U.S. patent application number 11/229781 was filed with the patent office on 2007-03-22 for packer washout assembly.
Invention is credited to Harold L. Witcher.
Application Number | 20070062690 11/229781 |
Document ID | / |
Family ID | 37882913 |
Filed Date | 2007-03-22 |
United States Patent
Application |
20070062690 |
Kind Code |
A1 |
Witcher; Harold L. |
March 22, 2007 |
Packer washout assembly
Abstract
A packer washout assembly for removing debris from a well bore
is disclosed. The packer washout assembly includes a tubing string
positioned in the well bore and forming an annulus with the well
bore. A packer is interposed in the tubing string and is sealable
against the interior of the well bore. A packer washout sub is
connected to an upper end of the packer. The packer washout sub
includes a mandrel having at least one fluid flow port extending
through a sidewall and a rupture disk positioned in the fluid flow
port of the mandrel. The rupture disk is adapted to rupture upon
the application of a predetermined pressure within the fluid
passage of the mandrel so as to place the fluid passage in fluid
communication with the annulus to permit fluid to pass through the
fluid port from the mandrel to the annulus and thereby circulate
fluid over the top of the packer so as to wash debris from the top
of the packer.
Inventors: |
Witcher; Harold L.; (Atoka,
OK) |
Correspondence
Address: |
DUNLAP, CODDING & ROGERS P.C.
PO BOX 16370
OKLAHOMA CITY
OK
73113
US
|
Family ID: |
37882913 |
Appl. No.: |
11/229781 |
Filed: |
September 16, 2005 |
Current U.S.
Class: |
166/222 ;
166/312 |
Current CPC
Class: |
E21B 31/03 20130101;
E21B 33/12 20130101 |
Class at
Publication: |
166/222 ;
166/312 |
International
Class: |
E21B 37/00 20060101
E21B037/00 |
Claims
1. A packer washout assembly for removing debris from a well bore,
comprising: a tubing string positioned in the well bore and forming
an annulus with the well bore; a packer interposed in the tubing
string and sealable against the interior of the well bore, the
packer having an upper end and a lower end; a packer washout sub
comprising: a mandrel having an upper end connected to the tubing
string, a lower end connected to the upper end of the packer, and a
sidewall extending from the upper end to the lower end, the
sidewall defining a fluid passage extending from the upper end to
the lower end, the mandrel having at least one fluid flow port
extending through the sidewall; and a closure member positioned in
the fluid flow port of the mandrel, the closure member adapted to
open upon the application of a predetermined pressure within the
fluid passage of the mandrel so as to place the fluid passage in
fluid communication with the annulus to permit fluid to pass
through the fluid port from the mandrel to the annulus and thereby
circulate fluid over the top of the packer so as to wash debris
from the top of the packer.
2. The packer washout assembly of claim 1 wherein the mandrel
includes a plurality of fluid ports, each fluid port has a closure
member positioned therein.
3. The packer washout assembly of claim 1 wherein the mandrel
includes a plurality of fluid flow ports extending through the
sidewall, the fluid ports longitudinally axially aligned from the
lower end to the upper end of the mandrel, each fluid flow port
having a closure member positioned therein.
4. The packer washout assembly of claim 1 wherein the mandrel
includes a plurality of fluid flow ports extending through the
sidewall, the fluid ports arranged in a helical pattern about the
sidewall of the mandrel, each fluid flow port having a closure
member positioned therein.
5. The packer washout assembly of claim 1 wherein the mandrel
includes a plurality of fluid flow ports extending through the
sidewall, the fluid ports circumferentially spaced an equal
distance about the mandrel, each fluid flow port having a closure
member positioned therein.
6. A packer washout assembly for removing debris from a well bore,
comprising: a tubing string positioned in the well bore and forming
an annulus with the well bore; a packer interposed in the tubing
string and sealable against the interior of the well bore, the
packer having an upper end and a lower end; a packer washout sub
comprising: a mandrel having an upper end connected to the tubing
string, a lower end connected to the upper end of the packer, and a
sidewall extending from the upper end to the lower end, the
sidewall defining a fluid passage extending from the upper end to
the lower end, the mandrel having at least one fluid flow port
extending through the sidewall; and a rupture disk positioned in
the fluid flow port of the mandrel, the rupture disk adapted to
open upon the application of a predetermined pressure within the
fluid passage of the mandrel so as to place the fluid passage in
fluid communication with the annulus to permit fluid to pass
through the fluid port from the mandrel to the annulus and thereby
circulate fluid over the top of the packer so as to wash debris
from the top of the packer.
