under hydraulic pressure applied against the drillhead. The bottom of the guide tube includes a whipstock to turn the drillhead, from a vertical to a horizontal direction, to form a radial. The whipstock includes a number of connected assemblies which, when extended from a retracted position within the structure, form an arcuate tube-bending guideway including rotatable sheaves.

Description

~Z~ 5 This invention relates generally to earth well drilling apparatus and methods. Particularly it relates to apparatus and methods applicable to drilling one or more bores extending lateral]y from a lower region of a well into a mineral bearing formation.
Reference is made to United States Patent 4,497,381, issued February 5, 1985 assigned to the same assignee as the present application, namely application entitled EARTH DRILLING
APPARATUS AND METHOD in the joint names of Irving Odgers, James McGhee, Wade Dickinson and Robert Wayne Dickinson.
It has been recognized that minerals may be recovered from mineral-bearing formations by introducing such agents as steam, hot water, chemical solutions and the like. For example steam has been introduced into petroleum-bearing sands (e.g. tar sands or heavy oil) and other porous formations to effect the release and removal of petroleum not otherwise having sufficient fluidity to permit pumping from the well. Certain of drilling apparatus for drilling a laterally extending bore from a region of the well at the level of the formation, after which steam or other treating fluid is introduced into the bore. An example of such drilling apparatus is disclosed in United States Patent

2,258,001, October 7, 1941 and United States Patent 1,865,85~, July 5, 1932. Such prior drilling equipment and methods have been subject to certain disadvantages. In instances where drilling the lateral bore has employed a rotated cutting head which is directed laterally against the formation, the torque may be applied to the head through driving means extending from the top of the well, which requires complicated and expensive means to transmit power through a vertically rotated pipe or shaft to the laterally directed drillhead. If an electrical driving motor is located within the well and coupled to the drillhead, it poses problems in applying the necessary electrical energy and the motor may not be readily salvageable before injecting steam or other treatment fluid. Use of laterally directed jet drilling as shown in United States Patent 2,258,001 requires special flexible piping which carries the drillhead and to which hydraulic liquid under pressure is applied. Among other objections, flexible conduits are not self-supporting when projected laterally and thus require additional supporting means such as a surrounding housing as shown in Patent 2,258,001.
Applicants are also aware of an apparatus and method making use of hydraulic jet drilling with the drillhead being attached to a drilling tube of the solid wall type. The drilling tube initially is carried within piping extending downwardly into the well, and has an open upper end.

A seal is provided between the drilling tube and the piping, whereby when hydraulic liquid (e.g. water) under pressure is applied to the piping, it is propelled downwardly. A special form of tube bending means is carried at the lower end of the pip-ing adjacent the mineral bearing formation, and forms an arcuate guideway through which the drilling tube is propelled, thereby causing the drilling pipe to be bent and the drilling head pro-jected laterally into the formation.
It is an object of the present invention to provide an improved embodiment of the aforesaid apparatus and method pre-viously known to the Applicants herein.
A further object is to provide an apparatus and method which applies the required bending forces to the drilling tube without requiring application of excessive hydraulic pressure.
Another object is to provide bending means for such apparatus and methods which can be extended from a retracted to an extended position to form a complete arcuate guideway.
Another object of the invention is to provide effective means for straightening the drilling tube as it exits from the guideway.
In general the present invention consists of a structure adapted to be positioned within a well adjacent a mineral pro-ducing region, and which is carried by piping extending to the surface of the well.

s A drilling tube of the s~id wall type is disposed w~thin the pip~ng, and the tube has a hydraulic jet type of dnlling head secured to its lower end. The upper end of the drilling tube is open within the 5 p~ping and a seal is provided between the tube and the piping. Tube bending means ic carried by the structure and consists of two connected assembliPc which when extended from a retracted position within the structure, form an arcu2te tube bending gui~e-10 way. ~hen hydraulic pressure is applied to the pipingit app~ies force to the drilling tube tD propel it downwardly through the piping and through the guide-way, thereby causing the tube to be bent to project the d~lling head laterally against the formation. Each 15 of the assemblies of the bending means has a series of r~lers or sheaves r~at bly carried by the same to form a segment of the arcuate guideway. The bending means also includes means ~or straightening the tubing as it exits from the gui~eway. The invention includes 2 0 bo~h novel apparatus, and a novel method making use of such apparatus.

