Note: Descriptions are shown in the official language in which they were submitted.
WO 92/06270 _ 1 PCT/GB91/01679
- 209~~m
Valve Control Apparatus
This invention relates to valve control apparatus,
and concerns in particular a multi-operation valve
control apparatus usable as a resettable safety
circulating valve in a downhole well test string.
Whether at sea or on land, the first stages in the
production of a new hydrocarbon well - an oil well - are
the drilling of the well bore itself through the various
formations within the earth's crust beneath the drilling
rig, followed by "casing" (the introduction and
cementing into position of piping which will serve to
support and line the bore) and the placing in the bore,
at the depth of a formation of interest, of a device
known as a packer, into which inner tubing (of smaller
diameter than the casing) can subsequently be lodged.
The next work carried out is normally some
programme of testing, for the purpose of evaluating the
production potential of the chosen formation. The
testing procedure usually involves the measurement of
downhole temperatures and pressures, in both static and
flow conditions (the latter being when fluid from the
relevant formation is allowed to flow into and up the
well), and the subsequent calculation of various well
parameters. To collect the necessary data there is
lowered into the well and onto the packer a test string
- a length of tubing containing the tools required for
testing. The flow of fluid from the formation of
interest into the test string and thus to the test tools
is controlled by a valve known as a sub-surface control
valve.
WO 92106270 - 2 - PCT/GB91f01679
2493331
The opera ion of the various tools included in the
downhole test string can be effected using one of three
main types of mechanism. These types are those ar.tnaled
by reciprocal motion of the pipe string f he inner tube.
of which the test string constitutes a part), by
rotational motion of the pipe string, or by changes in
the pressure differential between the tubing and the
annular space which surrounds it in the well -
hereinafter referred to simply as "the annulus". Test
strings wherein the tools thereof are actuated by
changes in annulus pressure are at present much in
vogue, and it is this type of actuation mechanism that
is to be employed with the apparatus of the invention.
A mechanism of the annulus pressure-responsive type
requires the provision and maintenance of a fixed
"reference" pressure within the tool. This, used in
conjunction with an adjustable (and higher) annulus
pressure, allows the establishment of the chosen
pressure differential necessary to control the operation
of the appropriate component of the test string. The
achievement of such a fixed reference pressure is the
subject of our co-pending British Patent Application
No. 89/07,098.1 (Publication No: 2,229,748; P1049).
Following completion of the well testing procedure,
it is necessary safely to "shut down" the test tools,
and then to remove the test string from the packer
assembly and pull it to the surface. These operations
do, however, require careful control and planning. In
the case of pressure-differential-actuated test tools,
for example, the string will, at the end of testing,
still contain the high pressure reference gas which has
been used in creating the required differentials. It is
extremely desirable for this gas in some way to be
vented before the string reaches the well head, so that
WO 92/06270 _ 3 _ PCT/GB91/01679
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2~9~33~
there are no potentially dangerous pressures trapped
within the tools when the test string is received at the
surface .
Additionally, it is an advantage if there be
incorporated within the test string some means of
isolating the upper portion of the tubing thereof, and
of subsequently providing a route for communication
between this tubing and the annulus, so that
tubing-contained well liquid above the test string can
then be circulated out of the tubing before it is raised
to the surface. The isolation is conveniently
accomplished using a ball valve suitably placed near the
top of the test string, and such a ball valve
particularly suitable for effecting this isolation is
described in our co-pending British Patent Application
No. 89/09,903.0 (Publication No: 2,231,069; P1062).
However, reliance upon a single valve is not advisable,
and consequently there is a strong case in favour of the
utilisation of a second valve in the test apparatus.
This latter valve can then be used either in addition to
the main valve or, in the event of the latter not
operating correctly, as an alternative thereto.
In the Specification of our co-pending British
Patent Application No: 90/06,58.3 !Publication
No: 2,230.802; P1069) there is described apparatus for
these venting and isolation procedures that should
facilitate the procedure for discontinuation of an oil
well testing programme. Moreover, the apparatus permits
those operations to be carried out as an automatic
sequence, following the application of a single
actuating pressure pulse to the annulus. F;=~ the
venting of the reference gas, the invention suggests
pressure release apparatus having two spaced pistons
located at opposite ends of a chamber filled with that
W0 92/06270 - 4 _ PCT/GB9t/01679
203331
gas and blocking both a gas vent to annulus and a
hydraulic liquid passageway (to further up the test
string), the pistons being Held together by a shear pin
until the application of a predetermined pressure
(higher than the gas reference pressure) at the outside
ends of those pistons causes the pin to shear, allowing
sequential movement of the two pistons towards each
other, with the effect of firstly opening the gas vent
to annulus, and secondly opening the passageway to a
chamber of hydraulic liquid.
The hydraulic liquid pressure within this
passageway then causes actuation of ball valve apparatus
for isolating the upper section of tubing. This
apparatus is in the form of a ball-valve-driving piston
blocking another passageway for hydraulic liquid, which
piston is forced to move under the influence of the
pressure, breaking a restraining shear pin as it does
so, and closing the ball valve while openinqr this other
hydraulic liquid passageway, permitting transfer of
hydraulic pressure to apparatus far venting the contents
of the tubing to annulus. Finally, this venting
apparatus contains a circulating valve - a valve (in
this case a longitudinally-movable sleeve member) the
position of which determines whether or not flow is
permitted, via a vent port, between the test string
tubing and the annulus.
This apparatus performs quite satisfactorily, but
nevertheless might be said to have the disadvantage that
it is a "one-off" system; once activated by the applied
pressure causing the various shear pins to shear, the
several operations resulting therefrom are irreversible,
and the tool cannot be put back into the initial state.
The present invention proposes a solution to this
problem, by providing a novel valve arrangement that
WO 92/062?0 - 5 - PCT/GB91/01679
2fl~3~~1
enables the opening and closing of the test string
circulation valve, and - when that valve is closed - the
opening and closing of the tubing isolating valve, as
many times as desired, a complete cycle of operations -
the closing of the isolation valve and the subsequent
operation of the circulation valve - also being
repeatable at will. To attain this end the invention
employs a number of arrangements and systems some of
which are inventive in their own right.
Firstly, it proposes the use of a J-slot indexer to
control the operation of a tool, the slot being in the
form of a closed loop track (so that after carrying out
the complete cycle the tool returns to its initial
state, and can be operated anew all over again), and
there is a second closed loop track part of which is in
common with the first track, which~second loop can be
gone round any number of times quite independently of,
and alternatively to, going round the first track, the
two tracks controlling two different (and independently
controllable) tool mode operations.
Secondly, it proposes the idea of operating a tool
having a plurality of modes by one or more of a
succession of annulus pressure pulses (a pulse may be
thought of as a pressure increment/decrement pair,
usually applied in that order), wherein ar initial
operation is effected by one of the constituent pressure
changes of a first pulse - the incremental one, say -
and the operation following the subsequent pressure
change, or a part thereof - the decrement - is effected
slowly - for instance, by constraining fluid flow
through a restriction (in parall~_s with a one-way valve)
- and if one or more second pulse (incremental change)
each occurs within a given time (of the preceding
pulses) the mode of the tool is altered, so that a third
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pulse thereafter causes a different operation to be initiated.
Thirdly, it proposes the use of two separate J-slot indexers,
each in the form of a closed loop track, to control tool operation,
one J-slot indexer controlling the movement of a first operating
mer~ber connected to and driving a second operating member the
movanent of which is controlled by the other J-slot indexer.
Fourthly, it proposes the linking of two operating members,
one driving the other, via a dog-tooth clutch mechanism in which
the mating teeth are spaced so as deliberately to allow limited
movement of one (the driving) member without any concomitant
movement of the other (the driven) member.
The invention also proposes the idea of operating a tool by
annulus pressure pulses, each consisting of an incremental and a
decrgnental pressure change (though not necessarily in that order),
in such a way that the actual operation (of a valve, say) is
effected by one of these changes - for instance, the positive-
going, incremental part of a pulse - the subsequent opposite change
- thus, the decremental part of the pulse - having no carparable
effect on the tool.
By a combination of various of these individual arrang~nents
and systems there is provided the desired novel and inventive valve
arrangement, wherein a tubing isolating valve can in response to
annulus pressure pulses be cycled open and closed indefinitely
while a circulation valve remains closed, and then, at any time
chosen by the operator, the isolating valve can be closed and the
mode of the tool changed so that the circulation valve opens and
closes in response to annulus pressure pulses, whereafter following
a "final" closing of the circulation valve the tool mode can again
be changed so that the isolation valve once again responds to
annulus pressure pulses ... and the whole cycle can begin anew, and
be gone through as many times as required.
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In a first aspect, therefore, the invention provides a J-slot
indexer useful to control the operation of a device such as a valve
in a drill stem test tool, which indexer is of the type wherein
there are two members movable one relative to the other, and one of
the mEmbers carries a track and the other carries a track-following
part, such as a projecting pin, that interacts with and is
constrained to follow the track, so as to guide and control the
relative movement of the two members in a pattern in accordance
with the shape of the track, and thereby to contral the operation
of the device, in which indexer there are effectively two tracks,
in the form of at least two different closed loops one of which
controls the operation of a first device while the other of which
controls the operation of a second device,
and wherein the two loops are so disposed that one is
adjacent thereto and outside but having a ca~ron section with the
other, movement of the pin around one loop operating the first but
not the second device, and around the other loop operating the
second but not the first device, and
there is means enabling the pin, when it is in the r.~n
section, to be caused thereafter to follow one or other of the
loops, and thus cause the relative movenent of the twn mer~bers to
take one or other of the corresponding twa patterns, and so to
control one or other of the two devices.
The invention relates primarily to the operation and control
of drill stem test tools, and particularly such tools operated by
annulus pressure changes, as cannonly employed in the testing of
hydrocarbon (oil) wells, and for the most part the following
description reflects this, relating for convenience to such a use,
even though the invention is not limited thereto.
