Note: Descriptions are shown in the official language in which they were submitted.
127~86~;
--i!--
BACKGROUND OF THE INVENTION
The present invention relates generally to methods
and apparatus for absorbing shock, and more particularly
relates to methods and apparatus for absorbing shock in
equipment utilized in earth boreholes in the oil and gas
industry.
In many applications in the oil and gas industry,
there is a need to protect systems utilized in earth bore-
holes from shock. For example, one such application is
during the completion or testing of oil and gas wells,
when the wells are either completed or tested through the
use of perforating guns. In a common type of well comple-
tion operation, a perforating gun will be run into anearth borehole on the tubing string. In addition to the
perforating gun, it is not uncommon to include other
' J eguipment or controlling or monitoring the well during
the completion operation. For example, measurement
devices-such as temperature and pressure recorders may be
included in the tool string. Additionally, the tool
- string may include other eguipment associated with the
well completion or testing operation, such as gravel
packing tools, vent assemblies or packers.
The perforating guns typically carry a plurality of
explosives, such as shaped charges, designed to penetrate
the earth formation surrounding the borehole. The detona-
tion of these explosives will generate a reaction or
"recoil" in the tool string which will tend to accelerate
the string both radially, or horizontally, within the
borehole, as well as longitudinally, or vertically, within
the borehole. Accelerations of the tool string can be
both high and low frequency. Acoustic vibrations can be
^;~ 35 transmitted both directly through the tool string to a
. . ' ~ .
- .
1~ 73866
vibration sensitive component or may be transmitted
through borehole fluids to components in the tool
string.
When the tool string includes additional
devices, as described above, the shock transmitted to
the string, either directly or indirectly, at the
time of the detonation of the perforating gun
increases the likelihood of damage to the devices.
This is particularly true in the case of relatively
delicate instruments such as the pressure or
temperature recorders described above, or such as
various types of electronic equipment which may be
utilized within the well.
Accordingly, the present invention provides a
new method and apparatus for isolating and absorbing
shock in a borehole environment. The method and
apparatus of the present invention are believed to
have particular applicability in minimizing the
transmission of shock caused by the detonation of
tubing conveyed perforating guns from the tubing
string and other equipment in the tool string.
SUMMARY OF THE INVENTION
- The present invention provides method and
apparatus for isolating and absorbing shock in a tool
string within an earth borehole. The present
invention encompasses a plurality of components
particularly adapted to absorb such shock.
A construction in accordance with the present
invention comprises an apparatus for minimizing the
transfer of shock caused by the detonation of a
tubing conveyed perforating gun to other components
in a tool string. The tubing conveyed perforating
:~; D
., ~
. . .
~ ~ .
1273866
-3a-
gun is connected to the tubing string by being
releasably secured thereto. The tool string extends
through a portion of a well bore. The apparatus
comprises a longitudinal shock absorber mounted in
the tool string being releasably secured therein on a
first side of the tubing conveyed perforating gun to
absorb at least a portion of the longitudinal shock
to the tool string when the tubing conveyed
perforating gun is detonated. The apparatus also
comprises a radial shock absorber mounted in the tool
string being releasably secured therein to absorb at
least a portion of the radial shock to the tool
string when the tubing conveyed perforating gun is
detonated.
Also in accordance with the present invention,
there is provided a tubing conveyed perforating gun
tool string assembly for use in an earth borehole
which comprises a shock sensitive component coupled
to the tool string which is to be isolated from a
portion of the shock to the assembly. A tubing
conveyed perforating gun is coupled to the tool
~ string. A means is provided for damping a portion of
- the longitudinal and radial accelerations of the
shock sensitive component due to the detonation of
the tubing conveyed perforating gun.
Also in accordance with the present invention,
there is provided a method of minimizing the transfer
of shock caused by the detonation of a tubing
conveyed perforating gun to other components in a
tool string. The tubing conveyed perforating gun is
releasably connected to the tool string. The tool
string extends through a portion of a well bore. The
method comprises the step of mounting a longitudinal
shock absorber in the tool string on a first side of
the tubing conveyed perforating gun to absorb at
,
- :
.
, ~ . ,
',
lZ'^~3866
-3b-
least a portion of the longitudinal shock to the tool
string when the tubing conveyed perforating gun is
detonated. The method also comprises the step of
mounting a radial shock absorber in the tool string
to absorb at least a portion of the radial shock to
the tool string when the tubing conveyed perforating
gun is detonated.
The present invention includes a longitudinal
shock absorber which is particularly useful in
damping longitudinal movement of a component within a
tool string. In one preferred embodiment, a
longitudinal shock absorber in accordance with the
present invention includes a mandrel which is adapted
to couple to other components in the tool
.
:;
D
. ~. ~ . . .
~ - ~ . . . - . .
.
~,-- .: . . . ~
~ - ' .
12738~6
--4-
string. This mandrel i8 telescopingly received within a
housing which is adapted to couple to other components in
the tool string. Shock absorbing elements, such as
compressible members, are situated in an annular area
between the mandrel and the housing. Thrust shoulders-are
provided on both the mandrel and the housing such that
mo~ement of the mandrel relative to the housing in either
direction will cause compression of at least one
compressible member, progressively damping such longitu-
dinal acceleration.
The present invention also encompasses a radial shockabsorber for restricting radial movement of a tool string
within a borehole. In a preferred embodiment, this radial
shock absorber includes a support member adapted to couple
at each end to other components of the tool string. The
~ radial shock absorber includes a plurality of contact
.J shoes which are reciprocatingly supported relative to the ` support member. These contact shoes are preferably
resiliently mounted, such as by springs, such that they
- are urged radially outwardly relative to the support
member. The contact shoes are arranged around the
periphery of the radial shock absorber such that radial
movement of the tool string in any direction will cause
compress~on of the resilient medium urging the contact
shoes outwardly, thereby cushioning, or damping, the
radial acceleration of the tool string.
The present invention also includes a carrier for
supporting gauges or other components, such as temperature
or pressure recorders, within the borehole. In a
preferred embodiment this carrier includes a cage
structure which is conformed to support each gauge or
, other component in a shock absorbing medium, such as a
~; 35 relatively low resilience rubber compound. In one of
: -
.
