U.S. patent application number 09/076964 was filed with the patent office on 2002-01-03 for disconnect tool.
Invention is credited to GISSLER, ROBERT W..
Application Number | 20020000320 09/076964 |
Document ID | / |
Family ID | 22135285 |
Filed Date | 2002-01-03 |
United States Patent
Application |
20020000320 |
Kind Code |
A1 |
GISSLER, ROBERT W. |
January 3, 2002 |
DISCONNECT TOOL
Abstract
A disconnect tool includes a housing that has a first segment
and a second segment. A first collet is coupled to the first
segment and has a first plurality of fingers, each of the first
plurality of fingers is bendable between a first position in which
the fingers engage the first segment and prevent relative sliding
movement between the first and second segments, and a second
position in which the fingers do not engage the first segment and
do not prevent relative sliding movement between the first and
second segments. A first piston is positioned in the housing and
has a third position wherein the piston engages and prevents the
fingers from bending from the first position, and a fourth position
wherein the piston does not engage and prevent the fingers from
bending from the first position. The disconnect tool includes means
for selectively retaining the first piston in the third position
and means for moving the first piston from the third position to
the fourth position. On-board and surface control systems may be
incorporated to permit selective active of the disconnect
mechanism. In addition, couplings and connector employing
shape-memory materials may be included to secure the tool to coiled
tubing and a wireline.
Inventors: |
GISSLER, ROBERT W.; (SPRING,
TX) |
Correspondence
Address: |
MARLIN R. SMITH, ESQ.
KONNEKER & SMITH, P.C.
660 N. CENTRAL EXPWY.
SUITE 230
PLANO
TX
75074
US
|
Family ID: |
22135285 |
Appl. No.: |
09/076964 |
Filed: |
May 13, 1998 |
Current U.S.
Class: |
166/340 ;
166/241.5; 166/322; 166/374; 166/377; 166/55 |
Current CPC
Class: |
F16B 1/0014 20130101;
E21B 17/023 20130101; E21B 17/06 20130101; F16L 29/04 20130101;
Y10T 403/581 20150115; E21B 47/007 20200501; E21B 34/06 20130101;
Y10T 403/61 20150115; E21B 47/092 20200501; E21B 17/028 20130101;
E21B 2200/05 20200501; E21B 17/206 20130101; E21B 41/0085 20130101;
E21B 23/04 20130101 |
Class at
Publication: |
166/340 ; 166/55;
166/377; 166/241.5; 166/322; 166/374 |
International
Class: |
E21B 023/00 |
Claims
What is claimed is:
1. A disconnect tool, comprising: a housing having a first segment
and a second segment; a first collet coupled to the first segment
and having a plurality of fingers, each of the first plurality of
fingers being bendable between a first position in which the
fingers engage the first segment and prevent relative sliding
movement between the first and second segments, and a second
position in which the fingers do not engage the first segment and
do not prevent relative sliding movement between the first and
second segments; a first piston positioned in the housing and
having a third position wherein the piston engages and prevents the
fingers from bending from the first position, and a fourth position
wherein the piston does not engage and prevent the fingers from
bending from the first position; means for selectively retaining
the first piston in the third position; and means for moving the
first piston from the third position to the fourth position.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates generally to disconnect tools, and
more particularly to a disconnect tool incorporating a coupling for
connecting to tool, tubing, or pipe, and a disconnect
mechanism.
[0003] 2. Description of the Related Art
[0004] Disconnect tools have long been known in the field of well
drilling and servicing equipment. A disconnect tool is employed in
a working string or bottom hole assembly ("BHA") to provide the
capability of disconnecting the coiled tubing or drill pipe
upstream from the working string or BHA. The disconnect tool is
activated in situations where the working string has become stuck
to such a degree that it cannot be readily dislodged from the
wellbore either through upward thrust on the drill pipe or coiled
tubing or via jarring forces imparted by a drilling jar, alone, or
in combination with an accelerator incorporated into the working
string. After the disconnect tool has been actuated and the
removeable portion of the tool and upstream portion of the drill
pipe or coiled tubing have been withdrawn from the wellbore, a
fishing tool is normally inserted in the wellbore to engage and
dislodge the stuck working string. Although the problem of stuck
tools is present in both coiled tubing and conventional drill pipe
operations, the requirement for a reliable disconnect capability is
often more important in coiled tubing operations, since coiled
tubing has a limited capacity to apply upward thrust on a stuck
tool.
[0005] Most conventional disconnect tools consist of a tubular
housing subdivided into two sections joined together at a joint
that may be selectively decoupled to enable the two sections to be
separated so that the length of tubing or string above one of the
sections may be removed from the wellbore along with one of the
sections. The upstream section of the housing ordinarily includes
some type of coupling for connecting the disconnect tool to the
drill pipe, coiled tubing, or wireline, as the case may be. The
lower section of the housing also includes a coupling of one sort
or another for connecting the disconnect tool to other components
in the string, such as additional drill pipe or other tools. In the
case of drill pipe, this lower connection is commonly a pin or box
connection.
[0006] The tool-to-coiled tubing coupling mechanism in many
conventional disconnect tools consists of a hydraulically actuated
mandrel which is movable longitudinally to set or wedge sets of
cooperating teeth together to engage the exterior of the end of a
piece of coiled tubing. These types of mechanisms may loosen over
time as a result of cyclic stresses that are commonly applied to a
working string in the downhole environment. As the coupling
loosens, there is the potential for the coiled tubing to disconnect
from the disconnect tool. The result is an unanticipated and
potentially costly fishing operation. In addition, hydraulically
actuated coupling mechanisms tend to be quite lengthy. The length
of a particular disconnect tool is ordinarily not a significant
issue in drilling operations where regular threaded drill pipe is
utilized. However, in coiled tubing applications it is desirable
that the length of all the tools in a particular drill string be no
longer than the length of the lubricator of the particular coiled
tubing injector. Thus, it is desirable that the disconnect tool be
economical in length to enable the operator to place as many
different types of tools in the working string as possible while
still keeping the overall length of the working string less than
the length of the lubricator.
[0007] Another type of conventional coupling mechanism commonly
employed in disconnect tools incorporates a sliding collar or a set
of grub screws. Like the aforementioned hydraulically actuated
mandrel mechanism, both the sliding collar and grub screw based
mechanisms are subject to inadvertent disconnection, due to
unavoidable play in the engagement between cooperating members or
to the mechanism employed to prevent relative axial movement of the
members. Undesirable length is also a drawback.
[0008] The disconnect mechanisms in most conventional disconnect
tools may be loosely grouped into three basic categorizes: pull or
thrust actuated; pressure actuated; and electrically actuated.
Thrust actuated systems contain some type of mechanism which
retards the axial movement of a mandrel or sleeve that is
concentrically disposed in the housing. In most conventional thrust
activated systems, the mechanism for resisting relative axial
movement consists of sets of shear pins or a collet that are
designed to fracture or collapse when a preselected axial thrust is
applied to the working string from the surface. In another type of
system used primarily on coiled tubing, the lower end of the coiled
tubing is fluted against an inwardly chamfered surface on the
housing. When the axial upward thrust applied to the working string
exceeds a preselected limit, the fluted portion of the coiled
tubing yields and releases from the disconnect tool.
[0009] Thrust activated disconnect tools present several
disadvantages. In systems where the entire weight of the working
string disposed below the disconnect tool is supported by the shear
pins or collet, the axial jarring loads that are commonly imparted
on the working string during operations may weaken the shear pins
or collet so that the required upward axial thrust required to fail
the shear pins or collapse the collet, as the case may be, is
reduced below the anticipated level. As a consequence, the
disconnect tool may be inadvertently triggered by applying an
upward thrust on the working string for operational reasons other
than tripping the disconnect tool. In addition, a given upward
axial thrust load may not be fully transmitted to the disconnect
tool. This circumstance may arise in wellbores with mechanical or
formation-based obstructions that engage portions of the working
string upstream from the disconnect tool. The problem may be
compounded in highly deviated wells where the coiled tubing
typically bottoms out against the sidewalls of the wellbore in the
vicinity, and downstream of the bend in the wellbore. As a
consequence, a greater than anticipated upward axial thrust must be
applied to the working string from the surface in order to trigger
the disconnect mechanism. This may be problematic in circumstances
where the amount of upward axial thrust required to overcome the
obstructions in the wellbore and provide a sufficient triggering
load on the disconnect mechanism exceeds the yield or fracture
strength of the tubing or any other components upstream from the
disconnect tool.
