U.S. patent application number 14/896107 was filed with the patent office on 2016-05-12 for trigger mechanism for ball activated device.
The applicant listed for this patent is TRICAN COMPLETION SOLUTIONS AS. Invention is credited to Roger ANTONSEN, Kristoffer BR KKE.
Application Number | 20160130915 14/896107 |
Document ID | / |
Family ID | 51210689 |
Filed Date | 2016-05-12 |
United States Patent
Application |
20160130915 |
Kind Code |
A1 |
BR KKE; Kristoffer ; et
al. |
May 12, 2016 |
TRIGGER MECHANISM FOR BALL ACTIVATED DEVICE
Abstract
A trigger mechanism for a ball activated device (100) comprises
a seat sleeve (130) with seat defining members (132) forming a
fluid tight seal with a ball (300) in an initial state and allowing
the ball (300) to pass in a final state. An alternating member
(125) can move radially in an aperture (124) through an inner
sleeve (120) and abuts an outer surface on the seat sleeve (130) in
the initial state, is received in a recess (134) on the seat sleeve
(130) in an intermediate state, and is received in a groove (114)
in the outer sleeve (110) in the final state. A protective sleeve
(150) may extend axially from the seat sleeve (130) over a seat
receiving area (115). The mechanism is suitable for cementing and
fracturing as particles cannot penetrate to its moving parts.
Inventors: |
BR KKE; Kristoffer;
(Stavanger, NO) ; ANTONSEN; Roger; (Houston,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TRICAN COMPLETION SOLUTIONS AS |
Stavanger |
|
NO |
|
|
Family ID: |
51210689 |
Appl. No.: |
14/896107 |
Filed: |
June 6, 2014 |
PCT Filed: |
June 6, 2014 |
PCT NO: |
PCT/IB2014/001164 |
371 Date: |
December 4, 2015 |
Current U.S.
Class: |
166/243 |
Current CPC
Class: |
E21B 41/00 20130101;
E21B 2200/06 20200501; E21B 43/12 20130101; E21B 34/14
20130101 |
International
Class: |
E21B 41/00 20060101
E21B041/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 4, 2013 |
NO |
20130777 |
Claims
1. A trigger mechanism for a ball activated device, the trigger
mechanism comprising: an inner sleeve axially slidably disposed
within an outer sleeve from an initial state wherein the ball
activated device is inactive to a final state wherein the ball
activated device is activated; a seat sleeve axially slidably
disposed within the inner sleeve, the seat sleeve comprising
radially moveable seat defining members configured to form a fluid
tight seal with a ball in the initial state and allowing the ball
to pass in the final state; and an alternating member is disposed
radially moveably in a radial aperture through a wall of the inner
sleeve, wherein the alternating member: abuts an upstream side of a
first axial stopper on an inner surface of the outer sleeve and a
radially exterior surface on the seat sleeve in the initial state,
is received in a recess on the seat sleeve in an intermediate
state, and is received in a groove in the inner surface in the
final state.
2. The trigger mechanism of claim 1 wherein the spaces between and
behind the sleeves are filled with an incompressible,
water-repelling fluid kept at the pressure of the ambient well
fluid.
3. The trigger mechanism of claim 1 wherein the alternating member
is radially biased.
4. The trigger mechanism of claim 3 wherein the seat sleeve is
retained by the alternating member and an initial state holding
shoulder on the seat sleeve in the initial state.
5. The trigger mechanism of claim 1 wherein the seat sleeve is
retained by the alternating member and a final state holding
shoulder on the seat sleeve in the final state.
6. The trigger mechanism of claim 1 further comprising a separate
axial stopper on the seat sleeve and a complementary member
configured to temporarily halt the axial motion of the seat sleeve
at a position wherein the alternating member can enter the
recess.
7. The trigger mechanism of claim 1 wherein an inner surface of the
seat sleeve further comprises key grooves configured to receive a
fishing tool.
8. The trigger mechanism of claim 1 wherein the seat defining
members comprise axially extending collet fingers disposed in close
contact with each other around the circumference of the seat
sleeve.
9. The trigger mechanism of any claim 1 wherein the seat defining
members are slidably mounted on guides oriented radially and
perpendicular to a central axis of the seat sleeve.
10. The trigger mechanism of claim 1 further comprising a
protective sleeve extending axially from the seat sleeve over a
seat receiving area in the initial state, the protective sleeve
permitting the seat defining members to enter into the seat
receiving area in the final state.
Description
BACKGROUND
[0001] 1. Field of the Invention
[0002] The present invention relates to well equipment for use in
the oil and gas industry, in particular to a trigger mechanism for
a ball activated device.
[0003] 2. Background Art
[0004] In order to produce hydrocarbons, i.e. oil and gas, a
borehole is drilled through several layers of rock in a formation.
Hydro carbons may be present in a zone comprising a layer of porous
rock under a layer of non-porous rock. Several such zones can be
present along the borehole. The borehole may extend horizontally
along one or more zones. All or part of the borehole can be lined
by a steel casing or liner cemented to the rock to form a wellbore.
One or more production strings can be inserted into the wellbore.
As used herein, the term `tubing` means any casing, liner or
production string having a central bore through which a fluid may
flow. Different tubings are provided with various devices such as
valves, loggers, plugs, packers etc. in order to complete the well
or to control the production from the different zones as known in
the art.
[0005] One or more injection wells can be provided in a similar
manner. An injection well is typically used to increase the
pressure in a remote part of a zone to force the hydro carbons in
the direction of a production well and thereby increasing the
production.
[0006] The devices in the well can be operated in a number of known
manners, including by so-called drop balls. A ball activated device
is included in a tubing, and comprises a ball seat which forms a
fluid tight obstruction with a drop ball of a suitable size. When
it is desired to activate the device, the drop ball is dropped or
pumped down within the tubing until it lands on the ball seat.
