Note: Descriptions are shown in the official language in which they were submitted.
1
Title: Valve Actuator
Description of Invention
The present invention relates to a valve actuator, particularly, but not
exclusively, for use in actuating a rotatable valve member mounted in a
tubular
used in oil or gas drilling and / or production.
The drilling of a borehole or well is typically carried out using a steel pipe
known as a drill pipe or drill string with a drill bit on the lowermost end.
The drill
string comprises a series of tubular sections, which are connected end to end.
The entire drill string may be rotated using a rotary table, or using an over-
ground drilling motor mounted on top of the drill pipe, typically known as a
'top-
drive', or the drill bit may be rotated independently of the drill string
using a
fluid powered motor or motors mounted in the drill string just above the drill
bit.
As drilling progresses, a flow of mud is used to carry the debris created by
the
drilling process out of the borehole. Mud is pumped down the drill string to
pass through the drill bit, and returns to the surface via the annular space
between the outer diameter of the drill string and the borehole (generally
referred to as the annulus). The mud flow also serves to cool the drill bit,
and
to pressurise the borehole, thus substantially preventing inflow of fluids
from
formations penetrated by the drill string from entering into the borehole. Mud
is
a very broad drilling term and in this context it is used to describe any
fluid or
fluid mixture used during drilling and covers a broad spectrum from air,
nitrogen, misted fluids in air or nitrogen, foamed fluids with air or
nitrogen,
aerated or nitrified fluids to heavily weighted mixtures of oil and or water
with
solid particles.
Significant pressure is required to drive the mud along this flow path, and to
achieve this, the mud is typically pumped into the drill string using one or
more
CA 2916904 2019-05-21
CA 02916904 2015-12-29
WO 2015/011434
PCT/GB2014/051527
2
positive displacement pumps which are connected to the top of the drill string
via a pipe and manifold.
Whilst the main mud flow into the well bore is achieved by pumping mud into a
main, axial, passage at the very top end of the drill string, it is also known
to
provide the drill string with a side passage which extends into the main
passage from a port provided in the side of the drill string, so that mud can
be
pumped into the main passage at an alternative location to the top of the
drill
string.
For example, as drilling progresses, and the bore hole becomes deeper and
deeper, it is necessary to increase the length of the drill string, and this
is
typically achieved by disengaging the top drive from the top of the drill
string,
adding a new section of tubing to the drill string, engaging the top drive
with
the free end of the new tubing section, and then recommencing drilling. It
will,
therefore, be appreciated that pumping of mud down the drill string ceases
during this process.
Stopping mud flow in the middle of the drilling process is problematic for a
number of reasons, and it has been proposed to facilitate continuous pumping
of mud through the drill string by the provision of a side passage, typically
in
each section of drill string. This means that mud can be pumped into the drill
string via the side passage whilst the top of the drill string is closed, the
top
drive disconnected and the new section of drill string being connected.
In one such system, disclosed in US2158356, at the top of each section of
drill
string, there is provided a side passage which is closed using a plug, and a
valve member which is pivotable between a first position in which the side
passage is closed whilst the main passage of the drill string is open, and a
second position in which the side passage is open whilst the main passage is
closed. During drilling, the valve is retained in the first position, but when
it is
time to increase the length of the drill string, the plug is removed from the
side
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
3
passage, and a hose, which extends from the pump, connected to the side
passage, and a valve in the hose opened so that pumping of mud into the drill
string via the side passage commences. A valve in the main hose from the
pump to the top of the drill string is then closed, and the pressure of the
mud at
the side passage causes the valve member to move from the first position to
the second position, and hence to close the main passage of the drill string.
The main hose is then disconnected, the new section of tubing mounted on the
drill string, and the main hose connected to the top of the new section. The
valve in the main hose is opened so that pumping of mud into the top of the
drill string is recommenced, and the valve in the hose to the side passage
closed. The resulting pressure of mud entering the top of the drill string
causes
the valve member to return to its first position, which allows the hose to be
removed from the side passage, without substantial leakage of mud from the
drill string.
The side passage may then be sealed permanently, for example by welding or
screwing a plug into the side passage, before this section of drill string is
lowered into the well.
This process is commonly referred to as continuous circulation drilling.
In other similar systems, instead of providing a single valve member which is
operable to close either the side passage or the main passage of the drill
string, it is known to provide two separate valve members ¨ a main valve
member which is operable to close the main passage, and an auxiliary valve
member which is operable to close the side passage. In this case, the
separate valve members may each have its own actuation mechanism, for
example as disclosed in W02010/046653.
A further alternative arrangement in which the actuator for the main valve
member is combined with the auxiliary valve member is disclosed in
W02012/085597. This arrangement is illustrated in Figures 1a and 1b.
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
4
In this arrangement, the main valve member 16 comprises a ball which is
mounted in the main passage 12 of the drill string 10, and which is rotatable
about an axis generally perpendicular to the longitudinal axis of the drill
string,
between an open position in which flow of fluid along the main passage 12 is
permitted, and a closed position in which it prevents flow of fluid along the
main passage 12. Rotation of the ball 16 between the open position and the
closed position is achieved using a tubular actuator 18, which is also mounted
within the main passage 12 of the drill string 10, coaxially with the drill
string
10. The actuator 18 is connected to the ball 16 such that sliding movement of
the 18 in the drill string 10 causes the ball 16 to move between the closed
position and the open position. The actuator 18 also acts to block or unblock
the side passage 14 as it slides along the drill string, and is configured to
open
the side passage 14 when the main valve 16 is in the closed position, and to
close the side passage 14 when the main valve 16 is in the open position.
