Note: Descriptions are shown in the official language in which they were submitted.
~:76~a:)7
.
This application relates to deflection apparatus and
method for use in deflecting a drill string for boring into the
side of an existing borehole.
BACR~:ROUND OF T~IE INVENTION
There are several instances where it is desirable to be
able to deflect or control the direction of a new borehole in any
desired direction and at any desired level out of the axis of an
existing borehole. This may be to facilitate examination or
production from a particular horizon after the borehole is drilled.
For example, one important area where deflection may be required is
in obtaining core samples, particularly continuous lateral samples,
at various levels of an existing borehole. The absence o~ existing
technalogy has made this last area generally impractical to date.
Present technology for achieving these objectives suffers from
serious shortcomings.
In general two methods have been utilized to achieve this
deflection above the bottom of an existing hole. First, the
whipstock method comprises the insertion into the borehole of
wedges of various configurations which then deflect the drill bit
in the desired direction. There are a substantial number o~
disadvantages to the use o~ the whipstock method. These include
limitations on the bit styles and boring methods that can be used,
primarily because of the contact of the bit with the durable
surface of the whipstock, which wedges or jams the bit into the
adjacent formation. Substantial extra time is required when using
whipstocks, includiny extra trips into the hole to set and retrieve
the whipstock.
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~ ~z~0[)7
The second method which has been utilized to obtain
deflected or directional drilling is the use of a deployable member
or element which is deployed adjacent the bit to press against the
side of the hole to influence the bit to deflect while drilling at
the bottom of a borehole. While these methods have provided some
improvement, a number of substantial disadvantages remain. For
example, in a number of these cases the deflection provided by the
weight of the drill string on the bottom of the hole is a required
element. In other cases the continued deployment o~ the defl~ction
member or element is completely reliant on differential hydraulic
pressure of the circulating drilling fluid.
Of suhstantial significance, earlier methods utilizing
the deflection element deployment t~echni~ue have generally been
applicable to the bottom of the drill hole only. Furthermore, the
`~ 15 deflection apparatus in these methods must move downhole with the
; bit and the drill string.
The present apparatus provides a deflection member or
; element which operates independently of drill string rotation and
longitudinal movement and of fluid pressure in the drill string.
It does not limit the type of bit to be utilized. The apparatus
acts as an independent non-moveable anchor in the borehole allowing
the drill string to pass through. It enables, ~r example, a
sizable core sample to be obtained at any level of an existing
borehole.
PRIOR AR~
Canadian Patent 637,067, issued February 27, 1962, to
Thompson, illustrates a typical whipstock deflection apparatus.
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76CIC~7
Canadian Patent 849,943, issued August 25, 1970, to
Whipstock Inc. illustrates an apparatus having deployable elements
utilized for straightening and stabilizing a borehole.
Canadian Patent 896,397, issued March 28, 1972, to Smith
Industries International Inc., illustrates a deflection apparatus
utilized with a non-rotating drill stem and wherein the deflection
apparatus moves downwardly in the hole with the bit.
Other Canadian patents in the area are No. 1,122,965,
issued May 4, 1982, to Conoco Inc. and 1,164,852, issued April 3,
10 1984, to Base.
United States patents in the area of interest are U.s.
Patent 2,643,859 issued June 30, 1953, to Brown, U.S. Patent
2,730,328, issued January 10, 195~, to Brown, U.S. Patent
2,~19,039, issued January 7, ~958, to Lindsay; U.S. Patent
15 3,045,767, issued July 24, 1962, to Rlassen; U.S. Patent 3,129,776,
issued April 21, 1964, to ~ann; U.S. Patent 3,196,959, issued July
27, 1965, to Kammerer; U.S. Patent 3,298,44g, issued January 17,
1967, to Bachman; and U.S. Patent 3,572,450, issued March 30, 1971,
to Thompson.
