U.S. patent application number 14/590085 was filed with the patent office on 2015-07-09 for mandrel for re-pressurization and downhole plugging apparatus.
The applicant listed for this patent is Shuhao Liu. Invention is credited to Shuhao Liu.
Application Number | 20150191992 14/590085 |
Document ID | / |
Family ID | 50813202 |
Filed Date | 2015-07-09 |
United States Patent
Application |
20150191992 |
Kind Code |
A1 |
Liu; Shuhao |
July 9, 2015 |
Mandrel for Re-pressurization and Downhole Plugging Apparatus
Abstract
A mandrel for re-pressurization is disclosed. Said mandrel
comprising a pipe body, connecting threads at both ends of the pipe
body of said mandrel; a containing section and a secondary
pressurizing section on the body pipe, wherein the secondary
pressurizing section has a larger diameter than that of the
containing section; a position of the containing section allows a
compressed seal assembly to be contained in the containing section
when in a setting state; a position of the secondary pressurizing
section allows a internal surface of the seal assembly that is
already compressed to be pressurized again in a compressing state.
A downhole plugging apparatus is disclosed as well.
Inventors: |
Liu; Shuhao; (Chengdu,
CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Liu; Shuhao |
Chengdu |
|
CN |
|
|
Family ID: |
50813202 |
Appl. No.: |
14/590085 |
Filed: |
January 6, 2015 |
Current U.S.
Class: |
166/122 ;
166/243 |
Current CPC
Class: |
E21B 23/06 20130101;
E21B 33/134 20130101; E21B 33/128 20130101 |
International
Class: |
E21B 33/128 20060101
E21B033/128; E21B 33/129 20060101 E21B033/129; E21B 23/06 20060101
E21B023/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 7, 2014 |
CN |
201420006040.2 |
Claims
1. A mandrel for re-pressurization, comprising: a pipe body 1 with
connecting threads 101 at its both ends; a containing section 103
and a secondary pressurizing section 104 on the pipe body 1; a
first position of the containing section 103 on the pipe body 1
allowing the compressed seal assembly to be contained in the
containing section 103; a second position of the secondary
pressurizing section 104 on the pipe body 1 allowing the secondary
pressurizing section 104 to pressurize an internal surface of the
already compressed seal assembly again when in a compressing
state.
2. According to claim 1, the secondary pressurizing section 104 is
a bulging outer surface of the pipe body 1; and, the containing
section 103 is a circular groove on the pipe body 1.
3. The containing section 103 and the secondary pressurizing
section 104 from claim 1, wherein the two are connected and the
secondary pressurizing section 104 is a conical pipe whose diameter
reduces towards the containing section 103.
4. The pipe body 1 from claim 1, further comprising a large
diameter section and a small diameter section; wherein the large
diameter section is the secondary pressurizing section, and the
small diameter section is the containing section.
5. The mandrel for re-pressurization from claim 1, further
comprising a anti-rotation slot 11, which is set on the end of the
secondary pressurizing section 104 and is close to the containing
section 103.
6. The mandrel for re-pressurization from claim 2, further
comprising a anti-rotation slot 11, which is set on the end of the
secondary pressurizing section 104 and is close to the containing
section 103.
7. The mandrel for re-pressurization from claim 3, further
comprising a anti-rotation slot 11, which is set on an end of the
secondary pressurizing section 104 and is close to the containing
section 103.
8. The mandrel for re-pressurization from claim 4, further
comprising a anti-rotation slot 11, which is set on an end of the
secondary pressurizing section 104 and is close to the containing
section 103.
9. A downhole plugging apparatus, comprising: (a) a mandrel for
re-pressurization, (b) a seal assembly arranged on the mandrel for
re-pressurization, (c) a upper anchor assembly and (d) a lower
anchor assembly located respectively at a upper end and a lower end
of the mandrel for re-pressurization; wherein the mandrel for
re-pressurization comprising a pipe body 1, at least one connecting
threads 101 set at both ends of the pipe body 1, a containing
section 103 and a secondary pressurizing section 104 set on the
pipe body 1, wherein a diameter of the containing section 103 is
smaller than that of the secondary pressurizing section 104; A
containing section 103 on the pipe body 1 allowing the the seal
assembly to be compressed and contained in the containing section
103, a second position of the secondary pressurizing section 104 on
the pipe body 1 allowing the secondary pressurizing section 104 to
pressurize an internal surface of the already compressed seal
assembly again when in a compressing state.
