Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02565998 2006-10-27
FULL BORE INJECTION VALVE
BACKGROUND OF THE INVENTION
Field of the Invention
Embodiments of the present invention generally relate to controlling the flow
of
fluids in a wellbore. More particularly, the present invention relates to a
valve for
selectively closing a flow path through a wellbore in a single direction.
Description of the Related Art
Generally, a completion string may be positioned in a well to produce fluids
from
one or more formation zones. Completion devices may include casing, tubing,
packers,
valves, pumps, sand control equipment, and other equipment to control the
production
of hydrocarbons. During production, fluid flows from a reservoir through
perforations
and casing openings into the wellbore and up a production tubing to the
surface. The
reservoir may be at a sufficiently high pressure such that natural flow may
occur despite
the presence of opposing pressure from the fluid column present in the
production
tubing. However, over the life of a reservoir, pressure declines may be
experienced as
the reservoir becomes depleted. When the pressure of the reservoir is
insufficient for
natural flow, artificial lift systems may be used to enhance production.
Various artificial
lift mechanisms may include pumps, gas lift mechanisms, and other mechanisms.
One
type of pump is the electrical submersible pump (ESP).
An ESP normally has a centrifugal pump with a large number of stages of
impellers and diffusers. The pump is driven by a downhole motor, which is
typically a
large three-phase AC motor. A seal section separates the motor from the pump
for
equalizing internal pressure of lubricant within the motor to that of the well
bore. Often,
additional components may be included, such as a gas separator, a sand
separator,
and a pressure and temperature measuring module. Large ESP assemblies may
exceed 100 feet in length.
The ESP is typically installed by securing it to a string of production tubing
and
lowering the ESP assembly into the well. The string of production tubing may
be made
up of sections of pipe, each being about 30 feet in length.
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If the ESP fails, the ESP may need to be removed from the wellbore for repair
at
the surface. Such repair may take an extended amount of time, e.g., days or
weeks.
Typically, a conventional check valve is positioned below the ESP to control
the flow of
fluid in the wellbore while the ESP is being repaired. The check valve
generally
includes a seat and a ball, whereby the ball moves off the seat when the valve
is open
to allow formation fluid to move toward the surface of the wellbore and the
ball contacts
and creates a seal with the seat when the valve is closed to restrict the flow
of
formation fluid in the wellbore.
Although the conventional check valve is capable of controlling the flow of
fluid in
the wellbore, there are several problems in using the conventional check valve
in this
type of arrangement. First, the seat of the check valve has a smaller inner
diameter
than the bore of the production tubing, thereby restricting the flow of fluid
through the
production tubing. Second, the ball of the check valve is always in the flow
path of the
formation fluid exiting the wellbore which results in the erosion of the ball.
This erosion
may affect the ability of the ball to interact with the seat to close the
valve and restrict
the flow of fluid in the wellbore.
Therefore, a need exists in the art for an improved apparatus and method for
controlling the flow of fluid in the wellbore.
SUMMARY OF THE INVENTION
The present invention generally relates to controlling the flow of fluids in a
wellbore. In one aspect, a valve for selectively closing a flow path through a
wellbore in
a first direction is provided. The valve includes a body and a piston surface
formable
across the flow path in the first direction. The piston surface is formed at
an end of a
shiftable member annularly disposed in the body. The valve further includes a
flapper
member, the flapper member closable to seal the flow path when the shiftable
member
moves from a first position to a second position due to fluid flow acting on
the piston
surface.
In another aspect, a valve for selectively closing a flow path through a
wellbore
in a single direction is provided. The valve includes a housing and a variable
piston
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surface area formable across the flow path in the single direction. The valve
also
includes a flow tube axially movable within the housing between a first and a
second
position, wherein the variable piston surface is operatively attached to the
flow tube.
Further, the valve includes a flapper for closing the flow path through the
valve upon
movement of the flow tube to the second position.
In yet another aspect, a method for selectively closing a flow path through a
wellbore in a first direction is provided. The method includes positioning a
valve in the
wellbore, wherein the valve has a body, a formable piston surface at an end of
a
shiftable member, and a flapper member. The method further includes reducing
the
flow in the first direction, thereby forming the piston surface. Further, the
method
includes commencing a flow in a second direction against the piston surface to
move
the shiftable member away from a position adjacent the flapper member.