Additional objects and features of the invention will appear from the f~Fl. wing descriptic n in which preferred embodiments have been set forth in detail in 25 oonjunction with the accompanving drawing.

Referring to the Drawing Figure 1 is a schematic vi~w in side elevatiDn, i'lustrating the apparatus disposed within an earth well, with the d~lling tube e~ctended in a ~t~ral bore.

3 0 Figure 2 is a detail in side elevation, illustrating the tube bending means and its mounting.

Figure 3 is a detail in sectiDn elevation, illustrating the bending means in si~le elevation and extended.

Figure 4 is a view looking toward the right hand side of Figure 3.

5 Figure 5 is a detail in section showing another embodiment of the invertion in side elevation.

Figure 6 is a view IDoking toward the right hand side of Figure 5.

Figure 7 is a detail in section showing sealing means 10 between the well piping and the drilling tube.

Figure 8 is a side elevation, par~Ly in section, showing another embodiment in which the guide means is in three sections.

Figure 9 is an elevation ~ooking toward the right hand l 5 side of Figure 8 .

Figure lO is a side elevation like Figure 8, but showing the bendirg means extended.

Figure 11 is an enlarged detail in section showing adjustable means for straightening the drilling tube.

20 Figure 12 is a detail in section showing a ~eal associated with the bending means and also means for introducing water.

Figure 13 shows a modified form of means for carrying the bending means.

Figure 1 schematically shows an earth we~l 10 which extends down to the mineral bearing formation 11. In this instance the well is shown provided with a casir.g 12, which may extend down to a cavity 13 that is 5 ad~acent the formation 11. The piping extending into the well consists in this instance of a pipe string 14 within which a drilling tube 15 is normally disposed.
As shown in Figure 7, a seal 16 is mounted within the pipe string 14, and forms a seal between the pipe 10 string and the drilling ~ube 15. The upper open end of the driU pipe 15 is above the seal 16, when the cnlling tube is fully extended as shown in Figure 1.
Before the drilling tube is extended i:t: is within the pipe :,~ing 14, with its dril~ing head 17 located below 15 the seal 16. The structure 21 serves to carry the pipe bending means 22. While the seal 16 may be incorporated in a coupling between sections of the pipe string 14, it is preferably incorporated in the coupling adiacent the upper end of the bending means 22.

20 Figure 1 also schematically shows a production rig 24 of the mobile type, and a reel carrying truck 25 which may carry a supply of the drillirlg tubing 15.

One embodiment of the bending ~eans is shown in Figures 2-4. It consists of the structure 21, which 25 carries the bending assemblies 26 hnd 27. Structure 21 can be in the form of a pipe section having one side cut away as indicated at 28. Assembly 26 consists of a rigid mounting made of rigid side plates 29 attached to a baclc plate (nc,t shown), and a top plate 31. This 30 assembly is secured to the structure 21 as indicated at 32. The assembly 27 similarly includes a rigid mount-ing formed by the connected side plates 33, which have a pivotal connec~on 34 with the lower end of the ~2~V8~

assembly 26 . T he upper assembly 26 carries two series of rbllers or sheaves 36 and 37. They are disposed to form a guideway 38, dimensioned to received the dri~ing tube 15. The lower assembly 27 5 is similarly provided with two series of rallers or sheaves 39 and 40. They are positioned to form the guideway 42.

- The bending means described above is extended to the position shown in Figure 3, by swinging the lower 10 assembly outwardly and upwardly. The guideway formed by each assembly becomes a segment of the entire guideway formed when the lower assembly is swung to the position in Figure 3.