Then, pressure is applied behind or upstream from the ball. When
the force exerted by the pressure on the piston area exceeds a
predetermined level, the ball seat shifts downstream and activates
the device, for example by shifting a sliding sleeve valve from a
closed position to an open position. In a cementing operation
cement can then be pumped through the open valve into an annulus
behind the casing, e.g. between the casing and the formation. In a
fracturing operation, fracturing fluid with suitable proppants can
be pumped through the open valve.
[0007] As known in the art, any suitable object can be dropped or
pumped down the well to prevent fluid flow through a seat. The
terms `ball` and `ball activated` are used for simplicity, and the
term `ball` should be regarded as any object capable of blocking a
flow as discussed above.
[0008] In some wells, several ball activated devices are provided
with seat diameters that decrease with the distance from the
surface, which is termed the downstream direction in the present
disclosure. To activate the `deepest` device, i.e. the device
furthest away from the surface, the smallest of a plurality of
balls is pumped down and passes all the larger seat diameters
before lodging or landing on the last seat. Thereafter,
successively larger balls are used to activate the devices closer
to the surface.
[0009] For simplicity, a sliding sleeve valve is used to illustrate
a ball activated device in the following description. However, it
should be understood that the ball activated devices considered in
the present invention are not limited to sliding sleeve valves. For
example, a linear motion is easily transformed to a rotation using
helical shoulders between two sleeves or a rack and gear
arrangement. Thus, an axially moving seat may turn an element
around its axis, e.g. a ball in a ball valve or a plate in a
butterfly valve.
[0010] U.S. Pat. No. 4,360,063 A (Kilgore) discloses a slide valve
with a ball seat comprising lugs on collet fingers defing a ball
seat. When it is desired to close the valve, a ball is dropped into
a tubing and pressure is exerted to move the ball downward and
close the slide valve. When the valve closes, the lugs expand into
a groove and permit the ball to fall through the slide valve
member. The lugs hold the slide valve in closed position. The
spaces between the lugs on the collet fingers may be dimensioned to
be of close tolerance or provided with resilient material to
restrict or prevent flow therethrough and/or the ball may be made
of resilient material or have a hard core with a resilient cover to
inhibit or prevent flow of fluid through the collet fingers when
the ball is seated on the fingers. In this manner, one ball can
lodge on several seats, all having the same diameter, and activate
corresponding valves one by one.
[0011] In U.S. Pat. No. 4,360,063 the seat is affixed to the
sliding sleeve. Thus, the force exerted on the ball and seat must
be sufficient to overcome an initial retaining force keeping the
sliding sleeve open plus a friction force between the entire
sliding sleeve and the surface within which it slides all at once.
This friction force can be significant, in particular if the slide
valve has been exposed to aggressive and/or contaminated well
fluids for an extended period of time. Further, before the ball
lands on the seat, particles in the well fluids or scaling may
deposit in the groove into which the lugs are supposed to expand.
If the lugs do not expand radially, the ball is prevented from
passing through and the intended operation fails.
[0012] U.S. Pat. No. 8,215,401 B2 (Braekke et al.) discloses a
collet configured to slide axially within an inner sleeve, which in
turn is configured to slide axially within an outer sleeve. The
collet comprises longitudinal fingers. Initially the fingers form a
ball seat and the collet is retained by a first release mechanism
designed to release the collet from the inner sleeve when a first
pressure exceeds a predetermined level. A second release mechanism
is designed to release the fingers when the device is activated,
e.g. when the valve has shifted from an initially closed to a final
open state. Once released, the fingers flare out in order to permit
the ball to pass.
[0013] One problem with the expandable seat of U.S. 8,215,401 B2 is
the need for a second pressure greater than a first pressure in
order to release the second release mechanism after the to first
release mechanisms to ensure proper operation of the device. In
some applications, it might be advantageous to activate a device
once a predetermined pressure is reached, and still be guaranteed
that certain steps between the initial and final states are
performed in a predetermined sequence to ensure proper transition
from the initial to the final state.
[0014] Further, the collet fingers in U.S. 8,215,401 B2 are
preferably spaced apart such that one collet can be configured to a
desired ball seat diameter by mounting suitable lugs between the
distal ends of the fingers and the surface in which the collet
slides. However, in applications where a fluid containing
particles, e.g. in cementing or fracturing operations, particles
such as sand or proppant may enter between the fingers and settle
behind them such that they do not flare out to let the ball
pass.
[0015] In one embodiment disclosed in U.S. Pat. No. 8,215,401 B2,
the first release mechanism comprises a head intended to slide over
a small stopping shoulder. This head may require a space between
two sleeves into which sand or proppant may enter. In general,
particles may enter spaces between or behind sleeves and prevent
proper operation of the expandable ball seat.
[0016] In other applications, an expandable ball seat is designed
to stay in a production string for an extended period of time
before being activated. In such applications, scaling and/or
corrosion may cause similar problems. For example, scaling may
build up between the sleeves or in exposed grooves and prevent the
sleeve from moving axially or the ball seat from expanding
radially. Corrosion may affect mechanical parts such as exposed
shear pins or helical shoulders required for transforming a linear
motion into a rotation. Hence scaling and corrosion might prevent
proper operation of the trigger mechanism and/or the ball operated
device triggered by the mechanism.
[0017] An object of the present invention is to solve at least one
of the problems above.
SUMMARY OF THE INVENTION
[0018] This is achieved by a trigger mechanism for a ball activated
device according to claim 1.
[0019] In particular, a trigger mechanism for a ball activated
device comprises an inner sleeve axially slidably disposed within
an outer sleeve from an initial state wherein the ball activated
device is inactive to a final state wherein the ball activated
device is activated. A seat sleeve is axially slidably disposed
within the inner sleeve. The seat sleeve comprises radially
moveable seat defining members configured to form a fluid tight
seal with a ball in the initial state and allowing the ball to pass
in the final state. The trigger mechanism is distinguished in that
an alternating member is disposed radially moveable in a radial
aperture through a wall of the inner sleeve, wherein the
alternating member: abuts an upstream side of a first axial stopper
on an inner surface of the outer sleeve and a radially exterior
surface on the seat sleeve in the initial state, is received in a
recess on the seat sleeve in an intermediate state, and is received
in a groove in the inner surface in the final state.