Additionally,
the method includes closing the flapper member to seal the flow path through
the
wellbore.
BRIEF DESCRIPTION OF THE DRAWINGS
So that the manner in which the above recited features of the present
invention
can be understood in detail, a more particular description of the invention,
briefly
summarized above, may be had by reference to embodiments, some of which are
illustrated in the appended drawings. It is to be noted, however, that the
appended
drawings illustrate only typical embodiments of this invention and are
therefore not to
be considered limiting of its scope, for the invention may admit to other
equally effective
embodiments.
Figure 1 is a view illustrating a control valve disposed in a wellbore.
Figure 2 is a view illustrating the valve in an open position.
Figure 3 is a view illustrating the piston surface formed in a bore of the
valve.
Figure 4 is a view taken along line 4-4 of Figure 3 to illustrate the piston
surface.
Figure 5 is a view illustrating the valve in the closed position.
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CA 02565998 2006-10-27
DETAILED DESCRIPTION
Figure 1 is a view illustrating a control valve 100 disposed in a wellbore 10.
As
shown, the control valve 100 is in a lower completion assembly disposed in a
string of
tubulars 30 inside a casing 25. An electrical submersible pump 15 may be
disposed
above the control valve 100 in an upper completion assembly. As illustrated, a
polished
bore receptacle and seal assembly 40 may be used to interconnect the
electrical
submersible pump 15 to the valve 100 and a packer arrangement 45 may be used
to
seal an annulus formed between the valve 100 and the casing 25. Generally, the
valve
100 is used to isolate the lower completion assembly from the upper completion
assembly when a mechanism in the upper completion assembly, such as the pump
15,
requires modification or removal from the wellbore 10.
The electrical submersible pump 15 serves as an artificial lift mechanism,
driving
production fluids from the bottom of the wellbore 10 through production tubing
35 to the
surface. Although embodiments of the invention are described with reference to
an
electrical submersible pump, other embodiments contemplate the use of other
types of
artificial lift mechanisms commonly known by persons of ordinary skill in the
art.
Further, the valve 100 may be used in conjunction with other types of downhole
tools
without departing from principles of the present invention.
Figure 2 is a view of the valve 100 in an open position. The valve 100
includes a
top sub 170 and a bottom sub 175. The top 170 and bottom 175 subs are
configured to
be threadedly connected in series with the other downhole tubing. The valve
100
further includes a housing 105 disposed intermediate the top 170 and bottom
175 subs.
The housing 105 defines a tubular body that serves as a housing for the valve
100.
Additionally, the valve 100 includes a bore 110 to allow fluid, such as
hydrocarbons, to
flow through the valve 100 during a production operation.
The valve 100 includes a piston surface 125 that is formable in the bore 110
of
the valve 100. The piston surface 125 shown in Figure 2 is in an unformed
state. The
piston surface 125 is maintained in the unformed state by a fluid force acting
on the
piston surface 125 created by fluid flow through the bore 110 of the valve 100
in the
direction indicated by arrow 115. The piston surface 125 generally includes
three
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individual members 120. Each member 120 has an end that is rotationally
attached to
a flow tube 155 by a pin 195 and each member 120 is biased rotationally inward
toward
the center of the valve 100. Additionally, each member 120 is made from a
material
that is capable of withstanding the downhole environment, such as a metallic
material
or a composite material. Optionally, the members 120 may be coated with an
abrasion
resistant material.
As illustrated in Figure 2, the valve 100 also may include a biasing member
130.
In one embodiment, the biasing member 130 defines a spring. The biasing member
130 resides in a chamber 160 defined between the flow tube 155 and the housing
105.
A lower end of the biasing member 130 abuts a spring spacer 165. An upper end
of the
biasing member 130 abuts a shoulder 180 formed on the flow tube 155. The
biasing
member 130 operates in compression to bias the flow tube 155 in a first
position.
Movement of the flow tube 155 from the first position to a second position
compresses
the biasing member 130 against the spring spacer 165.
The valve 100 further includes a flapper member 150 configured to seal the
bore
110 of the valve 100. The flapper member 150 is rotationally attached by a pin
190 to a
portion of the housing 105. The flapper member 150 pivots between an open
position
and a closed position in response to movement of the flow tube 155. In the
open
position, a fluid pathway is created through the bore 110, thereby allowing
the flow of
fluid through the valve 100. Conversely, in the closed position, the flapper
member 150
blocks the fluid pathway through the bore 110, thereby preventing the flow of
fluid
through the valve 100.