10. Claim 9 further comprising the secondary pressurizing section
104 having a bulging external surface of the pipe body 1; and, the
containing section 103 having a circular groove on the pipe body
1.
11. The containing section 103 and the secondary pressurizing
section 104 from claim 9, wherein the two are connected sections,
and the secondary pressurizing section 104 is a conical pipe whose
diameter reduces towards the containing section 103;
12. The downhole plugging apparatus from claim 9, further
comprising an anti-rotation slot 11 set on an end of the secondary
pressurizing section 104 and is close to the containing section
103.
13. The downhole plugging apparatus from claim 10, further
comprising an anti-rotation slot 11 set on an end of the secondary
pressurizing section 104 and is close to the containing section
103.
14. The downhole plugging apparatus from claim 11, further
comprising an anti-rotation slot 11 set on an end of the secondary
pressurizing section 104 and is close to the containing section
103.
15. The downhole plugging apparatus from claim 9, wherein: the
upper anchor assembly includes (a) an upper locking nut 2 screwed
on the connecting thread 101 on an upper part of the mandrel for
re-pressurization, (b) a striper ring 3 contacted with the upper
locking nut 2, (c) multiple slips 4 contacted with the striper ring
3, and (d) a conical slip holder 5 contacted with the slips 4 and
with the seal assembly; the lower anchor assembly includes (a) an
lower locking nut 8 screwed on the thread 101 on a lower end of the
mandrel for re-pressurization mentioned above, (b) multiple slips 4
contacted with the lower locking nut 8, and (c) the conical slip
holder 5 contacted with the slips 4 and with the seal assembly;
wherein teeth widths of thread 101 on the upper locking nut 2 and
teeth widths of a upper end of the mandrel for re-pressurization
are regulated to ensure a maximum failure shearing stresses of the
thread on the upper locking nut 2 and the thread on the upper end
of the mandrel for re-pressurization are equal; wherein teeth
widths of thread 101 on the lower locking nut 8 and teeth widths of
a lower end of the mandrel for re-pressurization are regulated to
ensure a maximum failure shearing stress of the thread 101 on the
lower locking nut 8 is the same with that of threads 101 on the
lower end of the mandrel for re-pressurization.
16. The downhole plugging apparatus from claim 10, wherein: the
upper anchor assembly includes (a) an upper locking nut 2 screwed
on the connecting thread 101 on an upper part of the mandrel for
re-pressurization, (b) a striper ring 3 contacted with the upper
locking nut 2, (c) multiple slips 4 contacted with the striper ring
3, and (d) a conical slip holder 5 contacted with the slips 4 and
with the seal assembly; the lower anchor assembly includes (a) an
lower locking nut 8 screwed on the thread 101 on a lower end of the
mandrel for re-pressurization mentioned above, (b) multiple slips 4
contacted with the lower locking nut 8, and (c) the conical slip
holder 5 contacted with the slips 4 and with the seal assembly;
wherein teeth widths of thread 101 on the upper locking nut 2 and
teeth widths of a upper end of the mandrel for re-pressurization
are regulated to ensure a maximum failure shearing stresses of the
thread on the upper locking nut 2 and the thread on the upper end
of the mandrel for re-pressurization are equal; wherein teeth
widths of thread 101 on the lower locking nut 8 and teeth widths of
a lower end of the mandrel for re-pressurization are regulated to
ensure a maximum failure shearing stress of the thread 101 on the
lower locking nut 8 is the same with that of threads 101 on the
lower end of the mandrel for re-pressurization.
17. The downhole plugging apparatus from claim 11, wherein: the
upper anchor assembly includes (a) an upper locking nut 2 screwed
on the connecting thread 101 on an upper part of the mandrel for
re-pressurization, (b) a striper ring 3 contacted with the upper
locking nut 2, (c) multiple slips 4 contacted with the striper ring
3, and (d) a conical slip holder 5 contacted with the slips 4 and
with the seal assembly; the lower anchor assembly includes (a) an
lower locking nut 8 screwed on the thread 101 on a lower end of the
mandrel for re-pressurization mentioned above, (b) multiple slips 4
contacted with the lower locking nut 8, and (c) the conical slip
holder 5 contacted with the slips 4 and with the seal assembly;
wherein teeth widths of thread 101 on the upper locking nut 2 and
teeth widths of a upper end of the mandrel for re-pressurization
are regulated to ensure a maximum failure shearing stresses of the
thread on the upper locking nut 2 and the thread on the upper end
of the mandrel for re-pressurization are equal; wherein teeth
widths of thread 101 on the lower locking nut 8 and teeth widths of
a lower end of the mandrel for re-pressurization are regulated to
ensure a maximum failure shearing stress of the thread 101 on the
lower locking nut 8 is the same with that of threads 101 on the
lower end of the mandrel for re-pressurization.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority under 35 U.S.C.