[0020] Thus, first the seat sleeve shifts axially within the inner
sleeve in order to align the recess on its exterior surface axially
with the alternating member extending through the wall of the inner
sleeve. Once the alternating member has entered into the recess in
the seat sleeve, it may pass the first axial stopper on the inner
surface of the outer sleeve such that the inner sleeve can start
sliding axially within the inner surface. Once the inner sleeve has
moved a predetermined axial distance within the outer sleeve so
that the ball activated device is activated, the alternating member
moves radially outward into a groove in the inner surface of the
outer sleeve. The predetermined axial distance can e.g. be
determined by a first complementary axial stopper disposed upstream
from the first axial stopper in the initial state.
[0021] Once the alternating member is out of the recess in the
outer surface of the seat sleeve, the seat sleeve is permitted to
proceed further within the inner sleeve until the seat defining
members are out of the inner sleeve and thereby allowed to flare
out radially in order to permit the ball to pass in the final
state. In the final stage, the seat sleeve is prevented from
leaving the inner sleeve by a second pair of axial stoppers on the
seat sleeve and inner sleeve respectively.
[0022] Before and during the above series of events, the
alternating member, the recess and the groove in which the
alternating member is received are disposed between the seat sleeve
and the inner surface at all times. Further, as the seat and ball
needs to form a fluid tight unit in order for an activating
pressure to build up behind the ball, well fluids cannot enter into
the spaces between and behind the sleeves. In other words, the
alternating member, recess and groove are protected from well
fluids with particles and/or well fluids causing corrosion and
scale deposits all of which might prevent or inhibit the radial
motion of the alternating member.
[0023] In a preferred embodiment, the spaces between and behind the
sleeves are filled with an incompressible water-repelling fluid
kept at the pressure of the surrounding well fluid. For example,
the spaces within the trigger mechanism may be filled with grease,
petroleum jelly or liquid mineral oil which are contained by seals
and the pressure may be equalized with bellows, membranes or piston
arrangements in any known manner. When the fluid within the
mechanism is kept at the same pressure as the surrounding well
fluids, there can be no pressure difference to force the well
fluids into the spaces behind the sleeves and cause aqueous
emulsions within the trigger mechanism. In particular, water with
dissolved carbonate is prevented from entering, whereby scaling and
corrosion is prevented.
[0024] In some embodiments, the alternating member is radially
biased. A biased member may be combined with a protrusion such as a
shoulder to retain a sleeve, as the bias must be overcome before
the alternating member can pass the protrusion. Thus, a biased
alternating member and protrusions may provide an alternative or
supplement to shear pins and other known retainers in the art, for
example to retain the seat sleeve in the initial state.
[0025] Some embodiments further comprise a temporary axial stopper
and a complementary member configured to temporarily halt the axial
motion of the seat sleeve at a position wherein the alternating
member can enter the recess. Without the temporary axial stopper
and complementary member, the recess on the seat sleeve might race
past the alternating member such that the inner sleeve would still
be retained in the un-shifted position while the seat sleeve
proceeds within the inner sleeve and perhaps even releases the
ball. If the inner sleeve remains in the initial position, the ball
activated device remains inactive.
[0026] In some embodiments, an inner surface of the seat sleeve
further comprises key grooves configured to receive a fishing tool.
In these embodiments a fishing tool, e.g. provided on a slick line,
can engage the key grooves and be used to pull the trigger
mechanism back to the initial state.
[0027] In embodiments of the present invention, the seat defining
members can comprise axially extended collet fingers disposed in
close contact with each other around the circumference of the seat
sleeve. This feature primarily prevents particles in the well fluid
from entering the space behind the collet fingers. For this, the
term `close contact` defines a space between the fingers which is
less than a predetermined minimum particle size. In addition or
alternatively the collet fingers may form part of the fluid tight
seat required to allow pressure to build up upstream from a lodged
ball. Further, it should be understood that the seat defining
members do not necessarily comprise collet fingers. For example,
seat defining members arranged to slide radially in or on a guide
affixed to a rigid seat sleeve might be used in other
embodiments.
[0028] In some embodiments a protective sleeve may be arranged such
that it extends axially from the seat sleeve over an area receiving
the seat defining members in the final state. The protective sleeve
primarily prevents debris, particles or scaling from entering or
building up in grooves or a reduced diameter into which the seat
defining member are moved in the final state in order to let the
ball pass. Obviously, if scaling or debris prevents the seat defing
members from moving outward, the ball will not pass through in the
final state and the trigger mechanism will not work in the intended
manner.
[0029] These and other features and advantages of the invention are
defined in the claims, and will become apparent from the detailed
description below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The invention will be described in greater detail using
specific embodiments and with reference to the accompanying
drawings in which:
[0031] FIG. 1 is a longitudinal cross section of a first embodiment
in an initial state;
[0032] FIG. 2 shows the embodiment in FIG. 1 in an intermediate
state;
[0033] FIG. 3 shows the embodiment in FIG. 1 in a final state;
[0034] FIG. 4 is a detailed view of a second embodiment in the
initial state shown in FIG. 1;
[0035] FIG. 5 shows the embodiment in FIG. 4 with the seat sleeve
displaced axially;
[0036] FIG. 6 shows the embodiment in FIG. 4 in the intermediate
state;
[0037] FIG. 7 shows the embodiment in FIG. 4 in the final
state;
[0038] FIG. 8 is a view of a seat sleeve comprising temporary
stopping means;
[0039] FIG. 9 is a section through the temporary stopping means in
FIG. 8;
[0040] FIG. 10 is a longitudinal cross section of a third
embodiment in an initial state;
[0041] FIG. 11 is a perspective view of an inner sleeve shown on
FIG. 10;
[0042] FIG. 12 is a perspective view of a seat sleeve shown on FIG.
