Note: Descriptions are shown in the official language in which they were submitted.
CA 02291991 1999-12-10
1 "JUNK BASKET AND METHOD FOR USE"
2
3 FIELD OF THE INVENTION
4 The present invention relates to apparatus and methods for collecting
debris so as to protect a well bore and its contents during well bore
operations, such
6 as perforating the well. Particularly, a junk basket is disclosed which is
run into the
7 well bore atop a bridge plug.
8
9 BACKGROUND OF THE INVENTION
After casing is placed in a well bore, various operations can be
11 performed. Workover operations, including perforation of the casing produce
12 significant quantities of debris. It is usually desirable to isolate those
portions of the
13 well which are not being worked on. Where the unaffected zones are lower in
the
14 well bore, a bridge plug is run in and set in position below the intended
work zone
and above the zone to be protected. A junk basket is subsequently placed on,
or
16 above, the bridge plug to collect debris generated from the operation.
17 For instance, in the case where hydraulic fracturing of a formation is
18 performed at an upper set of perforations in the casing, in a first trip, a
retrievable
19 bridge plug is set below the upper perforations to block the lower well
bore. A
setting tool is run in from the surface carrying the bridge plug. An insertion
rod
21 associated with the setting tool is attached to, and holds, the plug in
position while
22 an outer sleeve of the setting tool imparts a downward force, setting the
sealing
23 elements and slips. Then, a link is sheared to separate the insertion rod
from the
1
CA 02291991 1999-12-10
1 plug. In a second trip, a junk basket is lowered to sit atop the set bridge
plug. The
2 workover operation is performed. Frac balls or ball sealers are often used
in
3 fracturing so as to gravitate to and temporarily block some perforations for
better
4 distribution of fracturing fluid and proppant. Ball sealers must be later
removed or
they become a significant nuisance. After the workover, in a third trip, a
cleanout
6 tool is run into the hole, circulating fluid for washing light debris away
from the top of
7 the junk basket and carrying it uphole for removal at the surface. In a
fourth trip, a
8 retrieving tool is run in which includes a fish for attaching to the junk
basket and
9 fishing it out of the well.
The junk basket typically contains debris including particulate matter
11 (sand) and ball sealers. As required for the particular instance, a fifth
trip may be
12 expended to retrieve the bridge plug.
13 In summary, without including additional trips resulting from
14 experiencing problems, a least five trips are performed: run in and set the
bridge
plug; run in junk basket; cleanup well bore to junk basket, retrieve junk
basket,
16 retrieve the bridge plug.
17 Each run in operation and trip out costs time and correspondingly,
18 money. Beside the number of trips, several difficulties are associated with
the
19 above-described conventional operation. As the diameter of a junk basket is
necessarily close to that of the casing to which it is fitted, the sand from
the
21 workover tends to pack between the junk basket and the casing, binding and
22 generally making it difficult to pull the basket during retrieval.
Additional difficulties
23 are associated with the means for retrieval. As stated, junk baskets fit
closely within
2
CA 02291991 1999-12-10
1 the well casing. It is known with conventional baskets to use a central and
upward
2 projection or fish-neck. To maximize basket capacity, the fish neck diameter
is
3 minimized. The retrieval tool must locate and connect to the fish-neck,
however it
4 must do so without laterally deflecting it and bending it, which jeopardizes
chances
of retrieval. Another problem with the conventional baskets is the lack of
reliable
6 feedback which enables the operator to ascertain when the fish has actually
latched
7 onto the junk basket. Baskets are light and are not normally detected. Many
a trip
8 out is performed to find nothing on the end of the retrieving tool,
requiring one or
9 more additional fishing trips.
For addressing both economics and reliability issues, there is a need
11 for an improved junk-basket and means of installing and retrieving same.
12
13 SUMMARY OF THE INVENTION
14 A novel junk basket is provided and a method of operation, which in a
preferred form, is attached to a bridge plug with shear pins and set
simultaneously
16 therewith, thus requiring only a basket/plug setting step, a basket
retrieving step
17 shearing the pins, and a plug retrieving step; not the five or more steps
of the prior
18 art. Further, the preferred basket maximizes debris capacity, makes fishing
retrieval
19 more reliable, latching of the basket is positively identified and the
basket is more
easily withdrawn from a cased well bore.