.. The actuator 18 is hydraulically actuated by mean of an actuation chamber
38
which is provided between the actuator 18 and a lining 10a provided in the
wall
of the drill string 10. This is best illustrated in Figure lc, and simply
comprises
an annular space between the two parts 18, 10a. Two ports 40a, 40b are
provided through the drill string 10 into this chamber 38, one at each end of
.. the chamber 38. The first port 40a is closest to a second end 18b of the
actuator 18 (nearest the main valve member 16).
The chamber 38 is divided into two by a seal 41 which is mounted on the
exterior surface of the actuator 18. In one embodiment, the seal 41 comprises
2 0-rings. The seal 41 substantially prevents flow of fluid between the two
.. parts of the chamber 38 whilst permitting the actuator 18 to slide inside
the drill
string 10. The seal 41 ensures that flow of pressurised fluid into this
chamber
38 via the first port 40a causes the actuator 18 to move towards the main
valve member 16, whilst flow of pressurised fluid into the actuation chamber
38 via the second port 40b acts in the opposite direction to counterbalance
the
effect of pressurised fluid at the first port 40a. The actuator 18 therefore
acts
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
as a double acting piston with one pressure port 40a to move the actuator 18
towards the main valve member 16 and one pressure port to move the
actuator 18 away from the main valve member 16. In other words the actuator
18 is operated by means of a pressure differential across the first and second
5 .. ports 40a, 40b.
Figure 1a illustrates the actuator 18 when supply of pressurised fluid to the
port 40b has pushed it away from the main valve member 16, so that the
actuator 18 closes the side port 14, whilst Figure lb illustrates the sleeve
18
when supply of pressurised fluid to the port 40a has pushed it towards the
.. main valve member 16, thus opening the side port 14.
The mechanism whereby the actuator sleeve 18 is connected to the ball 16 so
that sliding movement of the actuator sleeve 18 causes the ball 16 to rotate
is
described fully in W02012/085597. Various similar arrangements are also
known from GB 2 413 373, US 3,236,255, GB 1 416 085, US 3,703,193 and
US 3,871,447.
These arrangements may also be used to control flow of fluid through a side
passage in what is known as a "pump in sub", which is used in the event of an
emergency, for example to facilitate the provision of additional mud pressure
required to control a sudden surge in well-bore pressure due to fluid inflow
from a formation penetrated by the well entering the well in what is known as
a
"kick".
This invention relates to an alternative configuration of actuator assembly
suitable for use in such a valve arrangement, where operation of the valve is
achieved by the sliding of an actuator sleeve relative to the drill string.
.. According to a first aspect of the invention we provide a fluid pressure
operated actuator assembly comprising a tubular body having a wall, with an
interior surface and an exterior surface and enclosing a main passage which
extends generally parallel to a longitudinal axis of the tubular body, an
actuator
CA 02916904 2015-12-29
WO 2015/011434
PCT/GB2014/051527
6
located in and movable along the main passage, a first direction chamber
formed between the wall of the tubular body and the actuator, and at least one
second direction chamber formed between the tubular body and the actuator,
wherein the assembly is configured such that when the pressure of fluid in the
first direction chamber exceeds the pressure of fluid in the or each second
direction chamber by a predetermined amount, the pressure of fluid in the
first
direction chamber exerts a force on the actuator which acts to push the
actuator in a first direction relative to the tubular body, and when the
pressure
of fluid in the or at least one of the second direction chamber(s) exceeds the
pressure of fluid in the first direction chamber by a predetermined amount,
the
pressure of fluid in the second direction chamber(s) exerts a force on the
actuator which acts to push the actuator in a second direction relative to the
tubular body, characterised in that the exterior surface of the tubular body
is
provided with a first port which communicates with a passage extending
through the wall of the tubular body from the first port to the first
direction
chamber, a second port which communicates with a passage extending
through the wall of the tubular body from the second port to the or one of the
second direction chamber(s), and a third port which communicates with a
passage extending through the wall of the tubular body from the third port to
the or another one of the second direction chamber(s), the first port lying on
a
first plane, the second port lying on a second plane and the third port lying
on
a third plane, the first plane, second plane and third plane being generally
parallel to one another and the first plane lying between the second plane and
the third plane.
In one embodiment, the longitudinal axis of the tubular body extends generally
normal to the first plane, second plane and third plane.
In one embodiment, one or both of the first and second directions is/are
generally parallel to the longitudinal axis of the tubular body.
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
7
In one embodiment, the first direction is generally opposite to the second
direction.
In one embodiment, the actuator is connected to a main valve member in such
a way that movement of the actuator in the first direction and second
direction
causes the valve member to move. In this embodiment, the main valve
member may be movable between a closed position in which the main valve
member closes the main passage of the tubular body and an open position in
which the main passage of the tubular body is open. The movement of the
main valve member caused by the movement of the actuator in the first
direction and second direction may comprise rotation.
In one embodiment, the main valve member moves to the closed position
when the actuator moves in the first direction and to the open position when
the actuator moves in the second direction.
The main valve member may comprise a ball valve member.
The actuator may be connected to valve member by means of a track and pin
arrangement whereby a pin extends from on of the valve member or actuator
into a slot or groove provided in the other of the valve member or actuator,
the
pin moving along the slot or groove as the actuator slides in the tubular body
and the valve member rotates.
In one embodiment, the tubular body is provided with a side passage which
extends through the wall of the tubular body from the exterior of the tubular
body into the main passage, and the actuator is movable between a closed
position in which the actuator substantially prevents flow of fluid along the
side
passage, and an open position in which flow of fluid along the side passage is
permitted. In this case, movement of the actuator in the first direction may
bring the actuator into the open position, and movement of the actuator in the
second direction may bring the actuator into the closed position. Where a
main valve member is also provided as described above, movement of the
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
8
actuator in the first direction may bring the actuator into the open position
and
the main valve member into the closed position, whilst movement of the
actuator in the second direction brings the actuator into the closed position,
and the main valve member into the open position.
