U.S. patent application number 10/552550 was filed with the patent office on 2006-11-30 for pump plug.
Invention is credited to Wilhelmus Christianus Maria Lohbeck.
Application Number | 20060266512 10/552550 |
Document ID | / |
Family ID | 33185906 |
Filed Date | 2006-11-30 |
United States Patent
Application |
20060266512 |
Kind Code |
A1 |
Lohbeck; Wilhelmus Christianus
Maria |
November 30, 2006 |
Pump plug
Abstract
A pump plug for flowline operations, which pump plug has a
resilient body and a flexible cage having a wear-resistant outer
surface arranged around the resilient body, wherein the flexible
cage has a tube having a first end and a second end, which tube is
provided with a number of slits closed at at least one end.
Inventors: |
Lohbeck; Wilhelmus Christianus
Maria; (Rijswijk, NL) |
Correspondence
Address: |
SHELL OIL COMPANY
P O BOX 2463
HOUSTON
TX
772522463
US
|
Family ID: |
33185906 |
Appl. No.: |
10/552550 |
Filed: |
April 13, 2004 |
PCT Filed: |
April 13, 2004 |
PCT NO: |
PCT/EP04/50505 |
371 Date: |
October 12, 2005 |
Current U.S.
Class: |
166/105 ;
166/207 |
Current CPC
Class: |
F16L 55/38 20130101;
E21B 33/16 20130101; B08B 9/0553 20130101; E21B 23/10 20130101 |
Class at
Publication: |
166/105 ;
166/207 |
International
Class: |
E21B 23/02 20060101
E21B023/02 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 15, 2003 |
EP |
03076115.9 |
Claims
1. Pump plug for flowline operations, which pump plug comprises a
resilient body and a flexible cage having a wear-resistant outer
surface arranged around the resilient body, wherein the flexible
cage comprises a tube having a first end and a second end, which
tube is provided with a repeating pattern of slits closed at at
least one end.
2. Pump plug as claimed in claim 1, wherein the repeating pattern
comprises two slits, a first slit that is closed at the first end
of the tube and open at the second end and a second slit that is
closed at the second end of the tube and open at the first end.
3. Pump plug as claimed in claim 1, wherein the repeating pattern
comprises a first, second and third slit, wherein the first slit is
closed at both ends of the tube, wherein the third slit is aligned
with the second slit, and wherein the second and third slit are
open at opposite ends of the tube and closed in the middle of the
tube.
4. Pump plug as claimed in claim 3, wherein the repeating pattern
is extended in axial direction with its mirror image.
5. Pump plug as claimed in any one of the claims 1-4, wherein the
resilient body comprises a rigid core and a mantle of resilient
material fixed on the outer surface of the rigid core.
Description
[0001] The present invention relates to a pump plug for use in
flowline operations, such as for displacing well tools via a
flowline to a well, for well swabbing operations, for displacing
well tools through a production tubing in a well, or for displacing
a device for expanding a well tubular, such as an expandable
slotted tube or an expandable solid tube. In general, the pump plug
is used to displace a tool through a flowline having a flow
passage, wherein the pump plug is pumped through the flowline.
Examples of such flowlines are flowlines, surface pipe, well
tubulars and so on.
[0002] An example of such a pump plug is described in British
patent specification No. 1 321 152. The known pump plug had been
developed to provide a pump plug that could pass through a flowline
having abrupt changes in diameter of the flow passage. To this end
the known pump plug comprises a cylindrical body, a tubing of
elastomeric material surrounding the body, and rigid fittings
attached to the outer surface of the tubing, wherein the rigid
fittings comprise a first series of segmental fittings spaced-apart
around the centre of the body at right angles to its longitudinal
axis and a second series of fitting, the fittings of the second
series being elongate and each having one end in contact with a
fitting of the first series. Furthermore an elongated fitting is
situated adjacent a space between two fittings of the first series,
and between every two elongated fittings adjacent a space there is
arranged at least one other elongated fitting.
[0003] A disadvantage of the known pump plug is that its
manufacture is complicated, because of the two series of fittings
that have to be made separately and assembled so as to form a
seal.
