Note: Descriptions are shown in the official language in which they were submitted.
CA 02526837 2001-03-12
1
DOWNHOLE SURGE PRESSURE REDUCTION AND
FILTERING APPARATUS
This is a divisional application of Canadian Patent Application Serial No.
2,400,973 filed on March 12, 2001.
The present invention provides a downhole surge pressure reduction apparatus
for
use in the oil well industry. More particularly, the invention provides a
surge pressure
reduction apparatus that is run into a well with a pipe string or other
tubular to be
cemented and facilitates the cementing by reducing surge pressure and inner
well
sediments during run-in. It should be understood that the expression "the
invention" and
the like encompasses the subject matter of both the parent and the divisional
applications.
In the drilling of a hydrocarbon well, the bore hole is typically lined with
strings
of pipe or tubulars (pipe or casing) to prevent the walls of the bore hole
from collapsing
and to provide a reliable path for well production fluid, drilling mud and
other fluids that
are naturally present or that may be introduced into the well. Typically,
after the well is
drilled to a new depth, the drill bit and drill string are removed and a
string of pipe is
lowered into the well to a predetermined position whereby the top of the pipe
is at about
the same height as the bottom of the existing string of pipe (liner). In other
instances, the
new pipe string extends back to the surface of the well casing. In either
case, the top of
the pipe is fixed with a device such as a mechanical hanger. A column of
cement is then
pumped into the pipe or a smaller diameter run-in string and forced to the
bottom of the
bore hole where it flows out of the pipe and flows upwards into an annulus
defined by the
bore hole and pipe. The two principal functions of the cement between the pipe
and the
bore hole are to restrict fluid movement between formations and to support the
pipe.
To save time and money, apparatus to facilitate cementing are often lowered
into
the bore hole along with a hanger and pipe to be cemented. Cementing apparatus
typically includes a number of difference components made up at the surface
prior to run-
in. These include a tapered nose portion located at the downhole end of the
pipe to
facilitate insertion thereof into the bore hole. A check valve at least
partially seals the
end of the tubular and prevents entry of well fluid during run-in while
permitting
cement to subsequently flow outwards. Another valve or plug typically located
in
a baffle collar above the cementing tool prevents the cement in the annulus
from back
flowing into the pipe. Components of the cementing apparatus are made of
plastic,
CA 02526837 2001-03-12
WO 01 /69036 PCT/C B01 /01070
2
fibreglass or other disposable material that, like cement remaining in the
pipe, can be
drilled when the cementing is completed and the borehole is drilled to a new
depth.
There are problems associated with running a cementing apparatus into a well
5- with a string of pipe. One such problem is surge pressure created as the
pipe and
cementing apparatus are lowered into the borehole filled with drilling mud or
other well
fluid. Because the end of the pipe is at least partially flow restricted, sane
of the well
fluid is necessarily directed into the annular area between the borehole and
the pipe.
Rapid lowering of the pipe results in a corresponding increase or surge in
pressure, at or
below the pipe, generated by restricted fluid flow in the annulus. Surge
pressure has
many detrimental effects. For example, it can cause drilling fluid to be lost
into the
earth formation and it can weaken the exposed formation when the surge
pressure in the
borehole exceeds the formation pore pressure of the well. Additionally, surge
pressure
can cause a loss of cement to the formation during the cementing of the pipe
due to
formations that have become fractured by the surge pressure.
One response to the surge pressure problem is to decrease the running speed of
the pipe downhole in order to maintain the surge pressure at an acceptable
level. An
acceptable level would be a level at least where the drilling fluid pressure,
including the
surge pressure is less than the formation pore pressure to minimise the above
detrimental effects. However, any reduction of surge pressure is beneficial
because the
more surge pressure is reduced, the faster the pipe can be run into the
borehole and the
more profitable a drilling operation becomes.
The problem of surge pressure has been further addressed by the design of
cementing apparatus that increases the flow path for drilling fluids through
the pipe
during run-in. In one such design, the check valve at the downhole end of the
cementing apparatus is partially opened to flow during run-in to allow well
fluid to
enter the pipe and pressure to thereby be reduced. Various other paths are
also provided
higher in the apparatus to allow the well fluid to migrate upwards in the pipe
during
run-in. For example, baffle collars used at the top of cementing tools have
been
designed to permit the through flow of fluid during run-in by utilising valves
that are
held in a partially open position during run-in and then remotely closed later
to prevent
CA 02526837 2001-03-12
3
back flow of cement. While these designs have been somewhat successful, the
flow of
well fluid is still impeded by restricted passages. Subsequent closing of the
valves in
the cementing tool and the baffle collar is also problematic because of
mechanical
failures and contamination.
Another problem encountered by prior art cementing apparatus relates to
sediment, sand, drill cuttings and other particulates collected at the bottom
of a newly
drilled borehole and suspended within the drilling mud that fills the borehole
prior to
running-in a new pipe. Sediment at the borehole bottom becomes packed and
prevents
the pipe and cementing apparatus from being seated at the very bottom of the
borehole
after run-in. This misplacement of the cementing apparatus results in
difficulties having
the pipe in the well or at the wellhead. Also, the sediment below the
cementing
apparatus tends to be transported into the annulus with the cement where it
has a
detrimental effect on the quality of the cementing job. In those prior art
designs that
allow the drilling fluid to enter the pipe to reduce surge pressure, the fluid
borne
sediment can foul mechanical parts in the borehole and can subsequently
contaminate
the cement.
There is a need therefore for a cementing apparatus that reduces surge
pressure
as it is run-into the well with a string of pipe. There is a further need, for
a cementing
apparatus that more effectively utilises the flow path of cement to transport
well fluid
and reduced pressure surge during run-in. There is a further need for a
cementing
apparatus that filters sediments and particles from well fluid during run-in.
According to a first aspect the present invention provides a tool for use in a
tubular string comprising:
a tubular inner member constructed and arranged to allow fluid to be filtered
therethrough to pass therein as the tool is run into a borehole; and
a flow restrictor proximate the downhole end of the inner member to at least
partially prevent fluid from enteri-ng the end of the inner member while
allowing fluid to
exit the end of the inner member.
CA 02526837 2001-03-12
3a
The present invention also provides a tool for use in a tubular string
comprising a tubular inner member constructed and arranged to allow fluid to
be
filtered therethrough to pass therein as the tool is run into a borehole, a
flow restrictor
proximate the downhole end of the inner member to at least partially prevent
fluid
from entering the downhole end of the inner member while allowing fluid to
exit the
downhole end of the inner member, a tubular outer body substantially open at a
downhole end to the inward flow of fluid, and an annular area defined between
the
outside of the inner member and the inside of the outer body.