, . . . . .
, ' '
. ,
1~7~866
--5--
these preferred embodiments, the carrier includes aplurality of shock absorbing segments, made, for example,
from rubber, which are distributed over the length of the
gauges or other components to restrict their motion and
S to prevent the gauges or other components from contacting
the carrier housing. The gauges are also mounted such
that a relatively low resilience member supports the
gauges at either end so as to restrict movement and to
damp longitudinal acceleration of the gauges.
The above-described components may be combined in
various combinations, and in various numbers, to form
shock absorbing systems offering optimal protection to
components in a tool string. For example, a perforating
gun or other device which may generate sudden forces, and
therefore shock, within the borehole may be coupled
, between two longitudinal shock absorbers to damp movement
i of the perforating gun relative to components both above
and below the perforating gun. Additionally, a radial
shock absorber may be provided proximate the perforating
gun to restrict radial movement of the tool string in
response to the detonation of the perforating gun. The
carrier may be utilized to support delicate devices such
as temperature or pressure gauges or electronic eguipment
and optimally protect the devices. In most systems, the
carrier will preferably be located on the opposite side of
one of said longitudinal shock absorbers from the perfor-
ating gun.
The use of shock absorbing components such as the
longitudinal shock absorber and the radial shock absorber,
either individually or as a part of a system as described
above, helps to minimize the likelihood of damage to the
integrity and operation of the tool string. For example,
.
shocks such as those occurring as the result of the
. , - ~, .
.
~ . . . .
--6--
detonation of perforating guns have been known to cause
the unsetting of previously set packers or the uncoupling
of tubing joints. The use of longitudinal shock absorbers
and/or radial shock absorbers, as disclosed herein,
provides optimal protection from such damage.
BRIEF DESCRIPTION O~ THE DRAWINGS
FIG. 1 depicts a shock absorbing system in accordance
with the present invention, and including both radial and
longitudinal shock absorbers, in association with a tubing
conveyed perforating gun.
FIGS. 2A-B depict the longitudinal shock absorber of
FIG. 1, illustrated in one-quarter cross-section.
FIG. 3 depicts the longitudinal shock absorber of
i FIGS. 1 and 2 in an operating configuration, also
, ....
illustrated in a one-quarter cross-section.
2D
FIGS. 4A-B depict the radial shock absorber of FIG.
1, illustrated in one-quarter cross-section.
FIG. 5 depicts the selectively threadable coupling of
~5 the radial shock absorber of FIG. 4, illustrated in
greater detail and in vertical section
FIGS. 6A-C depict an alternative shock absorbing
system in accordance with the present invention, including
a plurality of longitudinal shock absorbers, a radial
shock absorber, and a shock absorbing carrier.
FIG. 7 depicts the gauge carrier of FIG. 6,
illustrated in quarter-sectional view:
,~. i
~: 35
' '
12 7;~866
--7--
FIG. 8 depicts a portion of the gauge carrier of FIG.
~, in greater detail.
FIG. 9 depicts the gauge carrier of FIGS. 7 and 8,
illustrated in an exploded perspective view.
FIG. 10 depicts the gauge carrier of FIG. 8 in
cross-section along lines 10-10 in FIG. 8.
FIG. 11 depicts a mounting tool for the gauge carrier
of FIG. B, illustrated in side view.
FIG. 12 depicts the mounting tool of FIG. 11
illustrated in top view.
FIG. 13 depicts an alternative embodiment of a
~, carrier in accordance with the present invention.
.,J
FIG. 14 depicts another alternative embodiment of a
carrier in accordance with the present invention.
FIG. 15 depicts a carrier of FIG. 14 in cross-section
along lines 15-15 in FIG. 1~.
FIG. 16 depicts the carrier of EIG. 14 in cross-
~ection along lines 16-16 in FIG. 14.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Referring now to the drawings in more detail, and
particularly to FIG. i, therein is illustrated a.shock
, absorber system 10 in accordance with,the present
invention, illustrated as a part of a tool string 11
including tubing string 13 and a tubing conveyed perforat-
~; 35 ing gun 12 an,d situated within an earth borehole 14. In
: ~ . -. : . .
. . ' :
'
.
~ ' ' . ~' , ' ' ' ' '
lZ~3866
-B-
the illustrated environment, earth borehole 14 has been
lined with casing 16 which will typically be secured in
place by cement (not shown) in a conventional manner. All
or part of shocX abs~rber system 10, however, may also be
advantageously utilized in uncased boreholes.
Additionally, all or part of shock absorber system 10 may
also advantageously be utilized outside~of a tubing-
conveyed string, such as, for example, in conjunction with
a wireline-conveyed perforating gun.
Shock absorbing system 10 includes a radial shock
absorber 18 and a longitudinal shock absorber 20. In
operation of the system depicted in FIG. 1, upon detona-
tion of perforating gun 12, longitudinal shock absorber 20
will primarily absorb or damp longitudinal recoil of
perforating gun 12 while radial shock absorber 18 will
, damp radial accelerations o tubing string 13.
' ,.;~
..~
Referring now to FIGS. 2A-B, therein is illustrated
iongitudinal shock absorber 20 of FIG. 1, depicted in -
quarter-sectional view. Longitudinal shock absorber 20
includes a box connector 22 adapted to provide a
mechanical coupling between longitudinal shock absorber 20-
and tubing string 13. Box connector 22 is threadably
coupled to a mandrel 24. Mandrel 24 is telescopingly
retained within a generally tubular housing 26.
,
A pin connector 30 is threadably secured to housing
26 at the lower end thereof. Pin connector 30 facilitates
the attachment of longitudinal shock absorber 20 to other
equipment, such as a perforating gun (item 12 in FIG. ~).
Pin connector 30 is internally configured such that it
will not interfere with the movement of lower end 40 of
mandrel 24 as mandrel 24 telescopes within housing 26. As
- 35 will be apparent from the discussion to follow, mandrel 24
.~ .