The passage from the third port may connect to the passage from the second
port into the or one of the second direction chamber(s).
The first direction chamber and the or each second direction chamber may be
formed in a space between an exterior surface of the actuator and an interior
surface of the wall of the tubular body. This space may extend around the
entire perimeter of the actuator. This space may be divided into the first
direction chamber and second direction chamber by means of a seal which
substantially prevents flow of fluid between the chambers whilst allowing the
actuator to move along the main passage of the tubular body. This space may
be divided into the first direction chamber and two second direction chambers
by means of a seal arrangement which substantially prevents flow of fluid
between the chambers whilst allowing the actuator to move along the main
passage of the tubular body. The first direction chamber may be located
between the two second direction chambers. In this case, the passages from
the first port, second port and third port into their respective chambers may
extend through the tubular body generally perpendicular to its longitudinal
axis.
Alternatively, at least one of the passages from the first port, second port
and
third port into their respective chambers may extend through the tubular body
generally at an angle of less than 90g to its longitudinal axis.
In one embodiment, the actuator assembly is configured such that if the
pressure in the first direction chamber equals the pressure in the or both
second direction chamber(s), there is no net force acting on the actuator, if
the
pressure in the first direction exceeds the pressure in the or both the second
direction chamber(s), there is a net force acting on the actuator pushing the
actuator in the first direction, and if the pressure in the first direction
chamber
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
9
is less than the pressure in the or either one of the second direction
chamber(s), there is a net force acting on the actuator pushing the actuator
the
second direction.
In one embodiment, the actuator assembly is configured such that when the
pressure in the first direction chamber equals the pressure in the or both
second direction chamber(s), there is a net force acting on the actuator.
In this case, the actuator assembly may be configured such that this net force
tends to push the actuator in the second direction.
Embodiments of the invention will now be described, by way of example only,
with reference to the following figures of which;
FIGURES 2a and 2b show a longitudinal cross-section through a portion of
one embodiment of actuator assembly according to the invention, the actuator
having been moved in the second direction in Figure 2a and in the first
direction in Figure 2b,
FIGURES 3a and 3b show a longitudinal cross-section through a portion of an
alternative embodiment of actuator assembly according to the invention, the
actuator having been moved in the second direction in Figure 3a and in the
first direction in Figure 3b, AND
FIGURES 4a and 4b show a longitudinal cross-section through a portion of an
alternative embodiment of actuator assembly according to the invention, the
actuator having been moved in the second direction in Figure 4a and in the
first direction in Figure 4b.
Referring now to Figures 2a and 2b, there is shown a fluid pressure operated
actuator assembly comprising a tubular body 110 having a wall enclosing a
main passage 112 which extends generally parallel to a longitudinal axis of
the
tubular body 110, an actuator 118 located in and movable along the main
passage 112, a first direction chamber 138a and a second direction chamber
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
138b formed between the wall of the tubular body 110 and the actuator 118.
The tubular body 110 may be part of a drill string or may comprise a sub for
mounting in a drill string.
In this embodiment, both the tubular body 110 and actuator 118 are tubular
5 with a generally circular cross-section. The first direction chamber 138a
and
the second direction chamber 138b are formed in an annular space around the
actuator 118 between an exterior surface of the actuator 118 and an interior
surface of the tubular body 110. This space is divided into the first
direction
chamber 138a and second direction chamber 138b by means of a seal 141
10 which substantially prevents flow of fluid between the chambers 138a
138b.
Two further seals 118a, 130a are provided between the exterior surface of the
actuator 118 and the interior surface of the tubular body 110, one at each end
of the annular space.
In this embodiment, the seals 118a, 130a, and 141 each comprise a pair of
generally circular 0-rings which are located in circumferential grooves around
the exterior surface of the actuator 118. It should be appreciated, however,
that the invention is not restricted to the use of this particular type of
seal, and
any other type of seal which substantially prevents flow of fluid between the
actuator 118 and the tubular body 110 whilst allowing the actuator 118 to
slide
in the tubular body 110, could be used instead. The seals could equally be
mounted on the tubular body 110 rather than on the actuator 118.
The tubular body 110 is provided with a first port 140a which communicates
with a first control passage 139a extending through the wall of the tubular
body
110 from the first port 140a to the first direction chamber 138a, a second
port
140b which communicates with a second control passage 139b extending
through the wall of the tubular body 110 from the second port 140b to the
second direction chamber 138b and a third port 140c which communicates
with a third control passage 139c extending through the wall of the tubular
body 110 from the third port 140c to the second control passage 139b. In this
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
11
example, the first and second control passages 139a, 139b extend through the
wall of the tubular body generally perpendicular to its longitudinal axis. The
third passage 139c is inclined at angle of less than 45 to the longitudinal
axis
of the tubular body. In this example, the first and second control passages
139a, 139b are co-planar and so both can be seen in the cross-sections
illustrated in Figures 2a and 2b. The third control passage 139c necessarily
extends along a different plane and so is shown in dashed lines in these
Figures.
The first, second and third ports 140a, 140b, 140c are spaced along the
longitudinal axis of the tubular body 110 so that if the first port 140a is
considered to lie on a first imaginary plane, the second port 140b on a second
imaginary plane and the third port 140c on a third imaginary plane, the first
plane, second plane and third plane being generally parallel to one another
and generally normal to the longitudinal axis of the tubular body 110, the
first
plane lies between the second plane and the third plane.
