Note: Descriptions are shown in the official language in which they were submitted.
CA 02249128 1998-10-O1
FLUID INJECTION TUBING ASSEMBLY AND METHOD
FIELD OF THE INVENTION
The present invention is directed to a well stimulation and production
apparatus and
method and in particular to an apparatus tubing valve assembly for control of
stimulation and production fluids to an oil or gas well and a method for using
the
assembly.
BACKGROUND OF THE INVENTION
Tubing having openings therein for delivery of stimulation fluids such as, for
example,
steam to, and for receiving fluids from, a formation are known. Often the
openings have
removable closures for use during tubing installation. Once the closures are
removed,
the openings are permanently open.
Recently, a tubing assembly including a sliding sleeve valve has been used in
controlling stimulation fluid flow into formations. The tubing assembly
includes a sliding
sleeve valve positioned over a port through the tubing wall. The sliding
sleeve valve is
moveable between a closed position, wherein the sleeve blocks the port, and an
open
position for permitting the flow of the stimulation fluid through the port and
to the
formation.
Various problems have been encountered by use of the previous sliding sleeve
valve
tubing assembly. In particular, the stimulation fluid passing through the port
tends to
cause damage to the formation because of the high pressures of the fluid. In
addition,
when the sleeve is maintained in the closed position for extended periods, it
tends to
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jam due to a pressure lock and the port tends to become
blocked with scale or debris.
The sliding sleeve valves are sometimes used in
series along a tubing string in a well. It is intended that
the provision of a series of valves will permit stimulation
fluid to be delivered along a length of the well. HowE:ver,
it often occurs that the stimulation fluid passes out
through the first few valves that it reaches so that the
deeper valves transport very little or no stimulation fluid
to the formation.
SUMMARY OF THE INVENTION
An injection fluid tubing assembly has been
invented which overcomes the disadvantages of injection
fluid tubing assemblies. The sleeve valves are useful for
placement in series along a length of tubing for use in the
injection of stimulation fluid to a formation.
An injection fluid tubing assembly according to
the present invention lowers the kinetic energy of and/or
diffuses the stimulation fluid prior to releasing it and,
thereby, reduces damage to the formation. When application
of stimulation fluids to the formation is stopped, the
injection fluid tubing can be left in place to act in sand
retainment.
In accordance with one aspect of the present
invention, there is provided an injection fluid tubing
assembly for handling a flow of fluid comprising: a tube
having a port formed through its wall; a valve retained
within the tube and moveable between a closed position in
which it blocks the port and an open position for permitting
the flow of fluid to pass through the port; and a flow
diverting means comprising a diffusing material in
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association with the port for diverting the flow of fluid to
a region outside the injection fluid tubing assembly.
In accordance with a second aspect of the present
invention, there is provided a system comprising: the
injection fluid tubing assembly as defined herein; and a
shifting tool to operate the valve.
In accordance with a third aspect of the present
invention, there is provided a method for injecting fluid
into a formation adjacent a wellbore, comprising: inserting
an injection fluid tubing assembly into the wellbore, the
injection fluid tubing assembly having a tube with a port, a
valve actuatable to a closed position to block the port and
to an open position to permit flow of fluid through the
port, and a flow diverting means having a diffusing
material; and injecting the fluid into the tube, wherein the
injected fluid is diverted through the port and diverting
means to an external region.
In accordance with another broad aspect of the
present invention, there is provided an injection fluid
tubing assembly for handling a flow of fluid comprising: a
tube having a port formed through its wall; a sliding sleeve
valve retained within the tube and moveable between a closed
position in which it blocks the port and an open position
for permitting the flow of fluid to pass through the port;
and a flow diverting means in association with the port for
diverting the flow of fluid against passing directly
radially outwardly through the wall of the tube.
The tube can be any tubular structure suitable for
withstanding borehole conditions and for conveying a flow of
fluid such as, for example, a stimulating fluid. The tube
can be
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a unitary member or can be formed of a plurality of interconnected parts such
as, for
example tubing sections and couplings.
The port extends through the wall of the tube to permit stimulating fluid to
pass
outwardly from the bore of the tube to the outer surface of the tube to, for
example,
enter a formation. The tube can also be positioned downhole in a producing
well and,
therefore, the ports can act to permit production fluids to pass from the
formation into
the tube bore.