.. . i. . ... , .. :, . - . - - -
1;~'7~66
cooperatively is retained within housing ~6 by endcap 28,
box connector 22 and pin connector 30.
Box connector 22, mandrel 24, endcap 2B, and pin
connector 30, each preferably include aligned longitudinal
apertures 32, 34, 35, and 36, respectively. Longitudinal
apertures 3~, 34, and 36 cooperatively define a passageway
38 through longitudinal shock absorber 20. Passageway 38
provides a path through which mechanisms or fluids may be
traversed either uphole or downhole.
Aperture 35 through endcap 28 is defined by surfaces
37 and 39 which meet to form a pivot pin 41. Pivot point
41 is radially dimensioned to contact mandrel 24 in
response to radial movement of housing 26. Optimally,
this contact will allow box connector 22 and mandrel 24,
-- and the portion of tool string ll above longitudinal shock
) absorber 20, to remain generally stationary while axial
loading and motion in longitudinal shock absorber 20 is
damped in response to the pivoting of housing 26 and
attached endcap 28 around pivot point 41.
As shown in FIGS. 2A-B, box connector 22, mandrel
- 24, endcap 28, housing 26, and pin connector 30 each
preferably contain "flats~, as illustrated at 44, to
facilitate the makeup or breakout of the described and
illustrated threaded connections.
- Mandrel 24 is a generally tubular member having a
- 30 radially extending shoulder 46 extending therefrom. An
upper shock absorbing bumper assembly 52a is situated
concentric to mandrel 24 and above shoulder 46.
Similarly, a lower shock absorbing bumper assembly 52b is
situated concentric to mandrel 24 and below shoulder 46.
Upper and lower bumper assemblies 52a, 52b contain
': -
- :
:
1273866
--10-
identical elements arranged symmetrically relative to
~houlder 46~ Accordingly, although only the elements of
upper bumper assembly 52a will be described in detail, it
will be understood that the elements of ?ower bumper
assembly 52b, identified as ''Inumeral]b" are ~tructurally
and functionally identical.
Situated adjacent to shoulder 46 is large retainer
ring 56a. Large retainer ring 56a is preferably formed of
a rigid, nondeformable material such as steel. Large
retainer ring 56a preferably has an outer diameter which
is proximate the inner diameter of housing 26. ~arge
retainer ring 56a, however, has an inner diameter which is
substantially larger than the outer diameter of mandrel
24, so as to provide an annular gap between large retainer
ring 56a and mandrel 24 when the two pieces are axially
aligned. In one preferred embodiment wherein mandrel 24
has an outer diameter of 3.0 inches and housing 26 has an
inner diameter of approximately 4.38 inches, large
retainer ring 56a has an inner diameter of 3.38 inches.
Adjacent to large retainer ring 56a is compressible
bumper 58a. Compressible bumper 58a is preferably made of
a relatively low-resilience rubber compound. In one
preferred embodiment, compressible bumper 58a is formed of
80 durometer peroxide-cured Hycar, identified as a 1091-50
- rubber compound. Compressible bumper 58a is a tubular
member having an inner diameter proximate the outer
diameter of mandrel 24 but having an outer diameter which
is substantially less than the inner diameter of housing
26. In the preferred embodiment having the dimensions
described above, compressible bumper 58a has an outer
diameter of 3.85 inches.
' ~ , ,
.
', ` ' ~. ~
,
.
.
. , ' ' ` ` ,
. , , ` ` ' ` : .
1i~7;~66
--11-- `
Adjacent compressible bumper 58a is radial bumper
60a. Radial bumper 60a is preferably formed of the same
rubber compound zs that of which compressible bumper 58a
is formed. Radial bumper 60a is a tubular member which i8
preferably sized to substantially fill the annular gap
between mandrel 24 and housing 26.
Adjacent radial bumper 60a is small retaining ring
62a. Small retaining ring 62a is pr~ferably formed of a
rigid, nondeformable material such as steel. Small
retaining ring 62a has an inner diameter which is proxi-
mate the outer diameter of mandrel 24 and an outer
diameter which is substantially less than the inner
diameter of housing 26. In the embodiment having the
dimensions as discussed earlier herein, small retaining
ring 62a has an outer diameter of 4.0 inches. Small
,~ retaining ring 62a contacts, and rests adjacent, shoulder
;~) 61 of end cap 28. Upper shock absorbing assembly 52a is
thus retained between shoulder 46 of mandrel 24 and end
20 cap 28 secured to housing 26. Shoulder 46 of mandrel 24
and shoulder 61 of end cap 28 provide opposing shoulder
surfaces for transmitting force through upper shock
absorber assembly 52a.
Referring now to lower shock absorbing bumper
assembly 52b, small retainer ring 62b rests adjacent a
shoulder 70 of pin connector 30. Shoulder 70 of pin
connector 30 and shoulder 46 of mandrel 24 thereby provide
opposing surfaces through which force may be transmitted
between pin connector 30, attached to housing 26 and
mandrel 24, through lower shock absorbing assembly 52b. A
pair of apertures 72a, 72b are provided in housing 26,
positioned one to either side of the resting position of
shoulder 46.
~,~ 35
c~ . .
.
' ,
'
, ~ ,
12~;'';~866
-12-
Shock will be absorbed in longitudinal shock absorber
20 through the longitudinal movement of housing 26
relative to mandrel 24 against the resistance of either
upper or lower shock absorbing assembly 52a or 52b. Upper
and lower shock absorber assemblies 52a, 52b are
preferably conformed such that compressible bumpers 58a
and 58b will be under load when longitudinal shock
absorber 20 is not subjected to external loading. The
longitudinal travel, or telescoping, of mandrel 24
relative to housing 26 is determined primarily by the
relation of the volume of compressible bumpers 56a, 56b
relative to the volume of the annular space which each
bumper fills. In the preferred embodiment having the
dimensions as described earlier herein, longitudinal shock
absorber 20 is conformed to facilitate approximately 4
inches travel between mandrel 24 and ~ousing 26. Thus,
f~ from a neutral, or "rest", position, mandrel 24 may move 2
~ ~ inches in either direction relative to housing 26.
~ .