10;
[0043] FIG. 13 is a perspective view of a pin shown on FIG. 10;
and
[0044] FIG. 14 is a perspective view of a protective sleeve shown
on FIG. 10.
DETAILED DESCRIPTION
[0045] In the description of FIGS. 1 to 3, `downstream` refers to
the axial direction from top to bottom of the drawings, and
`upstream` refers to the opposite direction.
[0046] FIGS. 1 to 3 show a sliding sleeve valve comprising a
trigger mechanism according to the invention. In particular, FIG. 1
depicts a cross sectional view of a first embodiment in an initial
state, FIG. 2 shows the cross sectional view of the first
embodiment in an intermediate state and FIG. 3 the cross sectional
view of the first embodiment in a final state.
[0047] In FIG. 1, a general ball activated device 100 is
represented by a sliding sleeve valve comprising an outer sleeve or
housing 110 included in a tubing 200 in a conventional manner, e.g.
by threaded pins and boxes. In the initial state, radial ports 105
through the walls of the housing 110 are closed by an inner sleeve
120 having seals 127 and 128 arranged around its exterior surface.
The seals 127 and 128 are configured to engage a sealing surface
forming the upstream part of an inner surface 101 within the
housing 110. In FIG. 1, the seals 127 and 128 are disposed upstream
and downstream from the ports 105 respectively in order to prevent
fluid from passing through the ports 105. The sliding sleeve valve
in FIG. 1 does not require a seal 129 around a downstream end of
the inner sleeve 120 as long as the seals 127 and 128 engage the
sealing surface and prevent fluid from passing through the ports
105. Thus, the element 129 might alternatively be a guide ring
provided merely to center the inner sleeve 120 within the housing
110. The ports 105, seals 127, 128 and guide element 129 are
considered parts of the slide valve, and are not considered part of
the trigger mechanism according to the invention.
[0048] In FIG. 1, a ball 300 is dropped or pumped downstream, and
has not yet landed on a ball seat formed by seat defining members
132.
[0049] An inner sleeve 120 is releasably retained within an inner
surface 101 by a radially moveable alternating member 125 engaging
a shoulder 112 on the inner surface 101. When released, the inner
sleeve 120 is free to slide axially within the inner surface 101
until a radially extending shoulder 122 on the inner sleeve abuts a
complementary shoulder 112 on the inner surface 101. The initial
distance between shoulders 112 and 122 must be sufficient to allow
the upsteam edge of sleeve 120 to pass the ports 105 in order to
open the slide valve, or in general to activate the ball activated
device.
[0050] A seat sleeve 130 is releasably retained within the inner
sleeve 120 by shear pins 135 designed to break at a predetermined
force. When released, the seat sleeve 130 is free to slide axially
within the inner sleeve 120 until a radially extending shoulder 133
on the seat sleeve 120 abuts a complementary shoulder 123 on the
inner sleeve 120. It is understood that the initial distance
between shoulders 123 and 133 must be sufficient to allow the seat
defing member 132 to slide out of the inner sleeve 120 such that
they are no longer supported and thereby allowed to move radially
outward in order to let the ball 300 pass between the members 132
in the final state shown in FIG. 3
[0051] The trigger mechanism of the invention comprises an aperture
124 extending radially through the wall of the inner sleeve 120.
The alternating member 125 is disposed in the aperture 124, and can
move radially inward or outward as it travels axially along a
profile. In the initial state in FIG. 1, the alternating member 125
is prevented from moving radially inward by an exterior surface on
the seat sleeve 130. As long as the alternating member 125 abuts
the shoulder 112, the inner sleeve is prevented from sliding
axially downstream within the inner surface 101.
[0052] A recess 134 in the outer surface of the seat sleeve 130 is
disposed upstream from the alternating member 125 in the initial
state shown in FIG. 1. The recess 134 must be able to receive the
alternating member 125, at least partly, as will be described
later.
[0053] In FIG. 2, a ball 300 has lodged on the ball seat within in
the seat sleeve 130, and a pressure sufficient to release the seat
sleeve 130 from the inner sleeve 120 has been applied. In the
intermediate state depicted in FIG. 2, the seat sleeve 130 has
shifted axially with respect to the inner sleeve 120, such that the
alternating member 125 has entered the recess 134. Thereby, the
alternating member 125 has been permitted to pass the shoulder 112
and the inner sleeve 120 has started to move axially along the
inner surface 101. The inner surface 101 downstream from the
sealing surface and shoulder 112 prevents the alternating member
125 from moving radially outward. In this embodiment, the
alternating member 125 prevents axial movement between the inner
sleeve 120 and the seat sleeve 130 such that the inner sleeve 120
still prevents the seat defining members 132 from moving radially
outward.
[0054] In other words, the seat defining members 132 still form a
ball seat in the intermediate state. The force exerted on the ball
300 and seat formed by the seat defing members 132 is transferred
to the inner sleeve 120 through the alternating member 125 such
that the seat sleeve 130 pulls the inner sleeve 120 downstream.
Thus, in the embodiment illustrated in FIGS. 1 to 3, the recess 134
must be sufficiently deep to allow the alternating member 125 to
pass within the smaller diameter of the inner surface 101, but not
so deep that it would permit the alternating member 125 to slide
along the inner surface of the inner sleeve 120 rather than pulling
on the inner sleeve 120. Hence, it should be understood that the
term `received in the recess` as used in the claim is not intended
to mean that the alternating member 125 has entered completely into
the recess 134, but rather that it has entered sufficiently to
allow the alternating member to move axially within the inner
surface 101 while transferring an axial force from the ball sleeve
130 to the inner sleeve 120.