J-slot indexers are nowadays well-known devices for
controlling the various valves and other mechanisms in drill stem
test tools, and so probably do not need any
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WO 92/06270 ~ - PCT/GB91/0167~9
~~9 331 _
detailed explanation at this time, save perhaps to point
out that they are conveniently employed to control the
movement of one member - such as a pressure-driven/
piston-driven mandrel within the tubing of the tool - to
open and close a "valve" either directly (as might be
the case where the mandrel bears apertures therein that
can be brought into and out of alignment with
corresponding ports in the tubing, useful as a
circulation valve) or indirectly (as might be the case
where one mandrel physically drives another which in its
turn either directly opens/closes ports or is linked to
some other device ... such as a ball valve controlling
flow through the tubing). Examples of these are
described hereinafter with reference to the accompanying
Drawings. In either case, the indexer - and there may
be two or more pin/track sets forming each indexer -
will usually have one of the two members fixed relative
to the tool - such a member could be the main tubing -
and the other movable relative thereto - typically, a
mandrel, or internal tube, sliding longitudinally within
the main tubing. Whether the track is on (or in) the
fixed member and the track-following pin is on the
movable member or v'ce v r a is usually a matter of
choice, though from a mechanical assembly point of view
it may be preferable to choose one rather than the
other. In the embodiments described hereinafter with
reference to the Drawings the track is on a moving
mandrel whilst the pin is on the tool's (fixed) main
tubing, and there are in fact two sets of each, spaced
either side of the tool, to balance the loads involved.
For the most part the track-following part on one
of the members is described herein as a pin (or lug)
projecting out from its support and into engagement with
the track on the other member. Of course, the "pin" may
take any comparable physical form, one such being a ball
W0 92/06270 _ Q _ PCT/GB91/O1679
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209333'
rolling in a bearing - this arrangement may reduce the
frictional forces acting to prevent the two members'
relative movement - but in general a fihed pin is quite
satisfactory, and hereafter the term "pin" is used to
represent the engaging track-follower regardless of its
actual form.
The pattern of the, or each, track may be any
required to control the relevant tool operation, and in
this respect each track may be like any of the tracks
presently used or suggested for use in the Art, save
that it must have a final portion that connects the
"end" of the track back to its "beginning", and so
closes the loop. Closed-loop tracks are not in
themselves new, although to date none have been
described having the double-loop format of those of the
present invention.
The main inventive feature of the J-slot indexer of
the invention is the use of multiple track loops with a
common section from which any one of the relevant track
loops may be chosen at will. The idea behind this is
that each track loop defines one (predetermined) tool
mode, or set of tool operations - opening and closing a
main tubing valve, say, or opening and closing a
circulation valve - that can be carried out either quite
independently of any other operations set or after some
such other operations set has been effected to place the
tool in a chosen state. For example, in one embodiment
described hereinafter with reference to the Drawings
there is shown a two-track system in which one track
controls the state of the main tubing ball valve when
' the circulation valve is shut (and the loop can be
traversed as many times as required without in any way
affecting the circulation valve) while the second track
controls the state of the circulation valve when the
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209333 ~ -
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main valve is closed (and this loop can be traversed as
many times as required without affecting the main
valve).
Each track loop has a common section with another,
and for any pair of loops the two are adjacent (like a
figure-of-eight).
Each track loop bears a section in common with
another, and while the common section of track may in
principle fall anywhere along the tracks involved, and
thus anywhere within the sequence of operations they
define, in practice the common section naturally needs
to
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WO 92/06270 - 11 _ PCT/GB91/01679
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be positioned so that the ~ _te of the tool the result
of one set of operations is compatible with the states)
to be gone through when changing to the other set. For
example, when having tracks controlling the operation of
both a main tubing valve and a circulation valve it is
highly desirable to leave the main valve track, and
enter the circulation valve track, only when the main
valve is shut - and then to return to the main valve
track only when the circulation valve is shut.
As is discussed further below, it may be desirable
specially to shape the common section, or the junctions
of the start and end parts thereof, so that the pins can
be guided into one or other depending on when a driving
force is applied.
The relative movement of the two members (the pin-
carrying one and the closed-loop-track-carrying one) may
be driven in any suitable way, but, in an annulus-
pressure-operated tool, will normally be driven by
applied pressure pulses acting upon a piston attached to
o~ part of one of the members. These pressure pulses
will normally be positive pulses, having first an
incremental part and then a decremental part, and it is
usually convenient if the incremental part be the
driving part, the subsequent reduction in pressure (the
decremental part) having no operative effect (though it
may allow a spring to return some part of the tool to a
previous position or state).
In accordance with the invention the pin may be
caused to follow one track loop or another in response
to some action effected while the pin is in the common
section. There are a number of ways in which the track
selection might be achieved, including the use of
"points" ("switches") as employed in connection with
railway tracks, but that one preferred, which involves
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2093331 w
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- 12 -
no extra moving parts, is the shaping of the section,
and/or of its start and end junctions, such that driving
forces applied at different times - when the pin is on a
different part of the section - will cause different
things to happen, and different parts of the track loops
to be traversed as a result. Thus, as shown in the
Drawings, if one portion of the track is defined as two
parts roughly parallel to the direction of the members'
relative movement, one of which parts has a slanting
sector by which it is joined to the other, then, if the
pin sits at rest where the one part and its slanting
(non-movement-direction-parallel) sector joins the other
part, and if a driving pulse will cause the pin in
effect to move away from its rest position, then when it
is already away from that rest position it will move
along whichever part it is in, but when it is actually
at that rest position it will only move up the non-
slanted part. Again, and also as shown in the Drawings,
if one or other junction (of the two track loops) is
angled to left or right of a "straight" part aligned
with the direction of relative movement of the two
members, then a driven movement of the pin along the
track towards and through this junction will always be
along the "straight" part rather than along the angled
part to left or right. In the particular case of this
shown in the Drawings each angled part is the relevant
track loop, and towards the middle of one loop common
section there is a pin rest point as just described
above, Thus, the junction into the track section is so
shaped that a further driving pressure pulse while the
pin is past but still adjacent that junction (and before
it has reached the rest point) will drive the pin back
to the side
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WO 92/~b270 - 13 - PCT/GB91/01679
°(~~.331
junction and on along the straight part into the second
loop rather than back round the first loop.
It will be evident that the timing of the various
driving pressure pulses is crucial in determining which
track loop is to be followed (and thus which set of tool
operations is to occur); it is clearl~l difficult for an
operator on the surface to ensure that the next pulse in
a set of pulses is applied at just the right point in
time to catch at the right position the pin in a tool
within a test string that is possibly several miles down
a borehole beneath the operator's feet. This problem is
solved by the relatively simple expedient of causing the
motion of the pin when in a re"evant (critical) part of
the section to be very much s.~wer - to take
considerably longer - than its movement in other parts
of the track. This, which forms a main feature of a
second aspect of the invention, can itself be achieved
in a number of ways. One involves the movement of one
or other member relative to the other in one direction
being constrained over at least part of its range by it
having to drive fluid through a constriction. This is
described further hereinafter.
As just noted, this idea of slowing the movement in
one direction of one member relative to the other
(conveniently by making that movement drive a fluid
through a constriction) is the central feature of a
second aspect of the invention. In this aspect, then.
the invention provides, for a tool having a plurality of
modes, a method of operating the tool by one or more of
a succession of pressure pulses, each pulse causing
relative movement between one tool member and another
first in one and then in the opposite direction,
WO 92/06270 - 14 - PCT/Gil!91/01679
209'3'31
wherein an initial operation, in an initial mode,
is effected by one of the constituent pressure changes
of a first pulse causing relative member movement in one
direction, and thereafter the subsequent opposite
relative member movement, or a part thereof, is effected
relatively slowly,
and if - and only if - one or more second pulse
occurs within a given time (of the preceding pulse) the
concomitant relative member movement causes the mode of
the tool to be altered, so that a third pulse thereafter
causes a second operation, in the second mode, to be
initiated.
The method the subject of this second aspect is one
suited to a tool with a plurality of different operating
modes - as typified by a tool like that described
hereinbefore which can act either to control tubing flow
of formation fluid (the initial operation) involving a
main tubing valve, or to control circulation between
tubing and annulus (the second operation), involving a
circulation valve.
This method is one in which relative movement
between one tool member, or part, and another causes
there to be taken some mechanical action, such as the
opening of a valve, and in which this relative movement
is reversible, such that after movement - relatively
rapid movement - in one direction the two members
undergo relative movement in the opposite direction.
This return movement is relatively slow, at least over a
part thereof, so as to take a relatively long time, and
it is this "lengthened" return period that eases the
selection of a moment - before or during this period -
when a further pulse-driven relative member movement
initiates a second operation rather than merely
WO 92/06270 _ 15 _ ~ ~ ~ ~ ~ ~ ~ PCT/GB91 /01679
repeating the first (as it would were it applied After
the return period). Of several mechanisms by which this
differential movement rata - slower in one direction
than the other - can be achieved, a preferred one is
that in which fluid is driven (by the relative movement)
back and forth through two passageways in parallel, one
being a restricted passageway (through which the fluid's
finite viscosity means it necessarily travels with
difficulty) and the second passageway (for the fluid)
being fitted with a one-way valve. In the direction in
which the valve opens, both passageways allow the fluid
to pass therealong, and so the overall rate of flow (and
the movement of whatever piston device is driving the
fluid) is "relatively" fast, but in the opposite
direction - that in which the valve closes - only the
restricted passageway allows fluid to pass, and so the
flow (and the associated movement) is necessarily
constrained, and thus relatively slow.
The delay induced depends upon the degree of the
restriction, and rather than this restriction being a
mere narrowing of the passageway it is very preferably
one of those special flow-control valves known as Jeba
Jets and available from Lee Products Ltd. These valves
are largely viscosity-independent, so no matter what the
temperature is, and what is the viscosity of the worki~g
fluid (usually a silicone oil), the delay induced by the
restriction will remain constant.
It is further preferred that the return relative
movement be in at least two parts - a first one in which
the movement is slow, followed by a second one in which
it is not so slow - and in fact that it be in three
parts - a slow movement both followed and preceded by
not so slow movement. This can conveniently be achieved
by arranging for there to be a third parallel passageway
WO 92/06270 - 16 _ PCT/GB91/01679
2093331
(for the fluid) which opens and closes in response to
the relative movement of the pin and track members.