[0004] It is an object of the present invention to provide a
simpler design of a pump plug.
[0005] To this end the pump plug for flowline operations according
to the present invention comprises a resilient body and a flexible
cage having a wear-resistant outer surface arranged around the
resilient body, wherein the flexible cage comprises a tube having a
first end and a second end, which tube is provided with a repeating
pattern of slits closed at at least one end.
[0006] The invention will now be described by way of example in
more detail with reference to the accompanying drawings,
wherein
[0007] FIG. 1 shows schematically a longitudinal section of the
pump plug according to the present invention;
[0008] FIG. 2 shows schematically a flattened view of part of the
pump plug according to FIG. 1;
[0009] FIG. 3 shows schematically a longitudinal section of an
alternative embodiment of the present invention; and
[0010] FIG. 4 shows schematically a flattened view of part of the
pump plug according to FIG. 3.
[0011] Reference is now made to FIG. 1, showing a first embodiment
of the pump plug 1 for flowline operations according to the present
invention. The pump plug 1 comprises a resilient cylindrical body 2
and a flexible cage 3 having a wear-resistant outer surface 4
arranged around the resilient cylindrical body 2.
[0012] We now refer to FIG. 2 to discuss the flexible cage 3 in
more detail. The flexible cage 3 comprises a tube 5 having a first
end 6 and a second end 7. The tube 5 is provided with a number of
axial slits 9 and 10 closed at at least one end. For the sake of
simplicity the resilient body is not shown in FIG. 2.
[0013] In the embodiment of the invention shown in FIGS. 1 and 2,
the slits 9 and 10 form a repeating pattern of two slits, a first
slit 9 that is closed at the first end 6 of the tube 5 and open at
the second end 7, and a second slit 10 that is closed at the second
end 7 of the tube 5 and open at the first end 6. Adjacent slits
define elongated bars 15 that are joined at their ends by
connection elements 16 that serve as a dam.
[0014] The repeating pattern of the slits 9 and 10 is repeated in
circumferential direction, so that the pattern is symmetrical about
an axis 17 that is parallel to the central longitudinal axis 18 of
the pump plug 1.
[0015] When the pump plug 1 is inserted in a flowline (not shown),
the flexible cage 3 serves as a sliding seal for the pump plug 1
because the connection elements 16 prevent fluids from flowing
along the resilient cylindrical body 2. Since the outer surface 4
of the flexible cage 3 is of wear-resistant material, the flexible
cage 3 forms a protective outer layer on the resilient cylindrical
body 2. The resilient cylindrical body 2 forms a static seal.
[0016] During normal operations, the pump plug of the present
invention is used for displacing a well tool through a flowline
(not shown). The dimensions of the pump plug should be so selected
that the outer surface 4 of the flexible cage 3 is in contact with
the inner surface of the flowline, in such a way that a seal is
formed. Assume that the pump plug 1 is displaced through the
flowline with its first end 6 in the direction of displacement, and
that it encounters a part with a reduced flow passage. When
encountering a reduced flow passage, the following will happen. At
the front end 6 of the pump plug 1 the bars 15 will be forced to
rotate in the direction of arrow 19, so that the ends of the bars
15 at the front end 6 will displace into the resilient cylindrical
body 2. This will enable the pump plug to pass along the part with
the reduced flow passage. The rotation can go on until the gaps of
the slits 10 close. Thus dimensions of the flexible cage 3 have to
be selected such that the pump plug can pass along the smallest
flow passage that is expected in the flowline through which the
pump plug is pumped.
[0017] Reference is now made to FIGS. 3 and 4 showing an
alternative embodiment of the present invention. The pump plug 1a
comprises a resilient cylindrical body 2a, 2b and a flexible cage
3a having a wear-resistant outer surface 4a arranged around the
resilient cylindrical body 2a, 2b, wherein the flexible cage 3a
comprises a tube 5a having a first end 6 and a second end 7, which
tube 5a is provided with a number of slits 41, 42 and 43 that are
closed at at least one end. For the sake of simplicity the
resilient body is not shown in FIG. 4.