Referring now also to FIG. 3, therein is shown
longitudinal shock absorber 20 in an operating configura-
tion, with housing 26 moved upwardly for approximately
one-half of its available travel relative to mandrel 24.
As indicated earlier herein, compressible bumpers 58a, 58b
are preferably configured such that when mandrel 24 is in
a~ rest position relative to housing 26, compressible
bumpers 58a, 58b are each under partial load.
Compressible bumpers 58a or 58b are also preferably sized
that such 2 inches movement in either direction will cause
one compressible bumper 56a, 56b to be fully compressed
into the annulus between mandrel 24 and housing 26, and
will allow the other compressible bumper 56a, 56b to be
fully relaxed.
':;''
:
.
,
':- ' ' - ' - '
1~'7~866
--13--
In operation, as can be seen in FIG. 3, as housing 26
moves upwardly relative to mandrel 24, compressible bumper
58b begins to extrude to fill annulus 63b. Pressure
relief port 72b is preferably situated such that as
shoulder 46 and large retaining ring 56b, of shoulder 70
moves toward box connector 30, causing compressible bumper
58b to extrude, large retaining ring 56b will cover port
72b before compressible bumper 58b will extrude through
port 7~b.
As housing 26 moves upward relative to mandrel 24,
and compressible bumper 58b compresses, compressible
bumper 58a relaxes. It will be readily appreciated that a
downward movement of housing 26 relative to mandrel 24
will cause opposite reactions in compressible bumpers 58a
and 58b. Longitudinal shock may be imparted to tool
,_~ string 11 in either an upward or downward direction. Such
shock may also initiate a generally oscillating motion in
tool string 11. Shock absorber 20 is therefore designed
to damp acceleration in either longitudinal direction.-
Radial bumpers 60a, 60b absorb radial "whipping", orshock, between mandrel 24 and housing 26. The gaps
between large retaining rings 56a, 56b and mandrel 24; and
the gaps between small retaining rings 62a, 62b and
housing 26, facilitate the pivoting action of housing 26
relative to mandrel 24. With the exception of the contact
between mandrel 24 and pivot point 41 of endcap 28, there
is preferably no metal-to-metal contact between mandrel 24
and housing 26 or components coupled thereto. In connec-
tion with avoiding this metal-to-metal contact, and
resulting shock, the longitudinal apertures through pin
connector 30 and endcap 28, except at pivot point 41, are
preferably sized to avoid contact with mandrel 24 as
.~,. . .
" .
.
:
127~866
--1~-- . .
mandrel 24 moves within the range allowed by radial
bumpers 60a, 60b.
Referring now to FIGS. 4A-B, therein is shown radial
S ~hock absorber 18 of FI~. 1 in greater detail, illustrated
in quarter-sectional view. Radial shock absorber 18
includes a generally tubular mandrel 80 havinq a longitu-
dinal aperture 82 therethrough. A generally tubular
housing 84 is situated concentric to mandrel 80. Radial
10 shock absorber 18 includes a plurality of drag shoes 86
which extend radially relative to housing 84. In one
preferred embodiment, radial ~hock absorber 18 includes
four drag shoes 86. Drag shoes 86 are reciprocatingly
mounted relative to mandrel 80 and are urged toward the
15 outer extent of their radial travel relative to mandrel
80. In a particularly preferred embodiment, a plurality
r-> of springs 88 are utilized to urge drag shoes 86 radially
outwardly relative to mandrel 80. A plurality of spring
carrier blocks 90, are each located between a respective
drag shoe 86 and mandrel 80 in an aperture 91 in housing
84. Each of the spring carrier blocks 90 is cooperatively
formed with a respective drag shoe 86 such that each drag
shoe 86 will cooperatively engage its respective spring
carrier block 90. me plurality of springs 88 are
retained between a spring carrier block 90 and an
associated drag shoe 86 and are utilized to exert an
outwardly radial force on such drag shoes 86.
In a particularly preferred embodiment, each drag
shoe 86 is urged radially outwardly by five coil springs
88. Springs 88 are preferably retained within opposing
recesses 92a, 92b, in spring carrier block 90 and drag
shoes 86, respectively. Springs 88 may be selected
according to anticipated operating conditions. In one
particularly preferred embodiment, springs 88 have been
: "
.
15-
.~ .
~- selected such that each drag shoe 86 is loaded by springs
88 to an initial preload force of 74 pounds. In this
particularly preferred embodiment, springs 88 are selected
such that a maximum travel of any one drag shoe 86 toward
mandrel 80 will require a total force of approximately 375
pounds on that drag shoe 86. Also in this preferred
embodiment, the maximum travel of each drag shoe 86 is
approximately .9 inches.
.
Drag shoes 86 are retained in radial shock absorber
lB by opposing upper and lower lip assemblies, 92 and 94
respectively. Upper and lower lip assemblies 92 and 94
restrain complementary upper and lower lip assemblies 96
and 98 on drag shoe 86. Lower housing lip assembly 94
15 extends from housing 84 and defines a recess 100 between
lower lip 94 and mandrel 80. Lower lip 98 of drag block
86 is free to move within recess 100.
.
Upper lip 96 of drag block 86 is retained by an upper
20 lip assembly 92 on retaining cap 102. Retaining cap 102
is preferably secured by a threaded coupling 104 to
housing 84. Upper lip assembly 92 is formed into
retaining cap 102. Upper lip assembly 92, cooperatively
with housing 84 defines a recess 106 in which lip 96 of
25 drag shoe 86 may travel. When retaining cap assembly 102
is secured by threaded coupling 104 to housing 84,
- threaded coupling 104 is se~ured through use of a set
screw 108 utilized in a conventional manner.
Retaining cap 102, housing 84, spring retention
blocks 90 and drag shoes 86 form a unit which is free to
rotate relative to mandrel 80. This freedom of rotation
facilitates movement or rotational manipulation of tool
~J-~ ' string 11 within the borehole without undue friction from
drag shoes 86 against the boundaries of the borehole. A
,
- . -
, .
. .
