Note: Descriptions are shown in the official language in which they were submitted.
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DEVICE FOR OPERATING DOWNHOLE EQUIPMENT
The present invention relates to a new construction for a device for conveying
a
pressure pulse to activate a fluid pressure operable equipment in a pipe, such
as a
well, as defined in the preamble of the appended claim 1. In particular, the
invention
is concerned with a construction which is capable of supporting operation of
down-
hole equipment which is hydraulically operated.
Background to the invention
It has been well known for a long time that, in connection with pressure-pulse
activation of mechanical equipment installed down in an oil- or gas-well,
there are
challenges related to convey theses pressure pulses forward to the equipment.
This is especially pertinent when a pipe which is introduced down into the
well is
pressurized up to transmit these pressure signals down to the equipment. A
problem
that is that is often encountered is that, over time, there is formed an
accumulation of
particles in liquid, which eventually forms a solid mass at a bottom of the
pipe, when
such particles sink to the bottom. This is especially a problem when plugs are
employed in the production pipe which operates in a manner to pump up pressure
over the plug from the rig.
A manner of limiting the problem is to couple the equipment via a hydraulic
control
line (a conductor) which is disposed outside the existing pipe wherein the
plug is
mounted. Such a control lines are routed upwards and through the wellhead-
installation and further up to the rig, such that it can be subject to
pressure directly
from the rig, and as a consequence one is still able to operate the equipment
despite
an accumulation of mud over the plug in the pipe.
The disadvantage of such a system is that, to a major extent, it renders
operation
more expensive and establishing a several kilometer long control line
(conductor)
introduces a risk that it is possible that the pipe which generally, for
example, is a
thin tube with a dimension 1/4" (6.3 mm) is worn against walls of the well,
and it is
thereby possible to lose all control of the equipment.
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A known solution is to use an kind of accumulator for introducing clean liquid
into the
well. Such a solution is described in Norwegian patent application no. 2008
0452.
There is described an accumulator which includes a limited volume for
supplying the
equipment with clean liquid for operating it.
That which is described in said Norwegian patent application is a piston
accumulator
which pursuant to the description accumulates pressure during introduction
into the
well.
This system continues to result in a considerable number of problems
associated
with functionality.
First and foremost, it is claimed that debris (supply of contamination) are
not able to
penetrate into the system. But such a claim is incorrect, on account of it
being
known that a blockage of the canal upstream of the piston, as described, would
not
be able to convey the pressure pulses which are necessary for the system to
function. It is correct that these particles would not be able to contaminate
downstream of the piston which is to actuate the cyclic mechanism in the
system,
, which is operable to open depending on a beforehand specified number of
pressure
pulses. The problem is namely that, by way of liquid communication through the
canal up-stream for the piston, particles may enter into the chamber and
thereby
block the piston from moving, such that pressure differences can arise between
upstream and downstream of the piston.
A cyclical-system which is based upon pressure differences would then cease to
function.
In respect of the state-of-the-art, reference is also made to US patents Nos.
US-2,964,116 and US 2,898,088.
Object of the invention
It is a principal object of the invention to provide a new construction which
is capable
of solving the aforementioned disadvantages and problems.
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The solution pursuant to the present invention includes installing a flexible
diffusion-
free membrane, for example fabricated from a rubber material, in its own
housing
/sleeve-section of the pipe). By using such a solution, it is possible to
achieve a quite
different effect than disclosed in the earlier known solutions.
Present invention.
The device pursuant to the present invention is characterized in that the pipe
includes a flexible membrane which isolates a fluid Fl in the fluid-conveying
pipe
from a fluid F2 in another canal which is in fluidic communication with the
equipment,
wherein the membrane, on account of its elasticity, conveys pressure changes
(pressure pulses) in the fluid P1 in the pipe to the fluid P2 in the other
canal. The
beneficial implementations appear in the dependent claims 2 to 9.
One of the advantages of the present invention, as defined, is that a piston
which
moves axial in a longitudinal direction will be limited in area which can be
affected,
whereas a bellows which moves radially is capable of providing an enormous
area
which can be affected. This area is limited only by the length of the bellow.
