Note: Descriptions are shown in the official language in which they were submitted.
CA 02596383 2008-09-25
Description OICA072049
Underbalanced downhole casing valve and force open tool thereof
Field of the Invention
The present invention relates to a hole-closure device used during
under-balanced drilling and well completion operation, in particular, to an
underbalanced down-hole casing valve and a force open tool used during
drilling
and well completion in oil and gas field.
io Background of the Invention
Recently, underbalanced drilling technology has been developed rapidly.
Especially, an underbalanced downhole hole-closure device is applied to
underbalanced drilling operation, which makes overall process of underbalanced
drilling operation complete successfully. A hole-closure device, such as an
underbalanced downhole casing valve, can entirely separate fluid above a
wellbore
from that under it at a specific position of cylinderan intermediate casing,
which
ensures tripping and running complete well pipes in an underbalanced state,
and
effectively reduces damage to oil storage layer as a result of controlling
well using
weighted mud for balancing downhole pressure when tripping and running
complete well pipes are being done in an underbalanced state.
However, the technique of the underbalanced downhole hole-closure device is
not perfect. During use of the underbalanced downhole hole-closure device, on
the
one hand, after a tongue board of the underbalanced downhole hole-closure
device
is closed for a long time, negative pressure is produced as a result of gas
moving in
stratums. Overhigh negative pressure under the tongue board can damage the
tongue board, and the longer time the tongue board is closed, the higher the
negative pressure. On the other hand, one person on the ground can not know
the
value of the negative pressure under the tongue board, so he/she can not
control the
pressure of the wellbore exactly, which can bring hidden trouble to switches
of the
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tongue board in the underbalanced downhole hole-closure device. If the
switches
are operated falsely, the tongue board will be damaged. Furthermore, during
opening or closing the underbalanced downhole hole-closure device, one person
on
the ground can not know whether the tongue board has been opened. If drilling
has been started when the tongue board has not been opened entirely, the
tongue
board also can be shattered. Therefore, the tongue board of the casing valve
can not
be opened when the underbalanced downhole hole-closure device, especially the
underbalanced downhole casing valve goes wrong in hydraulic controlling pipe ,
at
this time, a match tool will be required to force to open the downhole casing
valve
lo and lock it in a permanent open state.
Summary of the Invention
An object of the present invention is to provide an underbalanced downhole
casing valve controlled hydraulically. The casing valve can entirely separate
fluid
above a wellbore from that under it at a specific position of an intermediate
casing,
which ensures tripping and running complete well pipes in an underbalanced
state,
and effectively reduces damage to oil storage layer,as a result of controlling
well
using weighted mud for balancing downhole pressure when tripping and running
complete well pipes are being done in an underbalanced state. Furthermore,
when
the hydraulic pressure on the ground can not open the underbalanced downhole
casing valve, the underbalanced downhole casing valve can be opened and locked
in a permanent open state by matched force open tool.
The underbalanced downhole casing valve of the present invention can also
measure the downhole pressure so that the downhole pressure can be effectively
inspected during drilling operation.
According to one aspect of the present invent, an underbalanced downhole
casing valve controlled hydraulically is provided, which comprises an upper
fitting,
an inner cylindercylinder, an upper outer cylinder, a lower outer cylinder, a
valve
assembly and a lower fitting, wherein steps machined on the inner surface of
the
upper outer cylinder; the valve assembly situated within a first annulus
defined by
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the upper outer cylinder, the lower outer cylinder and the inner cylinder;
bosses
respectively disposed in the inner surface of the upper fitting and on the
outer
surface of the inner cylinder, the upper outer cylinder and the inner cylinder
being
clearance fit; a first hydraulic fluid chamber (11) formed between the bosses
in the
inner surface of the upper fitting boss and on the outer surface of the inner
cylinder
and the inner surface of the upper outer cylinder; a second hydraulic fluid
chamber
(12) formed between the lower portion of the bosses in the inner cylinder and
the
inner surface of the upper outer cylinder ; axial bores disposed on the upper
end of
the upper outer cylinder; hydraulic controlling systems connected to the axial
bores
lo by pipes, two of the axial bores respectively fluidly communicated with the
first
hydraulic fluid chamber (11) and the second hydraulic fluid chamber (12); a
second
annulus formed between the lower portion of the upper outer cylinder and the
inner
cylinder, the second annulus fluidly communicated with the bore disposed in
the
upper outer cylinder, and fluidly communicated with a third annulus defined by
the
upper outer cylinder and the valve assembly.
