U.S. patent application number 13/984339 was filed with the patent office on 2014-05-22 for tool and method to plug and abandon well.
The applicant listed for this patent is Morten Lerbrekk, Geir Arne Melhus. Invention is credited to Morten Lerbrekk, Geir Arne Melhus.
Application Number | 20140138078 13/984339 |
Document ID | / |
Family ID | 46602944 |
Filed Date | 2014-05-22 |
United States Patent
Application |
20140138078 |
Kind Code |
A1 |
Lerbrekk; Morten ; et
al. |
May 22, 2014 |
Tool and Method to Plug and Abandon Well
Abstract
A tool (10) is described for the handling of wells through a
formation, and which shall be taken out of operation with a device
for a closing plug of a material that can be hardened, such as
concrete, where there is a casing pipe in the well that is cemented
against the wall in the bore hole with concrete, and it is
characterised in that the tool comprises an assembled unit (10)
from the following three sections; a perforating lance (32)
comprising a number of explosive charges to form by detonation a
row of holes in the pipe and out into the surrounding layer of
concrete, a cleaning unit (34) for mechanical cleaning of the inner
wall of the pipe in the perforated area and a flushing unit (36) to
loosen, dissolve and flush away the hardened cement material
between the outer wall of the pipe and the wall of the bore hole.
Also described is a method to plug a well that shall be taken out
of operation.
Inventors: |
Lerbrekk; Morten; (Bryne,
NO) ; Melhus; Geir Arne; (Bryne, NO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lerbrekk; Morten
Melhus; Geir Arne |
Bryne
Bryne |
|
NO
NO |
|
|
Family ID: |
46602944 |
Appl. No.: |
13/984339 |
Filed: |
February 3, 2012 |
PCT Filed: |
February 3, 2012 |
PCT NO: |
PCT/NO12/50016 |
371 Date: |
December 17, 2013 |
Current U.S.
Class: |
166/55 ;
166/192 |
Current CPC
Class: |
E21B 43/116 20130101;
E21B 33/13 20130101; E21B 37/02 20130101; E21B 29/02 20130101 |
Class at
Publication: |
166/55 ;
166/192 |
International
Class: |
E21B 29/02 20060101
E21B029/02; E21B 33/13 20060101 E21B033/13 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 3, 2011 |
NO |
20110190 |
Claims
1. Tool for the handling of a well through a formation, and which
shall be taken out of operation by arranging a closing plug of a
material that can be hardened where there is a casing pipe in the
well which is cemented with concrete against the a wall in the bore
hole, characterised in that the tool comprises an assembled unit
from the following three sections: a perforating lance comprising a
number of explosive charges to form by detonation a perforated area
in the pipe and exposed to the surrounding layer of concrete, a
cleaning unit for mechanical cleaning an inner wall of the pipe at
said perforated area, and a flushing unit for the spraying in of a
fluid to release, dissolve and flush away hardened cement material
between an outer wall of the pipe and the wall in the bore
hole.
2. Tool according to claim 1, characterised in that said
perforating lance is arranged as an end piece of the said assembled
unit, said flushing unit is fitted to an operating line, the and
said cleaning unit is inserted between said lance and said flushing
unit.
3. Tool according to claim 1, characterised in that said
perforating lance is set up to be released from the rest of said
assembled unit after said explosive charges have been
detonated.
4. Tool according to claim 1, characterised in that said
perforating lance has a number of said explosive charges around and
along the circumference thereof.
5. Tool according to claim 1, characterised in that said explosive
charges in said perforating lance are formed with different
blasting strengths in different sections of said lance.
6. Tool according to claim 1, characterised in that an upper
section of said perforating lance is formed with greater explosive
power in said explosive charges than the rest of said explosive
charges.
7. Tool according to claim 1, characterised in that an upper and a
lower(C) section of said the perforating lance are formed with a
greater explosive power in said explosive charges than those
explosive charges in a middle section.
8. Tool according to claim 1, characterised in that a said cleaning
unit comprises a scrubbing unit for mechanical cleaning of the
inner wall of the pipe in said perforated area.
9. Tool according, to claim 1, characterised in that said cleaning
unit scraping edges on a radially outwardly facing head surface
thereof.
10. Tool according to claim 1, characterised in that said flushing
unit is set up to spray out a fluid to loosen, dissolve and flush
away the hardened mass of cement between the outer wall of the pipe
and the wall of the bore hole.