More specifically, if this third passageway is first
open, but is then closed after a first amount of
relative movement, and finally re-opens after a second
amount of relative movement, then in the return
direction the relative movement will be, as required,
first faster, then slower, and finally faster. In a
particular embodiment of this arrangement one member is
a tubular mandrel (carrying the track) moving within a
fixed tubular other member (carrying the pin>, and the
two define a pair of annular chambers joined/separated
by the restricted passageway, by the one-way valve
passageway and by a relatively constricted annular
portion, and the mandrel carries a fixed "piston" (ring)
that moves with the mandrel from the chamber on one side
of the constricted portion, into and through that
portion, within which it is a sealing fit, and thence
into the chamber on the other side. When the piston
(ring) is within the constriction it blocks off the
annular passageway between the two chambers, so that the
fluid flowing therebetween can only pass via the one-way
valve and the restricted passageway; when the piston
(ring) is not within the constricted portion then the
fluid can flow therethrough as well. In this way, on
the return stroke the fluid can flow first quickly, then
only slowly (as the constricted portion is blocked by
the piston), and finally quickly again.
The method of the invention is such that the
multi-mode tool is operated by a succession of pressure
pulses, a first initiating a first operation in a first
mode, a second (or several "seconds") within a given,
short, time of the first for each preceding) changing
modes, and a third then initiating a second operation,
in the second mode. The arrangement can be one in which
2 0 9 3 3 31 ~~~-~~T~~ . ~.~ ~ ~ ~ 7 9
- 17 -
a single second pulse within the given time of the first
pulse causes mode change, or it can be one in which
there must be a series of two or more second pulses -
say, four - each within a given short time of the
preceding pulse, to effect the mode change, a failure to
provide any one of these second pulses in time sending
the tool right back to the beginning of the series (so
that if, for instance, the fourth pulse of the necessary
four is late, then all four pulses must be applied all
over again). An example of each variety is described
hereinafter with reference to the Drawings.
The invention in its first aspect involves the use
of a J-slot slot indexer to control the operation of
various valves or other components of the test tool. On
occasion, however, the number of items to be controlled,
and the actions they perform, may make it difficult to
deal with them all using only a single J-slot indexer.
For example, one valve may be operated by the
longitudinal (along-tube) movement of a body, while
another may, possibly dependently, require the
rotational (around the tube's axis) movement of another
body. For this reason the invention provides, as its
third aspect, a drill stem test tool having at least two
operating members to be controlled one in at least
partial dependence upon the condition of the other,
wherein there are two separate but operatively linked
J-slot indexers, each in the form of a closed loop
track, to control overall tool operation, one J-slc>t
indexer controlling the movement of a first operating
member connected to and driving a second operating
member the movement of which is controlled by the other
J-slot indexer, at least one of the J-slot indexers
being a two-loop indexer of the invention.
_ ' . ; aC'~~.iio ia~T~
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WO 92/06270 - 18 - PCT/GB91/016,79
203331
Such an arrangement is of particular value in the
control of the operation of a multimode tool like that
of the invention having both a main tubing valve and a
circulation valve, the operating members being the
mechanical devices or links driving the two valves, and
the operation of the circulation valve needing to be
effectively dependent upon the condition of the main
tubing valve (so that the former can only be open when
the latter is closed) and yet being independently
controllable in that either valve can be opened and
closed at will without disturbing the state of the
other.
Although in principle it may be that the movements
of the two operating members can be of the same kind -
thus, both longitudinal, or both rotational - in the
preferred case of the present invention they are of
different kinds, for that makes much aasier the matter
of causing one to move, and so effect the relevant
operation, without the other also moving in an operative
way. Thus; in the case of the main tubing valve and
circulation valve combination, it is preferred if the
one - conveniently the main tubing valve - be worked by
a rotational movement of its operating member, while the
other - the circulation valve - be worked by a
longitudinal movement of its operating member. Indeed,
this is what is shown in the Drawings discussed further
hereinafter, where the main tubing valve is (as noted) a
ball valve, operable - albeit indirectly - by a rotating
member, while the other is a sliding sleeve valve
wherein a tube-internal apertured sleeve slides
longitudinally to bring its apertures into registration
with corresponding ports in the casing leading to
annulus, so enabling a path from the inside of the tube
out into the borehole.
WO 92/06270 PCT/GB91/01679
- 19 -
Most desirably one of the J-slot indexers is an
indexer of the invention, having at Ieast two closed
loop sections therein. In the main valve/circulating
valve combination already described it is preferred that
the J-slot indexer controlling the circulation valve be
the indexer of the invention, the main valve indexer
being simply a single track closed loop (although, for a
quite different reason, in the embodiment described with
reference to the Drawings the main valve indexer is also
a two-track device).
In the case of the preferred main valve/circulation
valve combination described herein there is a need for
the J-slot indexer controlling the main tubing valve (by
rotation) to rotate that valve's operating member back
and forth, as the circulation valve J-slot indexer
drives its operating member up and down, without
actually operating the main valve. This apparent
contradiction can be solved, so that at least some
limited rotational movement of the main valve operating
member is permitted without causing the valve to
operate, by coupling the drive from the operating member
to the valve via a "slack" device - that is, a device
wherein the drive in any one direction only positively
couples through to the driven member once some slack has
been taken up (whereupon there is now slack in the
opposite direction, which slack must similarly be taken
up before the drive is coupled through in that opposite
direction). In its fourth aspect, then, the invention
provides such a "slack"-utilising drive coupling
mechanism between a driving and a driven operating
member, wherein the linking of the two operating
members, one driving the other, is via a dog-tooth
clutch mechanism in which the mating teeth are so sized
WO 92/06270 - 2 0 - PCT/GB91/~1679
z~~~~v
and spaced as deliberately to allow limited movement of
one (the driving) member without any concomitant
movement of the other (the driven) member.
As noted, this slack drive arrangement is
especially useful in a drill stem test tool main valve/
circulating valve combination for indirectly connecting
the circulating valve operating member drivingly to the
main valve operating member (as indeed is shown in the
accompanying Drawings). In such a utilisation it is
convenient if the dog tooth arrangement be such that
each tooth is an arc subtending 45°, and that on each
side of the clutch there are two diametrically-opposed
teeth (thus, with 90°-subtending gaps therebetweenl, so
that when "fitted" together the arcuate distance any
tooth on one side can move between the other side's
teeth is only 90°. In this way the clutch driving
member can rotate a whole 90° between left and right
engagement without moving the driven member at all - and
it is this freedom to move that enables the circulating
valve operating member to move to operate the
circulating valve but without necessarily causing
operation of the main valve, despite the fact that the
circulating valve's operating member is physically
linked to the main valve's operating member, for the
latter, as the "driving" member, is coupled with slack
to the "driven" member taking the drive on to the main
valve.
In the embodiment shown in the Drawings the driving
side of the dog-tooth clutch arrangement is the
rotatable but longitudinally-fixed indexing sleeve of
the main valve indexer (which is itself driven by
longitudinal movement of the mandrel extending from and
controlled by the circulating valve indexer, and carries
the apertures alignable with the ports of the
'WO 92/A627~ - 21 _ ~ ~ ~ ~ ~:~f" PCT/GB91/01679
circulation valve), while the ::riven side is merely an
intermediate member carrying the drive through to the
main valve's ball cage (which itself actually drives the
ball). In this way longitudinal movement of the mandrel
is converted to rotary movement of the main valve
indexer sleeve, which is carried through to the
intermediate member who's rotary movement is then
converted back to longitudinal movement of the valve
cage ... which rotates the ball open or shut, as
appropriate, but only after any slack in the dog-tooth
clutch has first allowed some limited sleeve rotation
without any intermediate member rotation.
The use until now of annulus pressure pulses to
operate the various tools in, for example, a drill stem
test tool string.has been arranged in such a way that a
change of pressure in one direction - an increment, say
- has caused some action to occur while an
immediately-following change of pressure in the opposite
direction - a decrement - has caused some other action
(typically, a reversal of the first action). For
example, a pressure increment might cause a ball valve
to open, and the subsequent pressure decrement when the
increment is removed might cause it to shut. There are
problems with this, not least of which it is not always
easy, or convenient, to maintain the intermediate
pressure for the possibly lengthy time required to carry
out some other action (as, for instance, might be the
case when circulating out all the fluid within the
pipe), and the invention enables tool operation to be
effected in a novel and advantageo~; manner, in which
the tool is worked by complete anni. s pressure pulses,
each consisting of an incremental arid a decremental
pressure change. In yet another aspect, therefore, the
2093331 ~~:..
~_ . .
- 22 -
invention provides a method of operating a drill stem test tool
incorporating a main tubing valve and a circulatiora valve each
opened and closed by the relative movgnent of a driving mer,~bar
operatively linked thereto, the method being such that either valve
can be opened and closed as many times as rec;uired without
affecting the other,
in which method a two-track J-slot indexer as defined in any
of the preceding Claims is e~loyed to control the operation of the
twr~ valves, and one track guides and controls the driving mgnber to
operate the main tubing valve while the circulation valve is closed
and the other track guides and controls the driving member to
operate the circulation valve while the main valve is closed.
Each annulus pressure pulses consists of an incremental and a
decrenental pressure change, though not necessarily in that order
(although most conveniently they are so), in such a way that the
actual operation being carried out (the operation of a valve, say)
is effected by one of these changes - typically the positive-g«ing,
incrgnental part of a pulse - while the subsequent opposite change
- thus, the decremental part of the pulse - has no comparable
effect on the tool. It will often be the case that the operation
being carried out is itself a two-part one, as in the opening and
subsequent closing of a valve, and it can easily be seen that the
method of the invention then involves two pressure pulses, one of
which causes one part of the operation (opens the valve, say) while
the other of which causes the other (closes that valve).