[0010] In contrast to thrust activated disconnect mechanisms,
pressure activated disconnect mechanisms operate in response to an
increase in the pressure of the working fluid inside the working
string. These types of disconnect mechanisms commonly incorporate a
moving piston which moves axially in response to an increase in
pressure above a preselected level to release or otherwise trigger
a mechanical mechanism, such as a collet, or one or more radially
movable dogs. In some conventional pressure actuated disconnect
mechanisms, the requisite increase in working fluid pressure must
be supplied from the surface. Robust and costly high pressure
pumping equipment must normally accompany the use of such
disconnect mechanisms. In other types of pressure activated
disconnect mechanisms, the requisite build-up of working fluid
pressure inside of the disconnect tool is accomplished by
introducing an obstruction to the flow of working fluid through the
disconnect tool downstream from the tripping mechanism. This is
typically accomplished by dropping a scaling ball into the drill
pipe or coiled tubing from the surface. The ball travels down
through the tubing and seats on a shoulder in the disconnect tool
downstream from the tripping mechanism, thereby closing off the
flow path and enabling the pressure of the working fluid to build
to the requisite level. Proper operation of pressure activated
disconnect mechanisms places heavy demands upon the seals within
such tools. If one or more of the seals in a given pressure
activated disconnect tool fails, the pressurized working fluid
inside the disconnect tool may vent into the well annulus without
tripping the mechanism.
[0011] In addition, pressure activated disconnect mechanisms are
subject to inadvertent actuation as a result of unanticipated
pressure increases inside the disconnect tool caused by
obstructions in the flow path of the working fluid downstream from
the disconnect tool. As an example, an obstruction in the
disconnect tool itself may cause the same effect as a scaling ball.
The unanticipated increase in working fluid pressure may not be
sensed at the surface in time to bleed pressure from the surface
and avoid an inadvertent disconnection. Finally, in pressure
activated disconnect systems employing a scaling ball, obstructions
in the drill pipe, coiled tubing, or other components may prevent
the scaling ball from actually reaching the proper position in the
disconnect tool.
[0012] Electrically actuated disconnect mechanisms normally employ
an electric motor to release a collet or set of dogs. The
difficulty associated with such systems is that jarring forces and
manufacturing irregularities may produce misalignment of the moving
parts. As a result, the moving components may not readily move when
the motor is actuated, leading to a potential locked rotor current
condition that may quickly fail the motor. In addition, power loss
from the surface may cripple this type of tool.
[0013] A disadvantage common to most conventional disconnect tools
is the inability to reconnect following a deliberate or inadvertent
disconnect.
[0014] The present invention is directed to overcoming or reducing
the effects of one or more of the foregoing disadvantages.
SUMMARY OF THE INVENTION
[0015] In accordance with one aspect of the present invention, a
disconnect tool is provided. The disconnect tool includes a housing
that has a first segment and a second segment. A first collet is
coupled to the first segment and has a first plurality of fingers
each of which is bendable between a first position in which the
fingers engage the first segment and prevent relative sliding
movement between the first and second segments, and a second
position in which the fingers do not engage the first segment and
do not prevent relative sliding movement between the first and
second segments. A first piston is positioned in the housing and
has a third position wherein the piston engages and prevents the
fingers from bending from the first position, and a fourth position
wherein the piston does not engage and prevent the fingers from
bending from the first position. The disconnect tool includes means
for selectively retaining the first piston in the third position
and means for moving the first piston from the third position to
the fourth position.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The foregoing and other advantages of the invention will
become apparent upon reading the following detailed description and
upon reference to the drawings in which:
[0017] FIG. 1 is a schematic view of an exemplary embodiment of a
disconnect tool in accordance with the present invention;
[0018] FIG. 2A-2F are sectional views of the disconnect tool in
accordance with the present invention;
[0019] FIG. 3 is a detailed sectional view of an exemplary
embodiment of a wireline connector shown in FIG. 2A in accordance
with the present invention;
[0020] FIG. 4 is a sectional of FIG. 2C taken at section 4-4;
[0021] FIG. 5 is a detailed sectional view of an exemplary
embodiment of a hydraulic coupling shown in FIG. 2C in accordance
with the present invention;
[0022] FIG. 6 is a sectional view of FIG. 2D taken at section
6-6;
[0023] FIG. 7 is a sectional view of FIG. 2D taken at section
7-7;
[0024] FIG. 8 is a sectional view of FIG. 2E taken at section
8-8;
[0025] FIGS. 9A-9B are detailed sectional views of the tool showing
an exemplary gas generator assembly in accordance with the present
invention;
[0026] FIG. 10 is a sectional view like FIG. 2F, but showing a
different rotation;
[0027] FIG. 11 is a block diagram of the internal circuitry of the
tool in accordance with the present invention;
[0028] FIG. 12 is a sectional view like FIG. 2C depicting
triggering piston in the triggered position;
[0029] FIG. 13 is a sectional view of an exemplary embodiment of a
coiled tubing-to-coiled tubing coupling in accordance with the
present invention;
[0030] FIG. 14 is a sectional view of an alternate arrangement for
a coiled tubing coupling in accordance with the present
invention;
[0031] FIG. 15 is a pictorial view of the shrink ring assemblies
depicted in FIG. 14 in accordance with the present invention;
and
[0032] FIG. 16 is a sectional view like FIG. 2F depicting an
alternate arrangement for a gas generator in accordance with the
present invention.
DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
[0033] Turning now to the drawings, and in particular to FIG. 1,
there is shown an exemplary embodiment of a disconnect tool 10
suspended in a wellbore 12 by a length of coiled tubing 14. The
disconnect tool 10 is divided into two segments 16 and 18 that are
selectively separable at the joint 20. The lower segment 18 of the
disconnect tool 20 is coupled to another member 22, which may be
another downhole tool, such as a shifting tool, a logging tool, a
packer, or other type of downhole tool, or another segment of drill
pipe. As discussed in detail below, the segments 16 and 18 of the
disconnect tool 20 are selectively separable at the joint 20 to
enable the segment 16 and the coiled tubing 14 to be withdrawn from
the wellbore 12 in the event the member 22 and/or the segment 18
becomes irretrievably lodged in the wellbore 12.
[0034] Electrical power and control signals to and from the
disconnect tool 10 are transmitted via a downhole conductor or
wireline 24 that is run through the coiled tubing 14 downhole to
the disconnect tool 10. The wireline 24 is connected to a
surface/control system 26 that includes an AC power supply 28 and a
backup battery supply 30 connected to an uninterruptable power
supply 32. The output of the uninterruptable power supply 32 is
connected to a DC power supply 34 which converts the AC current to
DC. A controller 36 is provided to perform a variety of control and
data acquisition functions, such as controlling the power supply to
the disconnect tool 10, arming and disarming the disconnect tool
10, and retrieving and displaying data obtained by various sensors
in the disconnect tool 10. The controller 36 is connected to the
uninterruptable power supply and a transceiver 38. Note that the
outputs of both the transceiver 38 and the DC power supply 34 are
connected to the wireline 24 via a summing node 39. Accordingly,
the transceiver 38 is designed to feed signals from the controller
36 into the wireline 24 and vice versa, that is, receive signals
transmitted from the disconnect tool 10. The simultaneous
transmission of DC power and electronic control signals between the
controller 36 and the disconnect tool 10 is possible through use of
an appropriate data/power transmission protocol providing for
simultaneous transmission of power and data through a single
conductor. An example of a suitable protocol is the segnetted
network architecture ("SEGNET") supplied by PES, Inc. of The
Woodlands, Tex.