7. The packer washout assembly of claim 6 wherein the mandrel
includes a plurality of fluid ports, each fluid port having a
rupture disk positioned therein.
8. The packer washout assembly of claim 6 wherein the mandrel
includes a plurality of fluid flow ports extending through the
sidewall, the fluid ports longitudinally axially aligned from the
lower end to the upper end of the mandrel, each fluid flow port
having a rupture disk positioned therein.
9. The packer washout assembly of claim 6 wherein the mandrel
includes a plurality of fluid flow ports extending through the
sidewall, the fluid ports arranged in a helical pattern about the
sidewall of the mandrel, each fluid flow port having a rupture disk
positioned therein.
10. The packer washout assembly of claim 6 wherein the mandrel
includes a plurality of fluid flow ports extending through the
sidewall, the fluid ports circumferentially spaced an equal
distance about the mandrel, each fluid flow port having a rupture
disk positioned therein.
11. A method for removing debris from the top of a packer sealed
against a well bore, comprising: producing fluid through a tubing
string positioned in the well bore, the tubing string forming an
annulus with the well bore, the tubing string having a packer
interposed therein, the packer sealed against the interior of the
well bore and the packer having an upper end and a lower end, the
tubing string further having a packer washout sub, the packer
washout sub comprising: a mandrel having an upper end connected to
the tubing string, a lower end connected to the upper end of the
packer, and a sidewall extending from the upper end to the lower
end, the sidewall defining a fluid passage extending from the upper
end to the lower end, the mandrel having at least one fluid flow
port extending through the sidewall; and a rupture disk positioned
in the fluid flow port of the mandrel; sealing the tubing string;
and pressurizing the tubing string to a sufficient pressure to
rupture the rupture disk of the packer washout sub so as to place
the fluid passage of the mandrel in fluid communication with the
annulus to permit fluid to pass through the fluid port from the
mandrel to the annulus and thereby circulate fluid over the top of
the packer so as to wash debris from the top of the packer.
12. A method for removing debris from the top of a packer sealed
against a well bore, comprising: providing a tubing string in the
well bore so that the tubing string forms an annulus with the well
bore, the tubing string having a packer interposed therein, the
packer sealed against the interior of the well bore and the packer
having an upper end and a lower end, the tubing string further
having a packer washout sub, the packer washout sub comprising: a
mandrel having an upper end connected to the tubing string, a lower
end connected to the upper end of the packer, and a sidewall
extending from the upper end to the lower end, the sidewall
defining a fluid passage extending from the upper end to the lower
end, the mandrel having at least one fluid flow port extending
through the sidewall; and a rupture disk positioned in the fluid
flow port of the mandrel; sealing the tubing string; and
pressurizing the tubing string to a sufficient pressure to rupture
the rupture disk of the packer washout sub so as to place the fluid
passage of the mandrel in fluid communication with the annulus to
permit fluid to pass through the fluid port from the mandrel to the
annulus and thereby circulate fluid over the top of the packer so
as to wash debris from the top of the packer.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to an apparatus for
washing debris from a well bore, and more particularly, but not by
way of limitation, to an apparatus and method for washing debris
from a packer set in a well bore to permit the packer to be
released.
[0003] 2. Brief Description of Related Art
[0004] Packers are downhole tools widely used in the completion of
oil and gas wells to isolate and control producing and injected
fluids. A variety of packers are known. Packers are often
classified as either permanent or retrievable. A permanent packer
is recovered from the well bore by using milling tools, while a
retrievable packer is designed to be released and retrieved on the
production tubing or on a workstring.
[0005] A concern of well operators when setting a retrievable
packer is the possibility of debris, such as sand, shale, or rust,
settling on top of the packer and prohibiting the release of the
packer. When this occurs one of several things may be attempted to
retrieve the packer from the well bore. First, the tubing may be
shot off just above the packer thereby permitting the majority of
the tubing to be removed from the well bore. Next, an operator may
fish back on the tubing in attempt to release the packer. Finally,
if all the above fail, then the packer is milled out, or the well
may be abandoned.