A diverting means is provided in association with the port to divert the flow
of fluid
passing therethrough and to prevent it from passing directly radially
outwardly from the
bore of the tube. In one embodiment, the diverting means is a wall of the port
positioned to divert the flow of fluid to pass through a channel extending
substantially
longitudinally or substantially circumferentially, relative to the tube, and
opening to the
outer surface of the tube. There can be one or more channels extending through
the
tube from the port, as desired. Preferably, the port includes an inner opening
from the
bore of the tube and an outer opening to the outer surface of the tube and a
channel
extending between the inner opening and the outer opening. In this
arrangement, the
wall of the channel acts to divert the fluid through the tube wall. In one
embodiment,
the channel opens into a header arrangement from which the flow of fluid is
divided to
pass through a plurality of openings to the outer surface of the tube.
Preferably, the
plurality of openings cover a large area on the outer surface of the tube. The
plurality
of openings can be provided, for example, by use of a perforated plate.
In another embodiment, the diverting means is a diffusing material positioned
in the port
and defining a plurality of tortuous channels through the port. The diffusing
material
can be for example fibrous material, a slotted plate, or a wire wrapped
screen.
In one preferred embodiment, the port includes a longitudinally extending
channel which
acts to divert the flow of fluid passing through the port and the port further
contains a
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diffusing material, such as a fibrous material or a wire screen, which defines
a plurality
of tortuous passages through the port.
The sliding sleeve valve is retained within the tube and regulates the flow of
fluid
through the port. The sliding sleeve valve is moveable between a closed
position in
which it blocks the port and an open position for permitting the fi~ow of
fluid to pass
through the port. Any sliding sleeve valve arrangement can be used which
permits
regulation through the port. In one embodiment, the sleeve valve is formed to
permit
a reduced flow of fluid through the port when the valve is closed. In other
words, a
sleeve can be provided which does not completely close off the flow of fluid
through the
port when the valve is closed. This reduces the chance of a pressure lock and
tends
to prevent the formation of blockages in the port during periods when the port
is closed.
In one such embodiment, an opening is formed through the sleeve which is
positioned
to be in alignment with the port, when the sleeve is in the closed position.
The opening
is preferably less than 20% of the smallest cross sectional area of the port.
In accordance with another aspect of the present invention, there is provided
a method
for injecting fluid to a formation comprising: providing a first wellbore into
the formation;
inserting a tubing assembly into the formation, the tubing assembly including
a bore for
conveying fluid to the formation, a first port and a second port, the ports
opening
through the tubing providing access from the bore to the formation and an
actuatable
valve disposed at each port for regulating the flow of fluid therethrough;
providing a
second wellbore into the formation, the second wellbore being formed adjacent
the first;
monitoring wellbore conditions along the second wellbore; and actuating the
valves on
the tubing assembly to open or close in response to the wellbore conditions.
In a preferred embodiment, the fluid is steam under pressure.
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BRIEF DESCRIPTION OF THE DRAWINGS
A further, detailed, description of the invention, briefly described above,
will follow by
reference to the following drawings of specific embodiments of the invention.
These
drawings depict only typical embodiments of the invention and are therefore
not to be
S considered limiting of its scope. In the drawings:
Figure 1A is front elevation view, partly in longitudinal section, of an
injection fluid tubing
assembly according to the present invention with the port open;
Figure 1 B is a longitudinal section of an injection fluid tubing assembly
similar to Figure
1A, but with the port closed;
Figure 1 C is a sectional new along line C-C of Figure 1A;
Figures 2A and 2B are longitudinal sections along an injection fluid tubing
assembly as
shown in Figure 1A with a sleeve shifting tool positioned therein. For
simplicity only one
half of the assembly is shown, as the other half is a mirror image thereof;
and
Figure 3 is a schematic view of a injection fluid tubing string positioned in
a stimulation
well to act on a formation containing an adjacent production well.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
For the purposes of clarity, in the Figures only reference numerals of the
main
components are indicated and like reference numerals relate to like
components.
Referring to Figures 1A to 1 C, a fluid injection tubing assembly according to
the present
invention is shown, including a tube 10 having a port 12 extending
therethrough
between the bore 14 of the tube and the outer surface 16 of the tube. A
sliding sleeve
valve 17 is positioned in bore 14 of the tube and is moveable between a closed
position
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(Figure 1 B) blocking port 12 and an open position (Figure 1A) wherein port 12
is
uncovered by sleeve valve 17.
To facilitate manufacture, tube 10 preferably includes a plurality of
interconnected parts.