[0035] The detailed structure of the disconnect tool 10 may be
understood by referring now to FIGS. 2A-2F, inclusive. The
disconnect tool 10 is of substantial length necessitating that it
be shown in six longitudinally broken sectional views, vis-a-vis
FIGS. 2A, 2B, 2C, 2D, 2E, and 2F. The disconnect tool 10 generally
consists of a tubular housing 40 subdivided into two tubular
segments 16 and 18 selectively separable at the joint 20 shown in
FIG. 2C. Each of the segments 16 and 18 consists of a plurality of
tubular segments joined together, preferably by threaded
interconnections. The upper section of the segment 16 has an upper
tubular portion 42 threadedly attached to an intermediate tubular
portion 44 at 46 to provide a housing for a coiled tubing coupling
48 that connects the disconnect tool 10 to the coiled tubing 14.
The upper tubular portion 42 includes an internal bore 50 that is
dimensioned to receive the end of the coiled tubing 14.
[0036] The intermediate section 44 includes a collet 52 that has a
plurality of longitudinally projecting fingers 54 that bear against
the exterior of the coiled tubing 14. The fingers 56 are
advantageously composed of a material with sufficient strength and
flexure to enable the fingers to be moveable when squeezed against
the exterior of the coiled tubing 14, and to withstand the
anticipated loads. Exemplary materials include 4140 alloy steel,
inconel, and like materials. To enhance the physical engagement
between the fingers 54 and the tubing 14, the mating surfaces of
the fingers 54 and the tubing 14 may be provided with structures
that engage and resist axial movement. For example, some of all of
the fingers 54 may be provided with at least one, and
advantageously, a plurality of radially inwardly projecting members
or teeth 56 that are designed to securely engage the exterior of
the coiled tubing 14 when the fingers 54 are brought into tight
physical engagement with the coiled tubing 14.
[0037] The skilled artisan will appreciate that coiled tubing often
presents a less than perfectly circular cross-section. The fingers
54 will conform to a certain extent to noncircular cross-sections.
To facilitate engagement between the fingers 54 and more highly
deviated cross-sections of coiled tubing, each finger 54 may be
pivotally coupled to a bracket 58 by pins 60. Each bracket 58, is,
in turn, coupled to the intermediate section 44 by pins 62. Each
two adjacent fingers 54 are peripherally spaced apart and separated
by a longitudinally projecting finger 64 which is integral with the
intermediate section 44. The fingers 64 terminate short of the
toothed portions of the fingers 54 and define an upwardly facing
annular surface 66 against which the end 68 of the coiled tubing 14
abuts. Alternatively, the fingers 54 may be joined to a common
annular hub (not shown) that is secured to the intermediate section
44.
[0038] The fingers 64 are internally threaded at 70 and coupled to
the lower end 72 of a tubular member 74. The lower end 72 of the
tubular member 74 transitions to a reduced diameter portion 76,
thereby defining an upwardly facing annular shoulder 78. The outer
diameter of the intermediate portion 76 is dimensioned to be
slidably received within the end 68 of the coiled tubing 14 so that
the end of the coiled tubing 68 abuts not only the annular surfaces
66 on the upwardly projecting fingers 64, but also the upwardly
facing annular surface 78. The tubular member 74 provides a
relatively rigid cylindrical member which is designed to prevent
the coiled tubing 14 from crimping or otherwise collapsing when the
fingers 54 are engaged against the coiled tubing 14.
[0039] The collet fingers 54 are brought into secure physical
engagement with the exterior of the coiled tubing 14 by one or more
longitudinally spaced annular members 80. The annular members 80
are retained in longitudinally spaced-apart relation by a plurality
of annular spacers 82. The annular members 80 are advantageously
composed of a shape-memory material that deforms in response to a
particular stimulus, such as temperature change or exposure to
water, for example. A thermally sensitive shape-memory material
undergoes dimensional changes when heated above the phase
transition temperature for that particular material. When the
material has changed dimensions, the deformation is fixed and the
shape remains stable.
[0040] During fabrication, the annular members 80 are initially
fabricated with a permanent shape corresponding to an inner
diameter that is smaller than the outer diameter of the collet
fingers 54 when the collet fingers 54 are in secure physical
engagement with the coiled tubing 14. The fabrication process
allows the shape-memory material to be advantageously deformed into
a temporary shape with an inner diameter that is greater than the
outer diameter of the collet fingers 54 so that the coiled tubing
14 may be readily slipped into position between the tubular member
74 and the fingers 54.
[0041] The annular members 80 may then be heated in situ, that is,
after they have been installed over the fingers 54 and after the
coiled tubing 14 has been inserted in position. The in situ heating
may be performed by a resistance heater, a hot air gun, heated
blocks, by introducing a hot fluid into the coupling 48 or like
methods. Upon heating the annular members 80 above the phase
transition temperature, the annular members 80 automatically deform
back into their permanent shapes, thereby tightly squeezing the
fingers 54 into secure physical engagement with the exterior of the
coiled tubing 14. In this way, the coiled tubing 14 is secured to
the intermediate section 44 by structural components that, unlike
conventional methods such as threaded members and/or axially moving
wedges, are not subject to loosening over time as a result of
repeated jarring and torsional motions associated with the downhole
environment.
[0042] The number, size, and spacing, of the annular members 80 is
largely a matter of design discretion. Indeed, the plurality of
annular members 80 depicted in FIG. 2A may be replaced with a
single annular member that shrouds the entirety of, or some lesser
portion of the toothed portions of the fingers 54. Exemplary
materials for the annular members 80 include a nickel titanium
alloy manufactured under the trade names nitinol, tinel, or like
materials.
[0043] The aforementioned coupling 48 has been described in the
context of engagement with coiled tubing. However, the skilled
artisan will appreciate that the coupling may be secured to a wide
variety of member, such as, for example, a downhole tool, oilfield
pipe or like members.
[0044] The segment 16 includes a longitudinal bore 84 to permit a
working fluid transmitted through the coiled tubing 14 to be passed
through the disconnect tool 10 and to permit insertion of the
wireline 24 into a connector 86. It is desirable to prevent working
fluid pumped through the coiled tubing 14 to escape the housing 42,
and similarly desirable to prevent the influx of fluid from the
wellbore 12 into the disconnect tool 10. Accordingly, the joint
between the intermediate section 44 and the housing 42 is provided
with a pair of longitudinally spaced O-rings 88 and 90. Similarly,
longitudinally spaced O-rings 92 and 94 are positioned between the
exterior of the coiled tubing 14 and the inner diameter of the
housing 42. An annular member or spacer 96 is positioned between
the O-rings 92 and 94 and another annular member 98 is positioned
between the O-ring 94 and abuts the upper ends 100 of the fingers
54.
[0045] The wireline connector 86 is coupled at its lower end 102 to
an intermediate section 104 of the overall tool housing 40. The
connector 86 is secured to the intermediate section 104 by a pair
of opposed set screws 106 and 108. The detailed structure of the
wireline connector 86 may be understood by referring now also to
FIG. 3, which is a highly magnified sectional view of the connector
86. The connector 86 consists of a tubular housing 110 that has an
upper tubular portion 112 threadedly coupled to a lower tubular
portion 114 at 116. The upper tubular portion 112 includes a
reduced diameter portion 118 that defines a downwardly facing
annular shoulder 120 against which the upper end of the lower
tubular portion 114 is abutted. A collet 122 is positioned inside
the housing 110 and has a plurality of longitudinally projecting
and peripherally spaced, bendable fingers 124. The fingers 124 are
designed to engage the exterior of the wireline 24. In the
embodiment depicted in FIGS. 2A and 3, the outermost or thickest
insulating sheath 126 and the outer reinforcing wire sleeve (not
shown) of the wireline 24 is stripped uphole from the connector 86
so that the fingers 124 physically engage the exterior of the inner
reinforcing wire sleeve 128 of the wireline 24. The lowermost end
of the wireline 24 is stripped of the reinforcing wire sleeve 128
and the innermost insulating sheath (not shown) near the lower ends
of the fingers 124, to expose the individual conductor wires 130 of
the wireline 24. The number of individual conductors 130 of the
wireline 24 will depend upon the type of wireline involved. In the
illustrated embodiment, the wireline 24 contains seven individual
conductors 130. The internal diameter of the collet 122 expands
slightly at the roots 132 of the fingers 124 to define and upwardly
facing annular shoulder 134 against which the reinforcing wire
sleeve 128 of the wireline 24 may abut to prevent the wireline 24
from projecting into the connector 86 farther than desired.