The tool can further provide a flow path for fluid from the tool to a pipe
thereabove. The inner member can include a plurality of perforations formed
therein,
providing a fluid flow path therethrough. . The tool can further include at
least one
layer of filtering medium disposed around the perforations of the inner
member. The
filtering medium can be disposed within the inner member, and can be composed
of a
non-woven material.
The tool can further include a layer of braided material disposed around the
perforations of the inner member. The perforations in the inner member may be
selectively opened or closed to the flow of fluid therethrough. When the
perforations
in the inner member are closed, a sealed chamber can be formed within the
interior of
the inner member. When the tool is run-into the borehole with the perforations
closed,
a pressure differential can be created between the pressure in the borehole
and the
pressure in the inner member. When the perforations are opened in the
borehole, the
pressure differential urges material from the wellbore into the tool.
The inner member can further include an inner sleeve disposed therein, the
inner sleeve having perforations therethrough. The perforations through the
inner
sleeve may be aligned with the perforations through the inner member allowing
fluid
to flow therethrough and the perforations through the inner sleeve may be
misaligned
with the perforations through the inner member thereby preventing fluid from
flowing
therethrough. The perforations through the inner sleeve can be aligned and
misaligned
with the perforations through the inner member by moving the sleeve axially
within in
the inner member. Alternatively, the perforations through the inner sleeve can
be
aligned and misaligned with the perforations in the inner member by moving the
sleeve
rotationally within the inner member.
The perforations through the inner member can be remotely opened or closed.
The perforations can be remotely opened through the use of coiled tubing,
through the
use of wire line, or through the use of a projectile dropped from above.
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3b
The tool can further include a baffle collar disposed proximate an upper end
of
the tool, the baffle collar permitting the upward flow of fluid therethrough.
The
upward flow path of fluid through the baffle collar can be sealed remotely.
The baffle
collar can have:
at least one sealable by-pass channel permitting the upward flow of fluid as
the tool is
run into the borehole; and
a restrictor permitting one-way fluid passage therethrough for the downward
flow of
fluid.
The baffle collar can include a flapper valve that is temporarily opened as
the
tool is run into the borehole, allowing fluid to pass upward therethrough. The
flapper
valve can be remotely closeable, thereby preventing the upward flow of fluid
therethrough while allowing the downward flow of fluid therethrough. The tool
can
further include a plug assembly located in pipe above the tool, the plug
assembly
having an intermediate member disposed therein, the intermediate member having
a
central aperture therethrough and at least one sealable, by-pass aperture
formed
therearound to increase the flow volume of fluid through the intermediate
member.
The plug assembly can further include a dart constructed and arranged to land
in the
plug, thereby sealing the central and the at least one by-pass aperture.
The annular area between the inner member and the outer body can be divided
into an upper and lower chambers by an axially movable, donut-shaped member
sealing the annular area and creating an atmospheric chamber in the upper
chamber.
The donut-shaped member can be fixed within the annular area at a first
location and
retained by a releasable, locking member adjacent the donut-shaped member.
When
the releasable locking member releases the donut-shaped member, a pressure
differential between the upper and lower chambers can cause the donut-shaped
member to move axially into the upper chamber, thereby creating a suction in
the
lower chamber.
In another embodiment, the annular area between the inner member and the
outer body can be divided into an upper and lower chambers, the chambers
divided by
an axially locatable donut-shaped member sealing the annular area between the
upper
and lower chambers. That portion of the inner member extending through the
upper
chamber can include a shoulder formed therein and at least one aperture
therearound,
the shoulder arranged to hold an atmospheric chamber tool. An atmospheric
chamber
contained in the atmospheric chamber tool can create a pressure differential
between
the upper and lower chambers, thereby causing the donut-shaped member to move
CA 02526837 2001-03-12
3c
axially in an upward direction and reducing the volume of the upper chamber
and
creating a suction in the lower chamber.
The outer body can be a wellbore casing, and the tool can be constructed of
drillable material.
The tool can further include at least one collection member disposed within
the
annulus, the collection member constructed and arranged to allow fluid and
particles to
pass in the direction of the well surface while preventing the particles from
returning to
the borehole. In addition, the tool can further include at least one centring
member
disposed in the annular area. Also, the tool can further include a swabbing
member
disposable within a pipe thereabove, the swabbing member, when urged upwards,
creating a suction in the tool therebelow. The swabbing member can be disposed
in a
non-perforated portion of the inner member.
The invention also provides a perforated tubular outer body having a closed
downhole end, the perforations allowing:
well fluid from the borehole to be filtered therethrough; and
a tubular inner member disposed within the outer body, the inner member
isolated
from an annulus between the inner member and the outer body and having a
entryway
for fluid at an upper end and an exit way for fluid at a lower end.
The invention also provides a baffle collar for use with a cementing tool, the
baffle collar comprising:
an upper end constructed to receive a sealing member;
a lower end including a flow restrictor arranged to allow the downward flow of
fluid
though the collar; and
at least one selectively sealable, by-pass channel permitting upward flow of
fluid
through the collar and into a pipe thereabove.
The invention also provides a plug assembly for use in a well, the assembly
comprising:
a plug having an aperture therethrough, the plug connectable to pipe at an
upper and a
lower end;
a reduced diameter portion within the aperture constructed and arranged to
provide a
sealing surface whereby the aperture can be sealed with a first portion of a
dart; and
at least one bypass channel formed around the perimeter of the reduced
diameter
portion, the bypass channel constructed and arranged to permit the flow of
fluid
therethrough and to be sealed by a second portion of a dart.
CA 02526837 2001-03-12
3d
The at least one by-pass channel can be sealed by contract between an
enlarged diameter portion of a displaceable, inner member and an inside wall
of the
plug.
The invention also provides a tool for use in a tubular string, comprising:
an outer body perforated along its length for filtering fluid and having and
providing a
one way flow path to a pipe thereabove; and
an inner member disposed within the centre body, the inner member having a
flow
path for fluid into the upper end thereof and a one way flow path for fluid
from the
lower end thereof.
The invention also provides a tool for use in a tubular string, comprising:
a perforated inner member having a one-way flow path for fluid at a lower end
thereof and a closed upper end, the inner member constructed and arranged to
filter
fluid from the inside to the outside thereof, and
an outer body disposed around the inner member, the outer body providing a
flow
path for filtered fluid to a pipe thereabove and providing a one way flow path
therethrough for fluid.
The invention also provides a tool for use in a tubular string, comprising:
an outer body substantially open to the flow of fluid at a lower end and
having a
plurality of longitudinal channels formed in the upper end thereof providing
fluid
communication between the outer body and a pipe thereabove.