[0018] The resilient cylindrical body 2a, 2b comprises a rigid
cylindrical core 2a and a mantle 2b of resilient material fixed on
the outer surface of the rigid core 2a. The use of a rigid core is
particularly suitable for operations in which a large pressure
difference is applied over the pump plug.
[0019] The slits 41, 42 and 43 form a repeating pattern of a first
slit 41 a second 42 and a third slit 43. The first slit 41 is
closed at both ends 6 and 7 of the tube 5a. The third slit 43 is
aligned with the second slit 42. The second slit 42 and the third
slit 43 are open at opposite ends of the tube 5a and closed in the
middle of the tube 5a by connection elements 45. Between the slits
41 and 42 and 43 bars 15a are defined, wherein the bars 15a at
either side of a first slit 41 are joined at their ends by
connection elements 16a. The connection elements 45 and 16a serve
as dams. When the pump plug 1a is inserted in a flowline (not
shown), the flexible cage 3a serves as a sliding seal. The
resilient cylindrical body 2a forms a static seal.
[0020] In an alternative embodiment, the connection elements 16a at
the end 7 of the pump plug can be omitted.
[0021] The repeating pattern of the slits 41, 42 and 43 is repeated
in circumferential direction, so that the pattern is symmetrical
about an axis 17a that is parallel to the central longitudinal axis
18 of the pump plug 1a.
[0022] The repeating pattern of the slits 41, 42 and 43 can be
construed as a repetition of the pattern shown in FIG. 2 in axial
direction, wherein the pattern shown in FIG. 2 is mirrored about a
plane perpendicular to the central longitudinal axis 18. The
intersection of the plane and the plane of drawing of FIG. 2 is a
dot and dash line referred to with reference numeral 46.
[0023] It will be understood that the repeating pattern of the
slits 41, 42 and 43 can be repeated as well in axial direction, by
mirroring the pattern shown in FIG. 4 about a plane perpendicular
to the central longitudinal axis 18. The intersection of the plane
and the plane of drawing of FIG. 4 is a dot and dash line referred
to with reference numeral 47. The mirrored image of slit 41 is
shown in dashed lines and referred to with reference numeral 41a.
In this way the repeating pattern of the slits 41, 42 and 43 is
extended in axial direction with its mirror image.
[0024] The resilient cylindrical body (or the mantle) can be made
of a rubber, and the slits of the tube can be filled with rubber
that is vulcanised together with the rubber of the resilient body
so as to form an integral part.
[0025] In order to obtain more radial resilience, the resilient
cylindrical body (or the mantle) can be provided with
circumferential ridges. On these ridges the flexible cage is
provided. The ridges still prevent fluid from flowing along the
pump plug.
[0026] The slits shown in the embodiments of the present invention
discussed with reference to FIGS. 1-4 extend in axial direction,
however, the slits can as well be arranged under a sharp angle
(less than 45.degree.) with the central longitudinal axis of the
pump plug.
[0027] The slits are so formed that the bars 15 and 15a have a
rectangular cross-section. Alternatively, the cross-section is in
the form of a trapezium, wherein the shorter side points in to the
resilient body.
[0028] The flexible cage discussed above has a wear-resistant outer
surface, this requirement is also met when the tube from which the
flexible cage is made consists of wear-resistant material. Suitable
tube materials are beryllium, titanium, bronze, tool steel or a
ceramic.
[0029] When needed more than one pump plug can be used in series,
or a resilient body can be provided with more than one flexible
cage.
[0030] In order to increase the pressure exerted during normal
operation of the outer surface of the flexible cage on the inner
surface of a flowline, the pump plug shown in FIG. 3 can be
provided with a tapering space between the rigid cylindrical body
2a and the mantle 2b that is closed at one end, so that pressurized
fluid can enter under the mantle 2b.
[0031] In order to push or to pull devices through the flowline,
the pump plug is provided with suitable connectors, which are not
discussed.
[0032] The present invention provides a simple pump plug that is
easy to manufacture because the flexible cage is made of a tube
provided with labyrinth slits. The pump plug according to the
present invention is easy to manufacture and does not have small
parts that can be lost during operation.
* * * * *