11. Tool according to claim 1, characterised in that the tool is
fitted to the end of an operating line which is lowered down into
the well from an installation on the surface.
12. Method to close off a well including a casing pipe through a
formation in that a plug of a material that can be hardened is
established, whereby a section of the casing pipe through the well
is perforated, and a hardenable material is led down through the
pipe and is brought to flow out through the perforations and make
contact with the walls in the original bore hole, characterised in
that a three-part tool is used encompassing a lower part comprising
a perforating lance gun to form said perforations, a middle
cleaning part to clean the pipe internally and also an upper
flushing section with a cleaning fluid to flush loose and dissolve
concrete residues in the space between the pipe and the wall of the
bore hole, and the following steps are carried out in sequence, a)
the tool connected to an operating line is fed down through the
pipe until the perforating lance is in a position where the pipe is
to be perforated, b) the explosive charges are detonated to
establish the perforations in the pipe, c) the tool is conducted up
and down in the perforated area to scrub clean the inner wall of
the pipe with the help of the cleaning part, d) the tool is
positioned so that the flushing section in the pipe is placed
adjoining a set of perforated holes and such that a number of
perforated holes around the circumference lie above the flushing
section and form a fluid connection from the annular space between
the pipe and the wall of the well and into the annular space
between the operating line, e) flushing fluid is sprayed out
through the perforations to loosen bits of concrete and dissolve
the concrete in the space outside the pipe so that this is led back
through the upper perforations and into the pipe above the flushing
section, and f) the tool is removed and a material that can be
hardened is lowered down to fill a given section of the pipe and
the gap between the outer side of the pipe and the wall of the bore
hole, whereby the well is plugged when the material is
hardened.
13. (canceled)
14. A tool for plugging a well comprising a lance having a
plurality of explosive charges therein for forming a series of
holes in a pipe disposed within a well bore; a cleaning unit
disposed above said lance and having scraping edges on a radially
outwardly facing surface thereof for scraping of an inner wall of
the pipe; and a flushing unit disposed above said cleaning unit and
having a pair of longitudinally spaced apart bellows for sealing
against the pipe and defining a space therebetween and a plurality
of holes for communicating with said space for spraying a flushing
fluid into said space.
15. A tool as set forth in claim 14 wherein said lance is removably
mounted on said tool for ejection therefrom.
16. A tool as set forth in claim 14 wherein said scraping edges of
said cleaning unit are disposed circumferentially of said cleaning
unit and are radially retractable.
Description
[0001] The present invention relates to a tool for handling of
wells through a formation, and which shall be taken out of
operation by installing a closing plug of a hardenable material,
such as concrete, where there is a casing pipe in the well which is
cemented towards the wall of the bore hole with a concrete, as
defined in the introduction of claim 1.
[0002] The invention also relates to a special construction of a
perforating gun to provide perforations in a pipe in a formation
and comprising an extended lance fitted with a number of explosive
charges around the circumference and along the length of the lance,
and also means for the detonation of the explosive charges.
[0003] Furthermore, the invention relates to a method as described
in the introduction of claim 12 for the closing off of a well
including a casing pipe through a formation in that a plug of a
hardenable material is established, whereby a section of the casing
pipe through the well is perforated and a material that can be
hardened is conducted down through the pipe and is brought to flow
out through the perforations and make contact with the walls of the
original bore hole.
[0004] The invention concerns a tool that is used in connection
with the plugging of wells that shall be taken out of
operation.
[0005] When production of hydrocarbons from a porous HC containing
field in the rock formation is established, a well bore is drilled
down into the formation, and a casing pipe (production pipe) is set
down into the well bore and is secured and stabilised in relation
to the walls of the original bore hole in that concrete is sprayed
in between the outer wall of the pipe and the wall of the bore
hole.
[0006] When such a production well shall be taken out of production
it is completely plugged with a concrete plug so that one does not
risk future leakages. The plugging of such a well involves the
pumping in of a plugging material from a hardenable concrete. The
requirement of such a plug is that the concrete being pumped down
shall make direct contact with the porous formation.
[0007] Therefore, it is common that the production pipe (the casing
pipe) is perforated, the pipe is cleaned internally and an acidic
cleaning fluid is sprayed in to dissolve the concrete.