The tool can further include filter material disposed within the outer body.
The tool can also further include a baffle collar at an upper end thereof, the
baffle
collar having a central aperture therethrough and a plurality of sealable by
pass
apertures and providing a flow path through the wall of the outer member.
The invention also provides a filtering apparatus for facilitating the
filtering of
fluid in a borehole comprising:
a body, connectable in a tubular string;
a filter member;
a particulate retention portion for retaining filtered particles; and
a fluid flow channel directed through the retention portion and the filter
member.
The invention also provides a method of filtering the fluid in a borehole by
running a tubular string therein comprising the steps of:
attaching a filtering apparatus in the tubular string, the filtering apparatus
comprising
a filter member, a particulate retention portion and a fluid flow channel
directed
through the retention portion and the filter member; and
CA 02526837 2001-03-12
3e
running the tubular string into the borehole, thereby causing the borehole
fluid to be
filtered through the filtering apparatus.
The invention also provides a method of separating a first density material in
a
bore hole from a second density material in the bore hole by running a tubular
string
therein comprising the steps of:
attaching a separation apparatus in the tubular string, the separation
apparatus
comprising a separation chamber, a second density material retention chamber
and a
flow channel directed through the separation chamber and in communication with
the
second density material retention chamber; and
running the tubular string in to the bore hole, thereby causing the material
in the bore
hole to flow through the separation chamber.
The invention also provides a method of removing sediment from within a
borehole comprising the steps of
(a) inserting a tubular into the well to location proximate the sediment to be
removed; and
(b) creating a suction at a downhole end of the tubular through a pressure
differential
between a first chamber and a second chamber formed within the tubular,
thereby
urging sediment into the tool.
The first and second chambers can be separated by an axially movable member
sealing the inner diameter of the tubular.
The invention also provides a tool for use in a tubular string comprising:
an outer body;
an intermediate body disposed within the outer body;
a flow path for fluid into an outer annulus between the outer and intermediate
bodies;
a tube channelling the flow of fluid from the outer annulus to an inner
annulus
between the intermediate body an the inner body;
a fluid passage in the wall of the inner body to allow fluid to pass from a
filtering
portion formed along the inner body to filter fluid passing from the inner
annulus into
the inner body;
a sealable flow path from the top of the inner body to a pipe thereabove; and
a one way flow path from the inner body to the annulus therebelow.
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4
At least in its preferred embodiments the invention provides a downhole
apparatus run into a borehole on pipe. The apparatus is constructed on or in a
string of
pipe in such a way that pressure surge during run-in is reduced by allowing
well fluid
travel into a through the tool. In one aspect of the invention, an inner
member is
provided that filters or separates sediment from well fluid as it enters the
fluid pathway.
In another aspect of the invention, various methods are provided within the
apparatus to
loosen, displace or suction sediment in the borehole.
In another aspect, the invention provides a cementing tool for use in a
tubular
string comprising a tubular inner member constructed and arranged to filter
and pass
fluid through the member as the tool is run into a bore hole, a flow
restrictor at the
downhole end of the inner member to at least partially prevent fluid from
entering the
end of the inner member while allowing fluid to exit the end of the inner
member, a
tubular outer body substantially open at a downhole end to the inward flow of
fluid, and a
baffle collar disposed proximate an upper end of the tool, the baffle collar
permitting the
upward flow of fluid therethrough.
In another aspect, the invention provides a cementing tool for use in a
tubular
string comprising a tubular inner member constructed and arranged to filter
and pass
fluid through the member as the tool is run into a bore hole, a flow
restrictor at the
downhole end of the inner member to at least partially prevent fluid from
entering the
end of the inner member while allowing fluid to exit the end of the inner
member, a
tubular outer body substantially open at a downhole end to the inward flow of
fluid, and a
baffle collar proximate an upper end thereof, the baffle collar having at
least one sealable
bypass channel permitting the upward flow of fluid as the tool is run into the
bore hole,
and a restrictor permitting one-way fluid passage therethrough for the
downward flow of
fluid.
CA 02526837 2006-07-14
4a
In another aspect, the invention provides a cementing tool for use in a
tubular
string comprising a tubular inner member constructed and arranged to filter
and pass
fluid through the member as the tool is run into a bore hole, a flow
restrictor at the
downhole end of the inner member to at least partially prevent fluid from
entering the
end of the inner member while allowing fluid to exit the end of the inner
member, and at
least one collection member disposed within the annulus, the collection member
constructed and arranged to allow fluid and particles to pass in the direction
of the well
surface while preventing the particles from returning to the bore hole.
In another aspect, the invention provides a cementing apparatus for
facilitating the
filtering of fluid in a bore hole comprising a body, connectable in a tubular
string, a filter
member, a particulate retention chamber for retaining filtered particles, a
fluid flow
channel directed through the retention chamber and the filter member, and a
cement flow
channel that substantially bypasses the filter member.
In another aspect, the invention provides an apparatus for use in a bore hole
comprising a body, connectable in a tubular string, a filter member, a
particulate retention
chamber for retaining filtered particles, a fluid flow channel directed
through the
retention chamber and the filter member, and a cement flow channel that
substantially
bypasses the filter member.
In another aspect, the invention provides a cementing tool for use in a
tubular
string comprising a tubular inner member constructed and arranged to filter
and pass
fluid through the member as the tool is run into a bore hole, wherein the
inner member
includes a plurality of perforations formed therein and providing a fluid flow
path
therethrough, wherein the plurality of perforations may be selectively opened
or closed to
the flow of fluid therethrough, an inner sleeve disposed therein, the inner
sleeve having
perforations therethrough that may be aligned with the perforations through
the inner
member allowing fluid to flow therethrough and the perforations through the
inner sleeve
may be misaligned with the perforations through the inner member thereby
preventing
fluid from flowing therethrough, wherein the perforations through the inner
sleeve are
CA 02526837 2006-07-14
4b
aligned and misaligned with the perforations through the inner member by
moving the
sleeve axially within the inner member, and a flow restrictor at a downhole
end of the
inner member to at least partially prevent fluid from entering the end of the
inner member
while allowing fluid to exit the end of the inner member.
In another aspect, the invention provides a cementing tool for use in a
tubular
string comprising a tubular inner member constructed and arranged to filter
and pass
fluid through the member as the tool is run into a bore hole, the tubular
inner member
having a plurality of perforations formed therein and providing a fluid flow
path
therethrough, wherein the plurality of perforations may be remotely,
selectively opened
or closed to the flow of fluid therethrough through the use of coiled tubing,
and a flow
restrictor at a downhole end of the inner member to at least partially prevent
fluid from
entering the end of the inner member while allowing fluid to exit the end of
the inner
member.