[0046] The fingers 124 are held in secure physical engagement with
the exterior of the inner sleeve 128 by a plurality of
longitudinally spaced annular members 136 that, like the
aforementioned annular members 80 depicted in FIG. 2A, are
advantageously composed of a heat-sensitive shape-memory material
that is deformable in situ from a temporary shape with an inner
diameter larger than the outer diameter of the sleeve 128 and the
collet fingers 124 to a permanent shape that has an inner diameter
smaller than the outer diameter of the fingers 124. As with the
aforementioned coiled tubing coupling 48 shown in FIG. 2A, the
connector 86 maintains a snug reliable physical engagement with the
wireline 24 that is not prone to loosening as a result of downhole
forces. In addition, the requirement to separate and bend the
individual reinforcing wires of the wireline 24 outward and/or
backward to facilitate a conventional wireline coupling mechanism
is eliminated. As a result, the potential for fracturing or
significantly weakening the reinforcing wires is eliminated.
[0047] The exterior of the connector 86 is exposed to the working
fluid. Accordingly, it is desirable to seal the interior of the
connector 86 from the flow of working fluid. In this regard, O-ring
seals 138 and 140 are respectively positioned in an annular groove
141 between the housing 110 and the section 104 and in an annular
groove 142 between the exterior of the upper tubular portion 112
and the lower tubular portion 114.
[0048] A pin-socket type connector 142 is positioned inside the
housing 110. The connector 142 includes a number of terminals 144
coupled to the ends of the individual conductors 130. The terminals
144 may be pin, socket, or another type of connection suitable for
mating with the type of connector. e.g., pin or socket. A compliant
boot 146 shrouds the terminals 144 and is advantageously composed
of a compliant electrically insulating material, such as natural or
nitrile rubbers, or like materials. The number of terminals 144
will usually match the number of individual conductors 130 in the
wireline 24, but need not depending upon the electrical
requirements of the disconnect tool 10. Each terminal 144 is
connected to an elongated conductor that spans the length of the
connector 142 and is not visible.
[0049] An electrical pathway from the lower end 148 of the
connector 142 may be established by separate conductors 150
positioned in a conduit 152 in the intermediate section 104. The
conduit 152 is sealed against the intrusion of working fluid past
the connector 142 by a plurality of O-rings 154 disposed around the
connector 142. The conduit 152 extends to the bottom of the tool
10, spanning the various housing sections along the way. For
simplicity of illustration, a conductor is not always shown in the
conduit. However, the skilled artisan will appreciate that there
will typically be one or more conductors in the conduit 152.
[0050] The intermediate section 104 is joined to the intermediate
section 44 by an intermediate section 156 that is threadedly
attached to the intermediate section 44 at 158. The intermediate
section 104 includes a reduced diameter portion 160 that defines an
upwardly facing annular shoulder 162 against which the lower end
164 of the intermediate section 156 may abut. The intermediate
section 104 is coupled to the intermediate section 156 by a spin
collar 166 that engages a set of external threads 168 on the
intermediate section 104. The spin collar 166 may be rotated to
establish a fixed gap between the opposing annular shoulders 164
and 162. The overall joint between the intermediate section 156,
the intermediate section 104, and the intermediate section 44 is
sealed against fluid leakage by pairs of longitudinally spaced
O-rings 170, 174, and 176. The joint has a self-sealing function.
As a result of the differing cross-sectional areas of the annular
shoulder 164 and the annular shoulder 178, the differential
pressure acting on the intermediate section 156 will tend to urge
the intermediate section 156 to remain in physical engagement with
the intermediate section 44. Prior to installation of the spin
collar 166 and connection between the sections 44, 156, and 104,
access to the conductor wires 150 within the conduit 152 may be had
through an access port 180.
[0051] Referring specifically to FIG. 2B, the intermediate section
104 includes a pair of longitudinally spaced check or flapper
valves 182 and 184. The flapper valve 182 is shown fully open and
the flapper valve 184 is shown fully closed. The flapper valve 182
includes an annular valve body 186 longitudinally spaced from an
identical valve body 188 for the valve 184 by an annular spacer
190. A similar annular spacer 192 is positioned below the valve
body 188 and abuts an upwardly facing annular shoulder 194 of an
intermediate section 196. The check valves 182 and 184 are designed
to prevent working fluid and debris from the wellbore from flowing
back up through the disconnect tool 10. Working fluid and/or debris
is prevented from bypassing the check valves 182 and 184 by O-rings
198 and 200 respectively disposed around the valve bodies 186 and
188.
[0052] The intermediate section 104 is secured to the intermediate
section 196 by an intermediate section 202 and a spin collar 204
that are identical in structure and function to the intermediate
section 156 and the spin collar 166 described above. Similarly,
identical sets of O-rings 206, 208, and 210 are provided to seal
the joint. To enable the set of conductors 150 to be quickly
connected and/or disconnected from a complimentary set of
conductors 212 in the portion of the conduit 152 in the
intermediate section 196, a connector 214 like the connector 142
shown in FIG. 2A is positioned within the intermediate section
196.
[0053] Referring now to FIGS. 2B and 2C, the intermediate section
196 is provided with a reduced diameter portion 218 that defines a
downwardly facing annular shoulder 220 and accommodates a tubular
collet 222. The upper end of the collet 222 is abutted against the
annular shoulder 220. An adjustable split ring 224 secures the
collet 222 to the intermediate section 196. The collet 222 includes
a plurality of longitudinally projecting and peripherally spaced,
moveable fingers 226. Each of the fingers 226 has one or more
outwardly projecting teeth 228 that engage a corresponding inwardly
projecting tooth or set of teeth 230 formed on the interior of an
intermediate section 232 of the segment 18. The lower ends 234 of
the fingers 226 are provided with inner surfaces 236 that are
configured to mate with outer surfaces 238 formed on the exterior
of the intermediate section 196 proximate the surfaces 236. The
fingers 226 are bendable from a first position shown in FIG. 2C to
a second position wherein the fingers collapse inwardly until the
surfaces 236 engage the surfaces 238 and the corresponding teeth
228 and 230 disengage.
[0054] The fingers 226 are selectively retained in the straight or
uncollapsed position shown in FIG. 2C by a piston positioned in the
housing 40 between the exterior of the intermediate section 196 and
the interior of the intermediate section 232. The upper end 242 of
the piston 240 includes a lip 244 that engages the surfaces 236 of
the fingers 226 and prevents the fingers 226 from collapsing inward
to the bent position. The piston 240 is a generally annular member
that, as discussed more below, is selectively movable
longitudinally from a first position shown in FIG. 2C downward to a
second longitudinal position in which the lip 244 clears the
fingers 226 and no longer prevents the fingers 226 from bending
from the position shown in FIG. 2C to a position where the surfaces
236 engage the surfaces 238. The piston 240 is initially retained
in the position shown in FIG. 2C by one or more members 246 which
are coupled to the piston 240 and another structure within the
housing 40, in this case the intermediate section 196. In the
illustrated embodiment, the members 246 are shear pins composed of
a suitable material and suitably sized to fail when a preselected
axial force is imparted on the piston 240. Alternatively, as shown
schematically in FIG. 2C a spring 248 may be inserted into the
annular space 250 in lieu of or in addition to the members 246.