[0055] In FIG. 3, the inner sleeve 120 has traveled downstream
along the inner surface 101 until the valve is fully open and
further axial movement of the inner sleeve 120 along the inner
surface 101 is prevented by the complementary shoulders 112 and
122. Once the inner sleeve has reached its final position, the
alternating member 125 is allowed to slip into a groove 114 in the
inner surface 101. Now, the seat sleeve 130 is once more free to
slide within the inner sleeve 120. As the recess 134 moves
downstream, the alternating member 125 is prevented from moving
radially inward by an exterior surface on the seat sleeve 130
upstream from the recess 134. Thus, the alternating member 125
extends through the aperture 124 into the groove 114 and prevents
the inner sleeve 120 from moving axially within the inner surface
101. The alternating member 125 and the groove 114 can replace or
supplement the stopping shoulders 112 and 122.
[0056] As the alternating member 125 is received in the groove 114,
FIG. 3 shows the seat sleeve 130 further displaced along the inner
sleeve 120 to a final state wherein the inner sleeve no longer
supports the collet fingers 131 and permits them to flare out into
a seat receiving recess 115. Of course, any radially seat defining
members 132 may be permitted to move radially outward once they are
moved out of the inner sleeve. Thus, the invention is not limited
to an embodiment having collet fingers. Further, the seat defining
members 132 are radially displaced such that the ball 300 is
permitted to pass between them in the final state.
[0057] In the final state shown on FIG. 3, the shoulder 133 on the
seat sleeve abuts the complementary stop shoulder 123 on an
interior surface of the inner sleeve 120 in the same manner as the
shoulder 122 on the inner sleeve abuts the complementary stop
shoulder 112 on the inner surface 101.
[0058] A variety of seat configurations are known to provide a
fluid tight seal permitting a pressure to build up behind a lodged
ball. For example, the prior art documents U.S. Pat. No. 4,360,063
and U.S. Pat. No. 8,215,401 both exhibit seats comprising collet
fingers with spaces between each finger. In the embodiment on FIGS.
1-3, there are no spaces between the collet fingers that large
enough to allow particles, e.g. sand or proppant, to pass between
the collet fingers 131. Similarly, other embodiments of the present
invention preferably are designed such that particles do not enter
between elements of the seat sleeve. The purpose of this is to
ensure that the movable elements work properly, e.g. that the
alternating member 125 can enter the recess 134 and groove 114 in
turn, and that the seat defining members 132 can expand radially
into the seat receiving area 115.
[0059] In general, the design must be adapted to the operation at
hand. For example, a trigger mechanism according to the invention
designed for a cementing or fracturing operation would
advantageously be designed such that particles of the sizes
involved do not pass between the elements of the seat sleeve 130
under the pressures employed during the operation.
[0060] From the above discussion of FIGS. 1 to 3 it should be
understood that the alternating member 125 preferably is protected
between the inner surface 101 and the seat sleeve 130 at all times
before and during the activation procedure. Thus, particles such as
sand or proppant cannot jeopardize the operation of the trigger
mechanism even during cementing or fracturing operations involving
high pressures.
[0061] In a preferred embodiment, the spaces between and behind the
sleeves, including the aperture 124 and groove 114, are filled with
filled with an incompressible, water-repelling fluid kept at the
pressure of the surrounding well fluid.
[0062] Seals between the sleeves are omitted from the figures for
clarity. However, it is understood that conventional seals similar
to the seals 127, 128 of the ball activated device, for example
O-rings supported in a conventional manner, must be provided to
ensure a fluid tight connection such that a pressure may be built
up behind the ball 300. Conversely, if fluid was allowed to pass
through or between the sleeves, a pressure could not build up in
order to exert an axial force on the lodged ball. It is considered
within the capabilities of the skilled person to provide seals
suitable for this purpose as well as any additional seals required
for keeping a clean, incompressible fluid within the spaces behind
and between the sleeves. In particular, liquid filled spaces
prevent particles and water containing dissolved carbonates from
entering, and thereby prevent deposits of particles and/or scaling
from forming. When water influx is inhibited or prevented,
corrosion is also inhibited or prevented.
[0063] Suitable incompressible fluids are water-repelling liquids
such as grease, petroleum jelly or mineral oil. The specific carbon
numbers will depend on the expected pressure and temperature in the
well. In addition to prevent liquid from escaping from the spaces
within the trigger mechanism, the seals prevent well fluids from
entering into the spaces.
[0064] Pressure equalizers are advantageously provided to minimize
the pressure difference, and hence the driving force, from the
ambient well fluid to the interior of the trigger mechanism. For
example, a bellow, membrane or piston might be provided to equalize
the pressure within the trigger mechanism with the ambient pressure
in the well. Such pressure equalizers are known in the art, and are
not described further herein.
[0065] In the embodiment with collet fingers 131 illustrated in
FIGS. 1-3, the fingers 131 are arranged in close contact with each
other around the circumference of the seat sleeve. As discussed
above, the contact should be close enough to prevent a particle
with a predetermined minimum size from passing between them under
the pressures involved in the operation at hand. The contacts
between the fingers can advantageulsy also be fluid tight, so that
the fingers are integral parts of the pressure tight structure
required for exerting a force on the lodged ball.
[0066] In a still further preferred embodiment, a protective sleeve
150 extends axially from the downstream end of the seat sleeve to a
downstream part of the tubing 200. In the initial state on FIG. 1,
the protective sleeve 150 would thus extend over the entire seat
receiving are 115. The space behind the protective sleeve 150 is
advantageously filled with an incompressible water-repelling fluid
in order to prevent particle deposits, scaling and corrosion as
discussed above.
[0067] FIGS. 4 to 7 are enlarged, partial views of a second
embodiment of the invention in which only one side of the trigger
mechanism is shown. The downstream direction is from left to
right.
[0068] FIG. 4 illustrates an alternative embodiment of a trigger
mechanism according to the invention in the initial state
corresponding to the initial state illustrated in FIG. 1. In FIG.
4, the alternating member is depicted as a roller 126, i.e. a
cylinder or a ball. The roller 126 is biased radially inward as
illustrated by the arrow F. The bias can be provided in known
manner, e.g. by a disc spring, a leaf spring or a compression
spring and is not discussed further herein.