Description of the figure.
The present invention will now be described in more detail with reference to
the
accompanying diagrams.
Figure 1 is an illustration of a pipe which is installed within a borehole in,
for
example, a hydrocarbon-bearing formation, wherein the inventive device is
employed.
Figures 2 and 3 are illustrations of the details of the inventive construction
10 in two
positions, in that it is disposed a distance upstream in respect of down-hole
equipment 20 which is be operated hydraulically pursuant to the present
invention.
Figure 3B is an illustration of an elongate cross-section of a hole which is
arranged in
a radial direction through the pipe wall.
Figures 4 and 5 are illustrations of an enlarged portion of Figures 2 and
Figure 3,
and illustrates the hydraulic canal 30 through the pipe wall and which couples
the
pressure pulse device 10 with the equipment 20.
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The Figures provide illustrations of a pipe 12 which is deployed in a borehole
14 in a
formation 16. Described as a non-limiting example, a pipe section 18 is
installed at a
lowest portion of the pipe 12 with a seat accommodating a plug 22. The plug 22
is
used, for example, initially for testing and checking that the interior of the
pipe is
sufficient non-leaky under pressure, and will function as intended during
production
of hydrocarbons from the formation 16.
As a consequence of the upwardly-facing surface of the plug 23 being
susceptible to
collecting large deposits 25 of contamination comprising solid particles such
as
slime, the device 10 is positioned a distance up over the plug 20, and the
plug 20
and device 10 are mutually coupled via a canal 30 which extends axially along
and
through the wall of the pipe between these two regions.
The device includes a perforated pipe section 27 which is installed into the
pipe 12.
A hollow volume or chamber 26 is defined between the outer wall 21 of the
section
and the inner wall of the pipe 12.
Surrounding the pipe section 25 is threaded a sleeve-shaped elastic bellows or
membrane 24, and uppermost at 31 and lowermost at 33 is attached in the solid
material of the pipe section 25. The bellows 24 can subsequently bulge out
from a
position where in lies bonded onto the pipe section's outer wall 21 and to an
extent it
bulges out and lies against the inner wall 13. Outside the bellows 24 is a
ring-shaped
chamber 26 coupled with a drilled canal 30 which extends through the pipe wall
downwardly to the release mechanism (not especially shown here) which is used
to
explode the plug away.
The bellow's position or bulging will be dependent upon a difference in a
pressure P1
within the pipe 12 and a pressure P2 in the chamber or the canal 30 outside
the
membrane 24. Figure 2 illustrates the situation where the pressure P1 is
higher than
the pressure P2 (P1 > P2) such that the membrane bulges out.
Figure 3 is an illustration of a situation wherein the pressure P2 is higher
or equal to
the pressure P1 and the membrane lies in a wavy manner against the outer wall
21.
A release mechanism which removes the plug is adapted such that it counts a
number of pulses, wherein the pulses are generated by increasing and
decreasing
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the fluid pressure P1, and wherein the plug is exploded away at a
predetermined
number of pulses.
In the chamber radially outside the bellows, there is filled a clean liquid
which is
5 present in connection with an outside lying pipe or the internally bored
canal 30
which again is present in connection with, for example, a pressure-pulse
sensitive
valve.
The pressure-sensitive valve can be set, or be set up, either to read the
signals
electronically with help of a pressure transmitter, or it can be a purely
mechanical
system which reads pressure pulses for opening the valve at a predetermined
number of pressure pulses.
When the valve opens, the clean liquid flows past the valve and operates the
equipment which is hydraulically operated. The technology can be used to
operate
down-borehole equipment which is hydraulically operated, and requires clean
liquid
for operating correctly. Examples of such equipment can be detonation systems
for
removable (disappearing) plugs, sliding sleeves, hydraulically operated ball
valves
and hydraulically-operated flapper valves. These are only some few example of
equipment with which this new technological solution can be utilized. The
hydraulically operated system can for example be a layer-divided plug 22
fabricated
from glass. In whatever manner it is removed or smashed is not specifically
shown in
the Figures. The pressure-pulse controlled apparatus can include A device 39
which
is operable the count the number of pulses, and when it has counted a correct
number, the mechanism is activated and releases an explosive mechanism. This
can, for example, mean that an axially-disposed piston 38 in the pipe wall is
pushed
downwardly with large force and slides a horizontally-orientated smashing
piston in a
radial direction and into the plug 22 which thereby can be smashed. The plug
can be
fabricated from ceramics materials which can be smashed or from glass which is
adapted for this purpose.