The actuator assembly is configured such that when the pressure of fluid in
the
first direction chamber 138a exceeds the pressure of fluid in the second
direction chamber 138b, the pressure of fluid in the first direction chamber
138a exerts a force on the actuator 118 which acts to push the actuator 118 in
a first direction along the main passage 112 in the tubular body 110, and when
the pressure of fluid in the second direction chamber 138b exceeds the
pressure of fluid in the first direction chamber 138a, the pressure of fluid
in the
second direction chamber 138b exerts a force on the actuator 118 which acts
to push the actuator 118 in a second, opposite, direction along the main
passage 112 in the tubular body 110.
In this example, this is achieved by providing the interior of the tubular
body
110 with a portion of increased internal diameter 110a. At either end of this
portion 110a, the interior surface of the tubular body 110 forms a shoulder
110b, 110c where the internal diameter of the tubular body 110 decreases
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
12
slightly. The actuator 118 is substantially longer than the portion of
increased
internal diameter 110a and the outer diameter of the actuator 118 is less than
the internal diameter of the tubular body 110 either side of the portion of
increased internal diameter 110a. The first direction and second direction
chambers 138a, 138b are formed between the actuator 118 and the portion of
increased internal diameter 110a, and the seal 141 extends outwardly of the
exterior surface of the actuator 118 to engage with the interior surface of
increased internal diameter portion 110a of the tubular body 110. The first
direction chamber 138a is thus formed between the exterior surface of the
.. actuator 118, the first shoulder 110b, part of the increased internal
diameter
portion of the tubular body 110, and the seal 141. Similarly, the second
direction chamber 138b is formed between the exterior surface of the actuator
118, the second shoulder 110c, part of the increased internal diameter portion
of the tubular body 110, and the seal 141.
.. When pressurised fluid is supplied to the first port 140a, the fluid
pressure
pushes the seal 141 away from the first shoulder 110b to increase the volume
of the first direction chamber 138a. The actuator 118 is therefore pushed in
the
first direction. Similarly, when pressurised fluid is supplied to the second
or
third ports 140b, 140c, the fluid pressure in the second direction chamber
138b
pushes the seal 141 away from the second shoulder 110c to increase the
volume of the second direction chamber 138b. The actuator 118 is thus
pushed in the second direction. The actuator 118 therefore acts as a double
acting piston with a first port 140a to move the actuator 118 in a first
direction
along the main passage 112 in the tubular body 110 (in this example to the
left
in Figures 2a and 2b) and a second port 140b or a third port 140c to move the
sleeve 18 in a second direction along the main passage 112 in the tubular
body 110 (in this example to the right in Figures 2a and 2b).
It should be appreciated that this embodiment differs from the prior art
actuator
described in W02012/085597, and GB 2 413 373, for examples, by virtue of
the provision of the third port 140c. The third port 140c may be advantageous
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
13
as it may assist in preventing unwanted movement of the actuator 118 when
the exterior of the tubular body 110 is exposed to a pressure differential.
This
is particularly important where the tubular body is portion of a drill string,
or a
sub mounted in a drill string, and the drill string is used in managed
pressure
drilling (MPD).
In a conventional drilling fluid system, only one drilling fluid gradient
exists, and
differential pressure between two points in the drill string can be described
by
the hydrostatic head and any frictional forces associated with a dynamic
system. Managed pressure drilling (MPD) is a style of drilling in which the
bottom hole pressure (BHP) is maintained through various methods including
fluid level maintenance, effective fluid density manipulation, applied back
pressure, and potentially combinations of these and other practices. The use
of a rotating control device (ROD) is becoming increasingly common in
offshore applications to meet the demands of MPD wells in deep water
environments.
An RCD clamps around the drill string to main fluid pressure differential in
the
annulus around the drill string (typically there is higher pressure below the
ROD), whilst allowing the drill string to rotate as required for drilling. The
ROD
is intended as a means of isolating one part of the wellbore from another
during drilling operations, and can be inserted at any point in a riser
string,
depending on the application, for the purpose of dual gradient drilling (DGD)
or
applying back pressure to the riser annulus, or other purposes.
The ROD therefore creates an irregularity or discontinuity in the overall
pressure profile of the well, which, in practical terms, may mean that as the
drill string is inserted into the well, a point on the drill string may
experience a
sudden increase in pressure by 500 psi or more having travelled only 6 inches
or less. This differential pressure may act from below a drill string element,
i.e.
the area of high pressure being lower than the area of low pressure.
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
14
Differential pressure may also act from above, however, for example if the
riser and RCD is configured more toward well control.
The valve assembly described in W02012/085597 is reliable in conventional
single fluid gradient environments, as the distance between the first and
.. second ports 40a, 40b is relatively short. This means that as the portion
of the
drill string containing these ports 40a, 40b is advanced into the well, any
pressure differential across the ports as a result of the pressure gradient in
the
annulus is negligible, and is not sufficient to move the actuator 18. This may
not be the case, however, if the drill string were to pass through a
discontinuity
in the pressure gradient such as one introduced by an ROD. Where an ROD
is used, there may exist a point in the riser where, when the portion of the
drill
string including the ports 40a, 40b passes through, differential pressure may
be seen from above or below, which exceeds the actuating pressure of the
actuator 18. This may, therefore, result in unintended movement of the
actuating sleeve 18. The provision of the third port 140c may prevent this as
will be described below.
To achieve this, in use, the actuator 118 should be arranged such that its
default or rest position is as illustrated in Figure 2b, and is adopted by
virtue of
the supply of pressurised fluid to the second and/or third ports 140b, 140c.