[0008] This three part operation is carried out in that a
perforating tool which is fitted with a number of directed
explosive charges is lowered down. When these are fired, a set of
holes is blasted into the pipe to wash out and partially dissolve
the original concrete so that the new and fresh concrete can make a
proper direct contact with the rock formation while establishing
the plug.
[0009] After the perforating gun has been fired it is common to
clean the pipe internally by lowering down a cleaning tool that
grinds off protruding bits of metal and fibres from the pipe
inside, and which are formed as a consequence of the explosion.
[0010] The cleaning tool can be a brush that brushes, rubs or
grinds the pipe internally.
[0011] When the pipe is ground and cleaned, a flushing tool is
lowered down with an upper and a lower set of gaskets that seal
against the inner wall of the pipe. A cleaning fluid is sprayed out
between these sets of gaskets, usually containing an acid that can
flush loose bits of concrete or possibly directly dissolve the
concrete chemically. These bits of concrete and concrete remains is
then flushed with the flow of fluid upwards in through the annular
space between the pipe in which the tool is suspended from the
surface and the inside of the casing pipe.
[0012] With regard to prior art, reference is made to
US-2002/162657, US-2007/163783, U.S. Pat. No. 5,372,198,
US-2010/236781, U.S. Pat. No. 6,347,673 and US-2006/196693. For
example, it can be seen in FIG. 4 of said US-2002/162657 that the
lance can perforate the pipe and plug the well with concrete in a
combined operation.
[0013] It is an aim of this invention to further develop the known
solutions so that all these three operations can be combined into
one and the same apparatus, i.e. without the operating line or the
pipe having to be pulled up to the surface to change a tool a
number of times for each operation where a well shall be
plugged.
[0014] It is a further aim to provide a new construction of a
perforating un to be able to improve the cleaning of the concrete
from the annular space between the casing pipe and the wall of the
bore hole.
[0015] The tool according to the invention is characterised in that
it comprises an assembled unit of the following three sections: a
perforating lance comprising a number of explosive charges which,
by detonation, form a row of holes in the pipe and out into the
surrounding layer of concrete, a cleaning unit for mechanical
cleaning of the inner wall of the pipe at the perforated area and a
flushing unit to loosen, dissolve and flush away the hardened
cement material between the outer wall of the pipe and the wall of
the bore hole.
[0016] The unit is preferably fitted to the end of the operating
string or pipe that is guided down into the well from an
installation at the surface.
[0017] The perforating lance is preferably arranged at the bottom
of the unit, the flushing unit is fitted to the operating string,
while the cleaning unit is inserted between the lance and the
flushing unit.
[0018] The perforating lance is preferably set up to be released
from the other parts of the unit after the explosive charges have
been detonated/fired. The perforating lance has a number of charges
around and along the circumference.
[0019] The explosive charges are preferably formed, in connection
with the perforating lance, with different explosive strength in
the different sections (A,B,C) of the lance. Alternatively, an
upper (A) section of the perforating gun/-perforating lance is
formed with greater explosive power in the explosive charges than
the rest of the charges.
[0020] The preferred embodiments of the tool according to the
invention are characterised by the features that are given in
claims 1-11.
[0021] The method according to the invention is characterised in
that a three-part tool is used, encompassing a lower part
comprising a perforating gun (32) to establish said perforations, a
middle cleaning part (34) to clean the pipe (20) inside and also an
upper flushing section (36) with a flushing fluid to flush loose
and dissolve concrete remains in the space between the pipe (20)
and the wall of the bore hole The following steps are carried out
in sequence: [0022] a) the tool (10) connected to an operating
string (30) is guided down through the pipe until the perforating
gun (32) is in a position where the pipe shall be perforated,
[0023] b) the explosive charges (33) are detonated to establish the
perforations (35) in the pipe, [0024] c) the tool (10) is conducted
up and down in the perforated area to scrub-clean the inner pipe
wall with the help of the cleaning part, [0025] d) the tool (10) is
positioned so that the flushing section (36) in the pipe is placed
adjoining a set of the perforation holes and such that a number of
perforation holes around the circumference lie above the flushing
section (36) and form a fluid connection from the annular space
between the pipe (20) and the wall of the well and into the annular
space (12) between the operating string (30), [0026] e) flushing
liquid is pumped out through the perforations to loosen bits of
concrete and dissolve the concrete in the space outside the pipe
(20) so that this is led back through the upper perforations and
into the pipe (20) above the flushing section (36), and [0027] f)
the tool is removed and a material that can be hardened is lowered
down to fill a given section of the pipe (20) and the interstitial
space between the outer side of the pipe and the wall of the bore
hole, whereby the well is plugged when the material hardens.