.sctn.119 to Chinese patent application 201420006040.2, filed Jan.
7, 2014, the disclosure of which is incorporated herein by
reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable
THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT
[0003] Not Applicable
INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT
DISC
[0004] Not Applicable
BACKGROUND
[0005] The present application claims priority under 35 U.S.C.
.sctn.119 to Chinese patent application 201420006040.2, filed Jan.
7, 2014, the disclosure of which is incorporated herein by
reference.
1. FIELD OF THE INVENTION
[0006] The present invention relates to a downhole plugging
apparatus, and more particularly to a mandrel for re-pressurization
used for downhole blocking in oil-gas productions and mineral
mining fields.
2. GENERAL BACKGROUND OF THE INVENTION
[0007] In the oil-gas productions and mineral mining processes, the
downhole blocking is necessary. Currently, the most common way of
the downhole blocking is by adopting a plugging apparatus to block
a wellbore, and said apparatus is usually composed of a mandrel, an
anchor structure and a seal structure that is set on the mandrel;
after the apparatus being put into a predetermined position in a
well, it would be fixed through squeezing the anchor structure to
have it anchored into a wellbore wall. Meanwhile, the anchor
structure would squeeze the seal structure, which leads to its
radial expansion, and then to completion of sealing.
[0008] For the downhole plugging apparatus described hereabove, the
anchor structure at a lower end of the mandrel is relatively static
to the mandrel itself during a setting process; by applying force
to an upper end of the anchor structure, it would move downwards;
by pulling the mandrel, the lower anchor structure would move
upwards, thus a seal component is pressed to expand in a radial
direction so that it would be sealed against the wellbore wall.
[0009] After the setting is done, a high pressure from a upper well
would push the mandrel move downward while the anchor structure and
the seal structure are fixed statically, thus the plugging
apparatus is kept in a compressing state.
[0010] In oil-gas productions and mineral mining processes, the
downhole plugging apparatus needs to be drilled out. During the
drilling process, a drill would contact with and drill along the
mandrel for re-pressurization.
[0011] There is a problem that the mandrel for re-pressurization
could possibly rotate together with the drill, thus the torque can
not be fully used upon the mandrel for re-pressurization, and the
drilling efficiency will be impacted.
[0012] For the downhole plugging apparatus, their locking nuts and
their mandrels are usually manufactured with different materials,
but their threads are made as normal threads with the same shape
and dimension per standards, which results in different maximum
failure shearing strength between the threads on the mandrel and
threads on the locking nuts. And the problem is that the thread
with a relatively small maximum failure shearing strength would
become a weak part of the downhole plugging apparatus, the weak
part is easily to be damaged in processes of setting or
compressing, which would result in a failed connection between the
locking nuts and the mandrel, and eventually lead to breakage of
the downhole plugging apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] For a further understanding of the nature, objects and
advantages of the present invention, reference should be had to the
following detailed description, read in conjunction with the
following drawings, wherein like reference numerals denote like
elements and wherein:
[0014] FIG. 1 is a first kind of structural diagram of a mandrel
for re-pressurization;
[0015] FIG. 2 is a second kind of structural diagram of a mandrel
for re-pressurization;
[0016] FIG. 3 is a third kind of structural diagram of a mandrel
for re-pressurization;
[0017] FIG. 4 is a structural diagram of a downhole plugging
apparatus
[0018] FIG. 5 is a structural diagram of a downhole plugging
apparatus in a setting state;
[0019] FIG. 6 is a structural diagram of a downhole plugging
apparatus in a compressing state;
[0020] FIG. 7 is a structural diagram of a upper anchor
assembly;
[0021] FIG. 8 is a structural diagram of a lower anchor
assembly;
[0022] FIG. 9 is a structural diagram of a upper locking nut;
[0023] FIG. 10 is a structural diagram of a lower locking nut;
[0024] FIG. 11 is a structural diagram of a striper ring;
[0025] FIG. 12 is a structural diagram of a slips;
[0026] FIG. 13 is a structural diagram of a conical slip
holder;
[0027] Wherein the names of related components are as below: [0028]
1--pipe body, 2--upper locking nut, 3--striper ring, 4--slips,
5--conical slip holder, 6--middle rubber sleeve, 7--end rubber
sleeve, 8--lower locking nut, 9--release lever, 10--well, 11--anti
rotation slot, 31--conical surface, 32--separate protrusion,
51--conical surface, 52--separate protrusion, 81--conical surface,
82--separate protrusion, 101--connecting thread, 102--drilling
hole, 103--containing section, 104--secondary pressurizing
section.