As
the tubular body 110 passes through a pressure discontinuity such as one
introduced by an ROD, if the portion of the tubular body 110 shown on the left
hand side of Figures 2a and 2b encounters the high pressure first, the second
port 140b is exposed to high pressure (the high pressure also being
communicated to the third port 140c), whilst the first port 140a is at low
.. pressure. The high pressure at the second and third ports 140b, 140c will
act
to maintain the actuator 118 in its rest / default position. As the passage of
the
tubular body 110 through the pressure discontinuity continues, the first port
140a will then also be exposed to the high pressure, but as this is balanced
by
the same high pressure at the second and third ports 140b, 140c the actuator
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
118 will not move. As the pressure discontinuity passes, the pressure at all
three ports 140a, 140b, 140c is substantially equal.
Similarly, if the portion of the tubular body 110 shown on the right hand side
of
Figures 2a and 2b encounters the high pressure first, the third port 140c is
5 exposed to high pressure (which is also communicated to the second port
140b), whilst the first port 140a is at low pressure. The high pressure at the
second and third ports 140b, 140c will act to maintain the actuator 118 in its
rest / default position. As the passage of the tubular body 110 through the
pressure discontinuity continues, the first port 140a will then also be
exposed
10 to the high pressure, but as this is balanced by the same high pressure
at the
second and third port 140c, the actuator 118 will still not move.
Thus, the actuator 118 will not be moved from its default or rest position by
the
pressure discontinuity, whichever end of the tubular body 110 is exposed to
the high pressure first, and the actuator assembly can therefore cope with
15 pressure differential from above and below without unintended actuation.
Although not essential to the invention, in this embodiment, the tubular body
110 is provided with a side passage 114 which extends from the exterior of the
body 110 into the main passage 112. The actuator 118 is provided with a
further seal 130b which provide a substantially fluid tight seal between the
actuator 118 and the tubular body 110 to ensure that, when the actuator is in
a
closed position (illustrated in Figure 2b), the actuator substantially
prevents
flow of fluid along the side passage 114.
In this example, this further seal 130b comprises two seals each of which is a
generally circular 0-ring which are located in circumferential grooves around
the exterior surface of the actuator 118. The further seal 130b and the seal
130a provided to contain fluid pressure in the first direction chamber 138a
are
spaced such that when the actuator 118 is in the closed position, the side
port
114 lies between the two seals 130a, 130b. Again, it should be appreciated
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
16
that the invention is not restricted to the use of this particular type of
seal, and
any other type of seal which substantially prevents flow of fluid between the
actuator 118 and the tubular body 110 whilst allowing the actuator 118 to
slide
in the tubular body 110, could be used instead.
In this embodiment, movement of the actuator 118 from the closed position to
the open position comprises movement in the first direction, which movement
is, as described above, achieved by supply of pressurised fluid to the first
port
140a. Correspondingly, movement of the actuator 118 from the open position
to the closed position comprises movement in the second direction, which
movement is, as described above, achieved by supply of pressurised fluid to
the second or third port 140b, 140c. This means that, when the actuator 118
is in the closed position, it is maintained in that position even when the
tubular
body 110 passes through a pressure discontinuity such as created by an RCD
in a managed pressure drilling situation. Thus, leakage of fluid out of the
main
passage 112 of the tubular body 110 via the side port 114 when the tubular
body passes through a pressure discontinuity should be avoided.
Figure 2a illustrates the actuator 118 when supply of pressurised fluid to the
first port 140a has pushed it in the first direction, thus opening the side
port
114, whilst Figure 2b illustrates the actuator 118 when supply of pressurised
fluid to the second or third port 140b, 140c has pushed it in the second
direction, so that the actuator 118 closes the side port 114.
It will be appreciated, however, that the actuator assembly could equally be
configured such that the opposite is true ¨ i.e. movement of the actuator 118
from the closed position to the open position comprises movement in the
second direction etc, so that the actuator 118 is brought to or maintained in
the
open position when it passes through a pressure discontinuity.
In one embodiment the actuator 118 is connected to a main valve member
(not shown) in such a way that movement of the actuator 118 in the first
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
17
direction and second direction causes the main valve member to move. The
main valve member may be movable between a closed position in which the
main valve member closes the main passage 112 of the tubular body 110 and
an open position in which the main passage 112 of the tubular body 110 is
open. The movement of the main valve member caused by the movement of
the actuator 118 in the first direction and second direction may comprise
rotation, and the main valve member may be a ball valve.
In one embodiment, the actuator 118 is connected to valve member by means
of a track and pin arrangement whereby a pin extends from one of the valve
member or actuator into a slot or groove provided in the other of the valve
member or actuator, the pin moving along the slot or groove as the actuator
118 slides in the tubular body 110 and the valve member rotates. Various
possible mechanisms whereby the actuator 118 could be connected to the
main valve member so that sliding movement of the actuator 118 causes the
main valve member to rotate are described in WO 2012/085597, GB 2 413
373, US 3,236,255, GB 1 416 085, US 3,703,193 and US 3,871,447.
In a preferred embodiment, the main valve member moves to its closed
position when the actuator 118 moves in the first direction, which movement
is,
as described above, achieved by supply of pressurised fluid to the first port
.. 140a. Correspondingly, the main valve moves to its open position when the
actuator 118 moves in the second direction, which movement is, as described
above, achieved by supply of pressurised fluid to the second or third port
140b, 140c. This means that, the main valve member is brought to or
maintained in its open position when the tubular body 110 passes through a
pressure discontinuity such as created by an ROD in a managed pressure
drilling situation. Thus, unintentional blocking of the main passage 112 of
the
tubular body 110 by the main valve member when the tubular body 110
passes through a pressure discontinuity should be avoided. This is
particularly
advantageous when the assembly is used in a drill string in managed pressure
.. drilling, as closing of the main valve stops the flow of drilling fluid
down the drill
. .
18
string, and this could lead to potential sticking and well control issues, and
is likely to force
a trip out of the well at significant cost.