In the illustrated embodiment, tube 10 includes a first tube 18a having
longitudinal
channels 20a formed in the outer surface thereof and a second tube 18b also
having
longitudinal channels 20b formed therein. Tubes 18a and 18b are connected at
their
ends by a threaded coupling 22 having an inner annular groove 23. Coupling 22
is
limited in its threaded advancement over the tubes 18a, 18b by abutment
against
shoulders 24a, 24b formed about the ends of the tubes. This ensures that a
space,
indicated at 25, remains between the pin faces 26 of tubes 18a, 18b when the
tubes are
fully threaded into coupling 22.
Telescopically disposed about each tube 18a, 18b is an outer perforated sleeve
30.
The sleeve is mounted on its tube by any suitable means. In the illustrated
embodiment, a ring 32 is mounted about each tube and outer sleeve 30 is
secured
thereto, as by welding. Ring 32 is engaged to coupling 22 by set screws 34.
Contact
between coupling 22 and ring can provide a metal to metal seal.
Sleeve 30 is spaced from outer surface 16 of tube 10 such that an annular
chamber is
formed therebetween. The annular chamber acts as a header, receiving fluid
from
longitudinal channels 20a and distributing it through the plurality of
perforations in
sleeve 30. The chamber is filled with a diffusing material 36 such as a
fibrous material.
Diffusing material 36 can be disposed about tube 10 in any suitable way such
as, for
example, by packing between tube 10 and sleeve 30 or by wrapping about tube
10.
Diffusing material 36 is formed of a material capable of withstanding borehole
conditions such as, for example, stainless steel. While other diffusing
materials can be
used, a stainless steel material is preferred having long length fibers of
generally
ribbon-like shape. Such a steel fibrous material is known as MeshriteT"" and
is available
from Secure Oil Tools Inc., a division of Stellarton Energy Corporation. To
prevent
diffusing material 36 from moving back into bore 14 of tube 10, an inner
perforated
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sleeve (not shown) can be telescopically positioned between diffusing material
and tube
10. The area of the perforated sleeve which provides communication from the
annular
chamber to the outer surface of the tube is, in the preferred embodiment 2.5
to 3.5 -
meters in length and extends about the entire circumference of the tube. This
provides
that the fluids are applied to the formation over a large surface area, rather
than being
applied through a small number of jet holes. This reduces the damaging effect
of any
stimulating fluids applied to the formation and increases the amount of
formation which
is directly contacted by the fluids.
In the illustrated embodiment, port 12 includes space 25, inner annular groove
23,
channels 20a, 20b and the perforations in sleeve 30. Stimulating fluid, such
as steam,
applied from within the tube can pass through space 25 into annular groove 23,
and
through channels 20a and 20b, diffusing material 36 and out through the
perforations
in sleeve 30. Channels 20a, 20b are arranged to prevent the stimulating fluids
from
passing directly radially outwardly from the tube bore to the outer surface of
the tube.
In particular, channels 20a direct the fluids longitudinally through at least
a length of the
tube wall. This diversion of the stimulating fluid reduces the kinetic energy
of the
stimulating fluid passing therethrough and reduces damage to the formation as
the
stimulating fluid passes out of the injection tube. Other port arrangements
can be used,
as desired.
Sliding sleeve valve 17 is mounted in bore 14 to control flow through port 12.
Sleeve
valve 17 is mounted in an groove defined between shoulder 38 on tube 18a and
shoulder 40 on tube 18b. The outer diameter of sleeve 17 is just slightly less
than the
inner diameter of the tube at the groove such that sleeve 17 is slidable
within groove
until first end 1 T of the sleeve valve abuts against shoulder 38 (Figure 1 B)
and second
end 17" of the sleeve abuts against shoulder 40 (Figure 1A).
When end 1T abuts against shoulder 38, openings 42 formed through sleeve 17
are
aligned with space 25 and, thus, fluids can pass from bore 14 into port 12. It
is to be
understood that the sleeve could be formed in other ways to open the port. In
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particular, the sleeve can be shortened such that when the sleeve 17 is
abutted against
shoulder 38, the sleeve is fully retracted from over space 25. This however,
is not
preferred since end 17" can become jammed against pin face 26 of tube 18b.
To close port 12, sleeve 17 is moved within the groove to abut against
shoulder 40. In
this position, openings 42 are not aligned with space 25.
