U.S. patent number 3,627,356 [Application Number 04/877,978] was granted by the patent office on 1971-12-14 for directional drilling apparatus with retrievable limiting device.
Invention is credited to Edwin A. Anderson.
United States Patent |
3,627,356 |
Anderson |
December 14, 1971 |
**Please see images for:
( Certificate of Correction ) ** |
DIRECTIONAL DRILLING APPARATUS WITH RETRIEVABLE LIMITING DEVICE
Abstract
A deflection tool is provided for use in the directional
drilling of a well bore into the earth. The tool includes a lower
tubular assembly pivotally mounted within an upper tubular
assembly. I use, the upper assembly is coupled to the lower end of
a string of drill pipe and the lower assembly is coupled to a
downhole fluid motor unit which drives a rotary drill bit. Drilling
fluid flowing down the drill string drives a piston and lever
mechanism located in the upper tubular assembly for urging the
lower tubular assembly to pivot relative thereto. when a zero or
other less than maximum pivot angle is desired, a retrievable
limiting probe is run into the deflection tool for setting a
limiting plug which limits the extent of the pivotal movement.
Different pivot angles are obtained by using limiting probes of
different size.
Inventors: |
Anderson; Edwin A. (Houston,
TX) |
Family
ID: |
25371128 |
Appl.
No.: |
04/877,978 |
Filed: |
November 19, 1969 |
Current U.S.
Class: |
285/118; 175/61;
285/58 |
Current CPC
Class: |
E21B
7/067 (20130101) |
Current International
Class: |
E21B
7/04 (20060101); E21B 7/06 (20060101); E21b
007/08 (); F16l 027/04 () |
Field of
Search: |
;175/61,73-76,256
;285/118 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Calvert; Ian A.
Claims
What is claimed is:
1. A deflection tool adapted to be connected in a drill string for
use in the directional drilling of a well bore comprising:
first tubular means;
second tubular means pivotally coupled to the first tubular
means;
fluid-responsive means carried within the tubular means and
responsive to drilling fluid pressure in the tubular means for
urging one of the tubular means to pivot relative to the other;
and limiting means including a retrievable limiting device adapted
for passage through the drill string and into the tubular means for
limiting the extent of such pivotal movement while the limiting
device is in the tubular means.
2. A deflection tool in accordance with claim 1 wherein the second
tubular means is pivotally mounted within the first tubular means
and extends out one end thereof.
3. A deflection tool in accordance with claim 1 wherein the
fluid-responsive means includes a piston slidably located in one of
the tubular means.
4. A deflection tool in accordance with claim 1 wherein the
fluid-responsive means includes a plurality of longitudinally
spaced pistons located within one of the tubular means and
interconnected by tubular stem means for enabling the pistons to
work in unison with one another.
5. A deflection tool in accordance with claim 1 wherein:
the second tubular means includes an extended portion which extends
into the first tubular means;
the fluid-responsive means includes a longitudinally slidable
piston located in the first tubular means;
and the fluid-responsive means includes control lever means
pivotally mounted within the first tubular means adjacent the end
of such extended portion for converting the longitudinal movement
of the piston into a lateral thrust on the end of such extended
portion.
6. A deflection tool in accordance with claim 1 wherein the
retrievable limiting device includes a body portion the thickness
of which controls the extent of the pivotal movement.
7. A deflection tool in accordance with claim 1 wherein the
limiting means includes positioning means movably carried by one of
the tubular means and engageable by the retrievable limiting device
for establishing the angular relationship between the two tubular
means.
8. A deflection tool in accordance with claim 1 wherein the
limiting means includes positioning means movably carried by the
second tubular means and having a first portion for engaging the
first tubular means on one side thereof and a second portion which
extends into the center bore of the second tubular means for
engagement by the retrievable limiting device for establishing the
angular relationship between the two tubular means.
9. A deflection tool in accordance with claim 1 wherein:
the limiting means includes laterally movable positioning means
carried by one of the tubular means;
and the retrievable limiting device includes a body portion for
engaging the positioning means and moving it to a desired
position.
10. A deflection tool in accordance with claim 1 wherein:
the first tubular means is located above the second tubular
means;
the first tubular means includes interior longitudinal passage
means of reduced diameter;
the second tubular means includes receiving means for receiving the
retrievable limiting device;
and the retrievable limiting device is of an elongated construction
adapted for passage through the reduced diameter passage means and
includes a limiting portion adapted to be seated in the receiving
means and an enlarged portion located relative to such limiting
portion a distance such that it remains in the reduced diameter
passage means until the limiting portion has entered the receiving
means, such enlarged portion being sized to substantially reduce
the flow of drilling fluid through the tool as long as it is within
the reduced diameter passage means.
11. A deflection tool adapted to be connected in a drill string for
use in the directional drilling of a well bore comprising:
upper tubular means;
lower tubular means pivotally mounted within the upper tubular
means and having an upper portion located above the pivot axis and
extending upwardly within the upper tubular means and a lower
portion located below the pivot axis and extending downwardly and
out of the lower end of the upper tubular means;
fluid-responsive means carried within the upper tubular means and
responsive to drilling fluid pressure in the upper tubular means
for producing a lateral thrust on the upper portion of the lower
tubular means for causing the lower tubular means to pivot about
the pivot axis;
laterally movable positioning means movably carried by the lower
tubular means and extending into the center bore of the lower
tubular means;
and a retrievable limiting device adapted for passage through the
drill string and into the lower tubular means for engaging the
laterally movable positioning means and thereby controlling the
angular relationship between the two tubular means.