Each of these U.S. patents illustrates one or more of the
disad~antages to which reference was made above. Generally,
deployment of deflecting elements is achieved by utilizing the
hydraulic pressure of the drilling mud. Deflection is achieved in
a number o~ cases by flexing of the drill string due to its weight
where the bit is resting on the bottom of the drill hole. In all
cases the deflecting apparatus travels downhole with the drill
string and, at least in one case, the apparatus must be moved down
the hole with the end part o~ the drill string on a step by stsp
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basis, a very time consuming undertaking.
8UM~ARY OF ~H~ INV~NTION
A deflecting apparatus has now been provided which
alleviates several of the difficulties of the prior art. For
example, once deployment of a deflection member is initiated, final
deflection and maintaining of the deflection of the deflection
member is achieved by spring action independent of position in the
hole or of drilling mud circulation. Furthermore, the new
apparatus can be positively anchored at any point in a borehole.
The apparatus is independent of drill string movement and thus can
maintain its position in the hole as the drill string moves
d~wnwardly. The apparatus thus continues to act at the same
position in the hole against that section of the drill string which
is passing through the apparatus at any time.
~ 15Accordingly, the invention provides a deflection
; apparatus for use in directional drilling comprising a housing
which is adapted to be disposed about a drill string and to be
rotatable relati~e to the drill string; a deflection member
~ pivotally connected to the housing and moveable between a first
; 20 equilibrium position in which the mem~er is in a retracted position
adjacent the housing and a second position in which the member is
biased toward an extended position outwardly of the housing; means
for maintaining the member in the first equilibrium position; means
responsive to an external force for releasing the member from the
equilibrium position; means ~or biasing the deflection member into
the extended position; and means for locking said deflection member
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in the extended position; and wherein the means for biasing is
responsive to the release of the deflection member ~rom the first
equilibrium position to move the deflection member toward the
second position.
In a further embodiment of the invention the means for
locking is moved from a first non-locked position to a second
locked position responsive to the biasing means moving the
deflection member to the extended position~
There is also provided a method of deflecting a drill
string comprising: enlarging a section of a borehole; positioning
a deflection apparatus on a lowest section of a drill string;
lowering said apparatus to said enlarged section; deploying a
deflection member to an extended position whereby to cause said
apparatus to de~lect in said enlarged section; and commencing
borin~
RIEF DESCRIPTION OF T~E DRAWINGS
In drawings which illustrate embodiments of the
invention:
FIGURE 1 illustrates the apparatus of the invention with
the deflection member deployed in a borehole;
FIGURE 2 is a partially cut away elevation showing the
deflection member in the retracted position;
FIGURE 3 is a cross-section through thé apparatus at the
de~lection arm pivot point;
: 25 FIGURE 4 illustrates one manner of initiatin~ deployment
of a de~lection arm;
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$~007
FIGURE 5 illustrates a seco~d manner of initiating
deployment of a deflection member;
FIGURE 6 illustrates a third manner of initiating
; deployment of a deflection member;
FIGUR~ 7 is a side view partially in section of a trip
spring for use in the invention:
FIGURE 8 is a top end view of the spring of FIGUR~ 7;
FIGURE 9 illustrates the use of the trip spring of
FIGURES 7 and 8;
FIGURE 10 is a partial section of a locking mechanism for
use in the invention: and
FIGURE ll is a partial section of the locking mechanism
of FIGURE 10 in a different position.
While the invention will be described in con3unction with
illustrated embodiments, it will be understood that it is not
intended to limit the invention to such embodiments. On the
~; contrary, it is intended to cover all alternatives, modifications
~ and equivalents as may be included within the spirit and scope of
:~ the invention as defined by the appended claims.
DBTAIL~D DE8CRIPTION O~ ~ME I~VENTION
In the following description, similar features in the
drawings have been given similar reference numerals.