DESCRIPTION OF THE PRESENT INVENTION
[0029] One objective of the present invention is to provide a
mandrel for re-pressurization to further improve sealing
performance of a downhole plugging apparatus.
[0030] Another objective of the present invention is to provide the
downhole plugging apparatus with superior sealing performance.
[0031] Accordingly, the mandrel for re-pressurization comprising a
pipe body, at least one connecting threads at both ends of the pipe
body; a containing section and a secondary pressurizing section on
the pipe body, wherein the secondary pressurizing section has a
larger diameter than that of the containing section; a position of
the containing section allows a seal assembly to be compressed and
contained in the containing section when in a setting state; a
position of the secondary pressurizing section allows an internal
surface of the seal assembly, when compressed, to be pressurized by
the secondary pressurizing section again when in a compressing
state.
[0032] With the mandrel for the re-pressurization, the sealing
performance of the downhole plugging apparatus can be greatly
improved. Its working principle is as followed:
[0033] When in the setting state, the anchor assembly on the
mandrel for the re-pressurization would compress the seal assembly
so that it contracts with the anchor assembly in an axial direction
and expands in a radial direction, while the seal assembly is
pushed into the containing section on the mandrel which has a
smaller diameter, and the anchor assembly would continue to
compress the seal assembly so that it reduces its length in the
axial direction and increases its diameter in the radial direction;
after setting is done, the axial length of the seal assembly shall
remain unchanged at this state.
[0034] When in compressing state, the mandrel for the
re-pressurization would move downwards in a wellbore under
pressure, and the secondary pressurizing section would contact with
the seal assembly. Due to the relatively larger diameter of the
secondary pressurizing section, it would compress the seal assembly
again and a radial space of the seal assembly would become small,
thus an internal pressure acting upon the seal assembly would
increase and a superior sealing performance can be achieved for the
downhole plugging apparatus.
[0035] According to one embodiment of the present invention, the
secondary pressurizing section is a bulging outer surface on the
pipe body and the containing section is a circular groove on the
pipe body.
[0036] According to one embodiment of the present invention, the
containing section and the secondary pressurizing section are
connected sections. The secondary pressurizing section is a conical
pipe section whose diameter reduces towards the containing
section.
[0037] According to one embodiment of the present invention, the
pipe body is composed of a first end with a large diameter and a
second end with a small diameter; the first end is the secondary
pressurizing section, and the second end is the containing
section.
[0038] According to one embodiment of the present invention, an
anti-rotation slot is designed and set at the end of the secondary
pressurizing section and is close to the containing section.
[0039] According to yet another embodiment of the present
invention, the anti-rotation slot is provided on the mandrel for
re-pressurization. After the seal assembly is compressed, a part of
the seal assembly would be extruded into the anti-rotation slot,
and due to the tight contact between the seal assembly and the
wellbore wall, slipping between an outer surface of the mandrel and
the inner surface of the seal assembly can be avoided, thus the
secondary pressurizing section can be prevented from rotating with
the drill, and the torque can fully act upon the mandrel for the
re-pressurization, which improves drilling efficiency.
[0040] Yet another objective of the present invention is achieved
through the following technical scheme:
[0041] The downhole plugging apparatus consists of (a) a two-stage
mandrel for the re-pressurization, (b) the seal assembly arranged
on the mandrel for the re-pressurization, (c) a upper anchor
assembly and (d) a lower anchor assembly located respectively at
two ends of the two-stage mandrel.
[0042] The two-stage mandrel for the re-pressurization comprising
the pipe body, the connecting threads at both ends of the pipe
body; the containing section and the secondary pressurizing section
on the body pipe, wherein the secondary pressurizing section has a
larger diameter than that of the containing section; the position
of the containing section allows the compressed seal assembly to be
contained in the containing section when in the setting state; the
position of the secondary pressurizing section allows the internal
surface of the already compressed seal assembly to be pressurized
again when in the compressing state.
[0043] Further, the secondary pressurizing section is the bulging
outer surface of the pipe body and the containing section is the
circular groove on the pipe body.
[0044] Further, said containing section and said secondary
pressurizing section are the connected sections; the secondary
pressurizing section is the conical pipe section whose diameter
reduces towards the containing section;
[0045] In other words, the pipe body consists of a first end with a
large diameter and a second end with a small diameter, the end with
a large diameter is the secondary pressurizing section and the end
with a small diameter is the containing section.