The several aspects of the invention as described herein are
not only of value in themselves, they specifically provide a
carplete system for the working of a tubing isolating (main) valve
and a circulation valve associated therewith. By a cc~nbinatian of
various of the individual arrangements and systems there is
provided the desired novel and inventive annulus-pulse-driven valve
arranganent, wherein the tubing isolating valve can be cycled open
and closed indefinitely while the circulation valve remains closed,
. ~. ~. ~~, ~- ~ S ~ ~ ~T
,s v-. ...: J ~ i r:' : I
- .._v
WO 92/06270 PCT/GB91/01679
_ ~3 _
and then, at any time chosen by the operator, the
isolating valve can be closed and the mode of the tool
changed so that the circulation valve opens and closes
instead, whereafter, and following a "final" closing of
the circulation valve, the tool mode can again be
changed so that the isolation valve responds once again
... and the whole cycle can begin anew, and be repeated
as many times as required.
In more general terms, the apparatus of the
invention relates primarily to a dual vale nechanism to
be located downhole during the testing of hydrocarbon
wells, and which can be used for a multiplicity of
purposes. This apparatus, which offers a flexible and
rapid mode of operation, can be used to control the flow
of hydrocarbon fluids from a subterranean well to the
surface as well as the flow of stimulation fluids (e. g.,
acids) from the surface to the subsurface formation.
The apparatus can also be used to test the integrity of
the downhole pipework (such as the tubing and casing
strings). ~An important feature of this apparatus is the
ability to act as an annulus overpressure safety valve
providing a fail safe mode of operation when the annular
pressure exceeds a predetermined level either by choice
or because of a potential dangerous downhole problem
such as a leak of high pressure fluid from the tubing to
the annulus.
The apparatus of the invention, primarily a
resettable safety circulating valve, is operated and
controlled by the action of a unique and novel dual
indexing system incorporating a hydraulic delay
mechanism which itself is activated by the application
of differential pressures across a mandrel piston (these
pressure differentials are conveniently created between
the higher pressures applied to the annulus from surface
WO 92106270 ~ ~ ~ ~ PCT/GB91/01679
- 24 -
and a consf'aflf~"reference" pressure present within the
body of the tool). The two valves, a ball valve and a
circulating valve, can be operated when required. The
selection of which is to be operated is controlled by
the action of the dual indexing systems and the
hydraulic delay. The ball valve is used to control the
flow of fluid through the bore of the tool, from surface
to the downhole formation, and can be operated as many
times as is necessary without activating the second
valve. This second valve, a circulating valve, is used
to provide communication between the annulus and tubing
bore (which allows displacement of fluids in the tubing
bore above the ball valve and in the annulus). The fail
safe mechanism when activated automatically closes the
ball valve, to isolate the hydrocarbon bearing formation
from the surface, and opens the circulating valve to
allow fluid displacement above the closed ball valve.
This fail safe mechanism - and more particularly
the manner in which fail safe operation is here achieved
(essentially by the attachment of the J-slot tracked
index sleeve onto the moving mandrel by shear pins) - is
itself inventive. Accordingly, in yet another aspect
this invention provides a fail safe mechanism for a
valve system of the type employing a J-slot indexer
system to control the movement of a valve-operating
mandrel urged into longitudinal movement by the forces
applied thereto, wherein the J-slot track is formed on a
sleeve fixed to its support against longitudinal
movement therealong by shear pins, whereby if in
operation the forces applied to the mandrel cause the
shear pins to shear, freeing the mandrel from the
longitudinal movement constraints imposed thereon by the
indexer sleeve interacting with its indexer pin, the
mandrel will move, under the continuing influence of the
WO 92/06270 - 2 5 _ PCT/GB91/01679
applied force: to what osition~~~~~~~
p ich results in the
valve being placer ~n its fail safe state.
As explained in more detail in connection with the
embodiments discussed hereinafter with reference to the
accompanying Drawings, in the double indexer system
preferred in this invention, in which the J-slot indexer
sleeve is carried by (and thus shear-pin affixed to) the
mandrel itself, facing outwardly therefrom, the relevant
track-following pin being mounted on and facing inwardly
of the tubing, the fail safe operation of the mandrel
drives it further than it would normally travel under
indexer control, the final state be g one in which the
main ball valve is shut, having been so driven
regardless of its previous state, while the circulating
valve is open, also being made so regardless of its
previous state. This is _he fail safe state of the
system - with the well closed off, and with the inside
of the tubing string communicating with annulus.
WO 92/06270 - 2 6 - PCT/GB91/01679
2p93331
An embodiment of the invention is now described,
though by way of illustration only, with reference to
the accompanying Drawings in which:
Figure 1 is a simplified cross-sectional view of
an offshore oil well with a test string
including safety circulation valve
apparatus of the invention;
Figure shows a section through a safety
2
circulation valve section included in a
test string of the type used in the well
of Figure 1;
Figure (parts A and B) shows two closed loop
3
J-slot indexer slots as proposed by the
invention and used in the Figure 2
safety circulation valve;
Figure (parts A to D) shows in more detail and
4
in cross section a safety circulation
valve as shown in Figure 2 (the right
hand side of each individual Figure runs
on to the left hand side of the
subsequent one; the left sides are the
low sides, while the right sides are the
high ones);
Figure shows in exploded perspective a main
ball valve used in the safety
circulation valve of Figure 2; and
Figure (parts A to E) shows details of the
6
slack-providing dog-tooth clutch system
employed in the safety circulation valve
of Figure 2, being a sequence depicting
WO 92/06270 ~ ~ PGT/GB91/01679
2~9~3~1
the relative positions of the dog teeth
during operation.
Figure 1 depicts a floating drilling rig (101, not
shown in detail) from which has been drilled an oil well
(generally 1021 having a well bore (103) reaching down
to a rock stratum constituting the formation (109) of
interest. Located at the top of the well bore 103 is a
blow-out preventer mechanism (BOP; 104, not shown in
detail) which is connected to the rig 101 by a marine
riser (105). Cemented into the well bore I03 are a
shallow casing (106) and a deep casing (107); the lower
end of the latter has a multitude of perforations tas
108) permitting communication between the well bore 103
and the oil formation 109.
Situated within the well bore 103 is a test string
(110) comprising tubing (113) ending in a set of test
tools (see below). The string 110 is set at its lower
end into a packer (111), and a seal sleeve (112) seals
tha packer 111 to the test string 110, thus isolating
the tubing 113 thereof from the annulus (114).
Above the seal sleeve 112 is a gauge carrier (115)
which contains electronic or mechanical gauges (not
shown) which collect downhole pressure and temperature
data during the test sequence. Above the gauge carrier
115 are a constant pressure reference tool f117) and the
sub-surface control valve (118). A circulating sleeve
(119) permits removal of any formation fluid remaining
within the test string 110 prior to its withdrawal from
the well bore 103. At the top of the test string is a
subsea test tree (I20) which serves both as a primary
safety valve and as a support for the rest of the test
string 110.
WO 92/06270 . ~ ~ __ PCT/GB91 /01679
2093331
The present invention concerns the valve apparatus
within the circulat irwn sleeve ae~:~1 i.;~ii l J :~.
During the drilling of the well. and prior to
testing, the bore of the well is filled with drilling
fluid which provides hydrostatic pressure at the
formation depth (this is at a higher pressure than the
formation fluid pressure. and hence prevents the
formation fluids from entering the well bore and
escaping to surface). When it is required to test the
well the test string is lowered into the well bore from
the drilling rig. The test string includes the
circulation sleeve 119, and within that sleeve are a
main tubing bail valve and a circulation sleeve valve
(discussed in more detail hereinafter).
To enable production of the formation fluid it is
necessary to reduce the hydrostatic pressure of the well
fluid in the tubing to a level below that of the
formation fluid pressure. This is achieved either by
lowering the test string into the well bore with the
circulation sleeve's ball valve in the closed position
(so the pipe tubing is empty) or by using the operation
of the sleeve's circulating valve to enable the
displacement of the contents of the tubing string by a
"lighter" fluid pumped in once the string has been set
at the required depth (then, because this provides a
hydrostatic pressure at formation depth which is lower
than the formation fluid pressure, when the ball valve
is opened the formation fluids can enter the well bore
and flow to surface through the tubing string). The
testing of the well in order to evaluate its production
potential is therefore controlled by operation of the
ball valve section of the resettable safety circulating
valve. When the ball valve is open formation fl~:ids
WO 92/06270 _ z ~ - PC'T/G B91 /01679
will be able to flow to su t
race. while, c~-~versely, when
the ball valve is closed the well will be "shut-in" sc;
preventing format ion fluids hei»u E~roduced tc~ surface.
Figure ? shows a safety circulating valve tool
section - a Resettable safety Circulating Valve of the
invention - included in a test string of the type used
in the well of Figure 1 (the tool has three main states,
discussed in more detail with reference to Figure 4).
There are effectively two main parts to the tool: a ball
valve section (Figure 4A) the opening and closing of
which provides a mechanism for controlling the flow of
fluids from the hydrocarbon bearing formation to surface
(and hence is the basic mechanism used for testing the
reservoir), which is controlled by,the movement of a
first J-slot indexing system (Figure 4A, B) in
conjunction with a dog clutch arrangement (Figure 4A);
and a circulating valve section (Figures 4B, C, D) the
opening and closing of which provides communication
between the annulus and the tubing bore (this is
controlled by the movement of a second J-slot indexing
section (Figure 4D) incorporating a hydraulic delay
(Figure 4B) and the mandrel piston (Figure 4C). The
operation of the tool is initiated by creation of
differential pressure across the mandrel piston. A
shear pin release mechanism linked to the mandrel
indexer provides the fail safe operation when the
annulus pressure exceeds a predetermined level.
Figures 4A to D show in more detail the safety
circulating valve tool (Resettable Safety Circulating
Valve) as shown in Figure 2 (the Figure 3 two closed
loop J-slot indexer slots are shown in Figures 4Bii and
4Dii, the main ball valve is shown in Figure 5, and the
~E , a~ 'J
- 30 -
'~ X093331
slack-providing dog-tooth clutch system is shown in
Figure 6).