The apparatus 10 comprises a housing 12 which is adapted
to be positioned about a drill string 14. The housing 12 would in
the usual case be located initially at the bottom of drill string
14 adjacent to th~ bit 16 and, for example, hung from bit 16 by a
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connecting arrangement to be described. When anchored in a
borehole, housing 12 is axially rot.atable relative to the drill
string 14 and is in sealing contact with drill string 14 through
bearings or bushings 18 (not shown) within the bushing flange 20.
5A nut 22 is of greater diameter than the lower part of
housing 12 and so provides an abutment or flange on the lower side
24 thereof. Nut 22 is in threaded engagement with housing 12 and
so its position may be adjusted axially of housing 12. Below nut
22 is a collar 26.
10A spring 28 is located about the housing 12 below collar
26 so as to abut against the lower side 24 of collar 26.
At the other end of spring 28 is a second collar 32 which
is slidable along housing 12. The spring 28 is always in
compression o~er the limits of movement of collar 32. The actual
; 15 tension on the spring can be adjusted by adjusting the position of
nut 22 along its threaded engagement with housing 12.
t In one preferred embodiment, there is disposed below the
second collar 32 and about housing 12 a ge.nerally cylindrical trip
spring 90 (detailed in FIGURES 7, 8 and 9) comprising a lower
collar 92 and an upper spring section 94.
Spring section 94 comprises a series of spring fingers 96
- separated by slots 98. The spring fingers 96 are provided at the
top 100 thereof with at least one and preferably two inwardly
projecting tongues 102 having inner faces 104.
25The trip spring 90 is slidable relative to the housing
12, with the tongues 102 pressing against housing 12 ky virtue of
spring fingers 96, and subject to the following. At a preselected
axial position the housing 12 is pro~ided with a pair of
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circumferential grooves 106 corresponding to tongues 102 of trip
spring 90. As will be discussed below, as trip spring 90 slides
down along the housing 12, the tongues 102 will spring into the
grooves 106 to lock the trip spring in position.
The bottom 33 o~ collar 32 is bevelled to aid in locking
tongues 102 in grooves 106. The combination of spring 28, trip
spring 90 and the action of the bevelled bottom 33 of collar 32
provide a predetermined locking force which must be overcome to
release the trip spring once the tongues 102 and grooves 106 have
engaged.
A deflection member 36 is pivotally attached to housing
12 by means of a pair of pivot pins 38 and 40. The deflection
member 36 comprises a lower section 42 and upper extensions 44. As
; indicated in FIGU~E 2, the deflection member 36 in the retracted
position assumes a first equilibrium position in which force is
applied to the top 46 of extensions 44 by the spring 28 acting
; through the collar 32 and the trip spring 90. In that position the
-~ force acts either through the pivot pins 38 and 40 or, if any
moment is imposed about those pivot pins, it is to the left in
FIGURE 2. In that situation the lower part 42 of member 36 brings
up against the surface 48 of housing 12. Accordingly, in that
first equilibrium position the deflection member 36 is restrained
against rotation.
When apparatus 10 has been positioned in a borehole at
the desired level, means such as the floating pistons illustrated
in FIGURES 4, 5 and 6 are utilized to rotate the deflection member
36 out of the first equilibrium position illustrated in FIGURE 2
just to the point where a component of the force exerted by spring
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28 on upper extenslon 44 of deflection member 36 is to the right,
as shown in FIGURE 2, of the pivot pins 38 and 40. The spring 28
through the collar 32 and trip spring 90 will then force th2
deflection mem~er into the extended position illustrated in FIGURE
1. The limit of the rotation of the deflection member 36 is
defined by the position of grooves 106 in housing 12 and the
cooperating tongues 102 of trip spring 90. The tongues 102 engage
grooves 106 to lock the deflection member 36 in position. At the
same time the profiled upper edge 50 of lower ~ection 42 of
deflection member 36 brings up against housing 12 to provide a
positive limitation of rotation.