[0055] The piston 240 is movable downwardly by hydraulic fluid
flowing through a chamber 252 that is vented to the topside of the
piston 240 at 254 and extends longitudinally downward through the
disconnect tool 10 as shown in FIGS. 2C, 2D, 2E, and 2F. As
described more fully below, if it is desired to disconnect the
segments 16 and 18 at the joint 20, the pressure of the fluid in
the chamber 252 is increased until the downward force acting on the
piston 240 overcomes the restraining force of the members 246 or
the coiled spring 248, as the case may be, and urges the piston 240
to move longitudinally downward, clearing the fingers 226. The
annular space 250 is also provided with a volume of hydraulic fluid
and is vented to an elongated hydraulic chamber 256 shown in
phantom in FIGS. 2C., 2D, 2E, and 2F, and visibly shown in FIG. 4,
which is a cross-sectional view of FIG. 2C taken at section 4-4.
FIG. 4 illustrates the hydraulic chambers 252 and 256, and the
conduit 152, in which one or more electrical conductors are
positioned and connected to an electrical connector 258 like the
electrical connector 214 described above and shown in FIG. 2A. A
port 259 shown in phantom in FIG. 2C, leads from the exterior of
the intermediate section 196 to the chamber 256. The port 259 and
the chamber 256 are designed to enable high pressure hydraulic
fluid in the space 250 to be vented into the chamber 256 after the
piston 240 has moved to the lower position. It is anticipated that
the hydraulic pressure in the chamber 252 may be relatively high
even after the piston 240 has triggered. It is accordingly
desirable to vent that high pressure fluid if possible.
[0056] Several longitudinal keys 260 are positioned in between the
exterior of the intermediate section 196 and the interior of the
intermediate section 232, principally to establish a known
rotational alignment of the section 196 and to prevent relative
rotation between the section 196 and the section 232.
[0057] It is desirable to seal the piston 240 against the leakage
of hydraulic fluid so that pressure against the piston 240 is
maintained until the members 246 fail. In this regard, an O-ring
seal 264 and a wear ring 266 are positioned between the exterior of
the piston 240 and interior of the intermediate section 232.
Similarly, an O-ring seal 268 and a wear ring 270 are positioned
between the interior of the piston 240 and the exterior of the
intermediate section 196.
[0058] The lower end of the intermediate section 232 is threadedly
coupled to the upper end of an intermediate section 274 at 276. The
threaded engagement at 276 may be a standard pin box threaded
connection commonly used in oil tools, or a tapered threaded
connection with metal-to metal seal as depicted in FIG. 2C. The
tapered connection provides a more fluid leakage resistant
engagement between two tubular members. The sections of the
electrical conduit 152 on either side of the threaded joint 276 are
connected by the aforementioned electrical connector 258.
Similarly, the sections of the chamber 252 positioned above and
below the joint 276 are connected by a tubular hydraulic coupling
278.
[0059] The detailed structure of the hydraulic coupling 278 may be
understood by referring now to FIG. 5, which is a detailed
cross-sectional view of the hydraulic coupling 278. The coupling
278 includes a tubular housing 280 that has a first longitudinal
bore 281 extending therethrough and is dimensioned at its upper end
and lower end to thread into place over respective check valves 282
and 284 positioned in the chamber 252. The first check valve 282
includes a longitudinally movable poppet 286 that is spring biased
against an upwardly facing chamfered surface 288. In like fashion,
the check valve 284 includes a poppet 290 that is spring biased
toward a chamfered surface 292. The coupling 278 includes a mandrel
294 that is slidably positioned in the bore 281. The mandrel 294
includes a second longitudinal bore extending from a first tip 296
to a second tip 298 to convey fluid from the first check valve 282
to the second check valve 284. The first tip 296 includes one or
more openings 300 and the tip 298 includes a corresponding opening
or openings 302 to permit fluid to enter and exit the bore 295. The
first tip 296 includes an outwardly projecting annular member 304
that is longitudinally spaced from the end 306 of the tip 296 so
that when the annular member 304 shoulders against the body 308 of
the check valve 282, as shown in FIG. 5, the portion of the mandrel
294 distal to the annular member 304 projects into the valve body
308 and unseats the poppet 286 as shown. The mandrel 294 is
upwardly biased in the direction indicated by the arrow 310 by a
biasing member 312 positioned inside the housing 280 to bias the
mandrel 294 toward the check valve 282. The biasing member 312 may
be a coiled spring or other type of spring. First and second sets
314 and 316 and 318 and 320 of O-ring seals are provided between
the exterior of the housing 280 and the mating interior surface of
the intermediate section 196 and the mating interior surface of the
intermediate section 274 to prevent hydraulic fluid from bypassing
the bore 295 in the mandrel 294, and to prevent contamination of
hydraulic fluid by working fluid.
[0060] In operation, the hydraulic coupling 278 is inserted into
one or the other of the intermediate sections to be connected,
i.e., the section 196 or the section 274, and the sections 196 and
274 are brought together by the cooperating threads at 228 and 230.
For the purpose of this illustration, it is assumed that the
hydraulic coupling 278 is first inserted into the intermediate
section 274 above the check valve 284. When the coupling 278 is
secured above the check valve 282, the tip 298 of the mandrel 294
projects into the check valve 282 but does not open the poppet 290.
Next, the intermediate section 196 is slipped over the coupling 278
and the threaded connection at 228 and 230 is tightened to bring
the sections 274 and 196 together. The collet 222 serves as a spin
collar that brings the sections 274 and 196 together.
[0061] As the sections 196 and 274 are brought together, the
annular member 304 shoulders against the valve body 308, the poppet
286 is unseated, opening the check valve 282, and the mandrel 294
is moved longitudinally downward as a result of the engagement
between the annular member 304 and the valve body 308. The biasing
member 312 maintains the tip 296 in contact with the poppet 286 to
maintain the poppet 286 in an open position while the mandrel 294
is moved downward. At the same time, the tip 298 is engaging and
unseating the poppet 290 in the check valve 284. When the threaded
connection at 228 and 230 is fully tightened, the poppets 286 and
290 are held in open positions respectively by the tips 296 and 298
and retained in open positions by the dimensional difference
between the mandrel length and the joint makeup distance between
the poppets 286 and 290. The spring 312 ensures that the mandrel
294 moves and closes a given poppet when the joint at 20 is
broken.
[0062] The hydraulic coupling 278 provides the advantageous
capability of providing a structure for quickly connecting two ends
of a hydraulic conduit, namely the chamber 252, and for maintaining
the up and downstream check valves 282 in an open position during
normal operations. The ability to maintain an open pathway for
hydraulic fluid flow is desirable so that sudden closure of one or
the other of the valves 282 or 284 as a result of an unanticipated
pressure surge in the chamber 252 or shock loading is avoided. In
this way, a potentially damaging water hammer situation is
prevented which might otherwise damage various seals or other
components in the tool.
[0063] Referring again to FIGS. 2D and 2E, an intermediate housing
section 321 is threadedly engaged to the intermediate section 274
below the threaded joint 276 at 322. The joint is sealed against
fluid passage by O-ring seals 324 and 325 that are positioned
between the exterior of the intermediate section 274 and the
interior of the upper end of the intermediate section 321. The
intermediate section 274 includes three longitudinally spaced apart
reduced diameter sections 326, 327, and 328 separated by sets of
annular flanges 329, 330 and 332, each having a shock absorbing
elastomeric ring 332A. As best seen in FIG. 6, which is a
cross-sectional view of FIG. 2D taken at section 6-6, the reduced
diameter sections 326, and 328 are provided with generally
polygonal cross-sections to provide a series of elongated spaces
333 in which magnets 334 for casing collar location may be
positioned. A casing collar locator coil assembly 335 is positioned
around the section 327 and inductively coupled to the magnets
334.
[0064] Primary electrical power is supplied to the tool 10 via the
wireline conductor 24 shown in FIG. 2A. This includes the
electrical power necessary to trigger the disconnect feature and
operate the instrumentation of the tool 10. It is desirable to
incorporate a backup power supply so that, even if the primary
power supply fails, the tool 10 may still trigger to disconnect
downhole. In this regard, a power supply 336 in the form of a
plurality of peripherally spaced capacitors 338 is positioned
inside the tool 10. The capacitors 338 are connected to a conductor
in the conduit 152 via a connection that is not visible in FIG. 2D.