[0028] It is preferred that a tool as described in the claims 1-11
is used.
[0029] The invention shall be explained in more detail with
reference to the enclosed figures, in which:
[0030] FIG. 1 shows a tool according to the invention and how it is
set up to be installed in a well and operated from a platform on
the surface of the ocean.
[0031] FIGS. 2, 3 and 4 show an enlarged cross-section of the tool
installed down in the well.
[0032] FIG. 5 shows an enlargement to show details of the
perforating lance.
[0033] FIG. 1 shows a tool according to the invention 10 fitted to
a string or pipe 30 that runs down through a formation 14 from an
installation 100, a platform 100 on the ocean or the like. The
ocean surface is shown by 18 and the sea bed by 16. The
construction according to the invention can, of course, also be
used in connection with an HC exploring installation on land.
[0034] A casing pipe (production pipe) (20) is inserted into the
bore hole or the well and this is cemented with concrete 22 to the
walls of the bore hole.
[0035] The tool 10 according to the invention is also shown in the
figure. It is composed of the three parts, the perforating gun 32,
the scrubbing/cleaning unit 34 and the flushing device 36 seen in a
direction from below.
[0036] According to the invention the washing/flushing unit 36 is
placed at the top of the combined unit and is connected uppermost
in the tool 10 to the lower end of the pipe/line 30. Between the
pipe/line 30 and the inside of the casing pipe 20, there is an
annular space 12 through which loosened bits of concrete and other
impurities can be led during the cleaning/flushing.
[0037] The scrubbing/cleaning unit 34 is fastened immediately below
the flushing unit 36 and below this the perforating gun 32 is
placed. They consequently form a three part tool with all the
functions in one piece.
[0038] FIG. 2 shows an enlarged cross-section of the apparatus
according to the invention.
[0039] Perforating Gun 32.
[0040] This comprises a cylinder formed column or casing that
extends downwards below the scrubbing/cleaning unit and where a
number of dedicated explosive charges/explosives 33 are inserted
around the periphery and in several rows on the surface, in a
previously known manner, i.e. that the blast from the charges are
in a horizontal or an inclined direction radially outwards towards
the pipe to blow holes in the pipe wall. The explosive charges are
connected to a trigger unit, for example, via a primer cable which
runs from the surface through the pipe 30. The charges are made to
explode simultaneously and they are facing radially outwards and
each one of the charges blasts a hole 35 in the metal of the casing
pipe 20 so that a fluid connection is formed radially outwards to
the concrete outside the pipe. The size of the individual holes can
be regulated with the help of the blasting strength of the
individual charges 33.
The Scrubbing/Cleaning Unit 34
[0041] This cleaning unit comprises brushes, grooves, sharp
scraping edges or is grooved 37 on the radially outwardly facing
head surface. The diameter of the head is adapted to the inner
diameter of the pipe 20. After the detonation, metal remains with
sharp edges extending in from the pipe surface around these
openings are created. The brushes 37 that can comprise metal
brushes such as a so-called steel brush shall loosen and remove
such sharp edges. The cleaning brushes can be formed around the
circumference so that they can be pulled radially inwards into the
tool construction when they are not in use, and be pushed out to
make contact with the inner wall of the pipe when the cleaning
shall take place. A separate mechanism inside the scrubbing part,
for example, hydraulically operated, can be reset to be pushed out
against the wall, or be pulled in from the wall.
[0042] To adjust the tool to different inner diameters of the
casing pipe 20, the brushes can be extendable and retractable in a
radial direction. They scrape the inner wall only in that the whole
apparatus is moved up and down as shown by the arrow P in FIG.
2.
The Washing/Flushing Unit 36
[0043] This comprises two cupola formed bellows (for example, from
rubber) 36a and 36b which mutually are fitted a short distance
apart to the tool line/pipe 30. They form a seal against the inner
wall of the pipe 20. Between them they form an annular flushing
unit space 38. The pipe 30 is perforated in this annular space with
holes 40 for the spraying out of liquid (water-acid) to the space
38 and which is supplied with pressure from the surface through the
inside of the pipe 30. A fluid pressure arises in the intermediate
annular space 38 and the liquid is forced out through the
perforations 35 that are blasted out and loosens and sprays bits of
concrete in the annular space 22 between the casing pipe and the
wall of the bore hole.