FIGURES 10 and 11 illustrate a further preferred means of
locking the de~lection member 36 in the extended position. The
collar 32 and the trip spring 90 are replaced by an elongated
15 collar 13~ having a bottom edge 134 profiled to form a camming
; surface. The camming surface preferably comprises a first more
steeply cammed area 136 and a second less steeply cammed area 138.
These two surfaces will have opposite effects on the deflection
member 36.
Thus, when the deflection member 36 is in the first
equilibrium position (FIGURE 10), the cammed area 138 will tend to
maintain the deflection member 36 in that first equilibrium
; position. Only a small amount of movement of collar 132 against
spring 28 will allow the upper extension 44 of deflection member 36
to move to the right in FIGURE 10 out of the first equilibrium
position. Such mov~ment may be initiated as discussed below,
preferably utilizing a floating piston technique. De~lection is
then completed by spring 28 acting on the upper extension 44 of
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~.~7~7
deflection member 36 through elongated collar 132.
Once the deflection member 36 has been deployed, the top
46 of the extension 44 will have moved further to the right (FIGURE
11) and have passed over the steeply cammed area 136. The force of
spring 28 combined with the steeply cammed area 136 will serve to
lock the deflection member 36 in the deployed position.
As will be discussed later, the deflection member 36 must
be at least partially returned to the first equilibrium position
for removal from the hole. The radius o~ the top 46 of extension
44 of deflection member 36 and the radius or curvature of the
steeply cammed area 136 are chosen such that a predetermined force
exerted on the deployed deflection member 36 will overcome the
locking actian of the cammed surface and permit the deflection
~: memher 36 to rotate back toward the first ~quilibrium position.
While various techniques could be utilized to effect the
initial rotation of the deflection member 36, the preferred
technique is to utili~e a piston slidable in the housing to act on
an extension 37 of deflection member 36 which extends into the
interior of the housing 12. As illustrated in FIGURE 4, the
extension 37 comprises a hinged arm 52 which is caused to extend by
the downward movement of a piston 54.
In FIGURE 5 the extension 37 is integral with or attached
to the deflection member 36 and extendæ into the housing 12.
Extension 37 is sloped at itæ side 58, and the piston 54 may have
a correspondingly sloped side 60 or may have a conical bottom
section to co-operate with the sloped side 58 of extension 37.
Downward movement of piston 54 will then force the initial rotation
o~ deflection member 36.
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In the preferred case the piston 54 is spherical, as
illustrated in FIGURE 6.
The spherical piston or ball 54 is preferably placed
inside housing 12 and above the extension 37 during assembly of the
apparatus. This is essential in the pref~rred case, to be
discussed, where a universal joint is utilized above the apparatus
in the drill string.
The piston 54 is forced downwardly by hydraulic pressure
when required to initiate deployment of member 3 6 . To clear the
housing 12 to make room for passage of the bit and core barrel, the
piston is simply forced by the hydraulic pressure right out of the
housing.
In order to facilitate the positioning of the apparatus
in the ~orehole, a releasable connection is preferably provided
~ 15 between the lowest section of the drill stri~g, abo~e the bit 16,
:; and the apparatus housing 12. One form of such connection is
illustrated in FIGURE 1. The bottom section of the drill string 80
is provided with a coarse outer thread 82. The inside of the
housing 12 is provided with corresponding internal threads 84.
Threads 84 are for convenience positioned at the same level in
housing 12 as trip spring 90. When the housing 12 is fitted down
over the end section of the drill string and twisted in a clockwise
direction relative to the drill string, the threads 82 engage
threads 84. Once the apparatus 10 has been positioned at the
proper level and in the desired direction in the hole and the
deflection member 36 deployed, clockwise rotation of the drill
string will remove threads 82 from threads 84 and the drill string
can then operate independently of the apparatus 10 in the downward
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(37
direction.
When a sample has been obtained or drilling is completed,
and the drill string withdrawn, the threads 82 will bring up
against or re-engage the threads 84 to withdraw the apparatus 10
with the drill string.