12. A deflection tool in accordance with claim 11 wherein the upper
tubular means is adapted to be connected to the lower end of a
string of drill pipe and the lower tubular means is adapted to be
connected to a downhole fluid motor unit for driving a rotary drill
bit.
13. A deflection tool in accordance with claim 11 wherein the
interior of the lower portion of the upper tubular means is shaped
to allow pivoting of the lower tubular means in only one direction
and to limit the maximum extent of such pivoting movement.
14. A deflection tool in accordance with claim 11 wherein the fluid
responsive means includes:
longitudinally movable piston means slidably located within the
upper tubular means;
and means for converting downward movement of the piston means into
a lateral thrust on the upper portion of the lower tubular
means.
15. A deflection tool in accordance with claim 14 wherein the
movement converting means comprises a control lever pivotally
mounted within the upper tubular means adjacent the upper end of
the upper portion of the lower tubular means and having an upper
portion adapted to be engaged by the underside of the piston means
during its downward movement.
16. A deflection tool in accordance with claim 15 wherein the
length of the upper portion of the lower tubular means is of
suitable length to provide a mechanical advantage for pivoting the
lower tubular means.
17. A deflection tool in accordance with claim 11 wherein the
fluid-responsive means includes:
a plurality of toroidal pistons located for longitudinal movement
within an upper portion of the upper tubular means;
tubular stem means cooperating with the center bores of the pistons
for interconnecting the pistons in a spaced apart coaxial manner
and for providing a central flow passage through the upper portion
of the upper tubular means;
the interior of the upper portion of the upper tubular means being
constructed to provide individual piston chambers for the different
pistons;
and means for converting downward force produced by the pistons
into a lateral thrust on the upper portion of the lower tubular
means.
18. A deflection tool in accordance with claim 11 wherein the
laterally movable positioning means is carried within the upper
tubular means by the lower portion of the lower tubular means.
19. A deflection tool in accordance with claim 11 wherein the
laterally movable positioning means comprises a positioning plug
slidably mounted in a lateral passageway extending through the wall
of the lower tubular member.
20. A deflection tool in accordance with claim 11 wherein the
cross-sectional area of the retrievable limiting device is
substantially less than the cross-sectional area of the interior of
the lower tubular means for enabling a substantial flow of drilling
fluid through the tubular means when the retrievable limiting
device is in place in the lower tubular means.
21. A deflection tool in accordance with claim 11 wherein:
the retrievable limiting device includes an elongated cylindrical
probe member forming at least the lower part thereof;
the tool includes a guide bushing located within the center bore of
the lower tubular means and having a longitudinal center passage
for receiving the probe member, longitudinal side passages for
passing drilling fluid and a lateral passage running from the
center passage to an opening at one side of such guide bushing;
the lower tubular means includes a lateral passage extending
through the wall thereof and in alignment with the lateral passage
in the guide bushing;
and the laterally movable positioning means comprises a positioning
plug slidably mounted in the lateral passages in the guide bushing
and the lower tubular means, the length of such positioning plug
being greater than the combined length of such lateral
passages.
22. A deflection tool in accordance with claim 21 wherein the guide
bushing and the cooperating lateral passage in the lower tubular
means are located in a portion of the lower portion of the lower
tubular means which is within the upper tubular means.
23. A deflection tool in accordance with claim 11 wherein:
the upper tubular means includes an interior longitudinal passage
means of reduced diameter located at an upper location therein;
the lower tubular means includes receiving means for receiving the
retrievable limiting device;
and the retrievable limiting device is of an elongated construction
adapted for passage through the reduced diameter passage means and
includes a lower limiting portion adapted to be seated in the
receiving means and an enlarged portion located above such limiting
portion a distance such that it remains in the reduced diameter
passage means until the limiting portion has entered the receiving
means, such enlarged portion being sized to substantially restrict
the flow of drilling fluid through the tool as long as it is within
the reduced diameter passage means.
Description
BACKGROUND OF THE INVENTION
This invention relates to directional drilling methods and
apparatus for use in drilling well bores into the earth and is
particularly useful in connection with drilling apparatus wherein
the drill bit is driven by a downhole fluid motor.
In the drilling of oil and gas wells, the use of downhole fluid
motors for rotating the drill bit is becoming more widespread. In a
goodly number of such cases, it becomes desirable at some
intermediate point in the drilling process to change the direction
in which the well bore is being drilled. It has been heretofore
proposed to accomplish such change by pulling the drill string from
the well bore, inserting a bent tool or bent sub into the drill
string intermediate the drill bit motor and the lower end of the
drill pipe to impart a predetermined amount of inclination to the
motor-drill bit assembly, such inclination being anywhere from
1/2.degree. to 3.degree.. The drill string, motor, drill bit and
permanently bent sub are thereafter run back into the well bore.
Drilling is then recommenced and the angular bend in the bent sub
serves to urge the drill bit in the desired new direction.