By utilizing a bellows instead of a piston, it is also possible to bore a
large number of
holes radially through the wall around the periphery of the protective collar
which
supports the bellow and maintains the clean liquid in place. An elongate cross-
section of these bored out holes 50 in a radial direction through the pipe
wall 26, is
shown in cross-section in Figure 36. On both sides thereof (from each end
thereof),
there is bored out a hole through the wall. The central portion of the hole
through the
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wall beneficially has a form of a bored out region 56 with circular cross-
section,
whereas each end of the circular boring continue with a gradually increasing
cross-
section diameter towards the wall surfaces, namely showing a conical form. The
bored out region is of course widest out towards the wall surfaces, namely the
form
of holes 52 to 54 shown in the diagrams are such that that the outermost form
respectively cone-shaped form or conically formed holes, or substantially of
trumpet-
form. These borings can have other cross-sections than circular. An advantage
with
this form of hole is that each hole is not so easily blocked permanently by
slime and
particles.
The risk that the holes with such a form can be blocked by debris and solid
particles
and slime can be reduced by the holes being bored out such that they are
concentric
in both directions. This form of hole through the wall having an expanding
cross
section of the boring, towards the outer wall, resulting in there being
achieved an
effect, wherein there will always be fluid/liquid streaming both ways as a
result of
particles bound in the conical hole which is opened up with largest diameter
at an
opposite side to that which is influenced by pressure with a result that the
particles
become loosened when pressure is applied from the side that has smallest hole.
A
particle 60 in the pipe fluid, which may bind and block the entrance to the
bored hole
56, when the fluid Fl streams in a direction of the arrow P2, will simply
loosen and
be pushed back again when the fluid pressure P2 exceeds the fluid pressure P1
and
the fluid F2 streams back. The particle 60 will then be easier to be loosened
by the
back streaming.
Moreover, with reference to Figures 2 and 3, there are provided a breaking
plate (or
several), brushing disks which are arranged to break or burst when, for
example, 10
Bar pressure difference between the pressure in the clean fluid behind the
flexible
material and the liquid in the well pipe arising, further ensuring against
there arising a
pressure difference between the two liquids. The flexible membrane will also
always
bring about that identical pressures arise on both sides and return to its
original form
after a pressure excursion.
Through the wall of the pipe 27, namely above the perforated wall portion,
there are
bored out one (or more) holes 60 which forms a fluid connection between the
ring-
shaped chamber 26 outside the bellows and an inner of the pipe denotes by
F1/P1
(Figures 2 and 3). In the hole, there is installed a metal plate for providing
a bursting
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disk 62, wherein this plate is attached via an anchoring denoted by 58, such
as
screw or the similar on the diagrams.
The burst disk 62 is adapted for creating fluidic communication in an event
that an
excessive pressure is developed on the back side (P2) of the bellows, namely
when
the pressure is not the same as the pressure P1 within the pipe (tubing).
The boring for the break disk can, as a point of reference, be placed
anywhere, as
long as it stands positioned such that it separates fluid between the tubing
and back
side of the bellows and creates a communication path between them when it
bursts.
The burst disk 62 will also provide an eventual operation of the equipment
which is to
be controlled by later re-filling with liquid when the clean liquid behind the
membrane
is consumed, wherein the membrane is pre set towards the walls in its
respective
housing, so that a pressure difference arises between the well pipe (P1) and
the
back side (P2) of the membrane, whereafter the burst disk will break and
liquid from
the well will thereafter pour into the system.
There are thus many advantages in comparison to known state-of-the-art which
has
a limited volume surfaces which can be influenced with associated risk that
holes of
the system become blocked in operation.