Figure 4 shows the tubular form of the tool, which
has an internal bore (1). The operation of the tool is
performed by components contained within a main
housing (2) between the internal bore 1 and the outer
diameter of the tubing. In the Figure 4 diagrams of the
indexing sections the valve indexer loop (Figure 4Bii)
is shown featuring the relative positions on the loop -
lA, 2A, 3A and so on - which correspond to controlled
operations of the valves, while the mandrel indexer loop
(Figure 4Dii) is shown featuring the relative position
on the loop - 1B, 2B, 3B and so on - which correspond to
the controlled longitudinal movement of the mandrel.
Figure 4A shows the ball valve mechanism in its
position in the lower end of the tool located in the
main housing 2. Figure 5 shows the ball valve mechanism
in more detail. The mechanism comprises a valve
cage (3) held in position between the main housing 2 and
the internal bore 1 which has a limited longitudinal
movement from its initial position shown in Figure 4A to
its final position against end stop (4) of the main
housing 2. The valve cage 3 is restricted from
rotational movement by cage lock (5). The ball (6) of
the valve is held in position by fixed upper and lower
ball seats (7, 8), and is connected to the cage 3 by
ball pins (9). Movement of the cage 3 will via pins 9
rotate the ball 6 around the fixed position between the
upper and lower ball seats 7, 8.
A valve drive sleeve (10) is attached to the valve
drive slots (11) in the upper end of the valve cage 3 by
valve pins (12). The drive sleeve 10 is restricted to
rotational movement only in its position between the
. ..."'" ' -.. -as~
WO 92/06270 31 PCT/GB9l/01679
_ __
2~9333~.
main housing 2 and the upper ball ~ea~ . Rotational
movement of the sleeve will be translated to a
longi tudinal movemeW of the va lve cy~e j vja r_he
movement of the valve pins 12, which in turn will
control the opening and closing of ball valve b.
Rotational movement of the sleeve 10 is controlled by
engagement with radial drive sleeve tl3f via drive
disc (14). Drive sleeve 13 is restricted to rotational
movement only, being locked in a longitudinal position
between the main housing ~ and the mandrel (15). The
engagement between the valve drive sleeve lU and the
radial drive sleeve 13 is achieved between the valve
drive sleeve dogs (16) and the radial drive sleeve
dogs (17). When these dogs are engaged, clockwise or
anti-clockwise rotation of the radial drive sleeve 13
will be transferred to the valve drive sleeve 10 which
will in turn be translated to a longitudinal movement of
the cage 3.
Figure 6 shows the relative positions of the radial
and valve-drive sleeve dogs I7, 16. Eac7 of the drive
sleeves has two diametrically-opposed does each of a
size equivalent to 45° of the full 360°. Therefore
these dogs will not always engage, and so at certain
times rotational movement of the radial drive sleeve 13
will not result in rotational of the valve drive
sleeve 10. This free movement acts as a clutch
mechanism, enabling required directional changes to take
place during the indexing sequence.
Figure 6 shows the sequence of positions between
the radial and valve sleeve dogs 17, 1~. Position A
snows the initial start ~~sition, with :oth sets r~f dogs
engaged and ball valve 6 closed. Position B shows the
position after the radial drive sleeve I3 has rotated
by 90° to the right. This movement will also have
WO 92/06270 _ 3 2 _ PCT/GB91/01679
rotated the valve drive sleevA 1.0 ly 90° t-o the right.
This rotational movement will be cracislated to a
1 ongi tud i na 1 movemen l of t the va 1 ve cage i of °-r va 1 ve
pins 12 engaged in valve drive slots 11. This 90° of
rotational movement will be sufficient to move the valve
cage 3 its full travel to end stop 4 and open ball
valve 6 via ball pins 9.
Position C shows that the radial sleeve drive 13
has rotated 90° to the left. Since during this movement
the drive dogs were not engaged there is no movement of
the valve drive sleeve 10, and hence the ball 6 remains
in the open position. At the end of this rotation the
drive dogs become engaged. Position D shows that the
radial drive sleeve 13 has rotated a further 90° to the
left. Since the drive dogs are now engaged the valve
drive sleeve 10 will also be rotated 90° to the left.
This movement is now translated to a longitudinal
movement of the valve cage 3 via valve pins 12 in
slots 11, and the cage will be returned to its original
position, and in so doing will close ball valve 6.
Position E shows that the radial drive sleeve 13
has now rotated 90° to the right. Since the drive dogs
were not engaged the valve drive sleeve 10 will not
move, and ball valve 6 will remain closed. The valve
and radial drive sleeve dogs 16, 17 are thus returned to
their initial position fPositien A1.
Figure 4B shows the position of the valve indexer
profile (18) set on the mandrel 15 (and Figure 4Bii
shows the profile itself). The radial drive sleeve 13
is set into the indexer 18 via valve index pin (19).
The mandrel 15 is limited to longitudinal movement only,
with the extent of its movement being limited by end
stop (20l on the radial drive sleeve. As the mandrel
WO 92/06270 3 3 _ PCT/GB91/O1679
moves longitudinally the index pin 79 will traverse the
profile of the indexe~r 18, which deti.nes the rotati~~nal
movement of the drive :sleeve.
The longitudinal movement of mandrel 15 is governed
by the profile of the mandrel inde~er (21). Figure 4D
shows the mandrel indexer sleeve (22) set between the
upper ends of the main housing 2 and the mandrel. The
sleeve is free to rotate on the mandrel but is
restricted from moving longitudinally by mandrel
shoulder (23) and main housing shoulder (24). Therefore
the sleeve can only move longitudinally in step with the
mandrel. Movement of the mandrel is created by a
differential pressure, but the extent of its movement
will be governed by the profile of the mandrel indexer
defined on the mandrel index sleeve 22. When the
mandrel and its index sleeve are caused to move
longitudinally the mandrel index pin (25) locked to the
main housing 2 will traverse the mandrel indexer
profile 21. The free rotation of the sleeve 22 will
ensure that only longitudinal movement of the mandrel is
controlled by the indexer 21.
The operation of the dual valve system is
controlled by movement of mandrel 15, which is caused to
move longitudinally by the application of differential
pressures across the mandrel piston (26; Figure 4C).
The differential pressures are created between a higher
applied annulus pressure and a lower "reference"
pressure (this is established within the tool by the
Constant Pressure Reference Tool shown in the test
string below the Resettable Safety Circulating Valve in
Figure 1). This "reference" pressure ~~ supplied to the
Resettable safety Circulating Valve via reference flow
path (27) to spring chamber (28), as shown in Figure 4B
and 4C. The spring (29) in the spring chamber 28 is
WO 92/06270 _ 3 4 _ PCT/GB91 /01679
pre-set to a compression equivalent t:o about 3000 pounds
force. The spring is locked between main housina
point (30) and mandrel lock (31) with the upper end of
the mandrel being held by main housing shoulder 24.
Between mandrel lock 31 and the mandrel piston 26
is a hydraulic oil chamber (321. At the bottom of the
chamber 32 is a hydraulic delay (33> which incorporates
a hydraulic restrictor (34) and a non-return valve (35).
Both the lock 31 and the piston 26 are in fixed
positions relative to the mandrel. The hydraulic
delay 33 is fixed in a position relative to the main
housing 2. In its initial state, and prior to running
in the well, the hydraulic chamber 32 is filled with
silicone oil at atmospheric conditions. The upper face
of the piston 26 is in communication with the annulus
via annular flow path (36) and annulus port (37).
Figure 4C also shows the initial positions of the
mandrel sleeve port (38) and circulating ports 37. Once
the use of the circulating valve has been selected the
mandrel will move downwards sufficiently for the sleeve
port 38 and the circulating ports 37 to line up and so
establish full communication between the annulus and the
tubing bore 1.
Prior to running the tool in the well it is set up
as indicated in Figures 4A to 4D. The ball valve 6 is
closed and the valve index pins 19 and mandrel index
pins 25 are in their initial positions lA and 1B as
shown in Figures 4Bii and 4Dii. The valve and radial
drive sleeve dogs 16, 17 are engaged in initial
position A as shown in Figure 6.
The operation of the Resettable Safety Circulating
Valve is now described.
WO 92106270 ' 35 2 ~ 9 3 3 31 P~/GB91~01679
The tool is run in t-he hilt-. in rc~niun~~Clorl Wlth the
Constant Pressure Reference '1'001 n~ shown irr Figure 1
As the test striu~7 i;~ r-!rn clownhole Uhe hydrostatic
pressure will increase. However "reference" pressure
supplied by the Constant Pressure Reference Tool and the
annulus pressure remain equal at hydrostatic, so
pressure differences are created in the tool and the
spring forces of 3000 pounds will remain. The
mandrel 15 will not be able to move until hydrostatic
plus applied pressure overcomes the hydrostatic pressure
plus spring force. Therefore all remains at initial
position.
Once at depth the test spring is stabbed into the
packer assembly. At this point the "reference" pressure
in the Constant Pressure Reference Tool equals the
bottom hole hydrostatic pressure, and therefore the
pressures in the reference flow path 27 and the annular
pressure flow path 36 are equal at hydrostatic. To trap
the hydrostatic "reference" pressure in the Constant
Pressure Reference tool it is now necessary to apply an
annulus pressure at the surface circa 500 to 1000 psi.
This applied pressure will not only trap the "reference"
pressure but also set the Resettable Safety Circulating
Valve into operation.
At this time the pressure in the reference flow
path 27 will equal hydrostatic. The upward force on the
mandrel lock 31 will equal hydrostatic plus spring
force, while the downward force will now equal
hydrostatic plus applied pressure across the upper face
of the mandrel piston 26. The surface area of the upper
face of the mandrel piston 26 is in excess
of 6.3 sq ins, and therefore an applied annulus pressure
of about 500 psi will exceed the upward spring force of
about 3000 lbs. This downward force transmitted through
WO 92/06270 _ 3 6 _ PCT/GB91/01679
2~9'~3~1
the silicone oil LJ111 act on the upper force of the
mandrel lock 31. The downwar~? force will now exceed the
upper force, and the mandrel will be forced downwards.
further compressing spring 29 in spring chamber 28.
As the mandrel moves longitudinal downwards a
number of events will take place. Initially, silicone
oil will be forced around the hydraulic delay 33 between
the delay 33 and the mandrel, and the valve indexer 18
and mandrel indexer 21 will also move downwards causing
traverse of the valve index pin 19 and mandrel index
pin 25 in the profiles.