[0069] In FIG. 4, the roller 126 abuts the shoulder 112 and
prevents the inner sleeve 120 from moving downstream relative to
the inner surface 120. A radially exterior surface of the seat
sleeve 130 prevents the roller 126 from moving inward. This
corresponds to the initial state described in connection with FIG.
1. In addition, an initial state holding shoulder 133 on the
exterior surface of the seat sleeve 130 abuts the roller 126 on its
upstream side. The bias force F must be overcome before the roller
126 can pass the shoulder 133 so that the seat sleeve 130 can slide
axially downstream within the inner sleeve 120. The inclination of
the shoulder 133 and size of the biasing force F are adapted to
prevent the seat sleeve 130 from moving within the inner sleeve 120
before a predetermined force is applied. Thus, the bias force F and
shoulder 133 could be adapted in order to replace the shear pins
135 in FIG. 1.
[0070] FIG. 5 illustrates a state shortly after the predetermined
force is exerted on the ball. In this state, the roller 126 has
been forced radially outward against the biasing force F and is
disposed between an exterior surface on the seat sleeve 130 and the
inner surface 101 of the outer sleeve 110 such that the seat sleeve
130 is permitted to slide downstream within the inner sleeve 120.
The roller 126 still abuts the shoulder 112 on the inner surface
101 and is still prevented from moving radially inward by an
exterrior surface on the seat sleeve 130, so the inner sleeve 120
is still not free to slide axially downstream within the inner
surface 101.
[0071] In FIG. 6, the roller 126 is received in the recess 134 on
the seat sleeve 130 so that the roller 126 no longer abuts the
stopping shoulder 112 on the inner surface 101. Thereby, the inner
sleeve 120 is allowed to slide downstream within the inner surface
101. The state illustrated in FIG. 6 corresponds to the
intermediate state shown in FIG. 2.
[0072] In FIG. 7, the roller 126 is received in the groove 114 and
prevents the inner sleeve 120 from moving downstream relative to
the inner surface 120. A radially exterior surface of the seat
sleeve 130 prevents the roller 126 from moving inward. This
corresponds to the final state described in connection with FIG. 3.
In addition, a final state holding shoulder 137 on the exterior
surface of the seat sleeve 130 abuts the roller 126 on its upstream
side. The roller 126 cannot move radially outward, and hence it
cannot pass the shoulder 137. Thus, the roller 126 and shoulder 137
is an alternative stopping mechanism that might supplement or
replace the shoulders 123 and 133 in FIG. 3.
[0073] FIGS. 8 and 9 illustrate temporary stopping means comprising
a pin-in-groove arrangement.
[0074] FIG. 8 is a side view of the seat sleeve 130 in FIGS. 1-3.
Assume that an alternating member such as a lug 125 or roller 126
abuts the shoulder 133 in the initial state as depicted in FIG. 4.
When the seat sleeve is released and has traveled a predetermined
length L within the inner sleeve, the alternating member 125, 126
should enter into the external recess 134 on the seat sleeve 130 as
shown in FIGS. 2 and 6. Now, if the seat sleeve 130 moves too fast
relative to the inner sleeve 120, the alternating member 125, 126
might skip past the recess 134 without entering. If this happens,
the seat sleeve 130 would continue out of the inner sleeve and
perhaps release the drop ball 300, while the inner sleeve 120
remains unshifted within the inner surface 101. That is, the
trigger mechanism fails if the alternating member 125, 126 does not
enter the recess 134 when the seat sleeve is shifted the distance L
downstream from its initial position relative to the inner sleeve
120.
[0075] To ensure that the alternating member 125, 126 enters into
the recess 134 at a predetermined displacement L, a pin 1250
connected to the inner sleeve 120 is axially slidably disposed in a
longitudinal groove 138 on the seat sleeve 130. In the initial
position shown on FIG. 8, the pin 1250 is at the downstream end of
the longitudinal groove 138. An inclined shoulder 1380 (FIG. 9) is
arranged a distance L upstream in the groove 138. Thus, the length
L of the longitudinal groove 138 corrresponds to the length L the
alternating member 125, 126 travels from the initial state to the
recess 134. Obviously, the longitudinal groove 138 might be
arranged anywhere on the seat sleeve 130 with a complementary pin
on the inner sleeve 120. Alternatively, a longitudinal groove on
the inner sleeve 120 with a pin on the seat sleeve 130 would work
in the same manner.
[0076] FIG. 9 is a sectional view of the recess 138 in FIG. 8 and
the corresponding part of an inner sleeve 120 comprising the pin
1250. For this illustration, it is assumed that the pin 1250 is an
integral part of an arm 1200 cut out of the inner sleeve 120 and
then bent into the longitudinal groove 138 in the seat sleeve 130.
An inclined surface 1380 is disposed a distance L from the pin
1250. The distance L in FIG. 9 equals the distance L in FIG. 8.
However, the scales are different so the distance L seems longer in
FIG. 9.
[0077] When the seat sleeve 130 is displaced nearly a distance L
downstream, i.e. toward the right in FIG. 9, relative to the inner
sleeve 120, the pin 1250 engages the inclined surface 1380. Further
displacement of the seat sleeve 130 causes the pin 1250 to climb up
the inclined surface 1380 until the arm 1200 is bent back to a near
horizontal position. This climbing causes the seat sleeve 130 to
slow down momentarily relative to the inner sleeve 120 shortly
before and after the pin 1250 has traveled a distance L in the
longitudinal groove 138. As the length L corresponds to when the
alternating member 125, 126 passes the recess 134 on FIG. 8, the
temporary axial stopper 1380 in the longitudinal groove 138 and the
corresponding member 1250 on the inner sleeve 120 are easily
adapted to ensure that the alternating member 125, 126 enters
properly into the recess 134.