- ' '
127;~86~;
-16-
thrust ring 115 is preferably situated between retainer
cap 102 and box connector 112 to facilitate the free
rotation of housing B4 and retainer cap 102 relative to
box connector 112 and mandrel ~0. A grease nipple 110 is
preferably provided in housing 84 to facilitate the intro-
duction of grease or another lubricant to facilitate the
above-described rotation.
Radial shock absorber 18 includes an upper box
connector 112 secured to mandrel 80 by a threaded coupling
114. A conventional 0-ring seal 11~ is preferably
provided between mandrel 80 and box connector 112.
.
Radial shock absorber lB includes a lower pin
connector 118 which is secured to mandrel 80 by a threaded
coupling 120. A conventional 0-ring seal 122 is again
' ~ preferably provided between pin connector 118 and mandrel.
--J 80. As depicted in FIGS. 4A-B, box connector 112,
retainer cap 102, and pin connector 118 each include
externa-l flats, indicated generally at 138, to facilitate
the making up and breaking out of the described threaded
connections.
As discussed earlier herein, housing 84 and drag
shoes 86 are rotationally mounted relative to mandrel 80.
In a particularly preferred embodiment, radial shock
absorber 18 includes an optionally threaded coupling
assembly, indicated generally at 124. ln threaded
coupling assembly 124, the lower extension 126 of housing
84 includes a female threaded section 128. Lower pin
connector 118 includes a male threaded section 130
appropriately configured to mate with female threaded
section 128 on housing 84. Under normal operating
conditions, housing 84 is retained in an upper, longitu-
dinally spaced position from pin connector 118 such that
.
.
i;~ 66
--17--
female threaded Eiection 128 and male threaded section 130do not engage one another. Housing 84 is therefore free
to rotate relative to mandrel 80 and pin connector 118.
Housing 84 is preferably retained in this upper position
5 by means of a shear ring 132 coupled to mandrel 80 by
means of a shear pin 134. In one embodiment, shear pin
143 and shear ring 132 a~e designed to reguire 14,000 lbs.
of force to shear. A thrust bearing 136 facilitates the
rotation of housing 84 relative to shear ring 132.
Referring now also to FIG. 5, therein is illustrated
emergency thread mechanism 124 in an actuated position,
wherein housing 84 is nonrotatably secured relative to pin
connector 118 and mandrel 80. In a typical operating
15 ~ituation, threaded coupling assembly 124 will be actuated
by a downward force exerted on drag shoes 86. This down-
ward force may be exerted by an overshot or fishing tool,
as are well known in the oil and gas industry. Once this
downward force exceeds the capacity of shear pin 134 and
20 shear ring 132, the downward force will cause female
threaded section 128 to be moved to a position proximate
male threaded section 130. Thereafter, any rotation in
the appropriate direction for the threads will cause
female threaded section 128 and male threaded section 130
25 to threadably engage and thereby provide a secure coupling
between housing 84 and pin connector 118. After such
secure coupling is established, rotation may be applied to
drag shoes 86, such as in a milling over operation.
- 30 In the operation of radial shock absorber 18, a
radial force tendiny to move the tool string, including
radial shock absorber 18 to one side in the borehole 10,
will be damped by the compression of springs 88 supporting
drag shoes 86. The action of the spring-loaded drag shoes
i 35 86 will dampen radial accelerations of tool string 11 and,
."~.. ... .~ .,.... .. . . . . .. .. - .. . . - . . .. .. .. ... . ...
,
--
:
:, . . .
~7~866
-18-
within the limits of the compression range of such springs
88 as are acted upon, will minimize impacts of any portion
of the tool string against casing 14.
Referring now to FIGS. 6A-C, therein is illustrated
another embodiment of a shock a~sorbing system 160 in
accordance with the present invention. Shock absorbing
system 160 contains components previously described herein
which will be identified by the same numerals ~s
previously utilized for those components.
Shock absorbing system 160 is depicted as depending
from a tubing string 13. The tool string is depicted as
including a packer 144 which may be of any conventional
type. Coupled to packer 144 are a plurality of shock
absorbing gauge carriers 142a, 142b. A length of
- perforated pipe at 146 is suspended from packer 144.
; Perforated pipe 146 is preferably a heavy weight drill
pipe which is perforated where ever possible to facilitate
fluid communication between the interior of the tool
string and the borehole annulus surrounding the tool
string. Perforated pipe 146 serves as a mass to help damp
shock and further serves to space perforating gun 154 from
packer 144. A longitudinal shock absorber 20 as
previously described herein is coupled to perforated pipe
146. A perforated nipple 150 is coupled to longitudinal
shock absorber 20a, again to facilitate fluid communica-
tion between the interior of tool string 140 and the bore-
hole annulus surrounding the tool string 140. A perforat-
ing gun 154, and a conventional firing head 152 aresuspended from perforated nipple 150. Coupled to the
bottom of perforating gun 154 is radial shock absorber 18
having another longitudinal shock absorber 20b coupled
thereto. At the lower end of the tubing string, coupled
to longitudinal shock absorber 20b may be other pieces of
:. ~
66
-19-
e~uipment, such as, for example, conventional instruments
or gauges 156a, 156b. Tool string 140 i5 exemplary of
only one means of utilizing a shock absorbing system in
accordance with the present invention. Those skilled in
the art will appreciate that tool string 140 could include
either fewer or additional components and could include
components arranged in a different order than is depicted
in FIGS. 6A-C.
Shock absorber system 160 includes radial shock
absorber 18 located adjacent, and preferably below
perforating gun 154. Shock absorber system 160 then
preferably includes longitudinal shock absorbers 20a and
20b on upper and lower ends, respectively. Longitudinal
shock absorbers 20a, 20b serve to provide a mounting for
perforating gun 154 which is shock mounted both above and
below perforating gun 154. Accordingly, any longitudinal
acceleration of perforating gun 154 upon detonation will
recei~e a damping effect in`each direction through the
action-of longitudinal shock absorbers 20a, 20b.
,
In some systems, it may be desirable to utilize
longitudinal shock absorbers of different dimensions.