The use of a permanently bent sub has various disadvantages. Since
the downhole motor unit and drill bit extend a substantial distance
below the bent sub, the lateral displacement caused by the presence
of the angular bend in the bent sub substantially reduces the
clearance between the lower portion of the drill string and the
wall of the well bore. Among other things, this means that greater
care must be exercised when running in or withdrawing the drill
string from the well bore. Such running in or withdrawal must be
done at a slower rate of speed. Even with the exercise of care, the
chances of damaging the mud cake on the wall of the well bore or of
damaging the drill bit are increased. There is a much greater
tendency for the drill bit to gouge and scrape the wall of the well
bore. There is a much greater chance of the drill bit striking a
hard shoulder or ledge protruding into the well bore. In addition,
the screwing and unscrewing of the pipe joints may be more
difficult because of the binding effect caused by the presence of
the bent sub. For similar reasons, the orienting of the drill bit
and motor unit in the desired compass direction may be rendered
more difficult. Furthermore, the necessity of having to pull the
drill string in order to add or remove the bent sub requires a
substantial expenditure of rig time.
Another somewhat different method of changing the direction of a
fluid motor driven drill bit is described in U.S. Pat. No.
3,068,946, granted to Messrs. Frisby and Cook on Dec. 18, 1962.
Frisby and Cook employ a so-called "knuckle joint" which, at the
appropriate moment in the drilling operation, is connected into the
drill string between the drill pipe and the fluid motor unit. Their
knuckle joint is flexed or bent by applying weight to the drill
bit. Their knuckle joint, however, suffers from various
disadvantages. For one thing it requires the withdrawal of the
drill string from the well bore in order to insert or remove the
knuckle joint at the appropriate points in the drilling process.
More importantly, perhaps, their device does not provide any
positive control over the flexing or bending of the knuckle joint.
Weight can be applied to the drill bit, but there is no positive
assurance that the knuckle joint has flexed in the desired manner.
Depending on its orientation, it may have been limited in a
straight or unflexed position. Also, since their knuckle joint is
free to pivot at any time, there is increased danger of hanging up
the drill string when running it into the well bore with the
knuckle joint in the string.
Since the present invention may be characterized as a modified form
of knuckle joint, it is pertinent to note that various forms of
knuckle joints have been heretofore proposed for use in various
types of subsurface well bore operations other than the actual
drilling of the well bore. Representative of these is the knuckle
joint described in U.S. Pat. No. 2,680,483, granted to F. L. LeBus
on June 8, 1954. The LeBus knuckle joint is intended for use as a
fishing tool for recovering drill pipe from the well bore. As a
probable consequence of this different use, it includes features
which render it unsuitable for use in a drill string having a
downhole fluid motor for driving the drill bit. For one thing, the
LeBus device requires the running into the tool of a plug for
plugging the fluid flow passage through the tool in order to
operate a piston mechanism which causes the tool to bend or
knuckle. Such plugging of the flow passage would not allow
sufficient flow of drilling fluid to enable proper operation of a
downhole fluid motor located below the knuckle joint. In addition,
the LeBus tool has no means for keeping the joint in a straight
position for purposes of drilling a straight section of the well
bore. Thus, assuming the restriction plug were not present, the use
of the LeBus device would require the pulling of the drill string
from the well bore in order to insert and remove the knuckle joint
before and after the drilling of a curved section of the well bore.
Furthermore, since the LeBus knuckle joint is free to pivot when it
is being run into the well bore, there would be an increased
likelihood of hanging up the drill string when running it into the
well bore.
SUMMARY OF THE INVENTION
It is an object of the invention, therefore, to provide new and
improved apparatus of directional drilling which is easier, faster
and more accurate than those heretofore proposed.
It is another object of the invention to provide new and improved
apparatus of directional drilling which minimizes the chances of
damaging either the mud cake on the wall of the well bore or the
drill bit.
It is a further object of the invention to provide a new and
improved deflection tool for use with fluid motor driven drill bits
and which can be connected in the drill string the entire time the
well bore is being drilled.
It is an additional object of the invention to provide a new and
improved deflection tool for use with fluid motor driven drill bits
and which can be limited in a positive manner at different desired
angles (including a straight angle) at different stages in the
drilling operation without having to pull the drill string from the
well bore.
In accordance with the invention, a deflection tool adapted to be
connected in a drill string for use in the directional drilling of
a well bore comprises first tubular means and second tubular means
pivotally coupled thereto. The tool also includes fluid-responsive
means carried within the tubular means and responsive to drilling
fluid pressure in the tubular means for urging one of the tubular
means to pivot relative to the other. The tool further includes
locking means including a retrievable limiting device adapted for
passage through the drill string and into the tubular means for
limiting the extent of such pivotal movement.