In the case of the valve indexer 1B the valve index
pin 19 will move from its initial Position lA towards
Position 2A. In the case of mandrel indexer 21 the
mandrel index pin 25 will move from its initial
Position 1B towards Position 2B. During the movement of
the valve index pin between points 1A and 2A the
longitudinal movement of the mandrel will be translated
to rotational movement of the radial drive sleeve 13.
As shown in Figure 6, this right hand movement of the
radial drive sleeve will move the valve drive sleeve 10
in the same direction since the valve and radial drive
sleeve dogs 16, 17 are engaged and the sequence is
moving from Position A to Position B. This rotational
movement of the valve drive sleeve 10 will in turn be
translated to downward longitudinal movement of the
valve cage 3 and the downward movement of the cage will
start to open the ball valve 6.
During the mandrel's downward movement the silicone
oil in chamber 32 will continue to be forced past the
hydraulic delay 33 and the mandrel. This will continue
until the mandrel restrictor 40 reaches the delay 33 and
seals off the channel between the delay and the mandrel.
At this point the silicone oil in the chamber 32 will be
WU 92/06270 - 3 ~ _ PCT/GB91/01679
2~~~33~
forced through the non-return val~~e 35, so allowing ~_he
mandrel to continue downwards. further compressing
spring 29 in sprin~7 chamber 28.
With the applied annulus pressure of about 500 psi
the mandrel will continue to move downwards until
mandrel index pin 25 traverses to position 2B on the
mandrel indexer profile 21. By this time valve index
pin l9 will have traversed to position 2A on the valve
indexer profile, and as it does so the radial drive
sleeve 13 will rotate 90° to the right. Engagement of
the drive dogs will also have ensured that the valve
drive sleeve 10 will be rotated 90° to the right.
Transfer of this rotational movement to a lonaitudinal
movement of the ball cage 3 via valve drive pins 12 in
valve drive slots 11 will open ball valve 6 (Position B
in Figure 6).
The mandrel can now no longer move downwards since
its movement is restricted by the position of mandrel
index pin 25 in the mandrel indexer 21 (Position 28).
The ball valve 6 is now open - the circulating
valve 39 remains closed - and allows the flow of fluids
through the tubing bore 1 of the tool.
The applied annulus pressure of about 500 psi is
now bled off at surface, and the pressure exerted on the
upper face of the mandrel piston 26 via a~nulus flow
path 36 and annulus port 37 returns to equal hydrostatic
pressure only. At this point the downward force exerted
on the mandrel lock 31 equals hydrostatic pressure only.
and so the mandrel is forced upwards, the valve and
mandrel indexer profiles 10 and 21 respectively moving
with it. Silicone oil in the chamber 32 is forced back
through the gap between the delay 33 and the mandrel.
The valve index pin 19 will effectively traverse the
valve indexer profile 18 (although really it will be the
WO 92/06270 _ 3 8 _ PCTlG B91 /01679
~ a~~ ~~~~.~
profile that is moving), and move from Position 2A
to 3A. During this upward longitudinal movement of the
mandrel the travel of the pin 19 in the profile 18 will
cause the radial drive sleeve 13 to move rotationally to
the 1 ef t .
At the same time, the mandrel index pin 25 will
effectively traverse the mandrel indexer profile 21
(although again it will be the profile that is moving in
unison with the mandrel). Movement will be from
Position 2B to 3B. and when the mandrel index pin 25
reaches Position 3B the mandrel will be restricted from
further upward movement. By this time the valve index
pin 19 will have reached Position 3A on the valve
indexer profile 18 and the radial drive sleeve 13 will
have rotated back to the left to engage the valve drive
sleeve 10 and hence reach Position C (Figure 6). During
the latter stages of the movement the mandrel
restrictor 40 will move up to seal off the space between
the delay 33 and the mandrel. The silicone oiI in
chamber 32~is now forced through the restrictor 34 but
has no effect on the tool operation.
At this point the applied annulus pressure has been
bled off, and the ball valve 6 remains in the open
position. The valve index pin 19 is located at
Position 3A on the valve indexer profile 18, and the
mandrel indexer pin 25 is located at Position 3B on the
mandrel indexer profile 21. The circulating valve 39
remains in the closed position. When it becomes
necessary to close the ball valve 6, i.e. to shut in the
well and isolate the formation fluids from the tubing
bore 1, a further 500 psi is applied to the annulus from
surf ace .
As previously, the downward force exerted on the
upper force of the mandrel lock 31 will exceed the
V~O 92/06270 _ j ~ ~ PGT/GB91t01679
~~9333~.
upward force (spring force) exeoted on the lower face of
the mandrel lock 31, and the mandrel will be forced
downwards, compressing further spring 29 in chamber 28.
At this point mandrel index pin 25 begins to traverse
mandrel indexer profile 21 from Position 3B towards
Position 4B. Once Position 4B is reached then the
mandrel will be restricted from any further longitudinal
movement.
At the same time, valve index pin 19 begins to
traverse valve indexer profile 18 from Position 3A
towards Position 4A. This movement will be translated
into a rotational movement of the radial drive
sleeve 13, and it will begin to rotate to the left.
Since the valve and radial drive sleeve dogs 16. 17 are
already engaged then this rotation to the left of the
radial drive sleeve I3 will cause the valve drive
sleeve 10 also to rotate in the same direction. This
rotation of the valve drive sleeve 10 will be translated
to a longitudinal movement of the valve cage 3, tending
to pull the cage upwards, back towards its original
position, and hence start to close ball valve 6.
As previously the silicone oil in the chamber 32
will be forced past the delay 33 as the mandrel
continues to be forced downwards. Once the mandrel
restrictor 40 seals off the delay/mandrel gap, the
silicone oil will be forced through the non-return
valve 35 and the mandrel will continue on its downward
movement. Once the mandrel index pin 25 has reac:-:d
Position 4B in the mandrel indexer profile 21 and the
valve index pin 19 has reached Position 4A in the valve
indexer profile la the mandrel will be restricted from
further movement, and the radial drive sleeve 13 will
have rotated a full 90° to the left. This will also
have ensured that the valve drive sleeve 10 will also
WO 92106270 _ 4 a - PCT/GB91/01b79
209331
have rotated 90° to the left, which is sufficient to
move the valve cage 3 back to its original position and
fully close ball valve b. The dog clutch sequence as
shown in Figure 6 will now be at Position D.
The next step will be to bleed off the applied
annulus pressure at surface. However at this point a
choice exists regarding the mode of operation. Thus,
either the ball valve 6 can be recycled to enable a
second period of flow from the formation to the surface,
in which case the circulating valve will remain
inoperative, or the ball valve 6 can be kept in the
closed position and the circulating valve opened to
establish communication between the annulus and the
tubing bore 1.
For instance, in a normal type of well test
programme information will be required from a number of
flow periods and build ups. In such a case it would be
necessary to cycle the ball valve more than once. In
another example it may be that the production from a
particular~hydrocarbon formation is not as expected, and
it may be considered that the hydrostatic head of fluid
in the tubing bore is not light enough to allow
production from the formation to the surface. In such a
case it may be decided to lighten the fluid in the
tubing bore, and this would be achieved by maintaining
the ball valve in the closed position and opening the
circulating valve so establishing communication between
the annulus and tubing bore, the fluid existing in the
tubing bore then being displaced with a lighter fluid
such as diesel (or in some cases nitrogen), which is
pumped from the surface.
In considering these options, either will require
the applied annulus pressure to be bled off at surface.
WO 92/06270 ~ 4 1 _ PCT/GB91/01679
Selection of the op~ion must then he made as s~~on as the
pressure has been rK:ieased.
In the case of recycling the ball valve once the
pressure has been bled off very little has to be done.
As before, once the annulus has returned to equal the
hydrostatic pressure the upward force on the lower face
of the mandrel lock 31 will exceed the downward force on
the upper face of the mandrel lock 31. In this case the
mandrel 15 is forced upwards, traversing both the valve
indexer profile 18 across valve index pin 13 and the
mandrel indexes profile 21 across mandrel index pin 25.
In this event the valve index pin 19 traverses from
Position 4A towards Position lA, and mandrel index
pin 25 traverses from Position 4B towards Position 1B.
As previously, as the mandrel is forced upwards the
silicone oil in the chamber 32 is forced back between
the delay 33 and the mandrel. Once the restrictor 40
seals off this channel the silicone oil will be forced
through the restrictor 34 thus slowing up the flow and
restricting the movement of the mandrel. Once the
restrictor 40 has passed the delay the mandrel will
continue its rapid upward travel towards its original
position against main housing shoulder 24.
When the mandrel has completed its travel the
mandrel indexer pin 25 will have traversed profile 21 to
return to its initial Position 1B, and the valve index
pin 19 will have traversed profile 18 frees Position 4A
to return to its initial Position IA. During the full
movement from Position 4A to 1A the radial drive
sleeve 13 will rotate a full 90° to the right. Since
the valve and radial drive sleeve dogs 16, 17 were not
engaged during the movement, the valve drive sleeve 10
will not rotate, and hence will cause no corresponding
WO 92106270 _ 4 2 _ PCT/GB91/016_79
2pg3331
movement of the valve cage 3. The ball valve 6
therefore remains in the closed position.
The dog clutch sequence as shown in Figure 6 will
now have returned to its initial Position A.
To repeat the ball valve operating cycle the
annulus pressure is again increased by 500 psi at
surface. If instead of this it was required to operate
the circulating valve, the mandrel would not have been
allowed to complete its upward travel and return the
mandrel index pin 25 and valve index pin 19 to their
original Positions 1B and lA respectively. So instead
of allowing the silicone oil to pass through the
hydraulic restrictor 34, and the mandrel restrictor 40
to pass beyond the hydraulic delay 33, a further
application of 500 psi annulus pressure is provided from
surface. Since the fluid delay can take between 5
and 10 minutes there is sufficient time to apply the
annulus pressure. Therefore, as long as the pressure is
applied in time the upward travel of the mandrel will be
arrested, and since an imbalance again occurs across the
mandrel lock 31 in favour of the downward force the
mandrel will be forced downwards. In this case the
mandrel index pin 25 will traverse between Position 4B
and 5B, and once at Position 5B the mandrel will be
restricted from further movement. During this movement
of the mandrel the valve index pin 19 will move freely
in the track of the valve indexer profile 18 between
Positions 1A and 4A.