The more detailed connections of the capacitors 338 with other
components in the tool 10 are described below. In addition to
capacitors, thermal batteries may be used.
[0065] The intermediate section 274 includes printed circuit boards
340 and 342, shown in phantom in FIG. 2D and in section in FIG. 7,
which is a sectional view of FIG. 2D taken at section 7-7, and an
additional printed circuit board 344 shown in cross-section in FIG.
2E. The boards 340, 342, and 344 are positioned in spaces like the
spaces 334 described above. The boards 340, 342, and 344 may be
fabricated from polycarbonate plastic, ceramic materials, or other
suitable types of substrate/circuit board materials. The components
and interconnections of the boards 340, 342, and 344 will be
described in more detail below.
[0066] As shown in FIG. 2E, the intermediate section 274 is
provided with a reduced diameter portion 346 that provides an
annular chamber 348 between the exterior of the intermediate
section 274 and the interior of the intermediate section 321. The
annular chamber 348 provides room to accommodate one or more strain
gauges 352, 354, and 356 for measuring tensile, compressive,
torsional, and bending strains on the intermediate section 274. The
electrical outputs of the strain gauges 352, 354, and 356 are
connected to the internal circuitry of the tool 10 via a
longitudinal slot 358 in the section 274 shown in phantom leading
to the circuit board 344. The gauges 352, 354, and 356 are mounted
on the reduced diameter portion 346 and are not physically
connected to the interior surface of the intermediate section 321.
Furthermore, the gauges 352, 354, and 356 are additionally isolated
from strains subjected to the intermediate section 321 that might
otherwise contaminate the readings of the gauges 352, 354, and 356.
This is accomplished by physically connecting the intermediate
section 321 to the intermediate section 274 only at one end, namely
at the threaded connection 322 shown in FIG. 2C. At the lower
terminus of the intermediate section 321 shown in FIG. 2E and
partially in FIG. 2F, the intermediate section 321 is not
threadedly engaged with the intermediate section 274. Rather, a
sliding joint at 362 is established and sealed against fluid
intrusion by a pair of O-ring seals 364 and 366. Accordingly, axial
and torsional loads are transmitted directly through the
intermediate section 274 and loads applied to the intermediate
section 321 by wellbore pressure or other causes are not
transmitted directly to the strain gauges 252, 254, and 256 in the
intermediate section 274. The working fluid pressure does act on
the inner diameter of the section 274. It is therefore necessary to
monitor the pressure in the bore 84 so that the pressure effects
may be electronically subtracted out of the strain gauge
signals.
[0067] It is desirable to be able to sense the temperature and
pressure of the hydraulic fluid in the chamber 252. These
parameters provide verification of the condition of the hydraulic
fluid, as well as the proper function of the triggering mechanism
and pressure relief devices incorporated into the tool 10 as
described below, both before and after firing. Accordingly, a
temperature/pressure sensor 368A is positioned in a chamber 370
defined by the intermediate section 274 and the intermediate
section 321. One end of the temperature/pressure sensor 368A
includes electrical outputs that are routed to the circuit board
344 via conductors 372 shown in phantom in FIG. 2E. The other end
of the sensor 368A is coupled to a substantially sealed chamber
374. A compensating piston 376 is disposed in the chamber. The
chamber 374 is in fluid communication with the chamber 252 via the
port 378. The chamber 374 and the piston 376 are configured so that
the pressure on either side of the piston 376 is essentially equal.
Thus, the pressure of the fluid in the chamber 252 will be readily
sensed by the sensor 368A.
[0068] The piston 376 serves primarily as a structure to prevent
the influx of debris from the chamber 252 which might otherwise
contaminate and damage the sensor 368A. It is anticipated that heat
from the fluid in the chamber 252 will transfer to the fluid in the
chamber 374 and thus to the temperature/pressure sensor 368A. There
will be some time lag between a change in pressure and temperature
in the fluid in the chamber 252 and the sensing of those changes by
the sensor 368A. This time lag is due primarily to frictional
forces resisting movement of the piston and to the time lag
associated with the transfer of heat from the fluid in the chamber
252 to the fluid in the chamber 274. The types of sensors employed
to sense temperature and pressure are largely a matter of design
discretion. In an exemplary embodiment, the temperature/pressure
sensor 368A incorporates a thermocouple-like element, such as an
RTD, and a strain gauge transducer for sensing temperature and
pressure. Referring now also to FIG. 8, which is a sectional view
of FIG. 2E taken at section 8-8, temperature/pressure sensors 368B
and 368C may be positioned in the tool 10 to sense the temperature
and pressure of the working fluid in the bore 84 and the fluid in
the wellbore (See FIG. 1). The sensors 368B and 368C may be
substantially identical to the sensor 368A.
[0069] Referring now to FIG. 2F, the lower end of the intermediate
section 274 is threadedly coupled to an intermediate section 380
via an intermediate section 382 and a spin collar 384 in an
identical fashion to the joint incorporating the spin collar 204
and the intermediate section 202 depicted in FIG. 2B. The joint is
sealed by longitudinally spaced pairs of O-rings 386 and 388 and
390 and 392.
[0070] The electrical conduit 152 is connected to the upper end of
a gas generator 394 that is schematically represented in FIG. 2F.
The detailed structure and operation of the gas generator 394 may
be understood by referring now to FIGS. 2F, 9A, and 9B. FIGS. 9A
and 9B are magnified sectional views of the gas generator 394 and
the surrounding intermediate housing sections 321 and 380. The gas
generator 394 includes an electrical connector 396 of the type
described above and designated 86 in FIG. 2A, for example. The
lower end of the connector 396 is electrically connected to an
electric ignitor 398. The ignitor 398 is enclosed along with a
propellant charge 400 and a strainer screen 402 in a tubular
housing 404. The ignitor 398, as the name implies, is designed to
ignite the chemical propellant charge 400 when electrical current
is supplied to the ignitor 398 via a conductor in the conduit 152.
A variety of different types of commercially available electric
ignitors may be used. For example, a Titan model 6000-000-150
supplied by Titan Specialties, Inc. may be employed. The chemical
propellant charge 400 is designed to deliver a burst of hot
combustion gases through the strainer screen 402 and into a chamber
406 downstream from the strainer 402. A variety of different types
of chemical propellants may be used, such as, for example,
propellents based on potassium perchlorate, ammonium perchlorate,
ammonium nitrate, or like materials. The strainer screen 402 is
designed to readily pass the hot combustion gases into the chamber
406 while screening out uncombusted particulates which might
otherwise clog the narrowed portion 408 of the chamber 406.
[0071] Downstream from the narrowed portion 408 of the chamber 406,
an enlarged portion 410 is provided in which a piston 412 is
slidably disposed. The backside 414 of the piston 412 is in fluid
communication with the chamber 406 and the front side 416 is in
fluid communication with the chamber 252. The chamber 252 crosses
over to the opposite side of the intermediate section 380 via a
crossover 418 shown in phantom in FIGS. 2F and 9B, and transitions
through a hydraulic coupling 419 that is substantially identical to
the coupling 278 shown in FIG. 5. A removable plug 420 is coupled
to the intermediate section 380 to enable the chamber 252 to be
filled with an initial volume of hydraulic fluid. The piston 412 is
provided with a plurality of O-ring seals designated en masse as
422.
[0072] When the ignitor 398 is activated, hot gases from the
propellant charge propel the piston 412 downward, boosting the
pressure of the hydraulic fluid in the chamber 252. The high
pressure of the hydraulic fluid propels the piston 240 shown in
FIG. 2C downward, shearing the members 246. As noted above and
shown generally in FIG. 2C, hydraulic fluid in the chamber 250 is
permitted to vent to the chamber 256 after the piston 240 has moved
to the triggered position. Fluid venting into the chamber 256
encounters a compensating piston 424 disposed in a thermal pressure
compensation chamber 425 revealed in cut-away in FIG. 9B. The
piston 424 may be substantially identical to the piston 412.