Not only is it possible for the actuator 118 to either facilitate the opening
or closing of a
side port 114 through the tubular body 110 or control the opening or closing
of a main
valve member, it is possible for the actuator 118 to do both. In other words,
both a side
port 114 and main valve member as described above, may be provided. In this
case, the
assembly is advantageously configured such that movement of the actuator 118
in the
first direction brings the actuator 118 into the open position and the main
valve member
into the closed position, whilst movement of the actuator 118 in the second
direction
brings the actuator 118 into the closed position, and the main valve member
into the open
position.
An alternative embodiment of actuator assembly is illustrated in Figures 3a
and 3b. In
this embodiment, two second direction chambers 138b, 138c are provided, the
second
port 140b connecting the exterior of the tubular body 110 with the first
second direction
chamber 138b and the third port 138c connecting the exterior of the tubular
body 110 with
the second second direction chamber 138c. The first direction chamber 138a is
located
between the two second direction chambers 130b, 138c. In this embodiment, the
passages from the first port 140a, second port 140b, and third port 140c into
their
respective chambers 138a, 138b, 138c extend through the tubular body 110
generally
perpendicular to its longitudinal axis.
Again, in this embodiment, both the tubular body 110 and actuator 118 are
tubular with a
generally circular cross-section. The first direction chamber 138a and the
second
direction chambers 138b, 138c are formed in an annular space around the
actuator 118
between an exterior surface of the actuator 118 and an interior surface of the
tubular body
110. This space is divided into the first direction chamber 138a and two
second direction
chambers 138b, 138d by means of three seals 141, 143, 145 which substantially
prevent
flow of fluid
CA 2916904 2019-12-10
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
19
between the chambers 138a 138b, 138c. Again, two further seals 118a, 130a
are provided between the exterior surface of the actuator 118 and the interior
surface of the tubular body 110, one at each end of the annular space.
As before, in this embodiment, the seals 118a, 130a, 141, 143, 145 each
comprise a pair of generally circular 0-rings which are located in two
circumferential grooves around the exterior surface of the actuator 118. It
should be appreciated, however, that this invention is not restricted to the
use
of this particular type of seal, and any other type of seal which
substantially
prevents flow of fluid from the chambers 138a, 138b, 138c whilst allowing the
actuator 118 to slide in the tubular body 110, could be used instead. The
seals could equally be mounted on the tubular body 110 rather than on the
actuator 118.
Again, the actuator assembly is configured such that when the pressure of
fluid in the first direction chamber 138a exceeds the pressure of fluid both
of
the second direction chambers 138b, 138c, the pressure of fluid in the first
direction chamber 138a exerts a force on the actuator 118 which acts to push
the actuator 118 in a first direction along the main passage 112 in the
tubular
body 110, and when the pressure of fluid in either of the second direction
chambers 138b, 138c exceeds the pressure of fluid in the first direction
chamber 138a, the pressure of fluid in the second direction chamber in
question 138b, 138c exerts a force on the actuator 118 which acts to push the
actuator 118 in a second, opposite, direction along the main passage 112 in
the tubular body 110.
In this example, this is achieved by providing the interior of the tubular
body
110 with two portions of increased internal diameter 110a, 110a'. At either
end
of these portions 110a, 110a', the interior surface of the tubular body 110
forms a shoulder 110b, 110c, 110d, 110e where the internal diameter of the
tubular body 110 decreases slightly. The actuator 118 is substantially longer
than both the portions of increased internal diameter 110a, 110a' together,
and
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
the outer diameter of the actuator 118 is less than the internal diameter of
the
tubular body 110 either side of the portions of increased internal diameter
110a, 110a'. The first direction and second direction chambers 138a, 138b,
138c are formed between the actuator 118 and the portions of increased
5 internal diameter 110a, 110a', and two of the seals 141, 145 extend
outwardly
of the exterior surface of the actuator 118 to engage with the interior
surface of
increased internal diameter portions 110a, 110a' of the tubular body 110, one
being located in each portion of increased internal diameter 110a, 110a'. The
middle seal 143 engages with a portion of the internal surface of the tubular
10 wall 110 between the two portions of increased internal diameter 110a,
110a'.
As in the embodiment illustrated in Figures 2a and 2b, the first direction
chamber 138a is formed between the exterior surface of the actuator 118, the
first shoulder 110b, the middle seal 143, part of the first increased internal
diameter portion 110a of the tubular body 110, and the seal 141. Similarly,
the
15 first second direction chamber 138b is formed between the exterior
surface of
the actuator 118, the end seal 118a, the second shoulder 110c, part of the
first
increased internal diameter portion 110a of the tubular body 110, and the seal
141. The second direction chamber 138c is formed between the exterior
surface of the actuator 118, the middle seal 143, the third shoulder 110d,
part
20 of the second increased internal diameter portion 110a' of the tubular
body
110, and the seal 145.
When pressurised fluid is supplied to the first port 140a, the fluid pressure
pushes the seal 141 away from the first shoulder 110b to increase the volume
of the first direction chamber 138a. The actuator 118 is therefore pushed in
the first direction. Similarly, when pressurised fluid is supplied to the
second
port 140b, the fluid pressure in the first second direction chamber 138b
pushes
the seal 141 away from the second shoulder 110c to increase the volume of
the second direction chamber 138b. The actuator 118 is thus pushed in the
second direction. Also, when pressurised fluid is supplied to the third port
140a, the fluid pressure in the second second direction chamber 138c pushes
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
21
the seal 145 away from the third shoulder 110d to increase the volume of the
second second direction chamber 138c. The actuator 118 therefore acts as a
double acting piston with a first port 140a to move the actuator 118 in a
first
direction along the main passage 112 in the tubular body 110 (in this example
to the left in Figures 3a and 3b) and a second port 140b or a third port 140c
to
move the sleeve 18 in a second direction along the main passage 112 in the
tubular body 110 (in this example to the right in Figures 3a and 3b). In other
words, the effect of fluid pressure at the first, second and third ports 140a,
140b, 140c is exactly the same as in the embodiment described in relation to
Figures 2a and 2b, and any or all of the additional features of the earlier
embodiment can also be applied to this embodiment.