In another aspect, the invention provides a cementing tool for use in a
tubular
string comprising a tubular inner member constructed and arranged to filter
and pass
fluid through the member as the tool is run into a bore hole, the tubular
inner member
having a plurality of perforations formed therein and providing a fluid flow
path
therethrough, wherein the plurality of perforations may be remotely,
selectively opened
or closed to the flow of fluid therethrough through the use of wire line, and
a flow
restrictor at a downhole end of the inner member to at least partially prevent
fluid from
entering the end of the inner member while allowing fluid to exit the end of
the inner
member.
In another aspect, the invention provides a cementing tool for use in a
tubular
string comprising a tubular inner member constructed and arranged to filter
and pass
fluid through the member as the tool is run into a bore hole, the tubular
inner member
having a plurality of perforations formed therein and providing a fluid flow
path
therethrough, wherein the plurality of perforations may be remotely,
selectively opened
or closed to the flow of fluid therethrough through the use of a projectile
dropped from
CA 02526837 2007-03-22
4c
above, and a flow restrictor at a downhole end of the inner member to at least
partially
prevent fluid from entering the end of the inner member while allowing fluid
to exit the
end of the inner member.
The present invention also provides a tool for use in a tubular string
comprising:
a tubular inner member constructed and arranged to filter and pass fluid
through the
member as the tool is run into a borehole;
a flow restrictor at the downhole end of the inner member to at least
partially prevent
fluid from entering the end of the inner member while allowing fluid to exit
the end of the
inner member; and
a plug assembly located in a pipe above the tubular inner member, the plug
assembly
comprising:
an intermediate member disposed therein, the intermediate member having a
central aperture therethrough and at least one sealable, by-pass aperture
formed
therearound to increase the flow volume of fluid through the intermediate
member; and
a sealing member that is constructed and arranged to land in the plug
assembly,
thereby sealing the central aperture and the at least one by-pass aperture.
The present invention also provides a tool for use in a tubular string
comprising:
a tubular inner member constructed and arranged to filter and pass fluid
through the
member as the tool is run into a borehole;
a flow restrictor at the downhole end of the inner member to at least
partially prevent
fluid from entering the end of the inner member while allowing fluid to exit
the end of the
inner member; and
a baffle collar for use with a cementing tool, the baffle collar comprising:
an upper end constructed to receive a sealing member;
a lower end including a flow restrictor arranged to allow the downward flow of
fluid through the collar; and
at least one selectively sealable, by-pass channel permitting upward flow of
fluid
through the collar and into a pipe thereabove.
The present invention also provides a tool for use in a tubular string
comprising:
a tubular inner member constructed and arranged to filter and pass fluid
through the
member as the tool is run into a borehole;
CA 02526837 2007-03-22
4d
a flow restrictor at the downhole end of the inner member to at least
partially prevent
fluid from entering the end of the inner member while allowing fluid to exit
the end of the
inner member; and
a plug assembly comprising:
a plug having an aperture therethrough, the plug connectable to pipe at an
upper
and a lower end;
a reduced diameter portion within the aperture constructed and arranged to
provide a sealing surface whereby the aperture can be sealed with a first
portion of
a sealing member; and
at least one by-pass channel formed around the perimeter of the reduced
diameter portion, the by-pass channel constructed and arranged to permit the
flow
of fluid therethrough.
The present invention also provides a tool for use in a tubular string
comprising:
a tubular inner member constructed and arranged to filter and pass fluid
through the
member as the tool is run into a borehole;
a flow restrictor at the downhole end of the inner member to at least
partially prevent
fluid from entering the end of the inner member while allowing fluid to exit
the end of the
inner member; and
a plug assembly located in a pipe above the tubular inner member, the plug
assembly
comprising:
a plug having an aperture therethrough, the plug connectable to pipe at an
upper
and a lower end; and
an intermediate member disposed in the plug, the intermediate member having a
central aperture therethrough and at least one by-pass aperture formed
therearound
to increase the flow volume of fluid through the intermediate member;
wherein the intermediate member is configured to receive a sealing member and
is displaceable relative to the plug so that the central aperture is sealed by
the
sealing member and the at least one by-pass aperture is sealed by displacement
of
the intermediate member into contact with an inner surface of the plug.
The present invention also provides a method for using a tool in a wellbore
comprising:
providing a tool, comprising:
CA 02526837 2007-03-22
4e
a tubular inner member constructed and arranged to filter and pass fluid
through
the member as the tool is run into a borehole;
a flow restrictor at the down hole end of the inner member to at least
partially
prevent fluid from entering the end of the inner member while allowing fluid
to
exit the end of the inner member; and
a plug assembly located in a pipe above the tubular inner member, the plug
assembly comprising an intermediate member disposed therein, the intermediate
member having a central aperture therethrough and at least one sealable, by-
pass
aperture formed therearound to increase the flow volume of fluid through the
intermediate member; and cementing a string of tubulars in the wellbore using
the
tool.
Some preferred embodiments of the invention will now be described by way of
example only and with reference to the accompanying drawings, in which:
Figures IA and B are section views of the tool of the present invention as it
would appear in a borehole of a well;
Figure 2 is a section view showing a first embodiment of a baffle collar for
use.
with the tool;
Figure 2A is an end view of the baffle collar of Figure 2, taken along lines
2A-
2A;
Figure 3 is a section view showing a second embodiment of a baffle collar;
Figure 4 is an end view.of a centralise located within the tool, taken along
lines
4-4;
Figure 5 is a section view showing a third einbodiment of a baffle collar for
use
with the tool;
Figure 6A is a section view of a plug at the end of a run-in string
illustrating the
flow of fluid through the plug during run-in;
Figure 6B is an end view of the plug of Figure 6A;
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Figure 6C is a section view of the plug of Figure 6A showing the flow paths of
the plug sealed by a dart;
5 Figure 6D is a section view of a plug at the end of a run-in string
illustrating the
flow of fluid through the plug during run-in;
Figure 6E is an end view of the by-pass apertures illustrated in Figure 6D;
Figure 6F is a section view of the plug of Figure 6D showing the flow paths of
the plug sealed by a dart;
Figure 7 is a section view showing a plug and dart assembly landed within a
baffle collar.and sealing channels formed therein;
Figure 8 is an end view showing the nose portion of the tool, taken along
lines 8-
8;
Figures 9A and B are enlarged views of the lower portion of the tool;
Figures IOA and B depict an adjustment feature of the inner member of the
tool;
Figure 10C is an enlarged view of the inner member of the tool showing the
relationship between an inner member and an inner sleeve disposed therein;
Figures 11 A and B are section views showing the tool with an additional
sediment trapping member disposed therein;
Figures 12A and B are section views showing the tool with an atmospheric
chamber for evacuating sediment from the borehole;
Figures 13A, B and C are section views showing the tool of the present
invention with a remotely locatable, atmospheric chamber placed therein;
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6
Figures 14A and B are section views showing an alternative embodiment of the
tool;
Figures 1SA and B are section views showing an alternative embodiment of the
tool;
Figures 16A and B are section views showing an altemative embodiment of the
tool;
Figure 17 is a section view showing an alternative embodiment of the tool;
Figure 18 is a section view showing an alternative embodiment of the tool;
Figures 19A, B and C are section views showing an alternative embodiment of
the invention; and
Figures 20A, B and C are section views showing an alternative embodiment of
the invention.
