U.S. patent application number 11/766777 was filed with the patent office on 2008-02-28 for method and apparatus for plugging perforations.
Invention is credited to HOMER L. SPENCER.
Application Number | 20080047708 11/766777 |
Document ID | / |
Family ID | 38834929 |
Filed Date | 2008-02-28 |
United States Patent
Application |
20080047708 |
Kind Code |
A1 |
SPENCER; HOMER L. |
February 28, 2008 |
METHOD AND APPARATUS FOR PLUGGING PERFORATIONS
Abstract
Apparatus and method for plugging perforations in an oil or gas
well. A bridge plug is formed in the casing below the perforations.
A heating tool and a fusible alloy adjacent the heating tool is
lowered into the well to a position above the bridge plug and
adjacent the perforations. Heat is applied to melt the fusible
alloy and pressure is applied to the molten material to force it
through the perforations. The heating operation is terminated to
allow the molten material to solidify and plug the
perforations.
Inventors: |
SPENCER; HOMER L.; (CALGARY,
CA) |
Correspondence
Address: |
JOHN RUSSELL UREN
1590 BELLEVUE AVENUE
SUITE 202
WEST VANCOUVER
BC
V7V1A7
CA
|
Family ID: |
38834929 |
Appl. No.: |
11/766777 |
Filed: |
June 21, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60805734 |
Jun 24, 2006 |
|
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Current U.S.
Class: |
166/288 ;
166/60 |
Current CPC
Class: |
E21B 33/138 20130101;
E21B 36/00 20130101; E21B 29/10 20130101 |
Class at
Publication: |
166/288 ;
166/060 |
International
Class: |
E21B 33/13 20060101
E21B033/13; E21B 36/04 20060101 E21B036/04 |
Claims
1. A heating tool for use in plugging perforations in an oil or gas
well, said tool comprising a heating element, a circumferential
tube surrounding said heating element, a fusible alloy adjacent to
and outside said circumferential tube and means for releasably
connecting said circumferential tube and said fusible alloy to said
heating element.
2. A heating tool as in claim 1 wherein said circumferential tube
is a thermally conductive metal material.
3. A heating tool as in claim 2 wherein said fusible alloy is
formed around said heating tube.
4. A heating tool as in claim 1 wherein said means for releasably
connecting said circumferential tube and said fusible alloy to said
heating element is a latching means which in its closed position
retains said tube and which opens to release said circumferential
tube and said fusible alloy.
5. A heating tool as in claim 2 wherein said fusible alloy is
formed in segments which are mounted around said circumferential
tube.
6. Method of plugging perforations in the casing of an oil or gas
well comprising the steps of forming a bridge plug in said casing
at a position lower than the lowermost perforation sought to be
plugged, lowering a heating tool and a fusible metal alloy to a
position above said bridge plug and adjacent said perforations
sought to be plugged, melting said alloy and applying pressure to
said molten alloy to force said molten alloy through said
perforations in said casing, lowering the temperature of said
heating tool to allow said molten alloy to solidify within said
perforations, removing said pressure from said molten alloy and
withdrawing said heating tool from said oil or gas well.
7. Method as in claim 6 wherein said fusible alloy surrounds said
heating tool.
8. Method as in claim 7 wherein said fusible alloy is formed on the
circumference of said heating tool.
9. Method as in claim 7 wherein said fusible alloy is formed in
segments and said segments are fitted around said heating tool.
10. Method as in claim 9 wherein the quantity of fusible alloy
surrounding said heating is sufficient to fill said perforations in
said oil or gas well.
11. Method as in claim 10 wherein said fusible alloy is a
bismuth-tin alloy.
12. Method as in claim 11 wherein said heating tool further
comprises a heating tube and said fusible alloy extends around the
circumference of said heating tube.
13. Method as in claim 12 wherein said heating tube is made from
aluminum.
14. Method as in claim 13 wherein said heating tool is a resistive
type heating tool.
15. Method as in claim 13 wherein said heating tool is an inductive
type heating tool.
16. Method as in claim 6 and further comprising depositing a layer
of sand on top of said bridge plug.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from U.S. Provisional
Application Ser. No. 60/805,734 filed Jun. 24, 2006 entitled
PERFORATION PLUGGING TOOL AND PROCEDURE (Spencer).
INTRODUCTION
[0002] This invention relates to method and apparatus for plugging
perforations in an oil or gas well and, more particularly, to
plugging an oil or gas well which utilizes a fusible alloy for
plugging the perforations.