[0078] Generally, any radially protruding element on a first sleeve
engaging a complemetary member on a second sleeve could stop the
relative axial movement between the first and second sleeves. In
the claims, the terms `axial stopper` and `complementary member`
denotes one such pair of elements designed to prevent or inhibit
motion between two sleeves. In the description above, stopping
shoulders 112, 122 and 123, 133; shoulders 133, 137 agains roller
126; alternating member 125 in groove 114 and pin 1250 in
longitudinal groove 138 are examples of such pairs. Further
varieties, e.g. providing the groove 138 on the inner sleeve 120
and the pin 1250 on the seat sleeve 130, are considered obvious. A
practical design of axial stoppers and complementary members is
left to the skilled person.
[0079] In the drawings, some recesses and grooves are depicted
without inclined shoulders to illustrate the invention as clearly
as possible, i.e. without unnecessary details. However, the
recesses or grooves can be provided with inclined surfaces to
facilitate entry and/or exit of a complementary member such as the
lug 125 or roller 126 described above. In particular, it is noted
that the activating sequence shown in FIGS. 1 to 3 can be reversed
if the seat sleeve 130 is pulled back from the final position in
FIG. 3 to the initial position in FIG. 1. For this, inclined
surfaces at both axial ends of the recesses and grooves would be
advantageous. Further, the shear pins 135 should be replaced by an
alternative release mechanism such as the one shown on FIGS. 4 and
5 for such an application. In order to reset the ball activated
device 100, an inner surface of the seat sleeve could comprise key
grooves to receive a conventional fishing tool, for example
deployed on a slick line.
[0080] Next, assume that the ball activated device 100 in FIG. 1 is
left in a well for an extended period of time. As discussed, the
alternating member 125, 126 is protected behind the seat sleeve
130. A protective sleeve 150 extending axially from the downstream
end of the seat sleeve 130 protects the annulus or seat receiving
area 115 provided for the collet finger 131 and radially expanding
seat defining members 132 in the final state shown in FIG. 3.
However, corrosion, scaling and other deposits may still build up
during the extended period and cause the parts to stick to each
other or otherwise prevent the parts from moving relative to each
other.
[0081] According to the present invention, the different parts are
released in sequence rather than all at once. First, the friction
forces sticking the seat sleeve 130 to the inner surface 120 (plus
the force required to break the shear pins 135 in FIG. 1 or
overcome the bias F in FIG. 4) must be overcome. A force required
to tear loose the inner sleeve 120 is not required at this
stage.
[0082] When the seat sleeve 130 has shifted downstream a distance L
within the inner sleeve 120 as depicted on FIGS. 8 and 9, it has
built up a certain speed and and is suddenly stopped because the
alternating member 125, 126 enters into recess 134 and/or because a
complementary member 1250 hits a temporary axial stopper 1380. The
resulting sudden jar might help loosening any bonds between the
inner sleeve 120 and the inner surface 101 in which it slides, even
if the inner sleeve 120 is not permitted to slide within the inner
surface 101 before the alternating member 125, 126 is properly
received in the external recess 134 on the seat sleeve 130.
[0083] For trigger mechanisms designed to stay in a well for an
extended period of time, it might be advantageous to make the area
of the seat sleeve 130 exposed to the well fluids small compared to
the exposed area of the inner sleeve 120 and also in comparison to
the exposed area of an optional protecting sleeve 150, because a
smaller exposed area decreases the amount of deposits that might
cause the seat sleeve 130 to stick. The area of the seat sleeve
can, for example, be decreased by using pins on the seat sleeve 130
and longitudinal grooves on the inner sleeve as axial
stoppers/complementary members. Also, the collet fingers 131 and
members 132 shown in FIGS. 1 to 3 could be replaced with other seat
defining members 132 configured to move radially outward once they
are out of the inner sleeve 120. For example, the seat defining
members 132 coud be slidably disposed on radial guides (not shown)
arranged perpendicular to the central axis of the seat sleeve 130.
Further, the mass of the seat sleeve 130 may be increased to
improve the jarring effect.
[0084] FIG. 10 shows an alternative embodiment of the trigger
mechanism 100 in the initial state, i.e. the state shown on FIG. 1.
Reference numerals 100-200 correspond to those on FIG. 1, and are
discussed above. The differences from FIG. 1 will be explained in
the next paragraphs.
[0085] The alternating member 125 in FIG. 10 is mounted on an arm,
and may be cut out of the inner sleeve 120 by providing the
aperture 124 along three edges of the alternating member 125 as
shown on FIG. 10.
[0086] On FIG. 10, holes 1150 are provided for shear pins attaching
the inner sleeve 120 to the inner surface 101 of the outer sleeve
110 in the initial state. The shear pins (not shown) retain the
inner sleeve 120 in the outer sleeve 110 until a force sufficient
to break them is exerted on the ball and seat.
[0087] Pins 433 sliding in longitudinal grooves 423 provide an
alternative means for limiting the relative motion between the
inner sleeve 120 and the seat sleeve 130. That is, the pins 433 in
the grooves 423 serve the same purpose as the shoulders 123 and 133
on FIG. 1. The holes 4330 in the seat sleeve 130 are provided for
attaching the pins 433.
[0088] Similar pins 1250 in grooves 138 stops the axial motion of
the seat sleeve 130 within the inner sleeve 130 temporarily to
ensure that the alternating member 125 enters the groove 134
properly as discussed in connection with FIGS. 8 and 9 above. In
contrast to the embodiment on FIG. 9, which merely slows the
relative motion when the pin 1250 hits the inclination 1380, the
pin 1250 on FIG. 13 is prevented from moving outward through the
hole 1251 in sleeve 120 by the inner surface 101. Thus, the pin
1250 stops the relative motion between the inner sleeve 120 and the
seat sleeve 130 when it hits the upstream end 1380 of the groove
138. Referring to the discussion above, the pin 1250 is allowed to
travel a longitudinal distance L (not shown on FIG. 10) along
groove 138 before it hits the upstream end 1380 of grove 138. This
length L corresponds to the length which the alternating member 125
must slide along sleeve 130 before it enters groove 134. The pin
1250 on FIG. 13 is permitted to move radially outward once it is
aligned with the recess 114 later on in the activation sequence,
and thus halts the relative motion between sleeves 120 and 130 from
it abuts the end 1380 of groove 138 until it enters into groove
114. In other words, the pin 1250 halts the relative motion of the
seat sleeve 130 within the inner sleeve 120 temporarily.