A further alternative embodiment of the invention is illustrated in Figures 4a
and 4b. This embodiment is very similar to the embodiment described with
reference to Figures 3a and 3b, in that it too has a second second direction
chamber 1380 - the difference lies in relation to the order of the chambers
138a, 138b, 1380. Whilst in the Figure 3a/3b embodiment, the first direction
chamber 138a is located between the two second direction chambers 138b,
138c, in this alternative embodiment, the two second direction chambers 138b,
138c are next to one another. So that the first port 140a can lie on an
imaginary plane which is between the imaginary plane on which the second
port 140b and the third port 140c lie, the control passage 139a to the first
direction chamber 138a and the control passage 139c to the second second
direction chamber 138c extend diagonally through the wall of the tubular body
110. In this example, the control passage 139b to the first second direction
chamber 138b extends through the tubular body 110 generally perpendicular
to its longitudinal axis.
In this example, this arrangement of the chambers is achieved by providing the
interior of the tubular body 110 with three portions of increased internal
diameter 110a, 110a', 110a". At either end of each of these portions 110a,
110a', 110a", the interior surface of the tubular body 110 forms a shoulder
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
22
110b, 110c, 110d, 110e where the internal diameter of the tubular body 110
changes slightly. The internal diameter of the tubular body 110 in the first
and
third increased diameter portions 110a, 110a", is less than the internal
diameter of the tubular body 110 in the second increased diameter portion
.. 110a'. The second increased diameter portion 110a' lies directly between
the
first and third increased internal diameter portions 110a, 110a".
The actuator 118 is substantially longer than all the portions of increased
internal diameter 110a, 110a', 110a" together, and the outer diameter of the
actuator 118 is less than the internal diameter of the tubular body 110 either
side of the portions of increased internal diameter 110a, 110a', 110a". The
first direction and second direction chambers 138a, 138b, 138c are formed
between the actuator 118 and the portions of increased internal diameter
110a, 110a', and the three seals 141, 143, 145 extend outwardly of the
exterior surface of the actuator 118 to engage with the interior surface of
increased internal diameter portions 110a, 110a', 110a" of the tubular body
110, one being located in each portion of increased internal diameter 110a,
110a', 110a". The seal 141 engages with the first increased diameter portion
110a, the middle seal 143 engages with the second increased internal
diameter 110a', and the final seal 145 engages with the third increased
diameter portion 110a".
In contrast to the arrangement shown in Figures 3a and 3b, the first direction
chamber 138a is formed between the exterior surface of the actuator 118, the
middle seal 143, part of the third increased internal diameter portion 110a"
of
the tubular body 110, the end shoulder 110e and the seal 145. Similarly, the
first second direction chamber 138b is formed between the exterior surface of
the actuator 118, the shoulder 110c, the end seal 118a, part of the first
increased internal diameter portion 110a of the tubular body 110, and the
first
seal 141. The second second direction chamber 138c is formed between the
exterior surface of the actuator 118, the shoulder 110b, the first seal 141,
part
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
23
of the second increased internal diameter portion 110a' of the tubular body
110, and the middle seal 143.
When pressurised fluid is supplied to the first port 140a, the fluid pressure
pushes the seal 143 away from the first shoulder 110d to increase the volume
of the first direction chamber 138a. The actuator 118 is therefore pushed in
the first direction. Similarly, when pressurised fluid is supplied to the
second
port 140b, the fluid pressure in the first second direction chamber 138b
pushes
the seal 141 away from the shoulder 110c to increase the volume of the
second direction chamber 138b. The actuator 118 is thus pushed in the
second direction. Also, when pressurised fluid is supplied to the third port
140a, the fluid pressure in the second second direction chamber 1380 pushes
the seal 143 away from the shoulder 110b to increase the volume of the
second second direction chamber 138c. The actuator 118 therefore acts as a
double acting piston with a first port 140a to move the actuator 118 in a
first
direction along the main passage 112 in the tubular body 110 (in this example
to the left in Figures 4a and 4b) and a second port 140b or a third port 140c
to
move the sleeve 18 in a second direction along the main passage 112 in the
tubular body 110 (in this example to the right in Figures 4a and 4b). In other
words, the effect of fluid pressure at the first, second and third ports 140a,
140b, 140c is exactly the same as in the embodiment described in relation to
Figures 2a and 2b, and any or all of the additional features of the earlier
embodiment can also be applied to this embodiment.
As the tubular body 110 passes through a pressure discontinuity such as one
introduced by an ROD, if the portion of the tubular body 110 shown on the left
hand side of Figures 3a, 3b, 4a or 4b encounters the high pressure first, the
second port 140b is exposed to high pressure whilst the first and third ports
140a, 140c are at low pressure. The high pressure at the second port 140b
will only act to maintain the actuator 118 in its rest / default position. As
the
passage of the tubular body 110 through the pressure discontinuity continues,
the first port 140a will then also be exposed to the high pressure, but as
this is
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
24
balanced by the same high pressure at the second port 140b, the actuator 118
will not move. Finally, the third port 140c will also be exposed to the high
pressure, so the pressure at all three ports 140a, 140b, 140c is substantially
equal.