BACKGROUND OF THE INVENTION
[0003] In the oil and gas production industry, a perforated
interval in the casing of the well is created to allow enhanced oil
flow from the oil holding formation into the casing. The
perforations are holes that extend from the inside of the well
casing to the outside and are created by explosive shooting or
other perforation techniques which techniques form no part of the
present invention.
[0004] Following the long use of the perforations for oil or gas
flow into the casing, water flow becomes a problem. The water is
undesirable since it mixes with the oil and must be removed from
the oil at the surface. Furthermore, when water increases its flow
through the perforations, the oil or gas flow may diminish to a
point where the well is not longer commercially viable. In
addition, the water flow may hinder the recovery of oil or gas from
other areas of the formation. It therefore becomes advantageous to
plug the previously formed perforations.
[0005] In our earlier U.S. Pat. No. 6,828,531, the contents of
which are incorporated herein by reference, there is disclosed a
method and apparatus for plugging perforations using a squeeze
procedure and a heating tool that melts a fusible alloy and
squeezes the alloy into the perforations where the alloy cools and
expands thereby closing the perforations and terminating flow
therethrough. The use of such a technique, while useful to close
the perforations, also results in an residue of alloy being left
within the well as a solid alloy plug across the casing. The cost
of the alloy to effect plugging in such an application is
expensive. Further, the time to create the plugging in that
application is unnecessarily time consuming.
[0006] It would advantageous to use less alloy for plugging the
perforations and it further would be advantageous to enhance the
efficiency of the plugging operation.
SUMMARY OF THE INVENTION
[0007] According to one aspect of the invention, there is provided
a heating tool for use in plugging perforations in an oil or gas
well comprising a heating element, a circumferential tube
surrounding said heating element, a fusible alloy adjacent to and
outside said circumferential tube and means for releasably
connecting said circumferential tube and said fusible alloy to said
heating element.
[0008] According to a further aspect of the invention, there is
provided a method of plugging perforations in the casing of an oil
or gas well comprising the steps of forming a bridge plug in said
casing at a position lower than the lowermost perforation sought to
be plugged, lowering a heating tool and a fusible metal alloy to a
position above said bridge plug and adjacent said perforations
sought to be plugged, melting said alloy and applying pressure to
said molten alloy to force said molten alloy through said
perforations in said casing, lowering the temperature of said
heating tool to allow said molten alloy to solidify within said
perforations, removing said pressure from said molten alloy and
withdrawing said heating tool from said oil or gas well.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0009] An embodiment of the invention will now be described, by way
of example only, with the use of drawings in which:
[0010] FIG. 1 is a diagrammatic cross-sectional illustration of an
oil or gas well illustrating a perforated interval within the
casing of an oil or gas well;
[0011] FIG. 2 is a diagrammatic cross-sectional view of the oil or
gas well of FIG. 1 and illustrating the initial step of forming a
bridge plug in the well to plug the well and a sand pad interval
formed on the top of the bridge plug;
[0012] FIG. 3 is a diagrammatic cross-sectional view of the oil or
gas well of FIGS. 1 and 2 and further illustrating a heating tool
lowered into the well by way of electrical line cable together with
the fusible alloy material located on the outside of the tool;
[0013] FIG. 4 is a diagrammatic cross-sectional view similar to
FIG. 3 but illustrating pressure being applied on the molten alloy
material thereby to force the alloy through the perforations;
and
[0014] FIG. 5 is a diagrammatic cross-sectional view of the well of
FIGS. 1-4 but illustrating the solidified alloy within the
perforations and with the heating tool having been removed from the
well.
DESCRIPTION OF SPECIFIC EMBODIMENT
[0015] Referring now to the drawings, an oil or gas well is
generally illustrated at 10 in FIG. 1 with the production casing 11
being cemented in by cement 12 which seals the production casing
from the formation of interest which is an oil or gas bearing
formation generally illustrated at 13.
[0016] Perforations 14 have been formed in the casing 11 and extend
into the formation of interest 13.
[0017] It is desired to plug the perforations 14 and to terminate
flow from the formation 13 through the perforations 14 and into the
casing 11. To do so, a retrievable bridge plug 21 is set in the
casing 11 below the lowest one of the perforations 14 as
illustrated in FIG. 2. The bridge plug 21 is formed within the
casing 11 using wire line procedure which is known. A volume of
sand 22 is then dumped into the casing 11 and on top of the bridge
plug 21. The thickness of the sand layer 22 should extend upwardly
to a position just below the lowermost one of the perforations of
interest 14.