Suitable power means is provided for moving the lower 15 assembly 27 to the extended position shown in Figure 3. This may consist of a hydraulic actuator 44 of the cylinder-piston type, having its operating rod pivotally connected at 46 with the side walls 33 of the assembly 27. ~hen hydraulic liquid under pressure is app~i~?d 20 to the operator 44, it moves the lower assembly 27 from the position shown in Figure 2 ,'to that shown in Figure 3. Continued application of hydraulic pressure to the actuator 44, or hydra~ loading, serves to retain the assembly in the position shown in F_gure 3, during passage of a dri~ing tube through the same, and during subsequent drillirlg operations. Assuming that the operator is of the singl~ acting type, the control valve for admitting or venting hydraulic fluid may be cl~sed after actuation to lock the assembly 26 30 in extended po~on. F;gure 1 snows a tube 47 extending to the top of the well for the hydraulic operation of the operator 44.

When it is desired to salvage the bending means, follow-ing application of steam or other treatment fluid through the radially extending drilling tube, the pipe string 14, together with the hou~ing 21, can be pulled upwardly to force retraction of assembly 27 and crushing and breaking off of the extended position of the drill tube. In the event the operator 44 is of the double acting type, it can be used as power means to retract assembly 27 with crushing or buckling of the drilling tube.
As shown in Figure 3 the series of rollers or sheaves carried by the assemblies 26 and 27 provide a continuous curved guideway through which the drilling tube is caused to pass, to apply the desired bend. The sheaves of each assembly may engage either the inner or outer walls of the bent tube. It is assumed that the tube bend usually will be through 90, although this may vary depending upon particular requirements. By way of example the present invention makes it possible to employ bending radii of the order of 6 to 12 inches, for steel pipe ranging from 1 1/4 to 1~ inches, and a wall thickness of the order of 0.080 to 0.125 inches. The metal of the tubing may, for example, have a yield point ranging from 36,000 to 70,000 pounds or more per square inch.
One would normally expect the tubing to buckle or break upon bending to such relatively short radii. However, the fact that the tubing does not buckle or break is attributed in part to the presence of a liquid at relatively high pressure within the tube, while the tube is in transit through the bending means.
This imposes hoop stress in the metal walls in conjunction with stresses applied during bending.

.. --8--8~
g Again referring to Figure 3, it wiU be ncJted that the sheaves 39a, 39b, 39c and 39d, and the opposed sheaves 40a, 40b and 40d, are arranged to form a straight guideway. The purpose of these sheaves is 5 to form straightening means whereby the drilling tube leaving these sheaves is relatively straight. The sheaves 39d and 40d are large in diameter and have peripheral grooves such that they embrace - substanti lly the entire circumference of the tube.
10 Thus this arrangement serves to apply straigh'2ning forces to the tubing as it exits from the guideway. In addition to straightening the tube by applying unbending forces, shea~les 39d and 40d may have reforming forces to reform the tube from oval to more 15 circ-llAr configuration.

For the purpose of strengthening the structure 21 against side thrust, its upper end is shown att~ched to the template ex~ension 21a, which may be a pipe section which extends for a substanti~l distance into 20 the weU casing 12.
, Pipe 49 can be referred to as a ~oam downcomer.

The manner in which the invention is used in practice, is as fal~ows. Assuming that the well has been drill~d by conventional means, and that a cavi~y 13 has been 2 5 formed adjacent to the mineral bearing formation l 1, sections of the drill string 14 are assembled with the lowermost coupling attached to the member 51 of the tube bending means. An adequate length of the dr~g tube is provided with the hvdraul~ jet-type 3 0 r~rillir~g head 17 attached to its one end . This is then assembled within the drilL str~ng with the drillhead at or slightLy below the seal 16. An adequate length of s drilling tube is one which has 2 length sufflri~nt to extend laterally for the required distance, plus a further length suffi-iPnt to ensure that the upper open end of the tube is well above the seal 16, when the S tube is extended as shown in Figure 1. The assembly of the drill string 14, together with the attached housing 21 and bending means 22, is now lowered irto the well, at which time the bending means is in retracted condition. When the bending means has 10 reached a level corresponding to the mineral bearing formation, the upper end of the pipe 14 is connected to a source of hydrau~c 7;~uid (iOe., water) at a r~latively high avai~able pressure, which may range, for example, from l,OO0 to lO,OOO psi or more.
15 Assuming now that one desires to make a lateral bore into the mineral bearing formation, bending means 22 is extended as shown in Figure 1~ by applying hvdraulic pressure to the operator 44, and then high pressure hydra~ liquid is introduced into the upper 20 end of the pipe string 14. The hydraulic liquid flows into and through the d*ll;ng tube 15, and by virtue of the fluid pressure areas afforded by the drilling tube together with the dr;llhead 17, the tube is driven downwardly through the seal 16, the bending means 25 22, and then ~2teraLv against the formation. The jet drilling head 17 penetrates the formation to form a lateraliy extending bore as shown, for example, in Figure 1. At the conclusion of this operation, and assuming that the mineral bearing formation is to be 3 0 treated with steam or other fluids, application of hydraulic pressure to pipe string 14 is discontinued, and this string connected at the surface of the well with a source of the treating fluid . T hus the apparatus may then serve over an extended period of 3 5 time as means for introducing treating fluid well into the mineral bearing formation.