A pair of spaced apart annular grooves 44, 46 are formed in the inner surface
of tube
18a and are adapted to accept and releasably retain protrusions 48 formed on
the outer
surface of sleeve 17. Protrusions 48 can be formed as a continuous ring or
circumferentially spaced discreet protrusions. In the closed position,
protrusions 48
extend into groove 44, while in the open position protrusions 48 extend into
groove 46.
Thus, by interaction of protrusions 48 in grooves 44, 46, sleeve 17 is
releasably locked
into an open or a closed position. Sleeve 17 is preferably fluted at the
position of the
protrusions to increase the flexibility of the sleeve at this position and
thereby to
facilitate movement of the protrusions out of engagement with the grooves.
Longitudinally spaced from openings 42 are openings 50. Openings 50 are spaced
from openings 42 a suitable distance such that they will be aligned over space
25 when
the sleeve is in the closed position. Thus, openings 50 are spaced from
openings 42
a distance substantially equivalent to the space between grooves 44, 46.
Openings 50
are between about 5% to 15% of the area of openings 42. In one embodiment,
openings 50 have diameters of approximately 1/8" while openings 42 have
diameters
of approximately 3/8". Openings 50 serve to permit a small amount of
stimulating fluid
passing though bore 14 to pass through port 12, even when the sleeve is in the
closed
position. T his prevents the sleeve from jamming due to a pressure lock and
also
prevents the port from becoming clogged with debris or scale.
While any tool suitable for the purpose can be used for moving the sleeve
between the
open position and the closed position, a particularly useful sleeve shifting
tool is
generally indicated at 52 in Figures 2A and 2B. Tool 52 includes a tool body
53 having
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a central bore 54 extending from the tool's first end 52' to its opposite end
52".
Passages 55 can be provided at end 52" to provide communication between bore
54
and the outer surface of the tool. A threaded portion 56 is formed at end 52'
into which
a pin end of a tubing string 57 is connectable.
Tool body 53 has formed on its outer surface an annular recess defined by
shoulders
58a and 58b. Telescopically disposed about the tool body is a tube 59. Tube 59
at one
end is secured by threaded engagement to the tool body to extend out over the
recess.
The opposite end 59' of the tube is spaced from the tool body and forms an
annular
chamber 60 therebetween. A ring 62 is disposed in chamber and is slidably
moveable
therein. A radially inwardly extending protrusion 64 on tube 59 prevents ring
62 from
moving out of chamber 60 and a shoulder 65 on tool body 58 prevents movement
of
ring 62 therepast further into chamber 60. Seals 66, 67, which can be, for
example,
O-rings, are mounted in ring 62 to provide fluid tight seals between the tube
and the ring
and the ring and the tool body.
Extending over the recess opposite tube 59 is a plurality of, and preferably
four, spring
loaded dogs 68. Each spring loaded dog 68 includes a head portion 70 connected
to
a leaf spring 72. Leaf springs 72 bias the head portions radially inwardly
toward tool
body 53. Dogs 68 are connected to a single threaded ring 74 for ease of
assembly, by
threaded connection onto tool body 58. Head portion 70 includes an inner
ramped
surface 75 and an outer protruding face 76 having an outer shoulder 76' and a
base
shoulder 76".
Ring 62 includes an annular wall 78 formed to extend out past tube 59. Wall 78
is
chamfered at its outer edge 78' to formed a tapered leading edge. A spring 79
is
disposed in recess 57 under dogs 68 and extends under wall 78 of ring 62.
Spring 79
acts between shoulder 58a and ring 62 to bias ring 62 away from shoulder 58a.
A plurality of radially extending channels 80 connect between chamber 60 and
bore 54
to provide for communication therebetween.
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In use, sleeve shifting tool 52 is useful for shifting the sleeve of an
injection fluid tubing
assembly. The sleeve shifting tool 52 is unset during run in. In the unset
position,
illustrated in Figure 2A, spring 79 biases ring 62 away from shoulder 58a.
Head
portions 70 of dogs 68 are biased inwardly against wall 78 of ring 62. The
tool is
S selected such that there is sufficient clearance between head portions 70
and the inner
surface of the tubing string, for example tube 10 and sleeve 17 to permit the
tool to be
run in.