Longitudinal shock absorbers of different dimensions will
have different shock absorbin~ capacities. In shock
absorber system 160, there is relatiYely little suspended
mass beneath lower shock absorber 20b. Accordingly, it
may be desirable to use a lower shock absorber 206 which
will provide less resistance to acceleration between the
housing and mandrel of the longitudinal shock absorber so
as to optimally damp shock to carriers 156a, 156b.
Radial shock absorber 18 is preferably situated
immediately adjacent perforating gun 154 in this embodi-
.
.,
.~
' ' ' . ,
" ' ' '
'
~Z'73866
-20-
ment to minimize any radial "whipping" of perforating gun
154 which would cause similar movement in tool string 140.
Gauge carriers 142a, 142b are situated below packer
S 144, and are utilized to support relatively sensitive
instruments, such as temperature and pressure recorders.
Although gauge carriers 142a, 142b are illustrated
immediately below packer 144, it should be readily under-
stood that in alternative embodiments gauge carriers 142a,
142b may be situated in other positions within the tool
string.
Referring now to FIG. 7, therein is shown a gauge
carrier 142 in accordance with the present invention.
In one preferred embodiment, each gauge carrier 142a, 142b
is adapted to hold four cylindrical gauges or instruments
~- of substantial length. The depicted embodiment of gauge
carrier 142 is therefore illustrative only, and the
depicted components may be adapted to accommodate device
of other dimensions or conformities.
Gauge carrier 142 includes a generally cylindrical
housing 161 having a box connector 162 threadably coupled
at a first end and a pin connector 164 threadably coupled
at a second end. Retained within housing 161 between box
connector 162 and pin connector 164 is a shock absorbing
cage assembly, indicated generally at 166, supporting a
plurality of cylindrical gauges 168.
Referring now also to FIGS. 8 and 9, therein is shown
in FIG. 8 the portion of gauge carrier 142 containing
shock abs~rbing cage assembly 166, depicted in quarter-
sectional view; while in FIG. 9 is shown an exploded view
, of shock absorbing cage assembly 166, and a gauge 168,
.
.. - . , ~ .
: ` . ' '
.
:. ' ' ' . `: ' `
, .
i6
-21-
showing the relationship of-the vari~us types ~f
-components included therein.
Shock absorbing cage assembly 166 includes a base
plate 170 which contains a plurality of threaded apertures
172. In an embodiment adapted to support four cylindrical
gauges, as illustrated, base plate 170 contains four
threaded apertures 172, one to threadably couple to each
of four tie rods 174. For clarity, only one tie rod 174
and only one gauge 168 are illustrated in FIG. ~. A
plurality of spacers 176 are adapted to slidably fit onto
tie rods 174. In one preferred embodiment wherein tie
rods 174 are approximately six feet long, shock absorbin~
cage assembly 166 includes 20 spacers 176 arranged in five
sets of four, such sets being distributed in generally
equal spacings along the length of tie rods 174.
) Each spacer 176 is preferably formed of a low
resilience rubber compound such as 80 durometer,
peroxide-cured Hycar, as discussed earlier herein.
-Referring now also to FIG. 10, each spacer 176 represents
an approximately 90 section of a tubular member. Each
spacer 176 therefore exhibits a cross-section having an
external convex portion 180 and an internal concave
portion 182. Each spacer 176 cross-section also exhibits
a concave portion on either side, 184a, 184b, and a
central longitudinal aperture 186. Side concave portions
184a, 184b are configured such that when a set of four
spacers 176 are arranged in one plane, with each tie rod
174 extending through central aperture 186 of a spacer
176, side concave portions 184a, 184b of adjacent spacers
176 will cooperatively substantially define longitudinally
extending cylindrical apertures 187. Spacers 176 are
dimensioned such that apertures 187 will substantially
enclose cylindrical gauges 168.
~ ' '' ' ', ' '' . ' ' ' , ' ' ' _ ' ,
1''' '- '' ' ' '' '`'`,' ' ' ":'" "" ' ''" '', '
~' ', ' ' ' ' ~ '
. ~ ' .
'', ' ' ' ' ' '
' ''
lZ7~866
-22-
Spacers 176 are ~ecured in position along tie rods174 by an appropriate mechanism such as split rings or
tru-arc rings 188 ~FIG. 7) retained within recesses 190 in
tie rods 174. Rubber pads or washers 192 are preferably
situated between rings 18~ and spacers 176 to fill any
tolerance gaps ~etween recesses 190 and spacers 176.
Upper ends 194 of tie rods 174 are retained within
support ring 196. Upper ends 194 are configured to tele-
scopingly mate with a first set of apertures 198 insupport ring 196. Support ring 196 is retained proximate
upper ends 19~ of tie rods 174 by mechanisms such as tru-
arc rings 189 within recesses 191 in upper ends 194 of tie
rods 174.
The above described structures define the basic cage
'~3 assembly 166 which supports gauges 163. In the illu-
' strated embodiment, gauges 168 have male threaded
couplings 200 on each end. Accordingly, lower end fitting
202 includes a female threaded portion 204 adapted to
threadably couple to gauge 168. Lower end fitting 202
preferably includes a longitudinal extension 206 which is
~- telescopingly received within an annulus bumper pad 20R
; and a mounting ring 210. Bumper pad 208 is also
preferably formed of a relatively low resilience rubber
compound such as 80 durometer, peroxide-cured Hycar, as
discussed earlier herein. Mounting ring 210 is preferably
a metal ring including a central aperture 212. Mounting
ring 210 is securely attached, such as by welding, to base
plate 170.
A plurality of 0-rings, indicated generally at 214,
: are preferably housed within mountinq ring 210, concentric
~.~ to longitudinal extension 206 to prevent metal-to-metal
: ~!. 35 contact between extension 206 and mounting ring 210. 0-
,,~ , , ' ' ' . . .
,
'
~ Z'7;~t~66
-23-
rings 214 may be retained within mounting ring 210 by
upper and lower lips 216a, 216b, respectively, formed in
mounting ring 210.
