Note: Descriptions are shown in the official language in which they were submitted.
CA 02688765 2009-12-16
CONTINUOUS FLUID CIRCULATION
VALVE FOR WELL DRILLING
FIELD OF THE INVENTION
The present invention relates to a method and equipment for drilling a
well. More particularly, a circulation valve is provided for interconnection
with a
drill string joint, such that during conventional drilling the fluids pass
through the
drill string joint, the valve, and the drill string in the well. When the
drill string
connection is made up or broken apart, fluid is diverted through a side port
in the
valve, thereby maintaining substantially continuous fluid circulation.
BACKGROUND OF THE INVENTION
When drilling a hydrocarbon recovery well, the drill string is conventionally
rotated to drive the drill bit. When a mud motor is used along the drill
string to
rotate the bit, the drill string is frequently rotated at a speed less than
the bit to
keep solids desirably suspended in the well fluids. Drilling mud is thus
circulated
through the drill string and to the bit, and up the annulus between the drill
string
and the wellbore. As one or more joints are added to the string, the drilling
process is briefly stopped to make up the threaded interconnection of the
joint to
the drill string. Although the drill string is normally full of fluid, the
pressure
supplied by the mud pumps is lost when the pumps are shut off as the threaded
connection is made up. Restarting circulation can be difficult, and may lead
to
numerous drilling problems.
The prior art includes methods designed to allow a drill joint to be added
to or removed from a drill string while circulation of mud continues. This
prior art
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process utilizes a coupler for substantially surrounding the threaded
connection.
Various rams, preventers, slips, and other closing devices substantially seal
fluid
within the coupler as the connection is made up. Devices of this type are
disclosed in U.S. Patents 6,119,772, 6,591,916, 6,739,397, 7,028,586, and
7,252,151. Publication W098/16716 also discloses a continuous circulation
drilling method.
There are significant disadvantages to the above approach. First, the
mechanism for accomplishing continuous circulation involves an expensive
coupler, and numerous sealing devices are provided to minimize leakage of mud
from the encircling coupler. The device is also expensive, and at least in
some
applications slows down the makeup or breakout process, thereby contributing
to
higher drilling costs. U.S. Patent 4,478,244 discloses a mud saver valve which
may be threaded to a drill string to reduce mud spills. U.S. Application
11/786,495 discloses a safety valve with a ball rotatable engaging an actuator
sleeve.
The disadvantages of the prior art are overcome by the present invention,
in an improved technique for continuously circulating drilling mud in a drill
string
is hereinafter disclosed.
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SUMMARY OF THE INVENTION
In one embodiment, a fluid circulation valve is provided for use with a well
drilling operation, wherein a drill joint may be added to or removed from a
drill
string which extends into a well. The fluid circulation valve includes a valve
housing having a central flow path therein, a housing side port, an upper
threaded connector for threaded engagement with the lower end of the drill
joint,
and a lower threaded connector for threaded engagement with an upper end of
the drill string. A rotatable ball is positioned within the flow path in the
valve
housing has a throughbore. The ball throughbore is in fluid communication with
the housing central flow path when the ball is open, and a ball side port is
in fluid
communication with the housing side port when the ball is closed. The valve
housing side port is in fluid communication with a line radially exterior of
the
valve housing, and typically extending to a mud pump. The fluid circulation
valve
includes an upper valve seat for sealing between the ball and the housing, and
a
lower valve seat for sealing between the ball and the housing. Fluid may be
continuously circulated through the drill string even when adding or deleting
a
drill joint, since fluid may flow either through the ball throughbore or
though the
ball side port. The valve remains connected to the drill string as joints are
added
and the string is run in the well. The housing side port is closed when the
ball
throughbore is in fluid communication with the valve housing central flow
path.
The upper side of valve throughbore is closed when the ball is positioned to
open
the side port into the interior of the housing.
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These and further features and advantages of the present invention will
become apparent from the following detailed description, wherein reference is
made to the figures in the accompanying drawings.
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BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a cross-sectional view of one embodiment of a fluid circulation
valve.
Figure 2 is a cross-sectional view through the valve shown in Figure 1.
Figure 3 is a top view illustrating a suitable tool for sealing between the
valve body and a radially external flow line.
Figure 4 is a cross-sectional view of another embodiment of a fluid
circulation valve, with two circumferentially opposing operating stems for
rotatably guiding rotation of the ball.
Figure 5 is a cross-sectional view of yet another embodiment of a fluid
circulation valve.