[0044] Thus, this flushing unit 36 is placed uppermost in the
construction and connected to the above lying pipe and the brushing
unit 34 is placed below this and the perforating gun 32 is placed
underneath this again at the end of the tool.
[0045] FIG. 3 shows a first step in the process. The tool 10, with
the three parts, is set up for firing the explosive charges. A
blasting is carried out and holes 35 are made in the pipe. The
holes 35 run out through the pipe 20 and the explosion also leads
to holes being formed more or less in the concrete coat 22 radially
outside and which one wants to break up and remove as much as
possible.
[0046] After the blasting has been carried out the tool is led up
and down so that the brushes 37 of the tool 34 can clean the
internal surface of the pipe along the holes at the bottom of FIG.
3.
[0047] FIG. 4 shows an important feature of the invention. The
perforating gun 32 is loosened, with the help of a release
mechanism not described further, from the rest of the tool and
falls down into the well. After the gun 32 has been dropped, the
whole tool is lowered further down so that the flushing unit 36 is
aligned with the holes 35.
[0048] Now, the spraying starts in that water/acid is pumped down
through the pipe 30 shown by the arrows 42. It can be seen that the
bottom of the tool, i.e. the part which lies above the perforating
gun, is sealed with a plate 50 so that the cleaning fluid which is
sent down under pressure is forced out into the annular space 38.
The annular space 38 between the two sealing bellows 36a,36b is
filled with fluid and at a pressure that forces the fluid out
through the holes 35 and out into the concrete part one wishes to
remove. The acid in the water will contribute to dissolving the
concrete chemically. Furthermore, the water pressure out through
the holes will lead to parts of the concrete coat being broken up
into smaller and larger pieces. It is shown with the arrows P1 how
the fluid flows further upwards and radially back inwards through
the holes/openings above the sealing bellows. Then, flushed out
fluid can be led further upwards through the annular space 12
between the pipe 30 and the inner wall of the casing pipe.
[0049] After most of the concrete coat is removed, the construction
is ready for the feeding of concrete to form a plug in the well.
This concrete is filled internally in the casing pipe and will flow
out through the holes and also fill up the back space between the
outer wall of the casing pipe and the walls of the original bore
hole.
Preferred Embodiment of the Perforating Gun/Perforating Lance
[0050] According to a preferred embodiment which is outlined in
FIG. 5, the lance-formed perforating gun is fitted with sections
with different strengths of explosive charges. These sections are
marked A, B and C in FIG. 5. Initially, the directed charges are
designed to give an optimal hole diameter in the casing pipe in the
well plus some distance into the existing concrete coat which one
wishes to be able to flush loose and flush away or to dissolve
chemically with the acid content of the liquid.
[0051] By increasing the power of the explosive charges in the
upper A and lower C sections in relation to the middle section B,
the holes in A and C will have greater diameters, and thus a better
and higher circulation effect and pressure profile of the flushing
fluid during the circulation sequence. The counter pressure during
the washing sequence will be reduced so that the pumping rate can
be increased. With reference to the flow pattern shown by the
arrows P1 and P2 in FIG. 4, bits of concrete that have come loose
will flow upwards in the gap outside the outer wall of the pipe to
flow through the upper holes and back into the annular space 12
between the pipe 12 and the inside of the casing pipe. By the holes
in the upper pipe section A having a larger diameter than further
down means that larger loosened bits of concrete can be cleaned out
and flow through the holes at the top and thereby back into the
annular space 12 to be further carried away. A perforating lance of
this type can have a length of 5 to 50 meters and can be divided
into the sections A,B and C as mentioned above in the context of
explosive power for the individual charges.
[0052] After the charges in the perforating gun/perforating lance
have been fired, it is preferred to release the lance from the rest
of the tool.
[0053] A sealing plug 150, see FIG. 1, can be placed at the bottom
of the pipe and form the bottom of the pipe which shall now be
filled with concrete. This can take place in that the bottom of the
tool is removed and the concrete is pumped in from the surface and
downward through the pipe 30 to fill this and to flow into the
space below and outside the tool. The concrete will flow out
through the perforations 35 and partially fill the space cleaned of
concrete between the outer wall of the pipe and the rock formation
in the bore hole. In this way a direct concrete contact between the
rock formation 14 will be formed.
* * * * *