At the upper end of gauges 168, shock absorbing cage
assembly 166 includes an upper end fitting 218 which
includes a female threaded portion 220 adapted to thread-
ably couple to cylindrical gauge 168. Upper end fitting
218 also includes a longitudinal extension 222 which is
10 telescopingly received within an annular bumper pad 224
and in one of a set of second apertures 226 within support
ring 196. Bumper pad 224, is preferably formed of a
similar low resilience rubber compound as that of which
lower bumper pad 208 is formed. As can be seen in FIGS. 7
and 8, extension 222 of upper end fitting 218 preferably
extends only within support ring 196. However, upper ends
fr~ 194 of tie rods 174 extend through support ring 196 and
- J
~,; contact an annular pad 228 adjacent shoulder 230 of box
connector 162. Annular pad 228 is again formed of the~
20 same relatively low resilience rubber compound as
disclosed earlier herein.
.
When cage assembly 166 is placed within housing 160,
base plate 170 will rest against a shock absorbing ring
232. Shock absorbing ring 232 is again formed of a
relatively low resilience rubber compound as discussed
earlier herein. Shock absorbing ring 232 is retained
; against shoulder 234 of lower pin connector 164 by a
plurality of bolts 236.
~ 30
-~ In particular environments, it is often desirable to
include a central s~eeve 238 through shock absorbing cage
assembly 166. Sleeve 238 will provide a smooth cylindri-
cal path through gauge carrier 142, so as to facilitate
" ~ .
. ,~. . .
,~
.
'` `.'. ' ` '. ~ ' . " " ' ' ' ~ , `
`', ~ ' ' ~, ` : `
'
. ' ` ` . . ,
127~ i6
-24-
, .
the movement of objects such as "go-devilsn, or detonating
bar6, through the gauge carrier.
In operation, telescoping mountings at either end of
gauges 168 facilitate longitudinal movement of the gauges
168 to absorb longitudinal shock. The accelerations of
gauges 168 in either longitudinal direction due to shocks
experienced by housing 161 of gauge carrier 142 are damped
through the action of bumper pads 208 and 224.
Additionally, radial acceleration of the gauges is
- restrained by the sets of spacers 176. Spacers 176 serve
not only to prevent radial metal to metal contact between
gauges 168 and housing 160, but also serve to tie gauges
16B together radially to minimize any radial whipping of
gauges 168.
~ .. .
J As described herein, gauge carrier 142 provides a
unique cage assembly for supporting each of the gauges
such that no metal-to-metal contact will be made between
20 the gauge and any other component when cage assembly 168
is installed within housing 160. Cage assembly 166 there-
fore facilitates the preassembling of one or more cage
units with gauges which can be selectively placed into a
housing 160 as desired.
Referrinq now to FIGS. 11 and 12, therein is shown a
bracket 240 for facilitating easy insertion and removal of
cage assembly 166 from housing 160. Bracket 240 includes
a base plate 242 and a handle 244. Base plate 242
30 contains a plurality-of radially distributed keyslots 246
arranged to engage recesses 248 in upper ends 194 of tie
rods 174. By inserting upper ends 194 through keyslots
246 of base plate 242, and rotating base plate 242 with
handle 244 bracket 240 grips tie rods 194 at recesses 248
,
,
'
.,
lZ'î~;~866
~25-
and facilitates the insertion or withdrawal of cage
assembly 166 into or out of housing 160.
Referring now to FIG. 13, therein i8 depicted an
alternative embodiment of a gauge carrier 250 in
accordance with the present invention. The embodiment of
gauge carrier 250 may be of particular use when minimizing
the diameter of the gauge carrier is not critical. As
with the previous embodiment, gauge carrier 250 includes a
housing 256, a box connector 258, and a pin connector 260.
Cage assembly 254 of gauge carrier 250, however, utilizes
a central support tube 252 as the longitudinal structural
member, rather than the tie rods of the previously
described embodiment. Also as with the previously
described embodiment, an annular bumper pad 262 is secured
- to pin connector 260. For clarity, only one gauge is
illustrated in FIG. 13. It should be readily understood
,; that a number of gauges will typically be supported by
cage assembly 254. The number of gauges which may be
supported will be determined primarily by the size of the
gauges and the diameter of the annular area between
central support tube 252 and housing 256.
,
Cage assembly 254 includes central support tube 252
defining an interior passageway 266. Central support tube
252 may be threadably coupled, as at 264, to pin connector
260. Central support tube 252 is preferably perforated to
assure that no pressure differential will be established
between interior passageway 266 and the gauges, as
illustrated at 268.
Also threadably secured to central support tube 252
is support ring 270. Support ring 270 is an annul ar
member having a plurality of apertures 272 extending
- 35 therethrough. Each aperture 272 includes a bacXbore
~..
'
' ' ~ ' , . '
' . ' '
:
'
i27;~866
-26-
`- portion 274 which houses a plurality of 0-rings 276. As
will be apparent from the discussion to follow, these 0-
rings 276 serve as the retention mechanism for gauges 262.
Preferably, ~ix to ten appropriately sized 0-rings are
housed within backbore 274.
As with the previously described embodiment, a
mounting adapter 278 is affixed to gauge 268. As
previously discussed herein, where gauge 268 includes a
male threaded portion extending therefrom, mounting
adaptor 278 will include a female threaded member
cooperatively conformed to mate with the male threaded
portion of gauge 268. Mounting adapter 278 includes a
longitudinal extension~280 h~ing a plurality of ~ ~e~
~bO~ frusto conical sections, illustrated generally at
282. An annular bumper ring 284 is disposed on extension
~~ 280 between shoulder 286 of mounting adapter 278 and
-~~ support ring 270. Frusto conical extensions 282 are
cooperatively sized with 0-rings 276 to facilitate the
insertion of extension 280, but to prevent the ready
removal of extension 280. Thus, mounting adapter 278 and
attached gauge 268 are retained within support ring 270,
while 0-rings 282, extension 280 and annular bumper pad
284 cooperatively facilitate shock isolation of gauge 268.
Because lower mounting assembly 271 secures gauge 268
from vertical removal, upper ends 296 of gauges 268 are
not individually retained.