For a better understanding of the present invention, together with
other and further objects and features thereof, reference is had to
the following description taken in connection with the accompanying
drawings, the scope of the invention being pointed out in the
appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring to the drawings:
FIGS. 1A and 1B are partial cross-sectional elevational views of
different portions of a deflection tool constructed in accordance
with the present invention;
FIGS. 2, 3, and 4 are cross-sectional views taken along the
correspondingly numbered section lines of FIGS. 1A and 1B;
FIG. 5 is a perspective view of a guide bushing used in the FIG. 1B
portion of the tool;
FIG. 6 is a perspective view of a limiting plug used in the FIG. 1B
portion of the tool;
FIGS. 7A and 7B show the tool of FIGS. 1A and 1B after it has been
operated to put it in a bent position;
FIG. 8 is an enlarged view of the lower portion of the tool showing
the probe in nonseated position and the connector bushing
restricting fluid flow;
FIG. 9 shows in a cross-sectional manner a modified form of
construction for the lower portion of the tool of FIGS. 1A and
1B;
FIG. 10 is a cross-sectional view taken along section line 10--10
of FIG. 9; and
FIG. 11 is a perspective view of a removable pivot stop block
employed in the modified embodiment of FIG. 9.
DESCRIPTION OF THE FIRST EMBODIMENT
Referring to FIGS. 1A and 1B of the drawings, there is shown a
first embodiment of a deflection tool adapted to be connected in a
drill string for use in the directional drilling of a well bore
into the earth. These figures show the tool in its straight or
undeflected position. FIG. 1A shows the upper portion of the tool,
while FIG. 1B shows the lower portion of the tool.
As shown in FIGS. 1A and 1B, the deflection tool includes an upper
tubular assembly 12 which is of an elongated cylindrical
construction. This tubular assembly 12 includes a series of
cylinders 13, 14 and 15 which are threaded together in an
overlapping end-to-end manner. The tubular assembly 12 further
includes a hollow cylindrical body member 16 which is threaded onto
the lower end of the lower cylinder 15. The upper tubular assembly
12 further includes a cylindrical pivot joint seating member 17
which is connected to the lower end of the body member 16 by means
of an internally threaded connecting sleeve 18. Suitable tool
cleanout plugs 19 are threaded into cooperating passageways at
spaced points along the length of the tubular assembly 12. A top
sub 20 is threaded onto the upper end of the tubular assembly 12.
The upper end (not shown) of the top sub 20 is provided with a
threaded pin for connecting the top sub 20 to the lower end of a
nonmagnetic survey collar which forms part of the drill pipe
string. Top sub 20 includes an interior longitudinal passage 21
having a reduced diameter lower portion 22 and a shoulder 23 formed
at the boundary between the portions of different diameter.
The deflection tool further includes a lower tubular assembly 24
pivotally coupled to the upper tubular assembly 12. As indicated in
FIG. 1B, this lower tubular assembly 24 is pivotally mounted within
the lower portion of the upper tubular assembly 12. To this end,
the lower assembly 24 is provided with an enlarged spherical ball
joint portion 25 which is seated in a spherical socket 26 formed in
the upper end of the pivot-joint-seating member 17 of the upper
tubular assembly 12. A retaining ring 27 holds the spherical ball
25 in place in the socket 26. The lower end 28 of the retaining
ring 27 is provided with a spherical curvature which matches that
of the spherical ball portion 25. A pair of O-ring seals 29 are
located in lateral grooves which encircle the ball portion 25,
while a further O-ring seal 27a is located in a circular groove in
the lower part of body member 16 adjacent the retaining ring 27.
These seals 27a and 29 prevent leakage of the drilling fluid around
the ball and socket joint. The ball joint portion 25 can be
suspended on its pivot axis in the manner described in the
above-mentioned U.S. Pat. No. 2,680,483 to LeBus.
The lower tubular assembly 24 further includes an upper tubular
portion 30 located above the pivot axis (an axis passing through
the center of the ball portion 25 at right angles to the plane of
the paper in FIG. 1B) and extending upwardly within the upper
tubular assembly 12. Though the length of tubular portion 30 may
vary within limits, it preferably should be of suitable length to
provide sufficient mechanical advantage for insuring that the lower
tubular assembly 24 is pivoted in the desired manner.
The lower tubular assembly 24 further includes a lower tubular
portion 31 located below the pivot axis and extending downwardly
and out of the lower end of the upper tubular assembly 12. The ball
portion 25, the upper portion 30 and the lower portion 31 are
formed from a single piece of metal. A common longitudinal
passageway 32 extends from one end to the other of the lower
tubular assembly 24 provided by these portions. Passageway 32
includes a reduced diameter lower portion 33, which construction
provides a shoulder 34 near the lower end of such passage 32.
Threadedly connected to the bottom end of the lower portion 31 of
the lower assembly 24 is a bottom sub 35. Such bottom sub 35
includes at the lower end thereof a threaded pin 36 which is
adapted to be connected to a downhole fluid motor unit which drives
a rotary drill bit. Bottom sub 35 includes a longitudinal center
bore or passage 37 for passing the drilling fluid to the fluid
motor unit located therebelow for purposes of energizing such
unit.
As can be seen from FIG. 1B and the cross-sectional view of FIG. 4,
the interior of the lower portion of the upper tubular assembly 12
is shaped to allow pivoting of the lower assembly 24 in only one
direction and to limit the maximum extent of such pivotal movement.