[0006] Each of these procedures is time consuming and expensive. As
such, a need exists for a tool that may be used with a packer to
allow debris to be selectively removed from the packer when
required. However, such an improved tool must also be cost
efficient and substantially maintenance-free. It is to such a tool
and method of use that the present invention is directed.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0007] FIG. 1 is a schematic illustration, partially in cross
section, of a packer washout assembly constructed in accordance
with the present invention.
[0008] FIG. 2 is a cross sectional view of a packer washout
sub.
[0009] FIG. 3 is a cross sectional view of another embodiment of a
packer washout sub constructed in accordance with the present
invention.
[0010] FIG. 4 is a cross sectional view of another embodiment of a
packer washout sub constructed in accordance with the present
invention.
[0011] FIG. 5 is a schematic illustration, partially in cross
section, of another embodiment of a packer wash out assembly
constructed in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0012] Referring now to FIG. 1, a packer washout assembly 10
constructed in accordance with the present invention for removing
debris, such as sand, silt, shale, and rust, from the top of a
packer 20 to permit the packer to be released is schematically
illustrated. A well bore 12 is shown to be lined with a casing 14
extending down from a wellhead 15. The casing 14 provides a
permanent borehole through which production operations may be
conducted. The casing 14 is affixed in the well bore 12 in a
conventional manner, such as by cement (not shown), and is provided
with perforations 16 open to a producing subterranean formation
17.
[0013] The packer washout assembly 10 includes a tubing string 18,
a packer 20, and a packerwashout sub 22. The tubing string 18
provides fluid communication between the producing subterranean
formation 17 and a surface 24 such that a reservoir fluid (not
shown), for example oil and/or natural gas, is produced through the
tubing string 18. The casing 14 and the tubing string 18 define an
annulus 26 which also provides fluid communication through the well
bore 12.
[0014] The packer 20 is interposed in the tubing string 18 in a
manner well known in the art. The packer 20 is commonly known as a
retrievable packer in that it is designed to be inserted in the
casing 14 when in a deflated or relaxed condition, set so as to
seal against the interior wall of the well bore 12, and then
released when it is desired to remove the tubing string 18 and the
packer 20 from the well bore 12. As mentioned above, release of the
packer 20 may be hindered by the accumulation of debris on top of
the packer 20.
[0015] The packer washout sub 22 is interposed in the tubing string
18 by connecting the packer washout sub 22 to the top of the packer
20. As best shown in FIG. 2, the packer washout sub 22 includes a
mandrel 30 having an upper end 32 adapted to be threadingly coupled
to the tubing string 18, a lower end 34 adapted to be threadingly
coupled to the upper end 32 of the packer 20, and a sidewall 36
extending from the upper end 32 to the lower end 34. The sidewall
36 defines a fluid passage 38 extending from the upper end 32 to
the lower end 34 so as to permit fluid flow between the tubing
string 18 and the packer 20. The mandrel 30 has at least one fluid
port 40 extending through the sidewall 36; however, preferably, the
mandrel 30 has a plurality of fluid ports 40. FIG. 2 shows one
version where three fluid ports 40 are longitudinally aligned from
the lower end 34 to the upper end 32 of the mandrel 30 along one
side of the mandrel 30.
[0016] To close the fluid ports 40, a closure member 42 is
positioned in each of the fluid ports 40 of the mandrel 30 to close
the fluid ports 40 during normal well operations. The closure
members 42 are illustrated as being rupture disks that are screwed
into the fluid ports 40 or otherwise secured in the fluid ports 40.
The rupture disks 42 are adapted to rupture upon the application of
a predetermined pressure within the fluid passage 38 of the mandrel
30 so as place the fluid passage 38 in fluid communication with the
annulus 26 to permit fluid to pass through the fluid port 40 from
the mandrel 30 to the annulus 26 and thereby circulate fluid over
the top of the packer 20 so as to wash debris from the top of the
packer 20.