Once the tool is in position adjacent the sleeve which is to be moved, the
tubing string
is pressured up, as by forcing fluid through tubing string 57 and into bore
54. The
10 pressurizing fluid can pass through passages 55 and act in a jetting
operation to
remove debris from a region of the tubing string. The pressurizing fluid also
moves
from bore 54 of the tool and out through channels 80 into chamber 60. This
causes the
pressure in chamber 60 to be greater than the pressure around the tool. Thus,
ring 62
is driven outwardly from chamber 60. This drives wall 78 against ramped
surfaces 75
of dogs 68 to urge them radially outwardly. By this action, outer protruding
faces 76
extend out a sufficient distance such that their base shoulders 76" can latch
against end
1T of the sleeve (Figure 2B). The sleeve is then moved by pulling the tubing
string 57
and attached tool 52 towards surface. Once sleeve 17 abuts against shoulder 40
of
tube 18b, the sleeve can be moved no further. This is detectable at surface by
an
increase in load on the tubing string. The tubing string can then be de-
pressurized to
permit the dogs to be biased back in against the tool body and out of
engagement with
the sleeve.
While the tool illustrates the movement of the sleeve to a closed position, it
is to be
understood that the tool can also be used to return the sleeve to an open
position. This
is done by reversing the orientation of the tool so that threaded portion 56
is adjacent
the channels 80 rather than the ring 74.
In use in the stimulation of a underground formation, a plurality of injection
fluid tubing
assemblies, such as the one shown in Figure 1A, are connected in series into a
tubing
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string. Referring to Figure 3, a borehole 89 containing a tubing string,
generally
indicated as 90, for use in the stimulation of an underground formation 91 is
shown.
String 90 includes three spaced apart injection fluid tubing assemblies 92a,
92b, 92c
and a tubing string 94 passing to surface. An amount of stimulating fluid such
as, for
example, steam under pressure is fed to the string by tubing string 94. When
the
sleeves of the tubing assemblies are open, the stimulating fluid passes out
through the
ports of the assemblies into the formation, as indicated by the arrows s. In a
preferred
embodiment, the tubing assemblies 92a, 92b, 92c are spaced apart a distance of
about
100 meters. A wellbore isolating means, such as packer 96, is positioned to
confine the
stimulating fluid to a selected portion of the tubing string 90.
The stimulating fluid which is being passed through tubing string 90
stimulates
production of hydrocarbon fluids, such as oil, from formation 91. Another
borehole 98
containing tubing string 100 is positioned to extend proximate tubing string
90.
Borehole 98 should be sufficiently proximal to borehole 89 such that
stimulating fluids
injected through borehole 89 can have an effect on the production through
borehole 98.
Tubing string 100 collects and conveys the produced fluids to surface. Tubing
string
100, in the illustrated embodiment is position with its end within slotted
liner 102. Other
borehole assemblies can be used, as desired, for collection of produced
fluids.
A plurality of sensors 110a-110d are positioned within borehole 98 to sense
conditions
along the borehole within the producing formation. Sensors 110a-110d are
positioned
at known locations along borehole 98 and it is preferred that it is know which
of the
sensors are closest to each of injection fluid tubing assembly 92a, 92b, 92c.
As an
example, according to the method of the present invention, in the illustrated
embodiment, it is determined that: sensor 110a is closest to injection fluid
tubing
assembly 92a; sensor 110b is closest to injection fluid tubing assembly 92b;
and
sensors 110c, 110d are injection fluid tubing assembly 92c. Sensors 110a-110d
are
connected to surface by transmission line 112.
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A monitoring system such as a computer 114 is connected to line 112 to receive
signals
from sensors 110a-110c.
Signals representative of, for example, temperature and/or pressure are useful
indicators of borehole conditions and can represent the status of the
formation
stimulation process. Based on the received signals decisions can be made as to
whether certain of the fluid delivery ports of the injection fluid tubing
assemblies should
be opened or closed. As an example, where steam is used as the stimulating
fluid and
the temperature at one sensor, for example 110a, begins to increase at a
greater rate
than the other sensor 110b-110d closest to other injection fluid tubing
assemblies, it is
known that the stimulating fluid is passing from injection fluid tubing
assembly 92a
through the formation at a greater rate than from the other tubing assemblies
92b, 92c.
Thus, injection fluid tubing assembly 92a can be shut (as in Figure 1A) to
prevent
formation damage, as by channeling.
The sensors can be any suitable means for sensing downhole conditions. In a
preferred embodiment, thermal couples are used and are in communication with a
surface monitoring means such as a computer.
It will be apparent that many other changes may be made to the illustrative
embodiments, while falling within the scope of the invention and it is
intended that all
such changes be covered by the claims appended hereto.
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