Figures lA and B are section views showing the surge reduction and cementing
tool 100 of the present invention. Figures 9A, B are enlarged views of the
lower portion
of the tool. In the Figures, the tool is depicted as it would appear after
being inserted
into a borehole 115. The tool 100 generally includes an outer body 110, a
inner
member 135 disposed within the outer body 110, a nose portion 120 and a baffle
collar
125. Outer body 110 is preferably formed by the lower end of the pipe to be
cemented
in the borehole and the cementing tool 100 will typically be constructed and
housed
within the end of the pipe prior to being run-into the well. The terms
"tubing,"
"tubular," "casing," "pipe" and "string" all relate to pipe used in a well or
an operation
within a well and are all used interchangeably herein. The term "pipe
assembly" refers
to a string of pipe, a hanger and a cementing tool all of which are run-into a
borehole
together on a run-in string of pipe. While the tool is shown in the Figures at
the end of a
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7
tubular string, it will be understood that the tool described and claimed
herein could also
be inserted at any point in a string of tubulars.
Nose portion 120 is installed at the lower end of outer body 110 as depicted
in
Figure 1B to facilitate insertion of the tool 100 into the borehole 115 and to
add strength
and support to the lower end of the apparatus 100. Figure 8 is an end view of
the
downhole end of the tool 100 showing the nose portion 120 with a plurality of
radially
spaced apertures 122 formed therearound and a centre aperture 124 formed
therein.
Apertures 122 allow the inflow of fluid into the tool 100 during run-in and
centre
aperture 124 allows cement to flow out into the borehole.
Centrally disposed within the outer body 110 is inner member 135 providing a
filtered path for well fluid during run-in and a path for cement into the
borehole during
the subsequent cementing job. At a lower end, inner member 135 is supported by
nose
portion 120. Specifically, support structure 121 formed within nose portion
120
surrounds and supports the lower end of inner member 135. Disposed between the
lower end of inner member 135 and nose portion 120 is check valve 140. The
purpose
of valve 140 is to restrict the flow of well fluid into the lower end of inner
member 135
while allowing the outward flow of cement from the end of inner member as will
be
decried herein. As shown in Figure 1B, check valve 140 is preferably a spring-
loaded
type valve having a ball to effectively seal the end of a tubular and
withstand pressure
generated during run-in. However, any device capable of restricting fluid flow
in a
single direction can be utilized and all are within the scope of the invention
as claimed.
Along the length of inner portion 135 are a number of centralizers 145
providing
additional support for inner member 135 and ensuring the inner member retains
its
position in the center of outer body 110. Figure 4 is an end view of a
centralizer 145
depicting its design and showing specifically its construction of radial
spokes 146
extending from the inner member 135 to the inside wall of outer body 110,
whereby
fluid can freely pass though the annular area 155 fornned between inner member
135
and outer body 110. Also visible in Figures lA , IB and 4 are funnel-shaped
traps 147
designed to catch and retain sediment and particles that flow into the annular
area 155,
preventing them from falling back towards the bottom of the well. In the
preferred
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8
embodiment, the sediment traps are nested at an upper end of each centralizer
145.
Depending upon the length of the inner member 135, any number of centralizers
145
and sediment traps can be utilized in a tool 100.
Inner member 135 includes a inner portion formed therealong consisting of, in
the preferred embodiment, perforations 160 extending therethrough to create a
fluid
path to the interior of the inner member 135. The perforations, while allowing
the
passage of fluid to reduce pressure surge, are also designed to prevent the
passage of
sediment or particles, thereby ensuring that the fluid traveling up the tool
and into the
pipe string above will be free of contaminants. The terms "filtering" and
"separating"
will be used interchangeably herein and both related to the removal,
separation or
isolation of any type of particle or other contarninate from the fluid passing
through the
tool. The size, shape and number of the perforations 160 are variable
depending upon
run-in speed and pressure surge generated during lowering of the pipe. Various
material
can be used to increase or define the inner properties of the inner member.
For
example, the inner member can be wrapped in or have installed in a membrane
material
made of corrosive resistant, polymer material and strengthened with a layer of
braided
metal wrapped therearound. Additionally, membrane material can be used to line
the
inside of the inner member.
The upper end of inner member 135 is secured within outer body I10 by a
drillable cement ring 165 formed therearound. Inner member 135 terminates in a
perforated cap 168 which can provide additional filteringoffluids and, in an.
alternative
embodiment, can also serve to catch a ball or other projectile used to actuate
some
device higher in the borehole. Between the upper end of inner member 135 and
baffle
collar 125 is a space 180 that provides an accumulation point for cement being
pumped
into the tool 100.
At the upper end of tool 100 is a funnel-shaped baffle collar 125. In the
preferred embodiment, the baffle collar provides a seat for a plug or other
device which
travels down the pipe behind a column of cement that is urged out the bottom
of tool
100 and into the annulus 130 formed therearound. In the embodiment shown in
Figure
IA, the baffle collar is held within outer body 110 by cement or other
drillable material.
CA 02526837 2001-03-12
9
A mid-portion of baffle collar 125 includes by-pass holes 172 and by-pass
channels 175
extending therefrom to provide fluid communication between the baffle collar
125 and
space 180 therebelow. At a lower portion of the baflle collar 125 is a check
valve 178
to prevcnt the inward flow of fluid into the bafQe coIIar 125 whule allowing
cement to
flow outward into the space 180 therebelow. During run i.u, well fluid tzavels
through
channels 175. Fignre 2 is an enlarged section view showing the various
components of
the baffle collar. Figure 2A is a section view showing the by-pass channels
175 and the
plaeement of the check valve 178.
Figure 7 illustrates a plug and dart assembly 190, having Ianded in baffle
collar
125 sad sealed the fluid path of well fluid into the baffle collar'through by-
pass holes
172 and by-pass channels 175. In the preferred embodiment, after cement has
been
injected into the borehole and a dart has travelled down the run-in string and
landed in
the plug, the plug and dart assembly 190 are launched from the running string
and urged
downward in the pipe behind the column of cement that will be used to cement
the pipe
in the borehole 115. The plug and dart assembly 190 are designed to seat in
the bat'f1e
collar 125 where they also function to prevent subsequent back flow of cement
into the
baffle collar 125 and the pipe (not shown) thereabove.