Similarly, if the portion of the tubular body 110 shown on the right hand side
of
Figures 3a, 3b, 4a and 4b encounters the high pressure first, the third port
140c is exposed to high pressure whilst the first and second ports 140a, 140b
are at low pressure. The high pressure at the third port 140c will only act to
maintain the actuator 118 in its rest / default position. As the passage of
the
tubular body 110 through the pressure discontinuity continues, the first port
140a will then also be exposed to the high pressure, but as this is balanced
by
the same high pressure at the third port 140c, the actuator 118 will still not
move. Finally, the second port 140b will also be exposed to the high pressure,
so the pressure at all three ports 140a, 140b, 140c is substantially equal.
The embodiments described in relation to Figures 3a, 3b, 4a and 4b has an
advantage over the embodiments described in relation to Figures 2a and 2b
when passed through a device such as an RCD which seals around the
tubular body 110 to maintain a pressure discontinuity either side of the RCD.
Where the embodiment illustrated in Figures 2a and 2b is used, when one of
the second port 140b or third port 140c is exposed to the high pressure at one
side of the RCD, if the RCD seals do not close the other of the second port
140b or third port 140c, these ports provide a flow path for flow of fluid
across
the RCD. This cannot occur when the third port 140c connects to a second
second direction chamber 138c.
In the embodiments of the invention described above, the actuator assembly is
configured such that the first direction and second direction chamber(s) 138a,
138b, 138c are pressure balanced. This means that if the pressure in the first
direction chamber 138a equals the pressure in the or both second direction
chamber(s) 138b, 138c, there is no net force acting on the actuator 118, if
the
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
pressure in the first direction exceeds the pressure in the or both the second
direction chamber(s), there is a net force acting on the actuator 118 pushing
the actuator 118 in the first direction, and if the pressure in the first
direction
chamber 138a is less than the pressure in the or either one of the second
5 direction chamber(s) 138b, 138c, there is a net force acting on the
actuator
118 pushing the actuator 118 in the second direction. This is achieved by
configuring the first direction and second direction chamber(s) 138a, 138b,
138c in such a way that the cross-sectional area of the first direction
chamber
138a perpendicular to the first direction is equal to the cross-sectional area
of
10 the or each second direction chamber 138b, 138c perpendicular to the
second
direction.
This is realised in the embodiment illustrated in Figures 2a and 2b by
ensuring
that the shoulder 110c which partly encloses the second direction chamber
138b has substantially the same depth as the shoulder 110b which partly
15 encloses the first direction chamber 138a. This is realised in the
embodiment
illustrated in Figures 2a, and 2b by ensuring that the shoulder 110c which
partly encloses the first second direction chamber 138b, the shoulder 110b
which partly encloses the first direction chamber 138a, and the shoulder 110d
which partly encloses the second second direction chamber 138c are
20 substantially equal in depth.
This need not be the case, however, and the actuator assembly may
configured in an non-pressure balanced fashion so that when the pressure in
the first direction chamber 138a equals the pressure in the or both second
direction chamber(s), there is a net force acting on the actuator 118.
25 In this case, it is preferable for this net force to push the actuator
118 in the
second direction. If this is the case, it will be appreciated that to move the
actuator 118 in the first direction, it will be necessary to increase the
fluid
pressure in the first direction chamber 138a relative to the fluid pressure in
the
or both of the second direction chamber(s) 138b, 138c so that the fluid
CA 02916904 2015-12-29
WO 2015/011434 PCT/GB2014/051527
26
pressure in the first direction chamber 138a exceeds the pressure in the or
both of the second direction chamber(s) 138b, 138c by a predetermined
margin. Moreover, once the actuator 118 has been moved in the first
direction, it will be pushed back in the second direction once the fluid
pressure
in the first direction chamber 138a falls below the level set by that
predetermined margin, even if it still exceeds the pressure in the or both of
the
second direction chamber(s) 138b, 138c.
This can be achieved by configuring the first direction and second direction
chamber(s) 138a, 138b, 138c in such a way that the cross-sectional area of
the first direction chamber 138a perpendicular to the first direction is less
than
the cross-sectional area of the or each second direction chamber 138b, 138c
perpendicular to the second direction.
In the embodiment shown in Figures 2a and 2b one way this relative decrease
of the cross-sectional area of the first direction chamber 138a with respect
to
the cross-sectional area of the second direction chamber 138b could be
realised is by increasing the depth of the shoulder 110c which partly encloses
the second direction chamber 138b (by decreasing the internal diameter of the
tubular body 110 on the side of the shoulder 110c outside the increased
internal diameter portion 110a and decreasing the outer diameter of the
actuator 118 on the second direction chamber 138b side of the seal 141
between the two chambers 138a, 138b). In the embodiment illustrated Figures
3a and 3b, one way this relative decrease of the cross-sectional area of the
first direction chamber 138a with respect to the cross-sectional area of the
second direction chambers 138b, 138c could be realised is by increasing the
depth of the shoulder 110c which partly encloses the first second direction
chamber 138b (by decreasing the internal diameter of the tubular body 110 on
the side of the shoulder 1100 outside the increased internal diameter portion
110a and decreasing the outer diameter of the actuator 118 on the second
direction chamber 138b side of the seal 141 between the two chambers 138a,
138b) and increasing the depth of shoulder 110d which partly encloses the
CA 02916904 2015-12-29
WO 2015/011434
PCT/GB2014/051527
27
second second direction chamber 138c (by increasing the internal diameter of
the second increased internal diameter portion 110a' of tubular body).
When used in this specification and claims, the terms "comprises" and
"comprising" and variations thereof mean that the specified features, steps or
integers are included. The terms are not to be interpreted to exclude the
presence of other features, steps or components.
The features disclosed in the foregoing description, or the following claims,
or
the accompanying drawings, expressed in their specific forms or in terms of a
means for performing the disclosed function, or a method or process for
attaining the disclosed result, as appropriate, may, separately, or in any
combination of such features, be utilised for realising the invention in
diverse
forms thereof.