The underbalanced downhole casing valve of the present invention further
comprises a lock collar and a shear pin, wherein: the lock collar installed
within the
lower fitting; steps formed on the inner surface of the lower fitting , and
the lower
end surface of the lock collar positioned on the step on the inner surface of
the
lower fitting; The lower fitting connected with the lock collar by the shear
pin;
inverted teeth machined on the outer surface of the upper end of the lock
collar and
on the inner surface of the lower fitting; the outer diameter of the lock
collar is
smaller than the inner diameter of the valve assembly.
A force open tool used for the underbalanced downhole casing valve of the
present invention is also provided, which comprises a body, a spring block, a
hydraulic anchor, a resilient sleeve, a ball seat and a guide head, wherein:
Steps
provided on the outer surface of the body; the spring block and the hydraulic
anchor respectively fixed to the upper portion and the middle portion of the
body;
the resilient sleeve covering the outer surface of the lower portion of the
body, a
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boss disposed on the middle portion of the outer surface of the resilient
sleeve, thru
slots distributed equably around the circumference throughout the entire
length of
the boss; the boss disposed on the middle outer surface of the resilient
sleeve
mating with a groove right disposed in the underbalanced downhole casing valve
according to the present invention; the ball seat mounted within the lower
portion
of the body; the guide head mounted on the end portion of the body.
The advantage of the present invention is that: during using the casing valve,
if
one person wants to open the casing valve which has been closed, he/she can
only
pump using one of the pipes. Pressure is applied through one of two assistant
pipes,
io and the pressure will enter into the first hydraulic fluid chamber 11
through the
upper outer cylinder 3 and pushes the inner cylinder 2 downwardly moving, in
turn
the inner cylinder 2 pushes the tongue board on the valve assembly 5 open. If
one
person wants to close the casing valve, he/she can only pump using the other
pipe.
Pressure is applied through the other assistant pipe, and the pressure will
enter into
the second hydraulic fluid chamber 12 through bores disposed in the upper
outer
cylinder 2 and pushes the inner cylinder 2 upwardly moving. The tongue board
on
the valve assembly 5 is closed under the action of an assistant spring.
When the casing valve is closed, the downhole pressure can be measured
through the radial bores 10 on the upper outer cylinder 3.
When the underbalanced downhole casing valve is closed and can not be
opened by the hydraulic pressure on the ground, the underbalanced downhole
casing valve can be opened and locked in a permanent open state by matched
force
open tool.
Brief Description of the Drawings
Figure 1 is a partial section view showing an underbalanced downhole casing
valve according to the present invention;
Figure 1 A and 1 B are section views showing clearly all the part of the valve
respectively;
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Figure 2 is a partial section view showing a force open tool for the
underbalanced downhole casing valve according to the present invention.
Figure 3 and 4 are section views showing how the axis bores are
communicated with hydraulic fluid chamber 11 and 12 respectively;
Figure 5 are a section view showing how the radial bore is communicated with
the downhole pressure when the valve is closed.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, a preferred embodiment of the present invention will be described
in detail with reference to the drawings.
Fig.l is a section view of an underbalanced downhole casing valve controlled
by hydraulic pressure for measuring downhole pressure. Figure 1 A and 1 B are
section views showing clearly all the part of the valve respectively. The
casing
valve includes an upper fitting 1, an inner cylinder 2, a upper outer cylinder
3, a
lower outer cylinder 4, a valve assembly 5 and a lower fitting 6. The upper
fitting 1
and the upper outer cylinder 3, the upper outer cylinder 3 and the lower outer
cylinder 4 and the lower outer cylinder 4 and the lower fitting 6 are
respectively
engaged each other by screw thread and the like. There are steps on the inner
surface of the upper outer cylinder 3. The valve assembly 5 is disposed within
a
first annulus defined by the upper outer cylinder 3, the lower outer cylinder
4 and
the inner cylinder 2, and which covers the outer surface of the inner cylinder
2 and
is positioned on the step on the inner surface of the lower outer cylinder 4.
Two
bosses are respectively disposed in the inner surface of the upper fitting 1
and on
the outer surface of the inner cylinder 2. Sealing loops can be disposed on
the
bosses. Clearance fit is provided between the upper outer cylinder 3 and the
inner
cylinder 2. A first hydraulic fluid chamber 11 is formed on the bosses in the
inner
surface of the upper fitting 1 and on the outer surface of the inner cylinder
2 and the
inner surface of the upper outer cylinder 3; a second hydraulic fluid chamber
12 is
formed between the lower portion of the boss on the inner cylinder 2 and the
inner
surface of the upper outer cylinder 3. Several axial bores are disposed on the
upper
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end of the upper outer cylinder 3. A hydraulic controlling system is fluidly
communicated with the bores by pipes. Two of the bores are respectively
fluidly
communicated with the first hydraulic fluid chamber 11 and the second
hydraulic
fluid chamber 12. A second annulus is formed between the lower portion of the
upper outer cylinder 3 and the inner cylinder 2. The second annulus is
communicated with a radial bore 10 disposed in the upper outer cylinder 3 and
communicated with a third annulus defined by the upper outer cylinder 3 and
the
valve assembly 5., as best shown in Figure 3 and 4.