As there seen, the pivot-joint-seating member 17 is provided with a
lower center bore 38 which is cylindrical on the right-hand side
thereof and which has formed in the left-hand side thereof a
tapered recess 39 having a cylindrical curvature for enabling the
lower portion 31 of the lower assembly 24 to move toward the left
as viewed in FIG. 1B. As such, the tapered recess 39 recedes from
the longitudinal center axis of the pivot joint seating member 17
as it progresses in a downwardly direction. As will be better
appreciated hereinafter, the wall of the tapered recess 39 sets the
maximum limit for the extent of pivotal movement of the lower
tubular assembly 24. The deflection tool further includes
fluid-responsive means carried within the upper tubular assembly 12
and responsive to drilling fluid pressure in such upper assembly 12
for producing a lateral thrust on the upper portion 30 of the lower
tubular assembly 24 for causing such assembly 24 to pivot about the
pivot axis. Such fluid-responsive means includes a series of three
longitudinally spaced pistons 40-42 slidably mounted for
longitudinal movement within the upper part of the upper assembly
12. Pistons 40-42 are of toroidal shape and, as such, include
longitudinal center bores 44-46, respectively, which extend
longitudinally therethrough. Pistons 40-42 are interconnected by
tubular stem members 48 and 49, the extremities of which are fitted
into enlarged portions of the center bores 44-46 of the pistons
40-42. A piston-shaped ram 43 is mounted on a lower stem member 50
which is fitted into the lower enlarged portion of the center bore
46 of the lower piston 42. Ram 43 includes a longitudinal center
bore 47 having a shoulder 47a which is engaged by a mating shoulder
50a on stem member 50 whereby stem member 50 can drive ram 43 in a
downwardly direction. As indicated in FIG. 1B, the lower stem
member 50 extends through the ram 43 and a goodly distance into the
upper portion 30 of the lower assembly 24.
The interior of the upper portion of the upper assembly 12 and,
more particularly, the interior of the cylinders 13-15 are
constructed to provide individual piston chambers 51-53 for the
different pistons 40-42, respectively. Chambers 51-53 are provided
with fluid outlets 55-57, respectively, at the lower extremities
thereof for enabling the lower ends of these chambers to
communicate with the lower pressure well bore fluid exterior to the
upper assembly 12. The upper ends of the piston chambers 52 and 53
are adapted to receive the higher pressure drilling fluid within
the drill string by way of inlets 58 and 59 which extend through
the sidewalls of the stem members 48 and 49, respectively. The
upper end of the upper piston 40 is exposed directly to the
drilling fluid leaving the lower passage 22 in the top sub 20. A
concave recess 60 is provided in the top of the upper piston 40 for
providing an exposed piston surface even when the piston 40 is at
the upper end of its range of movement. An inlet 61 is provided in
lower stem member 50 just above ram 43 for equalizing the pressure
on the top and bottom sides thereof.
O-ring seals 62 provide fluid seals between the various pistons
40-42 and their corresponding cylinder walls, between the various
stem members 48-50 and the center bores in the corresponding
pistons and at the various other indicated points where it is
desired to maintain a fluidtight barrier. In addition to
interconnecting the various pistons 40-42 so that they work in
unison with one another and are mechanically coupled to the ram 43,
the stem members 48-50 also provide a longitudinal flow passage for
conveying the drilling fluid through the upper tubular assembly 12
and into the lower tubular assembly 24. This flow passage provided
by the stem members 48-50 is of reduced internal diameter relative
to the remainder of the longitudinal flow passages within the
tubular assemblies 12 and 24.
In addition to the piston mechanism just described, the fluid
responsive means further includes means for converting downward
movement of the pistons into a lateral thrust on the upper portion
30 of the lower tubular assembly 24. This movement or force
converting means includes a control lever 63 pivotally mounted
within a tubular cage 64 which is located within the upper tubular
assembly 12 adjacent the upper end of the upper portion 30 of the
lower tubular assembly 24. The cage 64 rests on a shoulder 65
inside of the main body member 16. As indicated in the
cross-sectional view of FIG. 3, the control lever 63 is of a
U-shaped construction having side members 63a and 63b which
straddle the centrally located stem member 50. Pivot pins 66 and 67
pivotally connect these side members 63a and 63b to the cage 64. As
indicated in FIG. 1B, the downwardly extending legs of the side
members 63a and 63b include contact faces 63c and 63d which engage
oblique or slanted contact faces 68 formed by cutting away a corner
portion of the upper end of the tubular portion 30. Only the
rearward contact face 63c of control lever 63 is visible in FIG.
1B, the nearer face 63d being in front of the cross section plane.
The control lever 63 further includes an upper contact surface 63e
which is adapted to be engaged by the underside of the ram 43
during its downward movement. When ram 43 bears against this
contact surface 63e, it causes a pivoting of the control lever 63
which, in turn, causes the contact faces 63c and 63d to push the
upper end of the tubular portion 30 of the pivotal assembly 24
toward the right. In this manner, control lever 63 converts
downward movement of the pistons 40-42 and ram 43 into a lateral
thrust on the upper portion 30 of the pivotal assembly 24.