Figure 3 is a section view showing an alternative embodiment of a baffle
eollar
300. In this ecnbodiment, the upper portion of the baffle collar 300 fozms a
male
portioA 301 with apertures 302 in fluid communication with by-pass channels
303.
Male portion 301 is received by a plug and dart having a mating female portion
formed
therein. In this manner, the apertures 302 in the male portion of the baffle
collar are
= covered and seated by the female portion of the plug and dart assembly (not
shown).
Figure 5 illustrates a third embodiment of a baffle coIlar 400 for use in the
tool
of the present invention. In this embodiment, a flapper valve 405 is propped
open
during ran in tv allow well fluid to pass through the baffle collar 400 to
relieve surge
pressure. Once the pipe has been.run in into the well, the flapper valve 405
is reanotely
closed by dropping a ball 410 into a seat 415 which allows the spring-loaded
flapper
valve 405 to elose. Thexeafter, the baffle collar 400 is sealed to the upper
flow of fluid
while the flapper valve 405 can be freely opened to allow the downward flow of
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cement. In this embodiment, the plug and dart assembly (not shown) includes
wavy
formations which mate with the wavy 420 formations formed in the baffle collar
400.
This embodiment is particularly useful anytime an object must be lowered or
dropped
into the cementing apparatus. Because it provides a clear path for a ball or
other
5- projectile into the cementing tool, baffle collar 400' is particularly
useful with a remotely
locatable portable atmospheric chamber described hereafter and illustrated in
Figures
13A-C.
Figures 6A-C illustrate a plug 194 and dart 200 at the end of a run-in string
185.
10 The run-in string transports the pipe into the borehole, provides a fluid
path from the
well surface and extends at least some distance into the pipe to be cemented.
The run-in
string provides a flow path therethrough for well fluid during run-in and for
cement as it
passes from the well surface to the cementing tool at the end of the pipe. An
intermediate member 192, disposed within the plug 194 and having a centre
aperture
197 therethrough, provides a seal for the nose of dart 200 (Figure 6C) that
lands in the
plug 194 and seals the flow path therethrough. In order to increase the flow
area
through intermediate member 192 yet retain the dimensional tolerances
necessary for an
effective seal between the plug 194 and the dart 200, a number of by-pass
apertures 193
are formed around the perimeter of the intermediate member 192. Figure 6B is a
section view of the nose portion 190 of the plug 194 clearly showing the
centre aperture
197 and by-pass apertures 193 of intermediate member 192. In the preferred
embodiment, the by-pass apertures 193 are elliptical in shape.
Figure 6C is a section view showing the plug 194 with dart 200 seated therein.
Centre aperture 197 of the intermediate member 192 is sealed by the dart nose
198 and
the by-pass apertures 193 are sealed by dart fin 201 once the intermediate
member 192
is urged downward in interior of the plug 194 by the dart 200.
Figures 6D-F illustrate an altemative embodiment in which the by-pass
apertures 220 of an intermediate member 222 are sealed when the intermediate
member
222 is urged downward in the interior of the plug 225 by the dart 200, thereby
creating a
metal to metal seal between the plug surface 227 and outer diameter portion
226 of
intermediate member 222.
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11
Generally, the tool of the present invention is used in the same manner as
those
of the prior art. After the well has been drilled to a new dcpth, the drill
string and bit are
removed from the well leaving the borehole at least partially f.~lled with
drilling fluid.
Thereafter, pipe is lowered into the borehole having the cementing tool of the
present
invention at a downhole end and a run in tool at an upper end. The entire
assembly is
run into the well at the end of a run-in string, a string of tubulars
typically having a
smaller diameter than the pipe and capable of providing an upward flow path
for well
fluid during run-in and a downward flow path for cement durittg the cementing
operation,
During run-in, the assembly rn;nirnises surge by passing well fluid through
the
radially spaced apertures 122 of nose portion and into the outer body 110
where it is
filtered as it passes into the inner member 135. While some of the fluid will
travel up
the annulus 130 formed between the outer body 110 and the borehole 115, the
tool 100
is designed to permit a greater volume of fluid to enter the intetior of the
tubular being
run into the well. Arrows 182 in Figure IB illustrate the path of fluid as it
travels
between outer body 110 and inner member 135. As the run-in operation continues
and
the pipe continues downwards in the borehole, the fluid level rises within
inner member
135 reaching and filling space 180 between the upper end of the inner member
135 and
the baffle collar 125. Prevented by check valve 178 from flowing into the
bottom
portion of the baffle collar 125, the fluid enters the baffle collar 125
through by-pass
channels 175 and by-pass holes 172. Thereafter, the fluid can continue towards
the
surface of the well using the interior of the pipe and/or the inside diameter
of the run-in
string as a flow path.
With the nose portion 120 of the tool at the bottom of the well and the upper
end
located either at the surface well head or near the end of the previously
cemented pipe,
the pipe may be hung in place, either at the well head or near the bott,vm of
the
preceding string through the remote actuation of a hanger, usually using a
slip and cone
mechanism to wedge the pipe in place. Cementing of the pipe in the borehole
can then
be accomplished by kmown methods, concluding with the seating of a plug
assembly on
or in a baffle collar.
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12
Figures IOA-C illustrate an attemative embodiment of the tool 500 wherein the
perforations formed in an inner member 535 may be opened or closed depending
upon
well conditions or goals of the operator. In this embodiment, an inner sleeve
501 is
located within the inner member 535. The inner sleeve 501 has perforations 502
formed
therein and can be manipulated to cause alignment or misalignment with the
mating
perforations 503 in the inner member 535. For example, Figure l0A illustrates
the
inner member 535 having an inner sleeve 501 which has been manipulated to
block the
perforations 503 of the inner member 535. Specifically, the perforations of
the inner
member and the inner sleeve 502, 503 visible in Figure IOA at point "A" are
misaligned, vertically blocking the flow of fluid therethrough. In contrast,
Figure lOB
at point "B" illustrates the perforations 502, 503 vertically aligned whereby
fluid can
flow therethrough. The relationship between the inner sleeve 501 and inner
member
135 is more closely illustrated in Figure IOC, showing the perforations 502,
503 of the
inner sleeve 501 and inner member 535 aligned.