[0018] Referring to FIG. 3, a heating and perforation plugging tool
generally illustrated at 23 is lowered into the well 10 by
electrical wire line cable 24 until it rests on the sand layer 22.
Tool 23 is an electrical resistance type heater which has a heating
coil diagrammatically illustrated at 30 which is connected to an
electrical power supply (not shown) at the surface through
electrical cable 24. A tube 30 is positioned outside the heating
coil 31 and terminates at the lower end of the tool 23 with a
flanged cap 32. The tube 30 is conveniently made from a relatively
soft metal with high thermal conductivity such as aluminum although
copper or brass or other metals are also contemplated to be useful.
A latching mechanism generally illustrated at 33 maintains the tube
30 and flanged cap 32 in position relative to the heating coil 31
as will be described.
[0019] The layer 34 of meltable fusible alloy is formed around the
circumference of the tube 30 and is in solid form as the heating
tool 23 is lowered from the surface. The fusible alloy 34 is
conveniently a bismuth/tin alloy although other such suitable
alloys are also contemplated. The volume of the alloy 34
surrounding the tube 30 is earlier calculated and is such that the
perforations 14 will be completely filled when the alloy 34 is
melted.
[0020] Referring to FIG. 4, electric power is applied to the
heating coil 30 through the electrical wire line cable 24. The heat
is transmitted though the aluminum tube 31 and melts the fusible
alloy material 34. Simultaneously with the melting of the alloy 34,
pressure is applied to the melted alloy 34 by pumped water or by a
compressed gas. The pressure forces the molten alloy 34 into the
perforations 14 extending through the casing 11 and the cement 12
and into the formation 20.
[0021] Power to the heating tool 23 is then terminated and the
latching mechanism 33 opens thereby allowing the tube 31 and
flanged cap 32 to be released from the heating tool 23 where they
remain on the bridge plug 21 and sand 22. The pressure remains on
the molten alloy and the cessation of heating from the tool 23
causes the molten alloy 34 to solidify within the perforations 14.
The bismuth/tin alloy 34 expands as it solidifies thereby creating
a tight plug within the perforations 14 and blocking the entrance
of the undesired water into the well 10. Following a sufficient
time interval, the pressure on the alloy 34 within the well 10 is
terminated and the heating tool 23 is withdrawn from the well 10.
Any alloy remaining within the casing 11 is readily drilled out.
The bridge plug 21 and sand 22 are likewise removed as is known.
The solidified alloy 34 will remain in the perforations 14 thereby
plugging the perforations 14.
[0022] Many modifications will readily occur to those skilled in
the art to which the invention relates. It is desirable to have the
tube 31 and solid alloy 34 brought into close proximity with the
inside diameter of the casing 11 in order to enhance movement of
the melted alloy into the perforations 14 and also to minimize the
amount of alloy required for plugging the perforations 14.
Accordingly, tubing 34 of various diameters could be accommodated
by the heating tool 23. Likewise, while a latching mechanism 30 has
been described, other mechanisms for allowing the release of the
tubing 30 and alloy 34 such as shear pins, molded fusible metal
which melts under the influence of heat from the heating tool 23
contemporaneously with the melting of the fusible alloy 34 used for
plugging the perforations, and the like are likewise
contemplated.
[0023] The alloy material 34 on the outside of the releasable tube
of the heating tool 23 as is described and illustrated may be
formed on the outside of the tube 31 or it may conveniently be
pre-molded in segments which segments would be slipped over the
tube 31 in the desired quantities. The segments would then rest
against the flanged cap 32 but the operation of the heating tool 23
would be similar to the operation just described.
[0024] While a resistive type heating tool 23 has been described,
it is contemplated that an inductive type heating tool such as that
heating tool described in our U.S. Pat. No. 6,825,531 would also be
useful. There would be no need for a hollow center in such a tool
but the use of induction for heating the fusible alloy 34 is
contemplated to be useful for the present application.
[0025] Many further embodiments will readily occur to those skilled
in the art to which the invention relates and the specific
embodiments described should be taken as illustrative of the
invention only and not as limiting its scope as defined in
accordance with the accompanying claims.
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