The deflection tool further includes limiting means including a
retrievable limiting device 70 adapted for passage through the
drill string and into the tubular assemblies 12 and 24 for limiting
the extent of the pivotal movement of the lower tubular assembly 24
relative to the upper assembly 12. In addition to the limiting
device 70, this limiting means or limiting mechanism also includes
a guide bushing 71 located within the center bore or passageway 32
of the lower portion of the pivotal assembly 24 and resting on the
shoulder 34 formed therein. A perspective view of this guide
bushing 71 is shown in FIG. 5. As there indicated, the guide
bushing 71 includes a longitudinal center passage 72 for receiving
the lower end of the retrievable locking device 70 and a pair of
C-shaped longitudinal side passages 73 and 74 for passing drilling
fluid past the guide bushing 71. Guide bushing 71 further includes
a lateral passage 75 running from the longitudinal center passage
72 to an opening 75a at one side of such guide bushing 71.
As indicated in FIG. 1B, the limiting mechanism further includes
laterally movable positioning means movably carried by the lower
portion 31 of the pivotal lower tubular assembly 24 and extending
into the center bore 32 of such lower portion 31 for engagement by
the retrievable limiting device 70. This laterally movable
positioning means is comprised of a positioning plug or limiting
plug 76 which is slidably mounted in a lateral passage 77 through
the sidewall of the lower portion 31 and the lateral passage 75 in
the guide bushing 71. A perspective view of the limiting plug 76 is
shown in FIG. 6. Such limiting plug 76 includes an enlarged head
76a at one end thereof for engaging the tapered recess 39 formed in
the wall of the upper tubular assembly 12. The opposite end of plug
76, which end is adapted to extend into the guide bushing center
bore 72, is provided with a cylindrical curvature corresponding to
the curvature of the retrievable limiting device 70. Opposite sides
of plug 76 are cut to provide a pair of flat faces 76c which
cooperate with corresponding flat sidewalls 76b in the inner
portion of the guide bushing lateral passage 75 for maintaining the
proper alignment for the cylindrically curved end surface 76b of
the plug 76. As indicated in FIG. 1B, the length of the positioning
or limiting plug 76 is greater than the combined length of the
lateral passages 75 and 77 in the guide bushing 71 and the sidewall
of the lower tubular portion 31. An O-ring seal 76d provides a
fluid seal between the limiting plug 76 and the wall of passage
77.
As seen in FIG. 1B, the retrievable limiting device 70 includes an
elongated cylindrical probe member 80 having a cylindrical body
portion 80a and a tapered lower end portion 80b. A collar 80c is
formed at an intermediate point on the probe member 80 for purposes
of engaging the top of the guide bushing 71 and thus limiting the
downward movement of the probe member 80 through the guide bushing
center passage 72. The upper end of the probe member 80 is provided
with a threaded connector 81 which is threaded into the lower end
of an enlarged connecting bushing 82 which, as will be seen,
functions as a "tattletale" plug. Threaded into the upper end of
the connecting bushing 82 in a connecting rod 83 which extends
upwardly through the interior of the tubular stem members 48-50 and
is connected to the lower end of a retrievable fishing sub 84
located in the center passage of the deflection tool top sub 20
(FIG. 1A). As indicated in the cross-sectional view of FIG. 2, the
fishing sub 84 includes laterally extending blades 84a which are
seated on the shoulder 23 intermediate the top sub passages 21 and
22. Thus, fishing sub 84 does not block the flow of drilling fluid.
Fishing sub 84 further includes an upper fishing neck 84b which is
adapted to be engaged by a wire line overshot or retrieving device
(not shown) which may be lowered through the drill string by means
of a wire line for purposes of withdrawing the limiting device 70
from the deflection tool and returning it to the surface of the
earth. If the drilling medium or drilling fluid is a
liquid-drilling mud, then the limiting device 70 can be placed in
the deflection tool by dropping it through the drill string in a
free-falling go-devil manner. If, on the other hand, the drilling
fluid is air, the limiting device 70 is lowered into place by means
of the releasable wire line overshot device.
The diameter of the connecting bushing 82 is sized to substantially
restrict the flow of drilling fluid through the tubular stem
members 48-50 when such bushing 82 is within the stem members
48-50. As such, the diameter of the bushing 82 is slightly less
than the inside diameter of the tubular stem members 48-50, the
difference being such as to provide a clearance on the order of,
for example, one-sixteenth of an inch between the bushing 82 and
the inner wall of the stem members 48-50. Connecting bushing 82
thus serves as a tattletale device since the decrease in mud pump
pressure when the connecting bushing 82 emerges from the bottom end
of the lower stem member 50 serves to signal the operator at the
surface of the earth that the probe member 80 has properly entered
the guide bushing 71. For this reason, the bushing 82 is located
above the locking portion 80a of the probe member 80 a distance
such that it remains in the reduced diameter passage provided by
the stem members 48-50 until the probe member 80 has moved a
substantial distance through the guide bushing center passage
72.
It is noted that the maximum cross-sectional area of the
retrievable limiting device 70 is substantially less than the
cross-sectional area of the interior of the lower tubular assembly
24. Thus, once the connecting bushing 82 leaves the lower stem
member 50, a substantial flow of drilling fluid is provided through
the tubular assemblies 12 and 24. The deflection tool is
constructed so that such fluid flow is amply sufficient for
purposes of driving a downhole fluid motor unit when such motor
unit is connected to the bottom sub 35.