[0046] Preferably, the anti-rotation slot is set on the end of the
secondary pressurizing section and is close to the containing
section.
[0047] Preferably, the upper anchor assembly includes (a) an upper
locking nut that connects with the upper end of the mandrel for the
re-pressurization by the threads, (b) a striper ring that contacts
with the upper locking nut, (c) a plurality of slips that contact
with the striper ring, (d) a conical slip holder that contacts with
the slips, wherein the conical slip holder also contacts with the
seal assembly.
[0048] The lower anchor assembly includes (a) a lower locking nut
that connects to a lower end of the said mandrel for
re-pressurization, (b) the multiple slips that contacts with the
lower locking nut, (c) the conical slip holder that contacts with
the slips; the conical slip holder also contacts the seal
assembly.
[0049] The teeth widths of the thread threaded onto the upper
locking nut and the teeth widths of the thread threaded onto the
upper end of the mandrel for re-pressurization are regulated to
ensure that their maximum failure shearing stresses are equal.
[0050] The teeth widths of the thread threaded onto the lower
locking nut and the teeth widths of the thread threaded onto the
lower end of the mandrel for re-pressurization are regulated to
ensure their maximum failure shearing stresses are equal.
[0051] According to yet another embodiment of the present
invention, the dimensions of the teeth widths for threads of the
upper locking nut and the lower locking nut, and dimensions for the
connecting threads on the mandrel for re-pressurization are
adjusted to ensure their maximum shearing stress bring equal.
Breakages caused by weak part can be avoided and a better
reliability of the downhole plugging apparatus can be obtained in
the condition when the locking nuts and the mandrel are made of
different materials.
[0052] Accordingly, the advantages and benefits for this utility
are as follow:
[0053] 1. The mandrel for re-pressurization is used as the downhole
plugging apparatus, when it is in the setting state, the mandrel
for re-pressurization would provide more space for the seal
assembly in radial direction, and the axial length of the seal
assembly can be compressed shorter; when it is in the compressing
state, the secondary pressurizing section would compress the seal
assembly and increase the internal pressure act upon the seal
assembly, leading to a tighter sealing and thus improves the
sealing performance of the plugging apparatus.
[0054] 2. After the seal assembly is compressed, part of the seal
assembly would be extruded into the anti-rotation slot and due to
the close contact between the seal assembly and the wellbore wall,
there would be no slipping between the mandrel and seal assembly,
thus the anti-rotation slot on the mandrel for re-pressurization
can effectively prevent the secondary pressurizing section or the
mandrel from rotating with the drill during drilling, so that the
torque can be fully used upon the mandrel for re-pressurization,
which greatly improves the drilling efficiency.
[0055] 3. The downhole plugging apparatus, which adopting a mandrel
for re-pressurization, would provide more space in radial direction
for the seal assembly when in the setting state, also the axial
length of the seal assembly can be compressed shorter; and when in
the compressing state, the secondary pressurizing section would
extrude the seal assembly and increase the internal pressure act
upon seal assembly so that it could seal against the wellbore wall
more firmly, thus greatly improves the sealing performance of the
apparatus for plugging.
[0056] 4. Adjusting the dimensions of the teeth widths for threads
on the upper locking nut, threads on the lower locking nut and the
connecting threads on the mandrel for re-pressurization to ensure
the maximum failure shearing strength are equal, and in condition
that the locking nuts and the mandrel are made of different
materials, the breakage caused by the weak part (the section with
relatively small failure shearing stress) can be solved and a
better reliability of downhole plugging apparatus can be
achieved.
[0057] To provide a better understanding for this utility,
embodiments will be illustrated hereafter.
Embodiment 1
[0058] The mandrel for re-pressurization comprising the pipe body
1, the connecting threads 101 at both ends of the pipe body 1; the
containing section 103 and the secondary pressurizing section 104
set on the pipe body 1; the secondary pressurizing section 104 has
a larger diameter than that of the containing section 103; the
position of the containing section 103 allows the compressed seal
assembly to be contained in the containing section 103 when in the
setting state; the position of the secondary pressurizing section
allows the internal surface of the already compressed seal assembly
to be pressurized again when in the compressing state.