A plurality of annular spacers 288 are preferably
utilized along the length of gauges 268 to minimize radial
acceleration of gauges 268 along their length. Each
annular spacer 288 is preferably formed of a relatively
low resilience rubber compound as previously discussed
herein. Annular spacers 288 each includes a central
aperture 290 to allow annular member 288 to slidably fit
-~ ' -.: '
1273~66
-27-
over central support tube 252. Annular members 288 are
then each preferably retained in place on central support
tube 252 by a C-ring 292 which engages recesses 294 in
central support tube 252.
In the operation of gauge carrier 250, annular
spacers 288 will damp radial movement or acceleration of
gauges 268. In reaction to longitudinal forces, a
d~wnward l~ngitudinal force will cause acceleration of
gauge 268 to be damped through the compression of annular
bumber 284. An upward longitudinal acceleration on gauge
26B will be damped by the pull of frusto conical
extensions 288 against the resilient mounting of 0-rings
282. Accordingly, gauge carrier 250 damps both radial and
1~ longitudinal accelerations of gauges 26B.
- j Referring now to FIG. 14, therein is illustrated a
cage assembly 300 of another alternative embodiment of a
gauge carrier 302 in accordance with the present
~- 20 invention. Gauge carrier 302 is particularly adapted to
carry a small number of gauges 304 in a minimal
diametrical area, while still providing a passageway 306
to facilitate the movement of fluid or mechanisms through
g~uge carrier 302.
Cage assembly 300 includes a support tube 308 which
defines passageway 306. Rather than extending continually
alon~ the longitudinal axis of gauge carrier 302, support
tube 308 is bent, maintaining a constant interior
diameter, such that while upper and lower ends, 310 and
312, respectively, are aligned generally along the
longitudinal axis of gauge carrier 302, a central portion
314 will be eccentrically located relative to the
:: longitudinal axis. The bends in support tube 308 may be
-~ 35 relatively slight, such as on the order of 1-2 degrees, to
'
i~'7;~6~i
-28-
facilitate the passage of mechanisms through passageway
306. Support tube 208 i6 preferably conformed ~uch that
exterior wall 316 of central portion 314 will lie
substantially adjacent at the interior of housing 318.
5upport tube 308 again contains perforations, indicated
generally at 320 to prevent the establishing of a pressure
differential between passageway 306 and gauges 304.
Upper end 310 of support tube 308 is slidably
retained within box connector 305. Treadably secured to
lower end 312 of support tube 308 is a support plate 309.
Support plate 309 rests against an annular pad 311 as
described with respect to the previous embodiments of
gauge carriers.
In gauge carrier 302, gauges are supported by a
, mounting assembly, indicated generally at 320, which is
~") supported on support tube 308. Mounting assembly 320 is
preferably supported diametrically opposite central
portion 314 of support tube 308.
Mounting assembly 320 includes a lower mounting
member 322 which is operatively configured and functions
identically to lower mounting assembly 271 in the
embodiment of FIG. 13, with the exception that lower
mounting block 324 extends only to one side of support
tube 308. Mounting member 314 is preferably securely
attached to support tube 308, such as by welding. Lower
mounting member 322 may contain mechanisms for retaining
as many gauges as a particular design facilitates. As
will be apparent from the discussion to follow, the
illustrated embodiment of guage carrier is intended to
support two gauges.
~ ' .
~ .. ~ . ,- r - . ` ~ ' ' ` ` ` '
.~ ' '' .' , ' ~ ' .
.
~ ' ~ ,; , ' ', :, .
lZ73~66
-29-
Referring also now to FIG. 15, therein is depicted
-gauge carrier 302 in cross-section along line 15-15 in
FIG. 14. Spacers 326 may preferably be of a generally
half circle configuration, having a concave portion 334
adapted to cooperatively engage the perimeter of tube 308.
In the illustrated embodiment, spacers include two
apertures 336 which engage two _ gages 304.. A
plurality of spacers 326 are again distributed along the
length of gauges 304. Spacers 326 are again preferably
formed of a relatively low resilience rubber compound as
discussed earlier herein. Spacers 326 may be retained in
place along gauges 304 by appropriate mechanisms, such as
clamps 328 around gauges 304. As with the previous
embodiments, a plurality of spacers 326 will be
15 ~istributed over the length of gauges 304. An upper
mounting assembly 330 may optimally be utilized to retain
upper ends 332 of gauges 304 aligned in parallel with the
longitudinal axis of gauge carrier 320.
Referring also now to FIG. 16, therein is illustrated
gauge carrier 302 depicted in cross-section along line
16-16 in FIG. 14. Upper mounting assembly 330 may be any
appropriate mechanism. In the illustrated embodiment,
upper mounting assembly i5 a split ring mechaniam adapted
to retain upper ends 332 of gauges 304. Split ring
assembly 330 includes a first portion 340 which is
suitably affixed, such as by welding, to support tube 30B.
First portion 340 contains partial apertures 339a for
supporting upper ends 332 of gauges 304. A second portion
342 includes complimentary partial apertures 339b to
encircle upper ends 332 of gauges 304. Second portion 342
is appropriately secured, such as by bolts 344 to first
portion 340 to retain upper ends 332 of gauges 304.
Annular bumpers 341 are preferably supported concentric to
each upper portion 332 of gauges 304 beneath upper
~'
': ~
, ::
, , . " . ,,
,- - , - .
- , . . - -
- - -: - , . .
. , : ~- ., . -, :
. - ~,, - , . .
:' . ' - - ~ -
.
lZ7;~866
-30-
mounting assembly 330. Annular bumpers are preferably
conformed of a relatively low resilience rubber compound
as discussed earlier herein.
In operation, shock to gauges 304 will be damped by
lower mounting assembly 320 in the manner previously
described with respect to lower mounting assembly 271 in
the embodiment of FIG. 13. Annular bumpers 341 prevent
the impacting of gauges 304 against upper mounting
assembly 330.
Many modifications and variations may be made in the
techniques and structures described and illustrated herein
without departing from the scope of the present invention.
Accordingly, it should be readily understood that the
embodiments shown and discussed herein are illustrative
-~ only and are not to be considered as limitations upon the
~ scope of the present invention.
.
` .
-,"
. ~jJ' ,.
.:
, . : ,