A scribe line 85 in the form of a narrow longitudinal groove is cut
into the exterior of the upper tubular assembly 12 at the lower end
thereof on the side thereof to which the lower assembly 24 is
adapted to pivot. Such scribe line 85 enables an accurate
determination of the orientation of the line of deflection of the
deflection tool with respect to an orienting device in a
nonmagnetic directional survey collar which is connected in the
drill string immediately above the deflection tool. Such a
directional survey collar is of known construction and cooperates
with a known type of wire line directional survey instrument which
may be lowered into such collar for determining the azimuth or
compass direction in which the orienting device is facing.
OPERATION OF THE FIRST EMBODIMENT
Considering now the operation of the above-described deflection
tool, such tool is connected into a drill string immediately above
a downhole fluid motor unit which drives a rotary drill bit. As a
result of the novel manner of construction of the deflection tool,
it can remain in the drill string at all times during the drilling
operation, even when drilling a straight portion of the hole. This
will be assumed to be the case, namely, that the deflection tool is
connected into the drill string at the very beginning of the
drilling of the principal part of the well bore.
Since it is usually desired that the upper portion of the well bore
be a straight hole (either vertical or on a slant), the deflection
tool is initially limited in its straight position. This is the
position shown in FIGS. 1A and 1B. The limiting is accomplished by
placing the retrievable limiting device 70 in the deflection tool
with the probe member 80 extending through the passage 72 in the
guide bushing 71 and the probe collar 80c resting on the top
surface of such guide bushing 71. In order to obtain the desired
straight angle for the lower pivotal assembly 24, the diameter of
the limiting portion 80a of the probe member 80 is just slightly
less than the inside diameter of the central passage 72 in the
guide bushing 71, a slight clearance being provided to prevent the
probe member 80 from becoming stuck in the passage 72. The presence
of this probe member 80 causes a maximum extension of the limiting
plug 76. Thus, the limiting plug 76 is forced against the wall of
the tapered recess 39 which, in turn, forces the lower pivotal
assembly 24 against the opposite wall of the passage 38 through the
lower end of the pivot-joint-seating member 17. This locks the
deflection tool at a straight angle or in a straight position in a
positive manner. With the deflection tool in such straight
position, the drill string is used to drill a straight portion of
the well bore. The deflection tool is constructed to allow
sufficient flow of drilling fluid at this time for properly
operating the downhole fluid motor unit.
Assume now that at some later stage in the drilling operation it is
desired to change the direction in which the well bore is being
drilled. This is accomplished by placing the deflection tool in a
bent or deflected position. Assuming for the moment that a maximum
angle of deflection is desired, this is accomplished by removing
the retrievable limiting device 70 from the deflection tool and
then operating the drilling fluid or mud pump at the surface of the
earth to increase the fluid pressure in the drill string. This
produces the bent condition illustrated in FIGS. 7A and 7B.
The removal of the limiting device 70 is accomplished by lowering a
wire line overshot device through the drill string and allowing it
to grab the fishing neck 84b on the fishing sub 84 located at the
top of the retrievable limiting device 70. The limiting device 70
is then withdrawn from the drill string and retrieved at the
surface of the earth. Referring to FIGS. 7A and 7B, it is seen that
with the probe member 80 removed, the limiting plug 76 is free to
slide back into the lateral passages 75 and 77 in the guide bushing
71 and the wall of the tubular portion 31, respectively. Thus, the
lower tubular assembly 24 is now free to pivot.
Such pivotal movement is produced in a positive manner by means of
the piston and control lever mechanism located in the upper portion
of the upper tubular assembly 12. The pressure of the drilling
fluid in the interior of the drill string is increased, by
increasing pump pressure at the earth's surface to urge the pistons
40-42 to move in a downwardly direction. This causes the ram 43 to
bear against the arm portion of the control lever 63 and thus to
cause such control lever 63 to pivot in a counterclockwise
direction about the pivot pins 66 and 67. This causes the contact
faces 63c and 63d (latter not visible) to bear against the inclined
contact faces 68 of the upper portion 30 of the pivotal tubular
assembly 24. This produces a substantial lateral thrust on the
upper portion 30, which portion functions like a lever arm to cause
a pivoting of the entire lower tubular assembly 24. This forces the
lower portion 31 of the tubular assembly 24 against the tapered
recess 39 in a positive manner, the limiting plug 76 being pushed
into its retracted position in the lateral passages 75 and 77.
Before the deflection tool is actually bent, it is necessary to
rotate or orient the drill string so that the bent portion will
point in the proper compass direction after it is deflected. This
is accomplished by lowering a wire line directional survey
instrument into the survey collar located above the deflection tool
for measuring the compass direction in which the orienting device
in the survey collar is facing. The survey instrument is then
returned to the surface and its record examined. From this,
together with the known angular relationship between the orienting
device in the survey collar and the scribe line 85 on the exterior
of the deflection tool upper assembly 12, the present compass
direction in which the scribe line 85 is facing is determined. The
drill string is then rotated by the drilling rig rotary table the
proper amount to obtain the desired orientation for the direction
in which the lower end of the pivotal assembly 24 will pivot, such
direction being denoted by the scribe line 85. Following such
orientation, the rotary table is limited and the drilling fluid
pressure is increased to its normal operating or drilling level.
This causes the deflection tool to bend or deflect in the manner
previously considered. Drilling of the well bore is then resumed,
the bend angle in the deflection tool causing the drill bit to
follow a new course.