[0059] Accordingly, working principles of the sealing performance
of the downhole plugging apparatus is as followed:
[0060] In setting state, the anchor assembly on the mandrel for
re-pressurization compresses the seal assembly to get it compressed
in the axial direction and expanded in the radial direction,
meanwhile, the whole seal assembly is pushed into the containing
section 103 which has smaller diameter, this means a larger radial
space for the seal assembly, and the anchor assembly would further
compress the seal assembly to make it becoming shorter in the axial
direction and larger in the radial direction. After setting is
done, the axial length of the seal assembly will remain
unchanged.
[0061] When in compressing state, the mandrel for re-pressurization
would move downwards in the wellbore under pressure, and the
secondary pressurizing section 104 would reach and compress the
seal assembly, due to the relatively larger diameter of the
secondary pressurizing section 104, the radial space of the seal
assembly would become smaller, thus the internal pressure acting
upon the seal assembly would increase and a tighter sealing
performance can be achieved for the downhole plugging
apparatus.
[0062] In this embodiment, the containing section 103 and the
secondary pressurizing section 104 could be set in various forms,
such as the following three:
[0063] First, as shown in FIG. 1, the secondary pressurizing
section 104 is the bulging outer surface of the pipe body 1; the
containing section 103 is the circular groove on the pipe body
1.
[0064] While in setting state, the anchor assembly on the mandrel
for re-pressurization would compress the seal assembly and get it
compressed in the axial direction and expanded in the radial
direction, meanwhile, the whole seal assembly would be pushed into
the circular groove which has a smaller diameter, this means a
larger radial space for the seal assembly, and the anchor assembly
would further compress the seal assembly so that it contracts in
the axial direction and expands in the radial direction. Once
setting is done, the axial length of the seal assembly will remain
unchanged.
[0065] When in compressing state, the pressure from the upper well
would push the mandrel for re-pressurization move downwards in the
wellbore, and the secondary pressurizing section 104 will reach and
compress the seal assembly, due to the relatively larger diameter
of the secondary pressurizing section 104, the radial space of the
seal assembly would become smaller, thus the internal pressure act
upon the seal assembly would increase and a tighter sealing
performance can be achieved for the downhole apparatus for
plugging.
[0066] Second, as shown in FIG. 2, the containing section 103 and
the secondary pressurizing section 104 are the connected sections,
and the secondary pressurizing section 104 is a conical pipe
section whose diameter reduces towards the containing section
103.
[0067] Accordingly, same as the working principle of the first
embodiment described in Embodiment 1, while in setting state, the
seal assembly is located within the containing section, this means
it can be compressed in the axial direction and expanded in the
radial direction greatly; while in compressing state, the secondary
pressurizing section 104 would gradually insert into the seal
assembly and results in a smaller space for the containing section
for the seal assembly, and the secondary pressurizing section 104
would further extrude the seal assembly, thus the internal pressure
act upon the seal assembly would be increased, leading to a better
sealing performance.
[0068] Third, as shown in FIG. 3, the pipe body 1 is composed of
the first end with the large diameter and the second end with the
small diameter; the large diameter part is the secondary
pressurizing section 104 and the small diameter part is the
containing section 103.
[0069] The containing section 103 and the secondary pressurizing
section 104 are not limited to the three forms mentioned above;
other embodiments which can achieve the re-pressurizing for the
seal assembly by using a containing section 103 with small diameter
and a secondary pressurizing section 104 with large diameter are
also protected by the present invention.
[0070] Preferably, the mandrel is designed with a drilling hole 102
on the pipe body 1 in order to drill out the downhole plugging
apparatus easily.
Embodiment 2
[0071] As shown in FIG. 1.about.FIG. 3, the anti-rotation slot 11
is set on the the secondary pressurizing section 104 of the mandrel
for re-pressurization and is close to the containing section
103.
[0072] After being compressed, part of the seal assembly can be
extruded into the anti rotation slot 11 and due to the close
contact between the seal assembly and the wall, the mandrel for
re-pressurization would be prevented from rotating with the drill,
thus the torque can fully act upon the mandrel for
re-pressurization, which means the improvement of drilling
efficiency.
Embodiment 3
[0073] The downhole plugging apparatus consists of (a) the mandrel
for re-pressurization, (b) the seal assembly arranged on the
mandrel for re-pressurization, (c) the upper anchor assembly and
(d) the lower anchor assembly located at the two ends of the
two-stage mandrel respectively.
[0074] The mandrel for re-pressurization consists of the containing
section 103 and the secondary pressurizing section 104; at least
one connecting threads 101 at both ends of the pipe body 1; the
position of the containing section 103 allows the compressed seal
assembly to be contained in the containing section 103; the
position of the secondary pressurizing section 104 on the pipe body
1 enables the secondary pressurizing section 104 to pressurize the
internal surface of the already compressed seal assembly again when
it is in the compressing state.