.3lZ~ 5 The embodiment illustrated in Figures 5 and 6 has another form of tube straightening means. In place of the tube straightering rc~lers or sheaves 39d and 40d there is a cruciform-type of straightening means 51.
5 It consists of a body 52 which serves to mount the opposed sheaves 53 and 54, together with the laterally disposed sheaves 56 and 57. The grooves in the per~pheries of these sheaves are proportional whereby they embrace substan~lly the entire circumferenoe of 10 the tube. It has been found that although the dr;lling tube is not ccillapsed during bending, there is a plas~ deformation of the metal walls, whereby when the tube exi~s from the guideway, its con~igura~on in cross-section is slightly oval, rather than circ~ r.
15 The rc~lers 56 and 57 may be set whereby when the tube passes between them, side pressure is appl;Pd to the tube side walls to somewhat reform the cross-sectional configuration to near circul~Lr. It has been found that this aides straightening of the tube, 20 whereby, together with the action of sheaves 39a-39c and 40a, 40b, that portion of the tube extending from the straightening means to the formation, is 5l~ffir~ir~ntly straight ~ transmit the desired thrust of the drilling head into the formation, without further 2 5 bending .

The embodiment of Figures 8-11 is also provided with a plura~i~ of sheaves that form the arcuate guideway of the bending means. However the bending means is formed by three assemblies, instead of the two 3 0 assemblies of Figures 2 and 3 . Also an ad~ustable straightening means is provided. The housing 61 may be similar to the hou~ ng 21 of Figure 2. The tube bending means consists of the three assemblies 62, 63 and 64, each of which forms a segment of the arcuate lZ~ 8S

guideway. Assembly 62 consists of the rigid side walls 65 that are rigidly secured together in spaced reL tionship, and are fixed to the upper port~on of housing 61. The edges of the sidewalls are shcwn 5 connected by closure or cover plates 66a and 66b.
Assembly 63 likewise consists of spaced connected w~llc 67, the upper ends of which have pivotal connection 68 with the side walls 66 of assembly 62. W~ls 67 are also shown ccnnected by closure or cover plates 67a 10 and 67b. Assembly 64 aLso consists of spaced connected wAllc 69 that have pivotal connection 71 with the lower ends of the w~llc 67, and which have closure or cover pl~tes 69a and 69b.

Figures 8 and 9 show the assemblies 63 and 64 1 5 retracted within the housing structure 61. The power means for extending the assemblies to the position shown in Figure 10 may consist of a hydraulic operator 72 that ~s pivata~ly anchored at 73 to the housing 61 and has its operating rod 74 pivotally connected at 76 20 to the ~;~e walls of assembly 64. The side walls of assemblies 62 and 63 have their adjacent ends 76 and 77 formed whereby they come into abutting engagement when the bending means is fully extended. The opposed ends 78 and 79 of the side walls of assemblies 2 5 63 and 64 are similarly formed. In place of the power operator, assembly 64 may be connected to a pull cable extending to the top of the wall.

When operator 72 is actuated by hydra~ r pressure, the assemblies 62, 63 and 67 are extended to the 30 lini~ing position shown in Figure 10, with the ends 76 and 77, and 78 and 79 in abutting engagement.