As long as the deflection tool remains bent, the drill bit will
continue to follow a curved path. Usually, after a curved portion
of a certain length has been drilled, it is desired to resume the
drilling of the well bore on a straight path. With the present
deflection tool, this can be accomplished without the need of
pulling the drill string from the well bore. In order to return the
deflection tool to a straight position, all that is required is to
run the retrievably limiting device 70 back into the deflection
tool. If the drilling medium is drilling mud, this is accomplished
by dropping the limiting device 70 in a go-devil fashion. If the
drilling medium is air, the limiting device 70 is lowered into the
deflection tool by means of a releasable wire line overshot
device.
As the probe member 80 of the limiting device 70 enters the guide
bushing 71, it forces the limiting plug 76 toward the left which,
in turn, forces the pivotal assembly 24 toward the right. FIG. 8
shows the situation as the tapered end of the probe member 80
begins its entry into the guide bushing 71. Note that the
connecting bushing 82 is still in a "tattletale" position in the
lower stem member 50. Consequently, if the drilling fluid or mud
pump is operated with the bushing 82 in this position, the larger
than normal fluid pressure indication at the surface of the earth
would indicate that the probe member 80 is not properly seated in
the guide bushing 71. In such a case, the mud pump is turned off to
discontinue the hydraulic pump pressure. The drill string is then
slowly rotated through an angle of 180.degree.. This enables the
weight of the downhole fluid motor and drill bit to swing the
pivotal lower tubular assembly 24 into a straight position at some
point during such rotation. Such straightening enables the probe
member to descend into the guide bushing 71 in the desired manner.
Such occurrence is confirmed by the occurrence of normal drilling
fluid pressure when the drilling fluid pump is again activated.
Complete entry of the probe member 80 into the guide bushing 71
moves the longitudinal center axis of the lower tubular assembly 24
from a maximum deflected position, represented by reference line
86, to the straight position represented by reference line 87, both
reference lines being shown in FIG. 8. The maximum angle of
deflection .alpha. may be on the order of, for example,
3.degree..
It is a further feature of the present invention that the
deflection tool can be limited at any desired deflection angle
intermediate the zero and maximum angles. A desired intermediate
deflection angle is obtained by using a probe member 80 having a
limiting portion 80a of the appropriate diameter. In other words,
when the diameter of the limiting portion 80a is reduced, the
limiting plug 76 assumes a partially extending position, thus
limiting the pivotal movement of assembly 24 resulting from the
urging of the piston and lever mechanisms to a value less than
maximum but greater than zero.
By way of example, a straight portion of the well bore may first be
drilled using a limiting device 70 having a maximum diameter probe
member 80. This produces a straight portion of the well bore. The
limiting device 70 may then be retrieved from the well bore and the
maximum diameter probe member replaced by a probe member of lesser
diameter. The limiting device 70 is then run back into the
deflection tool and a second portion of the well bore is drilled
with the deflection tool bent at an intermediate deflection angle.
If, at a later stage, it should be desired to further change the
curvature of the course followed by the drill bit, the limiting
device 70 can again be retrieved from the drill string and the
second probe member replaced by a further probe member having a
third size for its diameter. If, of course, the maximum deflection
angle is desired, then drilling is carried on with the retrievable
limiting device 70 completely removed from the deflection tool.
DESCRIPTION OF THE SECOND EMBODIMENT
Referring now to FIGS. 9-11, there is shown a modified form of
construction for the lower portion of the deflection tool of FIGS.
1A and 1B. Corresponding parts are identified by the same reference
numerals as used in FIGS. 1A and 1B. Since a lower portion of the
upper tubular assembly is of a modified construction, such upper
tubular assembly is identified in FIG. 9 by the reference numeral
12'.
The embodiment of FIG. 9 differs from the embodiment of FIGS. 1A
and 1B in that a removable pivot stop block 90 is used in place of
the tapered recess 39 of the earlier embodiment for purposes of
limiting the pivotal movement. This pivot stop block 90 is mounted
in a rectangular recess 91 which is cut into the interior wall of
pivot joint seating member 17' on one side thereof. An inner
contact face 92 of the stop block 90 takes the place of the contact
face of the tapered recess 39 of the FIG. 1B construction. Stop
block 90 is held in place by means of a cap screw 93 which extends
through a lateral passage in the wall of the pivot-joint-seating
member 17' and is threaded into a threaded passage 94 in the stop
block 90. As perhaps best seen in the cross-sectional view of FIG.
10, a tapered semicylindrical recess 95 is also provided in this
second embodiment. The extreme left-hand portion of the inner wall
of this recess 95 is to the left of the contact surface 92 of the
stop block 90. Hence, the stop block 90 and not the recess 95 now
determines the maximum limit of deflection for the deflection
tool.
A perspective view of the stop block 90 is shown in FIG. 11. By
using stop blocks of different thickness, different maximum limits
can be established for the deflection angle. This provides a
greater degree of flexibility in the use of the deflection
tool.
While there have been described what are at present considered to
be preferred embodiments of this invention, it will be obvious to
those skilled in the art that various changes and modifications may
be made therein without departing from the invention, and it is,
therefore, intended to cover all such changes and modifications as
fall within the true spirit and scope of the invention.
* * * * *