[0075] The working principle of this embodiment is as followed:
[0076] While working, the upper end of the mandrel for
re-pressurization is connected to a release lever 9.
[0077] As shown in FIG. 5, the release lever 9 is gripped by an
external claw, and the external claw includes a clamping device
contacted with the anchor assembly. The clamping device would apply
pressure on the upper anchor assembly, so that the upper anchor
assembly and the lower anchor would compress the seal assembly to
have it compressed in the axial direction and expanded in the
radial direction; then the seal assembly would be pushed into the
containing section 103; as a result, both the upper anchor assembly
and the lower anchor assembly would anchor into the wellbore wall
10, so that the downhole plugging apparatus can be fixed in the
well, and the seal assembly is pressed against the wellbore wall 10
tightly to achieve the tight sealing performance. Then the release
lever 9 will be cut when being pulled, and the downhole plugging
apparatus will be left in the well. Since both the upper anchor
assembly and the lower assembly are fixed on the wellbore wall 10,
the axial length of the seal assembly will remain unchanged.
[0078] As shown in FIG. 6, the pressure from the upper well would
push the mandrel for re-pressurization move downwards in the
wellbore, the downhole plugging apparatus is in the compressing
state, and the secondary pressurizing section 104 would reach and
compress the seal assembly. Due to the relatively larger diameter
of the secondary pressurizing section, the radial space of the seal
assembly would become small, thus the internal pressure act upon
the seal assembly would increase and the tightersealing performance
can be achieved for the downhole plugging apparatus.
Embodiment 4
[0079] As shown in FIG. 4 and FIG. 7, the upper anchor assembly
includes (a) the upper locking nut 2 screwed on the connecting
thread 101 on the upper end of the said mandrel for
re-pressurization, (b) the striper ring 3 contacted with the upper
locking nut 2, (c) the multiple slips 4 contacted with the striper
ring 3 and (d) the conical slip holder 5 which contacts the slips 4
as well as the the seal assembly.
[0080] As shown in FIG. 9, the thread hole in the upper locking nut
2, and it connects with the mandrel for re-pressurization by the
connecting thread 101.
[0081] As shown in FIG. 11, the striper ring 3 sleeves the mandrel
for re-pressurization, and it moves axially along the mandrel for
re-pressurization under stress; a first face that the striper ring
3 contacts with the upper locking nut 2 is plane; an opposite face
of the striper ring 3 is a conical surface 31, there are several
separate protrusions 32 on the conical surface 31. As shown in FIG.
12, an end surface of the slip 4 is connected with the conical
surface 31 and each of the slips 4 is set between two adjacent
separate protrusions 32.
[0082] As shown in FIG. 13, the conical slip holder 5 sleeves on
the mandrel for re-pressurization, and it can move axially along
the mandrel under stress, the end face of conical slip holder 5
facing with the striper ring 3 is a conical face 51; the multiple
separate protrusions 52 set on the conical surface 51, the other
end of the slips 4 are connected with the conical surface 51 and
are set between two adjacent separate protrusions 52; the other end
face of the conical slip holder 5 is a flat surface which is in
contact with the seal assembly.
[0083] As shown in FIG. 4 and FIG. 8, the lower anchor assembly
includes (a) the lower locking nut 8 screwed on the connecting
thread 101 on the lower part of the said mandrel for
re-pressurization, (b) the slips 4 that are in contact with the
lower locking nut 8 and (c) the conical slip holder 5 that is in
contact with the slips 4, the conical slip holder 5 is in contact
with the seal assembly.
[0084] As shown in FIG. 10, the thread hole is in the lower locking
nut 8, and it connects with the lower end of the mandrel for
re-pressurization by the connecting thread 101; the end face of the
lower locking nut 8 close to the seal assembly is a conical surface
81; there are multiple separate protrusions 52 on the conical
surface 81. As shown in FIG. 12, the ends of the slips 4 are
connected with the conical surface 81, and each of the slips 4 is
set between the two adjacent separate protrusions 52.
[0085] As shown in FIG. 13, the conical slip holder 5 sleeves on
the mandrel for re-pressurization, and it can move axially along
the mandrel under stress, the end face of conical slip holder 5
connected to the striper ring 3 is the conical face 51; the
separate protrusions 52 are set on the conical surface 51, the
other ends of the slips 4 are in connected with the conical surface
51 and are set between two adjacent separate protrusions 52. The
other end face of the conical slip holder 5 is a flat surface which
is in contact with the seal assembly.