Figure 6 illustrates the fluid circulation valve shown in Figure 5 in another
ball position.
Figure 7 illustrates a tool for sealing between the valve body and a radially
external flow line.
Figure 8 is a cross-sectional view of yet another embodiment of a fluid
circulation valve, wherein the ball actuator is axially spaced from the ball.
Figure 9 illustrates the fluid circulation valve in Figure 8 in the closed
position.
Figure 10 illustrates a tool for sealing between the valve body and a
radially external flow line.
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DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Figure 1 illustrates one embodiment of a fluid circulation valve according
to the present invention. Circulation valve 10 includes a valve body, which as
shown consists of an upper valve body 16 having upper threads 18 for threaded
interconnection with the lower end of a pipe joint, and a lower valve body 12
having lower threads 14 for threaded connection with an upper end of a tubular
string which extends into a wall. The bodies 12 and 16 are joined by threads
20,
with shoulder 22 acting between the bodies 12 and 16 to obtain a rigid
connection, and to pass torque from above the valve to below the valve while
positioned along a drill string, thereby allowing torque to be transferred to
the bit
to rotate the bit, or to actuate components along the drill string. A seal 30
may
be provided for sealing between the housings 12 and 16. Those skilled in the
art
will appreciate that fluid may be pumped through the valve from the upper end
of
a pipe joint to the lower end of the pipe joint, then through the bodies 16
and 12,
then through a tubular pipe string which extends into a well.
Figure 1 illustrates a ball 24 rotatably positioned within the valve housing,
with the ball having a throughbore 41 defined by side walls 42, such that the
throughbore 41 is in fluid communication with the bore 17 in the housing when
the ball is in the open position, as shown in Figure 1. Mud or other drilling
fluid
may thus be pumped from above the fluid circulation valve, through the fluid
circulation valve, and into the drill string when the valve 10 is open.
The circulation valve preferably includes an upper valve seat 28 which
has a seal 32 for sealing engagement with the housing 12, and another seal 32
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for sealing engagement with the ball 24. The assembly further includes a lower
ball seat 26 similarly having a seal 32 for sealing engagement with the
housing
16, and another seal 32 for sealing with the ball 24. One or more biasing
members, such as a wave spring or a Bellville spring 27, may be included to
bias
upper seat 28 axially downward for sealing engagement with the ball, or to
bias
the lower seat 26 upward into sealing engagement with the ball. Each seat thus
may include a Bellville spring or a wave spring to exert a desired biasing
force to
press the seat into engagement with the ball. Figure 1 also illustrates an
operating stem or guide block 34 with seal 36 for sealing engagement with the
housing 16, a noncylindrical external access pocket 38 for receiving a ball
rotating tool, and a noncylindrical actuating tab 40 for fitting within a
similarly
shaped recess within the ball to rotate the ball when the operating stem or
guide
block 34 is rotated, as explained hereafter.
Figure 2 is a horizontal cross sectional view through the valve and the ball
in Figure 1, with the ball 24 in the open position. The operating stem 34 is
shown with a radially inward key 40 (see Figure 1) for inserting into a key
into a
receiving pocket in the ball 24, so that the ball rotates in response to
rotation of
the operating stem 34. The flange 33 retains the operating stem in position
with
respect to the valve housing, thereby monitoring the ball centered in spite of
high
pressure acting on the operating stem. Figure 2 also discloses an inlet ring
44
which is threaded at 46 into engagement with the housing 16, and is configured
for fluidly receiving an external flow line, as disclosed subsequently.
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Figure 3 shows a suitable tool 80 for engaging an outer surface of the
housing 16, and for temporarily sealing between the interior of valve 10 and a
flow line 82 radially external of the valve, with line 82 typically extending
to a mud
pump 83. The exemplary tool has an arcuate portion 81 which substantially
surrounds the valve body 16, with curved interior surface 84 engaging the
exterior surface of valve body. The tool 80 includes a latch-type locking lugs
50
and 54, locking handle 52, and at least one hollow pin 86 which fits within a
respective cavity or recess in the ring 85 when the handle is locked. Hinge 83
allows the ring shaped tool to be easily put on and removed from the valve.
Figure 3 also illustrates seal 87 for acting between the tool and the ring 85,
which
defines the cavity or recess for receiving the external fluid. The ball 24 is
shown
in Figure 3 in the closed position, i.e., fluid is blocked from flowing from
above to
below the valve, although fluid can flow from exterior flow line 82 to the
ball and
then downward into the drill string. Other types of tools may be used for
sealingly engaging the valve body and the external flow line.