Manipulation of the inner sleeve 501 within the inner member 535 to align or
misalign perforations 502, 503 can be performed any number of ways. For
example, a
ball or other projectile can be dropped into the tool 100 moving the inner
sleeve 501 to
cause its perforations 503 to align or misalign with the perforations 502 in
inner
member 535. Alternatively, the manipulation can be perfonned with wireline.
While
the inner sleeve can be moved vertically in the embodiment depicted, it will
be
understood that the perforations 502, 503 could be aligned or misaligned
through
rotational as well as axial movement. For example, remote rotation of the
sleeve could
be performed with a projectile and a cam mechanism to impart rotational
movement.
In operation, the perforations 502, 503 would be opened during run-in to allow
increased surge reduction and inner of well fluid as described herein. Once
the tool has
been run into the well, the perforations 502, 503 could be remotely misaligned
or
closed, thereby causing the cement to exit the tool directly through the
centre aperture
124 in the nose portion 120 of the tool, rather than through the perforations
and into the
annulus 130 between the inner member 135 and the outer body 110.
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13
Figures l IA and B show an alternative embodiment of a cementing tool 550
including a sediment trap 555 formed between an inner member 560 and an outer
body
110. As depicted in Figure I l B, the sediment trap 555 is a cone-shaped
structure
having a tapered lower end extending from an upper end of nose portion 120 and
continuing upwards and outwards in a conical shape towards outer body 110. An
annular area 565 is thereby formed between the outer wall of sediment trap 555
and the
inside wall of outer body 110 for the flow of well fluid during run-in. The
direction of
flow is illustrated by arrows 570 in Figure I 1B. As the too1550 is run into a
well, well
fluid and any sediment is routed through annulus 565 and into the upper
annulus 557
formed between inner member 560 and outer body 110. As the well fluid is
filtered into
inner member 560, particles 580 and sediment removed by inner member 560 fall
back
towards the bottom of the well into the sediment trap 555 where they are
retained as
illustrated in Figure 1 IB. Because that portion of inner member 565 extending
through
sediment trap 555 includes no inner perforations, contents of the sediment
trap 555
remain separated from well fluid as it is filtered into inner member 560.
Figures 12A and B show an alternative embodiment of a tool 600, including an
apparatus for displacing and removing sediment from the bottom of the
borehole,
thereby allowing the tool 600 to be more accurately placed at the bottom of
the borehole
prior to cementing. In the tool 600 depicted in Figures 12A and B an annular
area
between the inner member 610 and outer body 110 is separated into an upper
chamber
605 and a lower chamber 615 by a donut-shaped member 620. The upper chamber
605,
because it is isolated from well fluid and sealed at the well surface, forms
an
atmospheric chamber as the tool 600 is run into the borehole. Donut-shaped
member
620 is axially movable within outer body 110 but is fixed in place by a
frangible
member 625, the body of which is mounted in the interior of inner member 610.
Pins
621 between the frangible member 625 and the donut-shaped member 620 hold the
donut-shaped member in place.
After the tool 600 has been run into the borehole, a ball or other projectile
(not
shown) is released from above the tool 600. Upon contact between the
projectile and
the frangible member 625, the frangible member is fractured and the donut-
shaped
member 620 is released. The pressure differential between the upper 605 and
lower 615
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14
chambers of the tool causes the donut-shaped member 620 to move axially
towards the
well surface. This movement of the donut-shaped member 620 creates a suction
in the
lower chamber 615 of the tool which causes loose sediment (not shown) to be
drawn
into the lower chamber 615. In this manner, sediment is displaced from the
borehole
and the tool can be more accurately placed prior to a cementing job.
Figures 13A and B illustrate yet another embodiment of the tool 650, wherein a
remotely locatable, atmospheric chamber 655 is placed in the interior of inner
member
660. As with the embodiment described in Figures 12A and B, the annular area
between inner member 660 and outer body 110 is divided into an upper 665 and
lower
670 chambers with a donut-shaped member 675 dividing the two chambers. That
portion of the inner member 680 extending through upper chamber 665 is not
perforated
but includes only a plurality of ports therearound. In this embodiment,
pressure in the
upper and lower chambers remain equalized during run-in of the tool into the
borehole.
Atmospheric chamber 655 is contained within a tool 677. After run-in,
atmospheric
chamber tool 677 is lowered into the borehole by any known method including a
separate running string or wireline. The atmospheric chamber tool 677 lands on
a
shoulder 682 formed in the interior of the inner member 680 at which point
apertures
684 in the atmospheric chamber tool 677 and apertures 686 in the inner member
680 are
aligned. In order to actuate the atmospheric chamber tool 850 and create a
pressure
differential between the upper 655 and lower 670 chambers, the atmospheric
chamber
tool 677 is urged downward until the apertures 684 and 685 are aligned. Upon
alignment of the various apertures, the upper chamber 665 is exposed to the
atmospheric chamber 655 and a pressure differential is created between the
upper and
lower chambers. The pressure differential causes the donut-shaped member 825
to
move axially towards the top of the tool because the hydrostatic pressure in
the lower
chamber is greater than the in the upper chamber. Therefore, a suction is
created in the
lower chamber 820 which evacuates loose sediment from the borehole and
improves
positioning of the tool in the borehole for the cementing job.
In another embodiment, a swabbing device (not shown) is run-into the pipe
above the tool or may be run-into the inner member 135 of the tool 100 to a
location
above the perforations 160. The swabbing device is then retracted in order to
create a
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suction at the downhole end of the tool and urge sediment into the tool from
the bottom
of the borehole. The swabbing device is well known in the art and typically
has a
perimeter designed to allow fluid by-pass upon insertion into a tubular in one
direction
but expand to create a seal with the inside wall of the tubular when pulled in
the other
5 direction. In the present embodiment, the swabbing device is inserted into
the well at
the surface and run-into the well to a predetermined location after the pipe
assembly has
been run-into the well, but before cementing. The swabbing device is then
pulled
upwards in the borehole creating a suction that is transmitted to the downhole
end of the
tool, thereby evacuating sediment from the borehole.
In yet another embodiment, the tool 100 is run-into the well with the
perforations 502 and 503 misaligned. As the tool is run into the borehole with
the pipe
assembly, a pressure differential develops such that the hydrostatic pressure
in the
borehole is greater than the pressure in the pipe and/or the tool. When the
perforations
of the inner member are remotely opened at the pressure differential between
the inner
member and the fluid in the borehole creates a suction and sediment in the
borehole is
pulled into the tool and out of the well.