[0086] While working, the mandrel for re-pressurization is first
fixed via the release lever 9, then the force is applied to the
striper ring 3, the striper ring 3 together with the lower locking
nut 8 will push the slips 4 moving along the conical surface 51 of
the conical slip holder 5; at the same time, the pressure is
transmitted to the seal assembly through the conical slip holder 5,
and the seal assembly is compressed axially and expands radially.
Finally, the teeth of slips 4 would anchor into the wellbore wall
10, keeping the seal assembly in a compressing state and sealing is
accomplished.
Embodiment 5
[0087] This embodiment is based on embodiment 3 or 4, and it
provides a further statement of the containing section 103 and the
secondary pressurizing section 104.
[0088] The containing section 103 and the secondary pressurizing
section 104 has a variety of forms, such as the following
three:
[0089] First, as shown in FIG. 1, the secondary pressurizing
section 104 is the bulging outer surface of the pipe body 1 and the
containing section 103 is the circular groove on the pipe body
1.
[0090] Second, as shown in FIG. 2, the containing section 103 and
the secondary pressurizing section 104 are connected sections, and
the secondary pressurizing section 104 is a conical pipe section
whose diameter reduces towards the containing section 103.
[0091] Third, as shown in FIG. 3, the pipe body 1 is composed of a
large diameter section and a small diameter section, the large
diameter section is the secondary pressurizing section 104, and the
small diameter section is the containing section 103.
[0092] Further, the containing section 103 and the secondary
pressurizing section 104 are not limited to the three forms
mentioned above. Other embodiments that can achieve two-stage
pressurizing by using a containing section with small diameter and
a secondary pressurizing section with large diameter are also
protected by this utility model.
Embodiment 6
[0093] The anti-rotation slot 11 is set on the end of the secondary
pressurizing section 104 and is close to the containing section
103.
Embodiment 7
[0094] The seal assembly consists of a middle rubber sleeve 6 which
sleeves the mandrel for re-pressurization and an end rubber sleeves
7 which are arranged at both ends of middle rubber sleeve 6.
Embodiment 8
[0095] The teeth widths of the thread 101 on the upper locking nut
2 and the teeth widths of the upper end of the mandrel for
re-pressurization are regulated to ensure the maximum failure
shearing stress of the thread 101 on the upper locking nut 2 is the
same as that of thread on the upper end of the mandrel for
re-pressurization.
[0096] The teeth widths of the thread 101 on the lower locking nut
8 and the lower end of the mandrel for re-pressurization is
regulated to ensure the maximum failure shearing stress of the
thread 101 on the lower locking nut 8 is the same with that of
thread on the lower end of the mandrel for re-pressurization.
[0097] The thread of the upper locking nut 2, the thread of the
lower locking nut 8 and the connecting thread 101 could be triangle
thread, trapezoidal thread or other forms of threads.
[0098] In this embodiment, the dimensions of the teeth widths for
thread of the upper locking nut 2, the lower locking nut 8 and the
connecting thread 101 are adjusted so that their maximum shearing
stress is equal. For example, if the mandrel for re-pressurization
is made of metal with high strength, the upper locking nut 2 and
the lower locking nut 8 is made of composite materials with lower
strength, then the teeth width of the connecting thread 101 should
be designed smaller than the counterparts of the upper locking nut
2 and the lower locking nut 8, so that the maximum shearing stress
of them are equal.
[0099] The objective of this embodiment is to prevent the downhole
plugging apparatus from breaking caused by failure of the thread
connection.
[0100] The thread of the upper locking nut 2, the thread of the
lower locking nut 8 and the connecting thread 101 of the mandrel
for re-pressurization are only applied by the force along the axis
of the mandrel for re-pressurization and the direction of the force
is from the middle towards the both ends. Therefore, to improve the
strength of the thread of the upper locking nut 2, the thread of
the lower locking nut 8 and the connecting thread 101, we can adopt
one-way thread for all of these threads, such as buttress
thread.
[0101] In a condition that all of the upper locking nut 2, the
lower locking nut 8 and the connecting thread 101 are buttress
thread, the direction of the force applied on the teeth face is
inclined and points to the inside of the mandrel.
[0102] While the present invention has been disclosed with respect
to a limited number of embodiments, those skilled in the art will
appreciate numerous modifications and variations there-from, it is
intended that the appended claims cover all such modifications and
variations as fall within the spirit and scope of this
invention.
* * * * *