The underbalanced downhole casing valve of Fig. l further includes a shear pin
io 7 and a lock collar 8. The lock collar 8 is installed within the lower
fitting 6.
Inverted teeth are machined on the outer surface of the upper end of the lock
collar
8 and on the inner surface of the lower fitting 6. Steps are also formed on
the inner
surface of the lower fitting 6. The lower end surface of the lock -collar 8 is
positioned on the step on the inner surface of the lower fitting 6. The lower
fitting 6
is connected to the lock collar 8 by the shear pin 7. The outer diameter of
the lock
collar 8 is slightly smaller than the inner diameter of the valve assembly 5.
The casing valve is pre-connected to an intermediate casing before the
intermediate casing is ran. Two assistant pipes are connected to an annulus
between
the casing valve and a previous stage cylinder. If one person wants to open
the
casing valve which has been closed, he/she can only pump using one of the
pipes.
TPressure is applied through one of the two assistant pipes, and the pressure
will
enter into the first hydraulic fluid chamber 11 through the upper outer
cylinder 3
and pushes the inner cylinder 2 downwardly moving, in turn the inner cylinder
2
pushes the tongue board on the valve assembly 5 open. If one person wants to
close
the casing valve, he/she can only pump using the other pipe. Pressure is
applied
through the other assistant pipe, and the pressure will enter into the second
hydraulic fluid chamber 12 through the bores disposed in the upper outer
cylinder 2
and pushes the inner cylinder 2 upwardly moving. The tongue board on the valve
assembly 5 is closed under the action of an assistant spring. Figure 5 are a
section
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view showing how the radial bore is communicated with the downhole pressure
when the valve is closed. When the casing valve is closed, the bores on the
upper
outer cylinder 3 are fluidly communicated with a second annulus formed between
the lower portion of the upper outer cylinder 3 and the inner cylinder 2, and
the
secondannulus is fluidly communicated with a third annulus formed between the
upper outer cylinder 3 and the valve assembly 5, so the downhole pressure can
be
measured through the radial bore 10 on the upper outer cylinder 3.
Fig.2 shows a force open tool for the underbalance downhole casing valve of
the present invention. The force open tool includes a body 13, a spring block
14, a
io hydraulic anchor 15, a resilient sleeve 16, a ball seat 17 and a guide head
18. The
guide head 18 is connected to one end of the body 13 by screw threas or the
other
like manner. The outer surface of the body 13 is provided with steps. The
spring
block 14 and the hydraulic anchor 15 are respectively fixed to the upper
portion and
the middle portion of the body 13 by bolts. The resilient sleeve 16 covers the
outer
surface of the lower portion of the body 13. A boss is disposed on the middle
portion of the outer surface of the resilient sleeve 16. There are
predetermined
numbers thru slot distributed equably around the circumference throughout the
entire length of the boss. The stage disposed on the middle outer surface of
the
resilient sleeve 16 can mate with a groove right disposed in the underbalanced
2o downhole casing valve. The ball seat 17 is mounted within the lower portion
of the
body 13.
The casing valve is connected to the intermediate casing in advance before the
intermediate casing is ran. When the casing valve is closed and can not be
opened
by controlling hydraulic pressure on the ground, the force open tool for the
underbalanced downhole casing valve can be ran. When the force open tool is
ran,
the resilient sleeve 16 and the spring block 14 are contracted and the force
open
tool enters into the underbalanced downhole casing valve. The lower end of the
guide head forces the tongue board of the downhole casing valve open. When the
boss of the resilient sleeve 16 enters into a groove in the downhole casing
valve, a
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pump is opened to increase pressure in the pump and anchor flukes of the
hydraulic
anchor are protruded to support within the lock collar 8 in the downhole
casing
valve. Then the force open tool is lifted along with the lock collar 8. The
shear pins
7 are cut. Then the lock collar 8 comes into the valve assembly 5. The lock
collar 8
can only be moved upwardly because inverted teeth are provided on the outer
surface of the lock collar 8 and the inner surface of the lower fitting 6.
Therefore,
the underbalanced downhole casing valve will be locked in the open state
permanently. If the pump is stopped, the anchor flukes of the hydraulic anchor
are
contracted, while the force open tool can be pulled out successfully.
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