[0073] It should be understood that an identical gas generator 394
may be coupled to the backside of the piston 240, that is, to the
chamber 250 to enable the piston 240 to be moved upward in the same
manner as the piston 240 is moved downward by the activation of the
gas generator 394. This may be desirable in circumstances where the
gas generator 394 has unintentionally fired and moved the piston
240 downward, unlocking the collet fingers 226 and where it is
necessary to retrieve the entire tool. In such circumstances it may
be desirable to return the piston 240 to the locked position so
that the fingers 226 do not collapse when the tool 10 is retrieved
from the wellbore.
[0074] Several safety features have been incorporated into the
disconnect tool 10 to enable accumulated gas pressure generated by
the gas generator 394 to vent under certain conditions or to be
selectively vented by the operator. These features may be
understood by referring now to FIGS. 2F, 9A, and 9B. A rupture disk
assembly 428 and a vent plug 430 are positioned in the intermediate
section 380 above the piston 412 and ported to the bore 84. A
similar rupture disk assembly 431 is positioned near the midpoint
of piston 412 in the position shown in FIG. 9B. The rupture disk
assemblies 428 and 431 is designed to fail and vent gas from the
chamber 406 in the event the gas surpasses a preselected maximum
pressure that is ordinarily less than the pressure rating of the
various seals within the disconnect tool 10. In this way, if the
pressure inside the chamber 406 builds to a level that approaches
the failure rating of the seals, one or both of the rupture disk
assemblies 428 and 431 are sacrificed to enable the high pressure
liquid to vent before damaging or destroying the seals, which
require much more costly and complex maintenance to replace than
the rupture disk assemblies 428 and 431.
[0075] The vent plug 430 is provided to enable the operator to
manually vent built up pressure in the chamber 406 directly into
the bore 84 by screwing the plug 430 in until the O-ring seal 432
in the plug 430 clears into the bore 84. This may be desirable in
circumstances where the gas generator 394 has been activated and
there is residual high pressure in the chamber 252. The operator
may selectively vent that high pressure into the bore 84 under
controlled conditions at the surface.
[0076] Referring now to FIG. 10, which is a view similar to, but
out of rotation from FIG. 2F, a rupture disk assembly 434 may be
provided in the intermediate section 380 and configured to fail
when the pressure of the working fluid in the bore 84 exceeds a
preselected maximum and thereby permit the high pressure working
fluid to vent into the wellbore.
[0077] Referring again to FIG. 2F, the lower end of the
intermediate section 380 is threadedly coupled to a bottom section
436 via an intermediate section 438 and a spin collar 440 secured
in an identical fashion to the spin collar 384 and intermediate
section 382 also depicted in FIG. 2F, albeit in a flip-flopped
orientation relative to the section 382 and the collar 384. The
bottom section 436 includes an upwardly disposed reduced diameter
portion that defines an upwardly facing annular shoulder 442 that
abuts the lower end of the intermediate section 436. The overall
joint is sealed by respective sets of O-ring seals 444, 446, and
448. The connection between the bottom section 436 and the other
downhole tool 22 shown in FIG. 1 is not shown in FIG. 2F, but may
be a standard pin/box connection or other suitable threaded
connection for a working string.
[0078] The internal circuitry for the disconnect tool 10 may be
understood by referring now to FIG. 11, which is a block diagram of
the internal circuitry, and to FIGS. 1, 2D, 2E, and 2F. A
communications interface 450 is provided to transfer signals
between the controller 36 and an onboard controller 452 using the
aforementioned SEGNET downhole communications protocol. The
communications interface 450 is electrically coupled to the
wireline 24 by a transformer 454 and a capacitor 456. A
preregulator and DC-DC converter 458 is provided to receive high
voltage DC power from the wireline 24. The converter 458 provides a
+5V output to the controller 452 and an ignitor controller 460. The
voltage loss in the wireline conductor 24 will depend upon a
variety of factors, such as the size and configuration of the
surface power supply and the actual configuration of the wireline
itself 24. In an exemplary embodiment, DC voltage is supplied at
+250V. High voltage is supplied from the wireline 24 to the storage
capacitors 338 through a diode 462. A +13V output from the
convertor 458 is also provided to establish an alternate way of
charging the capacitors 338. The +13V output is connected to a
conductor 464 that is provided with a diode 466. There will be some
voltage drop across the diode 466. The capacitors 338 are
continuously charged when power is supplied to the wireline 24, and
as noted above, provide a backup power supply to power the ignitor
398 in the event that power is lost from the wireline 24.
[0079] The ignitor controller 460 is designed to operate in a stand
alone mode and respond to a loss of power from the wireline 24, or
be operated in a slave mode and receive commands from the
controller 452 via a command/status bus 468. If power is present in
the wireline 24, the igniter controller 460 provides status
signals, such as signals representing an armed or disarmed
condition of the ignitor 398 to the controller 452 via the command
status bus 468. When given a command to fire the ignitor from the
controller 36, the ignitor controller closes a switch 470, enabling
current to flow through the ignitor 398. The switch 470 may be a
solid state switch or an electromechanical switch. The ignitor
controller 460 may be programmed to close the switch 470
immediately after receipt of a fire command from the controller 36.
Alternatively, the controller 460 may be programmed to initiate a
time delay, that is, close the switch 470 after a preselected
period of time. The controller 460 may also be programmed to fire
the ignitor 398 in the event that main power is lost from the
wireline 24. The time delay feature may be advantageously employed
in this circumstance to provide operators with a time cushion in
which to reestablish power to the wireline 24. A power loss by the
wireline conductor 24 is sensed by a low voltage detector 472 that
is connected to the ignitor controller 460 and to the wireline 24.
A second low voltage detector 473 is connected the capacitors 338
to detect a low voltage condition therein so that the time delay
may be expedited before the capacitor voltage falls below a desired
level.
[0080] The strain gauges 352, 354, and 356 shown in FIG. 2E are
represented schematically in FIG. 11 by the triangle 474. The
outputs of the strain gauges 474 are connected to a strain gauge
signal filter 476. The output of the temperature/pressure sensors
368A, 368B, and 368C are connected to a signal scaler 478 which is
designed to enable the controller 452 to interpret a full scale
output from the sensors 368A, 368B, and 368C as a full scale input,
and thus, a full scale reading. The outputs of the strain gauge
signal filter 476 and the signal scaler 478 are connected to an
analog-to-digital convertor 480. The digital outputs of the A to D
convertor 480 are transmitted to the controller 452. Data
transmitted from the strain gauges 474, and/or the
temperature/pressure sensors 368A, 368B, and 368C is transferred to
the controller 36 by the controller 452 via the communications
interface 450. The casing collar locator coil 335 may be coupled to
the controller 36 directly through the wireline 24 as shown in FIG.
11 or, alternatively, may be interfaced with the controller 452 as
desired.
[0081] The arrangement of the various internal electronic
components for the tool 10 is largely a matter of design
discretion. For example, the communications interface 450 and the
transformer 454 may be implemented on the circuit board 340 shown
in FIG. 2D, and the DC-DC convertor 458 may be implemented on the
circuit board 342, also shown in FIG. 2D, and the remainder of the
circuitry shown in FIG. 11 and circumscribed by the dashed box 484
may be mounted on the circuit board 344 shown in FIG. 2E.
[0082] The disconnect operation of the tool 10 may be understood by
referring now to FIGS. 1. 2C. 2F, 9A, 9B, and FIG. 12 FIG. 11 is a
sectional view like FIG. 2C, but shows the piston 240 in the
triggered position. As noted above, the disconnect sequence may be
initiated manually by instructing the controller 36 to send a
command to the ignitor controller 460 or by default in the event
that a low voltage condition signifying a main power loss is sensed
by the low voltage detector 472. The first scenario will now be
illustrated. A command to activate the ignitor 398 is sent from the
controller 36 to the controller 452. The controller 452 passes the
command to the 460, which, in turn closes the switch 470 after the
preprogrammed time delay, if any, enabling current to pass through
the ignitor 398. The ignitor 398 ignites the propellant charge 400.