This position of the mandrel allows the integrity
of the tubing to be pressure tested prior to opening of
the circulating sleeve 39. Following this, the applied
annulus pressure of 500 psi is bled off at the surface.
The mandrel is then forced downwards for a short
WO 92/06270 _ 4 3 _ PCT/GB91/01679
distance governed by the traverse of the mandrel index
pin 25 in profile 21 between Positions 5B and fiB. The
valve index piru l9 will Iraverse briefly along
profile 18 between Positions 4A and lA.
To open the circulating sleeve, a further 500 psi
is applied to the annulus from surface. Again the
mandrel is forced downwards, and will continue its
travel towards the shoulder of the radical drive
sleeve 13. The mandrel index pin 25 will traverse to
Position 7H in the profile 21, while index pin 19 will
traverse to Position 5A in the profile 18, and since
there is no rotational movement in this section of the
valve indexer there will be no rotation of the radial
drive sleeve 13, and so the valve drive sleeve 10 and
ball valve 6 will be unaffected.
As the mandrel moves downwards the mandrel port 38
will break across sleeve seal 41 and line up with
circulating sleeve ports 37. The circulating valve is
now open, and communication established between the
annulus and tubing 1 above the closed ball valve. This
now allows fluids in the tubing bore and annulus to be
displaced from surface to change fluids prior to
continuing the test programme or pulling the strina_ out
of the hole.
Positions 8B, 9B, lOB and 11B in the mandrel
indexer profile 21 allow for any possible reductions it
the applied annulus pressure. For example, if for any
reason the applied annulus pressure declined to a poin~
where the spring force was the dominant force. and these
positions wee: not available, the mandrel would
automatically travel upwards. full tra i, and close off
the circulating valve. This would not be acceptable,
since such an occurrence could lead to a major pressure
WO 92/06270 _ ~ q _ PCT/GB91/01679
209331
build up if the circulating valve suddenly closed while
pumping fluids from surface.
Once circulation has been c::ompleted the circulating
sleeve 39 can be closed. Prior to closing it is
essential to ensure that the mandrel index pin 25 is at
Position 11B on the mandrel indexer profile with an
applied pressure of 500 psi on the annulus.
When the annulus pressure of 500 psi has been bled
off at the surface the spring force again will be the
dominant force, and the mandrel will be forced upwards.
As previously, silicone oil in the chamber 32 will be
forced around the delay 33 as the mandrel continues its
upwards progress. Mandrel port 38 will move out of
alignment with circulating sleeve ports 38, across seal
sleeve 41, and the circulating sleeve will be closed.
Mandrel index pin 25 will traverse from
Position 11B to 3B on the profile 21, while valve index
pin 19 will traverse from Position 5A to a point between
Positions 4A and lA. This will cause a rotational
movement of the radical drive sleeve 13, but since this
rotation is to the right, and the valve and radial drive
sleeve dogs 16, 17 will not be engaged, the ball valve 6
position is not altered - i.e., the ball valve remains
closed.
So, both ball valve and circulating valve are now
closed.
To complete the cycle and return the mandrel to the
initial position, annulus pressure of 500 psi is again
applied to the annulus from surface. Mandrel index
pins 25 will traverse from Position 3B to 4B on the
profile 21, and valve index pins 19 will traverse back
to Position 4A on profile 18. This will cause a
rotational movement of the radial drive sleeve 13, but
WO 92/06270 PCT/G B91 /01679
,.~, ._ 4 ~r _
~a933~1 s
since this otation is now to t-he left the tnoveme~:t w:i1
on 1 y re-enc_, . ;le t he va 1 vc~ and naci i. a 1 dr i ve s 1 eeve
dogs 16 , 17 , re turn i ng do;~ c: l o t ct~ ;sequence t: o
Position D.
With the mandrel 15 is this position, governed by
Position 4B on the mandrel indexer profile, the
integrity of the seal 41 of the closed circulating valve
can be checked.
Finally the annulus pressure is bled off at
surface. The spring again becomes the dominant force,
and the mandrel is forced upwards. Mandrel index
pins 25 traverse profile 21 back to the original
Position 18 via the hydraulic restrictor 34 (if for any
reason it is necessary to re-open the circulating valve
at this stage, further annulus pressure can be applied
before the delay is completed). At the same time, valve
index pins 19 traverse profile 18 hack to the original
Position lA. This movement causes rotation of the
radical drive sleeve 13, but since the rotation is to
the right no rotation of the valve drive sleeve 10
occurs, and the dog clutch sequence returns to
Position A as shown in Figure 6 (i.e., the original
position). The full sequence has now been completed.
and further operation of the ball valve and circulating
valve can be carried out by repeating the sequence as
described herein.
The invention also includes a unique and novel
method of monitoring annulus overpressure, and prc~.rides
a fail safe method for ensuring that both valves are in
the fail safe position - ball valve closed and
circulating valve open - if the annulus pressure should
WO 92/06270 _ 4 U _ PCT/GB91/01679
2~J33~1
exceed a predetermined level (e.g. 4000 psi). The
device incorporates a shear pin system (42? on the
mandrel index sleeve 2%. This mandrel index sleeve 22
is able to rotate freely on mandrel 15 but is caused to
move longitudinally in unison with the mandrel bound
between mandrel shoulder 23 at its lower end and by the
sheer pin system 42 at its upper end. As and when the
annulus pressure increases above the standard 500 psi
applied pressure the differential pressure across
mandrel lock 31 will increase causing the mandrel to
move further downwards. As this occurs the movement of
the mandrel will normally be restricted by the mandrel
index pin 25 reaching any of the following positions in
the mandrel indexer profile 21:
2B, 4B, 5B, 7B, 9B or 11B.
As the annulus overpressure approaches the predetermined
level, the force exerted by the pins 25 on the limit
points in the indexer 21 will exceed the shear rating of
the shear pin system 42. The shear pins will shear, and
the mandrel index sleeve 22 will be released from the
mandrel. The mandrel is now free to travel downwards
fully to the end stop on the radial drive sleeve 13.
When this occurs the valve index pin 19 will be free to
travel to Position 6A on the valve indexer profile 18
regardless of its position prior to the overpressure
sequence.
If for instance the valve index pins 19 were at
Position 3A on the valve indexer profile 18 the free
movement would cause the pins 19 to traverse the
indexer 18 to Position 6A via 4A and 5A. The initial
movement from 3A to 4A would cause rotational movement
of the radial drive sleeve 13 and the valve drive
sleeve 10, which would cause longitudinal movement of
valve cage 3 closing ball valve 6. Similarly, if the
WO 92/OG270 - ~ ~ _ PCT/GB91/01679
X0933'31
valve index pins 19 were ~t Position 2A on the
indexer 18 the free movement wot.rl~i t raverse pius li to
Position tiA ~~ia ~.A. :;ar.l~ .-a movement woutJ aumr~ cause
rotational movement of the radial and valve drive
sleeves 13 and 10 and so close ball valve 6.
For any other position - i.e. lA, 4A and 5A - the
ball valve will already be closed.
So this overpressure shear of the mandrel index
sleeve 22 will automatically cause the ball valve to
close and the circulating valve to open simply by
allowing free and full downward movement of the mandrel,
and this will be achieved regardless of tool status
prior to the annulus overpressure.
The Resettable Safety Circulating Tool described
above is run in as an integral part of a Drill Stem Test
tDST) tool. The version now described, however, can be
used as an adjunct to a DST tool, and is run in
conjunction with. for example, the Subsurface Control
Valve and the Single Ball Circulating Valve. It can be
run at any required depth above the other DST tools,
though usually a few hundred feet above, separated from
the lower tools by a section of Drill Collars. It will
normally be separate from any Gas Reference Pressure
system in the DST tools, and so needs its own internal
reference pressure for operation (thus it is provided
with communication to a Constant Pressure Reference
Tool).
In this configuration the second version is only
used if and when required - for instance, to circulate
out hydrocarbon fluids from the test string above the
tool or to replace the fluid column with alternative
fluids such as diesel, nitrogen and water in order t~
WO 92/06270 ~ ~ ~ ~ _ 4 8 - _
PCT/GB91/01679
provide a lighter hydrostatic column in the test string.
Accordingly, the main test programme, requiring multiple
flowing and shut-in periods, would be carried out by
operation of the Subsurface Control Valve. During such
periods the resettable safety circulating tool would
need to remain inactive and only be activated when other
more specific operations are required (such as :.hose
mentioned above. It is essential therefore that the
tool is not activated by annulus pressures which are
applied to operate some other part of the DST tool - the
Subsurface Control Valve, say. As explained in more
detail hereinafter, the design of the mandrel indexer
profile (21R> ensures that this second version Can only
be activated if and when required, and if initiated by a
pre-determined sequence of annulus pressure pulses.
The design of the valve indexer and the other tool
sections are virtually as for the first version
described hereinbefore. The difference between the two
versions lies primarily in the design of the mandrel
indexer (discussed further below), coupled with the
initial valve configuration (in the case of the second
version the tool is run in with the ball valve in the
open position (closed in the first version) (the
circulating valve is in the closed position, preventing
annulus/tubing, as in the first version).
A summary of the operation of this second version
is now given with reference to Figures 4A to 4D coupled
with Figures 4Biii and 4Diii (these are the second
version's valve indexer and mandrel indexes
respectively, and take the place of the first section's
indexers as shown in Figure 4Bii and 4BDiil.
WO 92/06270 4 9 PGT/GB91/01679
_ - ~09333~:
Basically, a description of the econd version is
much the same as that of the fir;~t ~m:-,i.on, with the
exception of the mandrel indexer profile Gnd the initial
position of the ball valve (valve cage 3 now at the
lower limit of its travel against mandrel end stop 4).