[0017] The rupture disks 42 selected to be positioned in the fluid
ports 40 must maintain their integrity under normal fluid
production or injection operations. For example, if the tubing
string 18 will be subject to 1000 psi during production operations,
a rupture disk rated to rupture at 2,500 psi may be selected. On
the other hand, if the tubing string 18 is being used for the
injecting fluid into a formation, the tubing string 18 may be
subject to 5,000 psi. In this case, a rupture disk rated to rupture
at 10,000 psi may be selected.
[0018] FIGS. 3 and 4 illustrate other embodiments of a packer
washout sub 22a and 22b, respectively. FIG. 3 shows the packer
washout sub 22a having four fluid ports 40a arranged in a helical
pattern about the sidewall 36 of the mandrel 30a. A rupture disk
42a is positioned in each of the fluid ports 40a. FIG. 4 shows the
packer washout sub 22b having four fluid ports 40b that are
circumferentially spaced an equal distance about the mandrel 30b. A
rupture disk 42b is positioned in each of the fluid ports 40b.
[0019] The packer washout sub 22 is used in the event that the
packer 20 fails to release due to the accumulation of debris
(depicted in FIG. 1 by the reference numeral 48) such as sand,
shale, silt, or rust, on top of the packer 20. Upon determining
that the packer 20 is stuck, a standing valve 46 is landed on a
seating nipple (not shown) to close off the tubing string 18 from
below the packer washout sub 22. Next, the tubing string 18 is
pressurized with fluid, such as water, to a pressure sufficient to
rupture the rupture disks 42. Upon the rupture disk 42 rupturing,
fluid communication between the fluid passage 38 of the mandrel 30
and the annulus 26 is established to permit fluid to pass from the
mandrel 30 through the fluid port 40 and into the annulus 26. In
the annulus 26, fluid is circulated through the debris, over the
top of the packer 20, and finally to the surface 24 so as to carry
the debris to the surface 24 and thereby wash the debris from the
top of the packer 20. After the debris has been washed from the top
of the packer 20, the packer is released and the tubing string 18,
along with the packer washout sub 22 and the packer 20, is
withdrawn from the well bore 12.
[0020] FIG. 5 illustrates the use of a packer washout sub 22 in a
tubing string 18a. The tubing string 18a includes a packer 20a and
a plug 48. The tubing string 18 provides fluid communication
between producing subterranean formation 50 and a surface 52 such
that a reservoir fluid (not shown), for example oil and/or natural
gas, is produced through the tubing string 18a. A casing 14a is
affixed in a well bore 12a in a conventional manner, such as by
cement (not shown), and is provided with perforations 54 open to
the producing subterranean formation 50. It will be noted that the
producing subterranean formation 50 is above the packer 20a. As
such, the tubing string 18a is provided with perforations 56 to
permit fluid passing from the formation 50 to pass into the tubing
string 18a.
[0021] In the situation where the packer 20a fails to release and
the tubing string 18a is perforated above the packer 20a, the
perforations 56 are first sealed prior to pressuring the tubing
string 18a for the purpose of rupturing the rupture disks 42. The
perforations 56 may be sealed by inserting balls 58 into a stream
of fluid injected into the tubing string 18a at the surface 52. The
balls 58 will lodge in the perforations 56 and thereby seal the
perforations 56. Upon determining that the perforations 56 are
sealed by an increase in fluid pressure, the fluid pressure in the
tubing string 18a is further increased to a pressure sufficient to
rupture the rupture disks 42. Upon the rupturing of the rupture
disks 42, fluid is circulated through the debris (depicted in FIG.
5 by the reference numeral 60), over the top of the packer 20a, and
finally to the surface 52 so as to carry the debris to the surface
52 and thereby wash the debris from the top of the packer 20a.
After the debris has been washed from the top of the packer 20a,
the packer 20a is released and the tubing string 18a, along with
the packer washout sub 22 and the packer 20a, is withdrawn from the
well bore 12a.
[0022] From the above description it is clear that the present
invention is well adapted to carry out the objects and to attain
the advantages mentioned herein as well as those inherent in the
invention. While presently preferred embodiments of the invention
have been described for purposes of this disclosure, it will be
understood that numerous changes may be made which will readily
suggest themselves to those skilled in the art and which are
accomplished within the spirit of the invention disclosed and as
defined in the appended claims.
* * * * *