As shown in Figure 2, an upper portion of the flow tube 155 is disposed
adjacent
the flapper member 150. The flow tube 155 is movable longitudinally along the
bore
110 of the valve 100 in response to a force on the piston surface 125. Axial
movement
of the flow tube 155, in turn, causes the flapper member 150 to pivot between
its open
and closed positions. In the open position, the flow tube 155 blocks the
movement of
the flapper member 150, thereby causing the flapper member 150 to be
maintained in
the open position. In the closed position, the flow tube 155 allows the
flapper 150 to
rotate on the pin 190 and move to the closed position. It should also be noted
that the
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flow tube 155 substantially eliminates the potential of contaminants from
interfering with
the critical workings of the valve 100.
Figure 3 illustrates the piston surface 125 formed in the bore of the valve
100.
To seal the bore 110, the flow of fluid through the bore 110 of the valve 100
in the
direction indicated by the arrow 115 is reduced. As the flow of fluid is
reduced, the fluid
force holding the piston surface 125 in the unformed state becomes less than
the
biasing force on the piston surface 125. At that point, each member 120 of the
piston
surface 125 rotates around the pin 195 toward the center of the valve 100 to
form the
piston surface 125 illustrated in Figure 4. After the piston surface 125 is
formed, the
flow of fluid in the direction indicated by arrow 145 is commenced, thereby
creating a
force on the piston surface 125. As the force on the piston surface 125
increases, the
force eventually becomes stronger than the force created by the biasing member
130.
At that point, the force on the piston surface 125 urges the flow tube 155
longitudinally
along the bore 110 of the valve 100.
Figure 5 is a view illustrating the valve 100 in the closed position. After
the
piston surface 125 is formed, the flow tube 155 moves axially in the valve
100. This
moves the upper end of the flow tube 155 out of its position adjacent the
flapper
member 150. This, in turn, allows the flapper member 150 to pivot into its
closed
position. In this position, the bore 110 of the valve 100 is sealed, thereby
preventing
fluid communication through the valve 100. More specifically, flow tube 155 in
the
closed position no longer blocks the movement of the flapper member 150,
thereby
allowing the flapper member 150 to pivot from the open position to the closed
position
and seal the bore 110 of the valve 100.
The flapper member 150 in the closed position closes the flow of fluid through
the bore
110 of the valve 100, therefore no fluid force in the bore 110 acts on the
members 120.
To move the flapper member 150 back to the open position, the flow of fluid in
the
direction indicated by arrow 145 is reduced and the fluid on top of the
flapper member
150 is pumped or sucked off the top of the flapper member 150. At a
predetermined
point, the biasing member biasing the flapper member 150 is overcome and
subsequently the biasing member 130 extends axially to urge the flow tube 155
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CA 02565998 2006-10-27
longitudinally along the bore 110 until a portion of the flow tube 155 is
adjacent the
flapper member 150. In this manner, the flapper member 150 is back to the open
position, thereby opening the bore 110 of the valve 100 to flow of fluid
therethrough, as
illustrated in Figure 2.
In one embodiment, the valve 100 may be locked in the open position as shown
in Figure 2 by disposing a tube (not shown) in the bore 110 of valve 100. The
tube is
configured to prevent the axial movement of flow tube 155 from the first
position to the
second position by preventing the formation of the piston surface 125. Thus,
the
flapper member 150 will remain in the open position and the valve 100 will be
locked in
the open position. To lock the valve 100, the tube is typically pulled into
the bore 110
from a position below the valve 100. In a similar manner, the valve 100 may be
unlocked by removing the tube from the bore 110 of the valve 100.
Although the invention has been described in part by making detailed reference
to specific embodiments, such detail is intended to be and will be understood
to be
instructional rather than restrictive. For instance, the valve may be used in
an injection
well for controlling the flow of fluid therein. It should be also noted that
while
embodiments of the invention disclosed herein are described in connection with
a
valve, the embodiments described herein may be used with any well completion
equipment, such as a packer, a sliding sleeve, a landing nipple, and the like.
While the foregoing is directed to embodiments of the present invention, other
and further embodiments of the invention may be devised without departing from
the
basic scope thereof, and the scope thereof is determined by the claims that
follow.
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