Figures 14A and B depict a tool 700, another embodiment of the present
invention. In this embodiment, the outer body 705 is perforated along its
length to
allow the flow of well fluid therethrough during run-in of the tool into a
borehole. The
flow of fluid is indicated by arrows 710. Upon filling the outer body, the
well fluid
passes through two one-way check valves 715 into a baffle collar and
thereafter into
a pipe thereabove (not shown). The check valves 715 prevent fluid from
retuming into
the outer body 705. In this embodiment, the inner member 720 is non-perforated
and is
isolated from the annulus between the inner member and outer body. In
operation, the
inner member 720 carries cement from its upper end to its lower end where the
cement
passes through a lower check valve 725 and into the annular area between the
outer
body and the borehole (not shown).
Figures 15A and B are section views of another embodiment of the present
invention depicting a tool 750. In this embodiment, well fluid travels through
apertures
755 in the nose portion 760 of the tool 750 and into an annular area created
between the
CA 02526837 2001-03-12
16
inner member 765 and the outer body 770. From this annular area, flWd is
filtered as it -
passes into perforated filtering mernbers 775a,b which rernovE sand and
sediment from
the fluid before it passes through check valves 780 to a baffle collar and
into a pipe.
The check valves prevent fluid from returning into the filtering members
775a,b. Like
the cmbodiment of Figure 14, inner member 765 is a non-perforated member and
provides a flow path for cement through a check valve 777 at the downhole end
of the tool and,
into the annulus to be cemented.
Figures.16A and B are section views of tool 8.00, another embodiment of the
present invention. During run-in of the tool into the borehole, well fluid
enters a cmtre
aperture 815 at a downhole end of an inner member 805 passing through a
flapper valve
810 located in the centre aperture 815 which prevents well fluid from
subsequently
exiting the centre aperture. Well fluid is filtered as it passes fronl the
inside of the inner
member 805 to the outer body 825. The fluid continues upwards through channels
830
formed in the upper portion of the tool and into a pipe thereabove.
Subsequently,
cement is urged into the tool through the channels 830 and tmvels within the
outer body
=825 to the.bottom of the tool where it exits through one-way check valves
835.
Fignre 17 is a section view of tool 850,- another embodiment of the present
invention. In this embodiment, well fluid enters nose portion 885 of tool
through centre
aperture 860 and radial apertures 865 and is filtered tbmugh a filter medium
870 such as
packed fibre material, which is housed within an outer body 875. After being
filtered
through the filter medium, the well fluid passes through the upper portion of
the tool,
through channels 880 formed in the upper portion of the tool 850 and then
through a
baffle collar and into a pipe thereabove. Thereafter, the cement is introduced
into the
tool through the channels 880 and urged through the filter material to the
bottom of the
tool where it exits centre 860 and radial apertures 865 into the annular -area
to be
cemented.
Figure 18 is a section view of tool 900, another embodimeat of the present
invention_ Like the embodiment shown in Figure 17, during run-in well fluid
enters
centre 905 and side 910 apertures at the bottom of the tool and is then
filtered through
woven fibre material 920 housed in the outer body 925. The well fluid passes
through a
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17
baffle collar and into pipe thereabove through channels 930 formed at the
upper end of
the tool. In this embodiment, unlike the embodiment described in relation to
Figure 17,
the cement introduced into the annulus of the borehole by-passes the filter
material 920
in the outer body 925. Specifically, ports 935 formed in the tool above the
channels 930
provide an exit path for cement. During run-in, the ports 935 are sealed with
a
moveable sleeve allowing well fluid to pass from the filter material of the
tool into the
pipe thereabove. After the tool is run into the well, a plug is landed in the
sleeve and
urges the sleeve downward, thereby exposing the ports 935 which provide fluid
communication between the inside of the tool and the borehole therearound.
Because
the cement travels through the open ports 935 during the cementing job, there
is no need
to pump the cement through the woven fibre material 920 in the outer body 925.
Figures 19A, B and C are section views of an altemative embodiment of the
present invention depicting a tool 950 for reducing surge during run-in and
having a
vortex separator for filtering sediment from well fluid. The vertex separator
is well
known in the art and operates by separating material based upon density. In
the present
invention, the fluid having a first density is separated from particles having
a second
density. In this embodiment, fluid enters the nose portion 957 of the tool
through
apertures 955 formed on each side of the nose portion. Thereafter, the fluid
travels
through an annular area 960 formed between the outer body 962 and intermediate
member 964. The path of the fluid is demonstrated by arrows 965. At the upper
end of
annulus 960, the fluid enters swirl tube 968 where it is directed to another
annular area
966 formed between the inner wall of intermediate 964 and inner member 967. As
the
fluid travels downwards in annulus 966, it enters a third annular area 971
defined by the
outer wall of the inner member 967 and an inner wall of an enclosure 972 open
at a
lower end and closed at an upper end. The fluid is filtered as it enters
perforations 968
formed in inner member 967 and thereafter, filtered fluid travels upwards. in
inner
member 967 through a baffle collar (not shown) and into a pipe thereabove. In
the
embodiment shown in Figure 19B, any sediment travelling with the fluid through
annular area 966 is separated from the fluid as it enters inner member 967
through
perforations 968. The sediment falls to the bottom of annular area 966 as
illustrated in
Figure 19. Cement is thereafter carried downward through inner member 967,
exiting
centre aperture 969 through one-way check valve 970.
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18
Figure 20 is an alternative embodiment of the invention illustrating a tool
975
that includes a venturi jet bailer formed within. This embodiment is
particularly
effective for removing or bailing sediment encountered at any point in a
wellbore.
During run-in, well fluid enters the tool through centre aperture 976 formed
in nose
portion 977. Flapper valve 978 prevents fluid from returning to the wellbore.
After
entering the tool, fluid is filtered through apertures 980 formed along the
length of two
filtering members 982. Thereafter, filtered fluid travels into a pipe 988
above the tool
through nozzle 984, in order to reduce pressure'during run-in of the tool.
Wherever sediment is encountered in the wellbore, the tool can be operated as
a
bailer by pressurising fluid above the tool and causing a stream of high
velocity, low
pressure fluid to travel downward through nozzle 984. The flow of fluid during
the
bailing operation is illustrated by arrows 985. Specifically, fluid travels
through the
nozzle and into diverter 986 where the fluid is directed out of the tool
through ports 987
and into an annular area outside of the tool (not shown). As the high velocity
fluid is
channelled through nozzle 984, a low pressure area is created adjacent the
nozzle and a
suction is thereby created in the lower portion of the tool. This suction
causes any
sediment present at the lower end of the tool to be urged into the tool
through flapper
valve 978. The sediment is prevented from falling back into the wellbore by
the flapper
valve and remains within the interior of the tool. Cementing is thereafter
performed by
pumping cement through the nozzle 984, into diverter 986 and into the annular
area to
be cemented (not shown) through ports 987.
While foregoing is directed to the preferred embodiment 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.