Figure 4 is similar to the Figure 2 embodiment, except that a pair of
circumferentially opposing guide blocks or operating stems 34, 35 are
provided,
each with a tool recess pocket 38. One or both operating stems may thus be
rotated to rotate the ball between open and closed positions. In one
embodiment, one stem may be connected to the ball 24 for rotating the ball to
the open position and the opposing stem rotated to move the ball to the closed
position, as shown in Figure 3. Two radially opposing operating stems allow
fluid
pressure to act on both operating stems, so that the opposing forces cancel
and
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the ball remains centered in the valve body without using the flange 33 shown
in
Figure 3. Also, Figure 4 depicts spring biased pins 56, 58 for exerting a
biasing
force from the housing to the ball, and similar spring biased pins 57, 59 for
exerting a biasing force from ring 44 to the ball.
Referring now to Figure 5, this version of a continuous fluid circulation
valve 10 is depicted with a ball valve 24 shown in the open position for
transmitting fluid from above to below the ball valve. By rotating the
operating
stem 34, the ball may thus be rotated between the open and closed positions.
Figure 6 illustrates another cross sectional view of the valve shown in Figure
5,
and illustrates another ring 62 threadably positioned within the side body
access
port in the valve body, and a flapper member 66 pivotably connected to the
ring
member 62 and closing off the side port of the valve body when the valve is in
the open position, as shown in Figure 6. Figure 7 depicts in greater detail a
suitable tool 80 as previously disclosed for fluidly connecting flow line 82
to the
interior of the valve. The tool 80 thus seals to the ring 62, as previously
discussed. With the ball rotated to the closed position, fluid may be pumped
into
the valve body, and fluid pressure will be sufficient to swing the flapper 66
to the
open position, as shown in Figure 7, thereby allowing fluid to enter the
interior of
the ball and pass downward through the valve and into the drill string.
Figure 8 depicts another version of a continuous circulation valve 10
according to the present invention, with a ball 24 as previously discussed. In
this
embodiment, the ball is rotated between an open and closed position and by
rotating sleeve 72, which includes threads 74 for mating with sleeve 76
extending
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axially from connector 78, which interconnects the sleeve 76 with the ball. By
rotating the sleeve 72, the sleeve 76 moves axially relative to the housings
16,
12, thereby rotating the ball. A large pipe wrench or other suitable tool may
be
used for gripping the external surface of sleeve 72 to rotate the sleeve and
thereby the ball between open and closed positions. Figure 10 illustrates a
suitable tool 80 for sealingly engaging external flow line 82 to the interior
of the
ball when the valve is in the closed position. As with the prior embodiments,
the
tool is sealed to threaded ring 85 for passing fluid from a line radially
exterior of
the ball valve into the well when the flow line from above to below the ball
valve
is blocked.
In other embodiments, one of the rotating sleeve 72 and the ball rotating
member may include one or more projections which each fit within a
corresponding helical slot in the other of the rotating sleeve and the ball
rotating
member, so that rotation of the sleeve moves the ball rotating member axially
in
the same manner as the threads discussed above. Threads are preferred for
most applications since they provide a large surface area for transmitting
axial
forces to the ball to open or close the ball.
The term "ball" as used herein is intended in its broad sense to refer to a
rotatable closing member in a valve, with at least a portion of the outer
surface of
the ball being similar in configuration to a portion of a sphere. While the
ball as
disclosed herein obviously need not be a sphere, the ball does rotate about a
ball center.
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The fluid circulation valve as disclosed herein may be used in well drilling
operations wherein fluid passes through a drill joint, through the valve, and
into
the drill string while the valve is in the open position, and fluid passes
from an
external flow line, downward through a lower end of the valve body, and into
the
drill string when the valve is closed. During the valve closed cycle, the
drill joint
may be fluidly connected with the top of the valve, and once this connection
is
complete, the valve may be opened so that the external flow line is blocked
and
fluid can be pumped into the well through the drill joint, which is now part
of the
drill string.
Although specific embodiments of the invention have been described
herein in some detail, this has been done solely for the purposes of
explaining
the various aspects of the invention, and is not intended to limit the scope
of the
invention as defined in the claims which follow. Those skilled in the art will
understand that the embodiment shown and described is exemplary, and various
other substitutions, alterations and modifications, including but not limited
to
those design alternatives specifically discussed herein, may be made in the
practice of the invention without departing from its scope.
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