The operation of the tool differs considerably, however,
because of the changes to the mandrel indexer profile. A
s stated previously it is essential that annulus
pressures applied to operate the Subsurface Control
Valve do not activate the resettable safety circulating
tool (RSC tool), for during a standard test programme
when annulus pressures are applied to the Subsurface
Control Valve these same pressures would also be applied
to the upper face of mandrel piston 26 via annular
port 37. As explained below, this can be prevented from
activating the RSC tool, where Positions 2R, 3R and 4R
are simply to permit initialisation of the tool - i.e.,
until Position 5R has been attained no mechanical change
to either of the RSC tool's valves will occur (thus, the
ball valve remains open, and the circulating valve stays
closed). Thus, the Subsurface Control Valve (or any
other secondary annulus-controlled tool), can be
operated as many times as is necessary without causing
the RSC tool to operate.
The details of this version's operation are now
described.
The initial state of the tool is with the ball
valve open and the circulating valve closed, with the
mandrel 15 at the top of its travel and both mandrel and
valve index pins 25 and 19 in their initial Positions lk
and 1 in the mandrel and valve indexers 21R and 18
respectively. When the tool is required to function a
W092/06270 - 50 _ PCT/GB91/01679
~~~~'~~1
series of pressure pulses, each of about 500 psi, are
applied to the annulus from surface.
The first pressure application will force the
mandrel 15 to move downwards, its movement being
curtailed once mandrel index pin 25 travels from its
initial Position 1R to Position 2R on the profile of
mandrel indexer 21R. This longitudinal movement of the
mandrel will cause valve index pin 19 to travel from
Position 1 to Position 2 on the valve indeyer 18 which
in turn causes radial drive sleeve 13 to rotate. Since
the direction of the rotation does not cause the drive
sleeve dogs 16, 17 to engage then the valve drive
sleeve 10 will not rotate and hence there is no change
to the position of the ball valve 6 fi.e. ball valve
remains openJ.
When the applied annulus pressure is bled off at
surface and the spring force becomes the dominant force
in the tool the mandrel is forced to move upwards.
Mandrel index pin 25 will travel from Position 2R
towards Position 1R (along the dashed trackJ. The
silicone fluid will be metered through the delay
restrictor 34, and if no further annulus pressure pulse
is applied then the mandrel will return to its original
position - i.e., mandrel index pin 25 back to
Position 1R in mandrel indexer 21R. However, a second
application of annulus pressure before fluid has been
metered fully through the delay restrictor 34 will
ensure that the mandrel is forced downwards, and mandrel
index pin 25 will travel to Position 3R on mandrel
indexer 21R. Again, bleeding off this applied annulus
pressure will force the mandrel to move upwards, tending
to cause mandrel index pin 25 to travel from position 3R
towards Position 1R (along the dotted trackJ. But a
:tea 9vo6r~o
- 5, ... ~ o ~ ~ 3 ~ ~ PCT/GB91/01679
third appl icat ion of annn 1 ~.is press~i~ hefor_P fluid has
again been metered f.u) ly throuc7l~ t-he relay restrictor 34
wi 11 cause the mandre 1 aga i a t ~> rnwe downwards , mancire 1
index pin 25 moving to Position 4R on mandrel
indexer 21R.
During these three applications of applied pressure
from surface the valve index pin 19 has been travelling
back and forth between Positions 1 and 2 on the valve
indexer 18, governed by the movements of the mandrel 15.
and during these pin movements radial drive sleeve 13
has been rotating - but since the direction of the
rotation does not cause the drive dogs 16, 17 to engage,
the valve drive sleeve 10 will not rotate, and hence
there will have been no change to the position of the
ball valve 6 Ii. e.. the ball valve. remains in the open
positionl. This set-up changes with a fourth
application of annulus pressure while the mandrel is
still moving back - via the delay - to its initial
position.
When the third applied pressure is bled off the
mandrel again moves upwards, and mandrel index pin 25
travels from Position 4R towards Position 1R on the
mandrel indexer 21R. A fourth application of annulus
pressure at surface before the fluid has been fully
metered through the delay restrictor 34 will cause the
mandrel to move downwards and mandrel index pin 25 to
travel to Position 5R on the mandrel indexer 21R. This
time the downward movement of the mandrel will be
f:~~-ther than in the previous operations, and valve index
p.a 19 will travel to Position 3 in the valve
indexer 18, causing further rotation of the radial drive
sleeve 13. However, since drive dogs lb. 17 are still
not engaged there will be no resultant rotation of the
WO 92/06270 _ 5 2 _ PCT/GB91 /016.29
2093331
valve drive sleeve 10, and hence the ball valve 6 will
remain open.
When this fourth application c~f annulus pressure is
bled off the mandrel will move upwards, and mandrel
index pin 25 will travel from position 5R to
position 6R. At this point the profile will not allow
travel of the pin 25 back to Position 1R via the delay
restrict 34, and the tool has now been activated;
further pressure applications will now operate the
valves in a predetermined sequence. The valve finder.
pin 19 will have travelled to position 4 on the valve
indexer 18. Rotation of the radial drive sleeve 13
will, at the end of the pin's travel, engage the drive
dogs 16, 17. However, at this point the ball valve 6
will still remain open.
A fifth application of annulus pressure at surface
will move the mandrel downwards, and mandrel index
pin 25 will travel from Position 6R to Position 7R,
while valve index pin 19 will travel from Position 4 to
Position 5. the subsequent rotation of the radial drive
sleeve 13 will, via engagement of the drive dogs 16, 17,
cause rotation of the valve drive sleeve 10, and hence
longitudinal movement of valve cage 3. This will close
ball valve 6. So at this point both the ball valve and
the sleeve are closed.
Bleeding off the annulus pressure will cause the
mandrel to move upwards, mandrel index pin 25 to travel
to Position 8R, and valve index pin 19 to move to
Position 5A. No rotation of the radial drive sleeve 13
will yet occur.
A sixth application of annulus pressure at surface
will again move the mandrel downwards, and mandrel index
pin 25 will travel to Position 9R. This additional
downwards travel of the mandrel will align mandrel
92/06270 - 5 3 - PCT/GB91/01679
209~3~1
pc s 38 and annular ~:ort 37, and the circulating valve
will be open, allowing commuuicatioro between the annulus
and tubing. At the came _~mp, valve finder, ~~in 1~~ will
travel to Position 6 on the valve indexer 18, but there
will be no rotation of the radial drive sleeve 13.
Therefore at this point the ball valve is closed and the
circulating valve is open. This will allow circulating
operations to be carried out - i.e., circulating out
fluid contents in the test string above the RSC tool and
replacing with alternative fluids.
Positions lOR, 11R 12R and 13R on the mandrel
indexer profile 21R allow for indeterminate fluctuations
in the annulus pressure during circulation, and ensure
that a drop in the annulus overpressure below 500 psi
will not cause the circulating valve to close.
Following completion of the circulating
requirements the annulus pressure will be at about
500 psi, and the mandrel index pin 25 will be at
position 13R on the mandrel indexer 21R. Once this
annulus pressure has been bled off at the surface the
mandrel will move upwards, and mandrel index pin Z5 will
travel to Position 14R. During the movement of the
mandrel the mandrel ports 38 and the annular port 37
will become misaligned, and therefore the circulating
valve will now be closed. The valve index pin 19 will
travel back to Position 5A on the valve indexer 18, but
again there will be no rotation of the -adial drive
sleeve 13. Therefore at this point the ball valve and
the circulating valve are both closed.
A seventh application of applied pressure at
surface will move the mandrel downwards, and mandrel
index pin 25 will travel to Position 15R. This
operation allows a check on the integrity of the seal of
WO 92106270 - 5 4 - PCT/G B91 /Ol ~iI,9
209~~31
the closed circulating valve - i.e., no communication
between annulus and tubing. At the same time, the valve
index pin 19 will travel to position 5 on the valve
indexer 18 without causing radial drive sleeve 13 to
rotate.
Bleeding off this applied annular pressure will
cause the mandrel to move upwards, and mandrel index
pin 25 will travel to Position 1R or the mandrel
indexer 21R - its original position. The valve index
pin 19 will travel simultaneously to Position 1 on the
mandrel indexer 18 - its original position. During this
travel the radial drive sleeve 13 will rotate, but in a
direction which does not engage the drive dogs 16, 17
and hence causes no movement of valve drive sleeve 10
and the ball valve 6. However, at the end of the travel
the drive dogs 16, 17 will become engaged.
So at this point the ball valve and circulating
sleeve are both still closed.
To re-open the ball valve, and return the tool to
its initial state, it is necessary to apply a further
annulus pressure of about 500 psi. This applied annulus
pressure will cause the mandrel to move downwards, and
mandrel index pin 25 to travel from Position 1R to
Position 2R. Valve index pin 19 will travel from
Position 1 to Position 2 on valve indexer 18, which
causes radial drive sleeve 13 to rotate. Now that the
drive dogs 16, 17 are engaged the direction of rotation
of the radial drive sleeve 13 will cause rotation of the
valve drive sleeve 10, and a corresponding longitudinal
movement of valve cage 3 and hence ball valve 6 is
opened. Bleeding off the annulus pressure allows the
mandrel to move upwards, and mandrel index pin 25 to
travel back to its original~position 1R.
WO 92/06270 PCT/GB91/01679
,...-. - 5 5 -
At this point the ball valve is o =~n and the
circu:.ating sleeve i:, ciosed arucj all components of the
tool have ret.ttrr~ed Icy ~l~eir c:>ri<tinai t:o~it.ions.
If it had been required to re-open the circulating
sleeve instead of re-opening the ball valve a further
annular pressure could have been applied before fluid
had been fully metered through delay restrictor 34, and
hence mandrel index pin 25 would have travelled to
Position 3R instead of back to Position 1R. Additional
pulses of annulus pressure would then have taken the
tool back through its pre-determined sequence governed
by the profile of the mandrel indexer 21R from
Positions 3R through 15R. In t;:;s way the RSC tool
could be sequenced as many times as would be required
before returning to its inert status. Once back to its
inert state the other DST tools in the string could be
re-activated if required by relevant application of
annulus pressure.