[0089] An optional leaf spring 435 is shown on FIG. 10, where it
retains the seat sleeve 130 within the inner sleeve 120 in the
initial state. A longitudinal force exerted on the seat sleeve 130
causes the spring 435 to move radially inwards until the seat
sleeve 130 is free to travel downstream within the inner sleeve
120. The leaf spring 435 may serve as an alternative retainer to
the shear pins 135 on FIG. 1.
[0090] In the initial state on FIG. 10, the seat defining members
132 are prevented from flaring out by a portion 420 of the inner
surface of the inner sleeve 120. The length of the portion 420 is
sufficient to prevent radial motion of the seat defining members
132 when the seat sleeve 130 has shifted downstream relative to the
inner sleeve 120 such that the alternating member 125 is received
in groove 134, i.e. when the trigger mechanism is in an
intermediate state corresponding to the state shown on FIG. 2.
[0091] On FIG. 10, the fingers 131 are provided with a
frustoconical portion 1310. The upstream and largest diameter of
the portion 1310 is substantially equal to the outer diameter of
the seat defining members 132, while the lower end of the
frustoconical portion 1310 has a reduced diameter. The length of
the portion 1310 corresponds to the length that the pins 433 can
travel in the grooves 423. In the final position, the portion 1310
lies along the inner portion 420, and the seat defining members 132
have moved radially out into the seat receiving recess 115 in order
to permit the ball to pass as in FIG. 3. Thus, the frustoconical
portion 1310 must be longer than the length of the portion 420
within the inner sleeve 120.
[0092] In addition to guide(s) 129 centering the inner sleeve 120
within the inner surface 110, a seal 429 is provided in the
embodiment on FIG. 10. The seal 429 covers the groove 114 in the
initial state, such that water and/or particles do not enter the
groove 114 and cause scaling or deposits as discussed above.
[0093] The distal or downstream ends of the collet fingers 131
interlock with the upstream end of the protective sleeve 150 in a
castellation 140. The castellation 140 prevents relative rotation
between the seat sleeve 130 and the protective sleeve 150, and
permits the seat defining members 132 to flare outward into the
seat receiving recess 115 when the trigger mechanism 100 reaches
its final state.
[0094] FIG. 11 is a perspective view of the inner sleeve 120 on
FIG. 10. Annular grooves 1270 and 1280 are provided for receiving
the seals 127 and 128, respectively. The alternating members 125
and holes 1150 for attaching shear pins are described above. The
holes 1251 through the walls of the sleeve are provided for pins
1250 as discussed in connection with FIG. 13. An annular groove
1290 is provided for a guide 129 and an annular groove 4290 for the
seal 429 described in connection with FIG. 10.
[0095] FIG. 12 is a perspective view of the seat sleeve 130 on FIG.
10, and shows an annular recess 139 in addition to the elements
shown on FIG. 10 and described above. The annular recess 139 is
provided to receive a seal (not shown) between the seat sleeve 130
and the inner sleeve 120 such that a pressure can be built behind a
ball lodged on the seat.
[0096] FIG. 13 shows a pin 1250 with a frustoconical end 1252. The
larger diameter of the pin 1250 fits into a hole 1251 through the
wall of the inner sleeve 120, cf. FIG. 11. The frustoconical end
1252 fits into the longitudinal groove 138, and may travel a
distance L along the groove 138 from the downstream end to the
upstream end 1380. The axial length of the pin 1250 corresponds to
the distance between the exterior surface of the inner sleeve 120
and the bottom of groove 138. Thus, when the seat sleeve 130 has
shifted axially the distance L with respect to the inner sleeve
120, the frustoconical end 1252 hits the upstream end 1380 of
groove 138 and remains in contact with the end 1380 until it is
aligned with the groove 114 in the outer sleeve 110, causing a
temporary halt in the relative motion between the inner sleeve 120
and the seat sleeve 130 as described above. As above, the distance
L corresponds to the axial shift required for the alternating
members 125 to align with the grooves 134, and the temporary halt
ensures that the alternating members 125 enter the grooves 134.
After the temporary halt, the frustoconical end 1250 causes the pin
1250 to move out of the groove 138 and radially outward in the hole
1251 through the inner sleeve 120 and into the recess 114 in the
outer sleeve. The holes 1251 are shown on FIG. 11, and the assembly
with recess 114 and pins 1250 through the wall of the inner sleeve
120 appears on FIG. 10.
[0097] The means on FIGS. 8 and 9 and the end 1380 of groove 138
and pin 1250 on FIGS. 12 and 13 are both examples of a separate
axial stopper 1380 on the seat sleeve 130 and a complementary
member 1250 configured to temporarily halt the axial motion of the
seat sleeve 130 at a position wherein the alternating member 125,
126 can enter the recess 134.
[0098] When the pins 1250 shown on FIGS. 10 and 13 are received in
the recess 114, the seat sleeve 130 is free to move axially within
the inner sleeve 120 until stoppers 433 attached to the holes 4330
reaches the end of grooves 423 in the inner sleeve as described in
connection with FIG. 10.
[0099] FIG. 14 shows a protective sleeve 150 with a castellation
140 adapted to fit into a similarly shaped downstream end of the
seat sleeve 130. The castellation 140 prevents relative rotation
between the seat sleeve 130 and the protective sleeve 150
[0100] Various other embodiments of the invention will be apparent
to those skilled in the art reading the description above. However,
the invention is not limited to the specific exemplary embodiments
above, but is defined by the subject matter set forth in the
appended claims.
* * * * *