The discharge of hot gases into the chamber 406 propels the piston
412 downward, boosting the pressure of hydraulic fluid in the
chamber 252. The high hydraulic pressure moves the piston 240
downward, shearing the members 246 and causing the piston 240 to
stop in the triggered position shown in FIG. 12. Although the
piston 240 no longer prevents inward bending of the collet fingers
226, the fingers 226 do not automatically bend inward. Rather, the
fingers 226 are dimensioned and the engaging teeth 228 and 230 of
the fingers 226 and the interior surface of the intermediate
section are configured so that the fingers 226 will collapse
inwardly only if a preselected axial load applied to the tool 10 is
exceeded. The joint at 20 may be disengaged by applying an axial
thrust on the segment 16 that exceeds the preselected maximum. If,
however, it is desired to withdraw the tool 10 without
disconnecting the joint at 20, the tool 10 may be withdrawn while
care is taken to maintain the axial load below the preselected
maximum. This type of extraction may be desirable in circumstances
where the gas generator has unintentionally fired and triggered the
piston 240.
[0083] In the default activation mode, the ignitor controller 460
will close the switch 470 upon detection of a low voltage condition
signifying a loss of main power from the wireline 24. This may be
instantaneous or after any preprogrammed time delay. If main power
is restored to the wireline 24 during the time delay, the igniter
controller 460 will cancel the time delay and reset to its normal
state. If the operator desires to cancel the firing sequence, a
command may be sent from the controller 36 canceling the firing
instruction. If no such cancellation command is received, and the
time delay has expired, the ignitor controller 460 closes the
switch 470 and the ignitor 398 fires, triggering the piston 240 as
described above.
[0084] Referring now to FIG. 13, the structure and function of the
coiled tubing coupling 48 depicted in FIG. 2A may be implemented in
a coupling 486 for connecting first and second ends 488 and 490 of
tubular members, such as the coiled tubing shown. The coupling 486
includes a tubular housing 492 consisting of a upper section 494
and a lower section 496. The sections 494 and 496 cooperatively
define a longitudinal bore 498 in which a first collet 500 is
positioned to engage the first end 488 of coiled tubing and a
second collet 502 is positioned to engage the end 490 of coiled
tubing. The collets 500 and 502 may be formed as a integral member
and the sections threadedly attached thereto at 504. Alternatively,
the collets 500 and 502 may be disposed in the housing 492 as
separate members separated by an externally threaded spacer (not
shown) upon which the sections 494 and 496 may be threadedly
engaged. O-rings 506 and 508 respectively seal the sections 494 and
496 against the leakage of fluid proximate the joint between the
two sections 494 and 496. In other structural and functional
aspects, the collets 500 and 502 are substantially identical to the
arrangement of the collet 52 and the annular members 80 described
above and depicted in FIG. 2A.
[0085] Another arrangement for collet-like engagement to the
tubular member 14 shown in FIG. 2A or the members 488 and 490 shown
in FIG. 13 is depicted in FIG. 14. FIG. 14 is a sectional view like
FIG. 2A and depicts a coupling, now designated 48', for coupling to
a tubular member such as an end 510 of coiled tubing. In this
embodiment, a tubular housing 512 encloses the upper portion of an
intermediate housing section 514. The housing 512 is threadedly
coupled to the section 514 at 516. The end 510 of the tubular
member is disposed in the housing 512. A collet 517 is integrally
formed with the section 514 and includes a plurality of
longitudinally projecting and peripherally spaced fingers 518 that
project into the end 510 and are moveable radially. Each of the
fingers 518 is provided with at least one and advantageously a
plurality of outwardly projecting members or teeth 520 to engage
the interior surface 522 of the end 510. The fingers 518 have a
tapered or fluted internal surface that tapers inwardly, that is,
presents a decreasing internal diameter from point A downward to
point B. A tapered tubular insert 524 is positioned inside the
fingers 518. The insert 524 has a tapered outer surface 527 that
matches the taper of the fingers 518 and establishes a wedging
action therewith when the fingers 518 are moved longitudinally
relative to the insert 524 and vice versa. The lower ends of the
fingers 518 are expanded to define a downwardly facing annular
shoulder 528 A shrink assembly 530A is abutted against the annular
shoulder 528 by a spin collar 532 threaded to the exterior of the
lower end 534 of the insert 524. An identical shrink ring assembly
530B is seated on an upwardly facing annular shoulder 535 of the
upper end 536 of the insert 524. The upper ends 538 of the fingers
518 includes a shallow internal groove 540 in which the outer
diameter of the shrink ring assembly 535 is seated. A spin collar
539 is threaded to interior of the upper ends 538 of the fingers
518.
[0086] The detailed structure of the shrink ring assemblies 530A
and 530B may be understood by referring now also to FIG. 15, which
is a pictorial of the shrink ring assembly 530B with a wedge shaped
portion 543 exploded away in phantom to reveal the internal
structure. The structure of the assembly 530B is exemplary of the
assembly 530B. The assembly 530A includes a pair of shrink rings
544 and 546. A pair of annular wedges 548 and 550 are positioned
inside the shrink ring 544 and an identical pair of annular wedges
552 and 554 are positioned inside the shrink ring 546. The annular
wedges 548 and 550 are provided with cooperating tapered surfaces
556 and 558 and the wedges 552 and 554 are provided with
cooperating tapered surfaces 560 and 562. When the ring 544 shrinks
in diameter, the annular wedge 548 is squeezed against the annular
wedge 550 and thrust upward as a result of the wedging action of
the engaging surfaces 556 and 558. The upward thrust acts against
the spin collar 539. Similarly, when the ring 546 shrinks, the
annular wedge 554 is squeezed against the annular wedge 556 and
thrust downward as a result of the wedging action of the engaging
surfaces 560 and 562. The downward thrust acts on the insert 524.
In like fashion, the shrink ring assembly 530A exerts an upward
thrust on the fingers 518. The combined downward thrust on the
insert 524 and upward thrust on the fingers 518 wedges the fingers
outward, establishing a secure engagement with the interior 522 of
the end 510. The connection may be further enhanced by torquing the
spin collars 532 and 539 and locking them in place via crimp rings,
snap rings, or the like.
[0087] The shrinking action of the rings 544 and 546 is
advantageously provided by fabricating the rings 544 and 546 from a
shape-memory material of the types described above. In situ heating
will shrink the rings 544 and 546 and tighten the connection.
[0088] A fluid seal between the end 510 and the housing 512 is
provided by space O-rings 564 and 566 separated by annular spacers
568.
[0089] Other suitable mechanisms may be incorporated to selectively
move the piston 412. For example, as shown in FIG. 2F, the gas
generator 394 may be replaced with a linear electric motor, shown
schematically and exploded at 570. The motor 570 may be coupled to
the piston 412 and powered via a conductor in the conduit 152.
[0090] In another alternate embodiment depicted in FIG. 16, the
pressure to move the piston 412 is generated by an accumulator
arrangement. FIG. 16 is a view like FIG. 9A. A piston 572 is
slidably disposed in a chamber 574 that is filled with a high
pressure charge of fluid at the surface via the port 576 that has a
zero-leak check valve (not shown) and is later plugged by the plug
578. As the chamber 574 fills, the piston 572 moves upward,
resisted by a spring 580. The spring 580 enables a high pressure
charge to be filled. To release the fluid in the chamber, a
solenoid valve 582 coupled to the connector 396 via a conductor 584
shown in phantom and is activated in the same way as the gas
generator 394 described above. The fluid is released into the
chamber 406.
[0091] While the invention may be susceptible to various
modifications and alternative forms, specific embodiments have been
shown by way of example in the drawings and have been described in
detail herein. However, it should be understood that the invention
is not intended to be limited to the particular forms disclosed.
Rather, the invention is to cover all modifications, equivalents
and alternatives falling within the spirit and scope of the
invention as defined by the following appended claims.
* * * * *