Each of the assemblies 62, 63 and 64 have a plur~lity of rotatable sheaves that are disposed in such a manner as to form, when the assemb~ies are extended, a continuous tube bending guideway which progres-5 sively bends the drilling tube as the tube is driventhrough the same. The compl~te guideway is arcuate, with the assemblies 62, 63 and 64 forming segments of the arc. The sheaves for assembly 62 are designated 81 and 82, ~or assembly 63 they are desigr.ated 83 and 10 84, and designated 86 and 87 for assembly 64. The sheaves 86a, 86b, 86c, 86d and 96e, and 87a, ~7c and 87e cooperate ~ straighten the dr~1l tube before it exits from the assembly 64. Preferably sheave 87c is adjustable to adjust the straightening foroe that it 15 applies. Thus, in Figure 11, it is shown rotatably carried by the structure 88, which in turn is pivotally connected to the pin or shaft 89 that is car~ied by the side walls of assembly 64. The positioning of sheave 87c can be adjusted relative to sheaves 86b, 86c and 2 o 86d by adjtlstment o~ the screw 91. To enhance the straightening action, the sheaves 86b, 86c and 86d are shown disposed with their line of centers arched upwardl~ (Pigures 10 and 11). The sheave 87e is not essential for straightening action and may be omi~ted.

25 As in Figures 2 and 3 the sheaves 86e and 87e are of such size and wi~h grooves such that they substan-ti~lly embrace the circumference of the drilling tube.
They may somewhat reform the tube to more nearly circul~r form.

30 The embodiment of Figure 8-ll when extended func-tions in substanti~ly the same manner as the embodi-ments of Figures 2-6. However, when retracted, it is more compact since the assemblies 62, 63 and 64 have LV~S

a straight configuration. Also when operator 72 is energized to extend the assemblies, assembly 64 ic first to be swung outwardly because of the locations of the pivotal connec~ons 71 and 72, and is fc~lowed by S the assembly 63.

Figure 12 shows how the seal may be located adjacent to the bending means. Thus the guide pipe coupling - 91 is lDcated close to the assembly 62 and the lower part 91a of the coupling is directly connected to and a 10 part of the assembly 62. It serves to mount the seal 92 between the guide pipe and the drilling tube 15.

~ hen the dnll;ng tube is being driven through the bending means and into the adjacent formation, it is desirable to introduce water into the assemb~ies 62, 63 15 and 64. Thus a small duct 93 is indicated in Figure 12 which diverts some water from above the seal 92 to the assembly 62. It may discharge into assembly 62 or it may connect with ducts 94, 95 and 96 in the side walls of the assemblies. The latter ducts are so 2 0 located that they are in communication when the assemblies are extended. Duct 96 may discharge sprays of water through the nozzles 97. Introduction of water t nds to flush out and prevent clogging of the guideway or jamming of the sheaves due to 2 5 entrance of foreign materi~l (e. g . sand or sma rocks~ .

The clDsures or cover plates for the assemblies 62, 63 and 64 may be used to keep out rocks or other debris.
In some instances they may be perforated.

3 The structure 61 of Figures 8-10 can be fabncated from a pipe section. Figure 13 shows another form, 0~35 98, constructed from a salid metal cylindrical body which is m ed to provide the inner space 99 wh~ch accommodates the assemblies 62, 63 and 64 and asso-ci~ted pa~ts. This structure may likewise be used 5 with a template like 21a of Figure 1.

Various features of the foregoing embodiments are as f~llows. The bending means, with its series of sheaves, imposes a minimum amount of friction on movement of the dnlling tube thrcugh the bending 10 arc . T he series of sheaves that define the arcuate guideway effect continual incremental bending as the tube passes through the same. This makes possible use of hydraulic pressures that are compatible to pressures required for drill;ng through the mineral 15 bearing . formation . Straightening of the tub~ng is effective and reliable, particlllArly with the s~raightening means shown in Figures 5 and 6.
Possible damage to the dnllirlg tube is minimi7ed, whereby the tube functions properly in subsequent 2 0 treatment operations, which may frequently employ h gh temperature steam. _ -

Claims (15)

What is claimed is:

1. Earth well drilling apparatus comprising a structure adapted to be positioned within the well adjacent a mineral bearing formation, piping within the well to which the structure is secured, a drilling tube of the solid wall type disposed within the piping, means for applying hydraulic liquid under pressure through the piping to the tube, means forming a seal between the piping and the tube, a drilling head of the hydraulic jet type secured to the lower end of the tube, bending means carried by the structure, said bending means comprising a plurality of connected assemblies which when extended from a retracted position within the structure form an arcuate tube bending guideway, the arrangement being such that when hydraulic pressure is applied to the piping, the tube is propelled downwardly through the piping and through the guideway, thereby causing the tube to be bent to project the drilling head laterally toward the forma-tion, each of said assemblies having a series of sheaves rotatably carried by the same to form a segment of the arcuate guideway when extended.

2. Apparatus as in Claim 1 in which the series of sheaves carried by each assembly are disposed to engage the walls of the tube on the inner and outer sides of the tube bend to effect continual incremental bending of the tube.

3. Apparatus as in Claim 1 in which the first upper assembly of the bending means is secured to the structure and its lower end is pivotally connected to one end of the next lower assembly, and power means for moving the next lower assembly from a retracted (CLAIMS 3 CONTINUED) position within the structure to an extended position in which it forms the arcuate guideway in conjunction with the first assembly.

4. Apparatus as in Claim 1, together with tube straightening means carried by the exit end of the lowermost assembly.

5. Apparatus as in Claim 4, in which the tube straightening means includes sheaves disposed to apply opposed bending forces to the upper and lower sides of the tube to straighten the same, said sheaves being carried by the lowermost assembly.

6. Apparatus as in Claim 4, in which the tube straightening means includes opposed sheaves disposed to engage and press against the side walls of the exiting tube to reform the cross-sectional configuration of the same from oval to more nearly circular form.

7. Apparatus as in Claim 5, in which the tube straightening means consists of a cruciform-like assembly that includes upper and lower rollers that are disposed to engage the upper and lower sides of the tube and side rollers that engage and press against the side walls of the tube.

8. Apparatus as in Claim 7 in which the two side rollers are spaced apart a distance such that the tube in passing between the same is reformed from oval to substantially circular form as viewed in section.

9. Apparatus as in Claim 1 in which three connected assemblies are employed (termed first, second and third assemblies), the first being pivotally connected at its lower end to the second and the second being pivotally connected at its lower end to the third assembly, the first assembly being fixed to the structure, and power means connected to the third assembly for extending the second and third assemblies relative to the first assembly to form the arcuate guideway.

10. Apparatus as in Claim 9 in which each of the assemblies is substantially straight.

11. Apparatus as in Claim 4 in which the tube straightening means includes a sheave adapted to apply force to the tube on the outer side of the tube bend, and adjustable means for rotatably mounting the sheave whereby it may be advanced or retracted relative to the tube.

12. Apparatus as in Claim 1 together with means for introducing water into the bending means during application of hydraulic liquid under pressure to the piping.

13. Apparatus as in Claim 12 in which the means for introducing water includes a duct communicating with the piping above the seal.

14. A method of earth well drilling to provide a bore extending into a mineral bearing formation, the bore extending laterally from a lower region of an earth well which extends downwardly from the surface of the earth to the lower region, the method making use of piping extending downwardly to said region, and a tube (CLAIM 14 CONTINUED) adapted to be positioned within the piping, the tube having a drilling head of the hydraulic jet type secured to one end of the same and having its other end open; the method comprising positioning the tube within the piping with the open end of the tube uppermost and with a seal between the tube and the surrounding piping, the seal permitting lengthwise movement of the tube relative to the surrounding piping; introducing hydraulic liquid under pressure into the piping from the upper end of the well thereby causing hydraulic liquid to be applied to the upper end of the tube and to flow through the tube to the drilling head, the hydraulic liquid being of such pressure as to cause the tube to be propelled downwardly through the surrounding piping, applying successive bending forces to the tube as it reaches said region to bend the tube to arcuate form and to direct the drilling head laterally into the formation, the tube during such bending being in contact with rotatable sheaves, and straightening the tube after bending of the same.

15. A method as in Claim 14 in which straightening of the tube is carried out by applying unbending forces, and adjusting the magnitude of such forces to produce the straightening desired.