As the apparatus 10 is withdrawn, and particularly as the
deflection member 36 brings up against the shoulder 116 at the top
of the enlarged area 64, the force exertad on the deflection member
36 will be sufficient to overcome the force of the spring 28 and
whichever of the locking mechanisms is utilized. The deflection
member 36 will thus be forced toward the initial retracted position
of FIGURE 2 to allow the apparatus 10 to be readily withdrawn.
FIGURE l illustrates the apparatus of the invention in
the preferred use situation for obtaining a core sample or
deflecting a borlng operation of another natur~ at an lntermediate
level of a pre-existing borehole. By known techni~ues a borehole
~ 62 is preferably although not necessarily enlarged to form an
;; enlarged axea 64 including lower shoulder 66. As well, an enlarged
area might occur naturally in the borehole. The apparatus 10 is
20 lowered to the desired level and the deflection member 36 deployed
as described above. The entire length of the deflection apparatus
10 is preferably within the enlarged area 64. The apparatus 10 and
the contained drill string 14 are thus deflected into the position
illustrated in FIGURE 1 with the axis of apparatus 10 and of the
drill string at an angle to the axis of the hole. The bit 16 is
preferably positioned on shoulder 66~
Typically, a continuous side hole core sample having
dimensions of 10 feet in length by 2 1/2 inches in diameter can be
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q
obtained in this manner commencing from a 7 7/8 inch diameter
borehole. This is in contrast to current side hole coring
procedures which typically yield small plug samples from the
borehole wall having dimensions of about 1 inch by less than 1
inch.
It is highly preferred that the drill string be provided
with a universal joint llO above the lowermost section 112. This
arrangement offers several advantages. First, it greatly
facilitates obtaining a good angle of deflection.
Second, well defined axial and radial components of force
are set up, the latter of which acts about the pivot pins 38 and
40, which function as a fulcrum to lever the apparatus 10 laterally
toward the side of the borehole. This requires that the deflection
member 36 ~e stabilized and selected loc~i~g mechanism performs
::~ 15 this locking functio~.
The levering effect is enhanced by locating the pins 38
and 40 toward the bottom of housing 12.
The bottom section of the drill string 14 is made up of
a coring barrel 118 and an extension section 120. Since the
universal joint llO cannot pass through the apparatus lO, the
combined length of the coring barrel 118 and extension section 120
is chosen such that a sample of desired length can be obtained
before universal joint llO brings up against apparatus 10. It will
be noted that the de~lection angle will tend to increase as the
25 universal joint 110 approaches the apparatus 10.
Typically the apparatus lO may have an overall length of
4 to 5 feet, the enlarged area 64 of borehole 62 might extend over
a 10 foot length, and the combined length of coring barrel 118 and
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7~ 7
extension section 120; that is, the length from universal ~oint 110
to the bit 16, might be about 15 feet. Thus, prior to initiating
the coring operation, the universal joint 110 will be located in
the original borehole 62 above the enlarged area 64.
It is also preferred that the bottom 70 of the housing 12
be provided with teeth 72 (not shown~ or similar gripping members
to aid in stabilizing the apparatus 10 against rotation.
; Once the apparatus 10 is positioned with the deflection
member 36 deployed, the bit and drill string can move
longitudinally relative to the anchored apparatus 10 to obtain a
side tracking core sample or, as the case may be, to continue to
drill an offsetting borehole.
It should be noted throughout that the deflection
apparatus applies force to the drill string rather than to the bit
to effect deflection.
Thus it is apparent that there has been provided in
accordance with the invention a deflection apparatus ~or use in
directional drilling that fully satisfies the objects, aims and
advantages set forth above. While the invention has been described
in conjunction with specific embodiments thereof, it is evident
that many alternatives~ modifications and variations will be
apparent to those skilled in the art in light of the foregoing
description. Accordingly, it is intended to embrace all such
alternatives, modifications and variations as fall within the
spirit and broad scope of the invention.
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