21 The preferred apparatus is a basket having a tubular sleeve with a
22 substantially open bore therethrough, the sleeve fitting closely in the
casing. The
23 top end of the basket forms a robust internal latch and adjacent the top
end are fluid
3
CA 02291991 1999-12-10
1 slots to the casing. The basket has a bottom or floor which is movable in
the bore
2 but cannot escape the basket's bottom end. In the well bore, the basket
floor is
3 supported by a protuberance such as the bridge plug thereby spacing the
floor
4 upwardly in the basket bore. Once filled with debris and latched with a
retrieving
tool, the junk basket is lifted upwardly from the protuberance causing loss of
support
6 for the floor and allowing it to fall to the bottom of the basket where its
fall is
7 arrested, but not before the volume within the basket is suddenly increased
for the
8 loosening of the collected debris in the basket and loosening of the packed
debris
9 between the sleeve and casing through the slots, and thereby aiding in
recovery.
In a broad apparatus aspect then, a junk basket for collecting debris
11 comprises:
12 ~ a tubular sleeve which fits within a well bore, the sleeve having a
13 bore extending axially therethrough and having top and bottom
14 ends;
~ an internal retrieving latch formed at the top end of the sleeve;
16 ~ a basket floor for substantially blocking the sleeve's bore and being
17 axially movable therein;
18 ~ an internal shoulder formed within the sleeve's bottom end for
19 supporting the basket floor preventing its passage downwardly
therethrough, the basket floor being operative between at least two
21 positions being,
22 (1 ) a first collection position wherein basket floor is
23 supported and spaced somewhat upwardly from the sleeve's
4
CA 02291991 1999-12-10
1 bottom end for forming a collection volume for collecting debris,
2 and
3 (2) a second retrieving position wherein the basket floor
4 falls to the internal shoulder when the junk basket is lifted by a
retrieving device, thereby increasing the collection volume and
6 whereby the collected debris is loosened within and outside the
7 sleeve permitting ease of retrieving.
8 Preferably the basket floor is supported on a bridge plug anchored in
9 the well bore. More preferably, the sleeve is attached to the bridge plug
with shear
pins so that, once the retrieving latch is engaged, then at predetermined
weight of a
11 retrieving string, the pins shear and the operator is clearly aware the
basket was
12 caught and will be retrieved.
13 More preferably, the basket floor is formed with an axial port so an
14 insertion rod can be connected to the bridge plug through the floor, the
basket
thereby being capable of being run in with the bridge plug and does not
interfere
16 with the setting of the plug. Provision for axial slots through the sleeve
permits fluid
17 communication with the casing annulus which can aid in the retrieval
process.
18 The above apparatus enables a novel method of setting and retrieving
19 a bridge plug and junk basket simultaneously.
5
CA 02291991 1999-12-10
1 In a broad method aspect then, a downhole tool, such as a bridge plug
2 is deployed simultaneously with a junk basket using a setting tool and
insertion rod,
3 the downhole tool having a top protuberance comprising the steps of:
4 ~ connecting a junk basket to the top of the downhole tool, the junk
basket having a tubular sleeve with top and bottom ends, an open
6 bore extending axially through from the top end through to the
7 bottom end, and having a basket floor which blocks the sleeve's
8 bore, the insertion rod passing through the sleeve's bore and to an
9 axial port in the basket floor, and a ball which is movable within the
sleeve's bore and is capable of blocking the axial port;
11 ~ releasably connecting the insertion rod to a rod connection at the
12 top protuberance through the sleeve's bore;
13 ~ inserting the insertion rod, junk basket and downhole tool into the
14 well bore;
~ setting the downhole tool to anchor it within the well bore; and
16 ~ releasing the insertion rod from the rod connection so that the junk
17 basket remains in the well bore above the downhole tool and the ball
18 is able to block the axial port.
19 Preferably, the sleeve has one or more fluid ports for communication
between its bore and the well bore and basket floor is movable within the
sleeve's
21 bore and initially spaced upwardly by the protuberance so that when the
basket is
22 retrieved, the ball is blocking the axial port and the floor drops,
increasing the
23 basket volume and loosening debris within and outside the basket. More
6
CA 02291991 1999-12-10
1 preferably, the basket's sleeve is attached to the downhole tool with shear
pins for
2 enabling confirmation of the latching of a retrieval tool and thus
completing the
3 method for deploying, collecting debris and retrieving the debris.
4
BRIEF DESCRIPTION OF THE DRAWINGS
6 Figure 1 is a cross-sectional, axially compressed view of a junk basket
7 according to one embodiment of the present invention;
8 Figures 2a - 2b are cross-sectional views of the junk basket
9 accordingly to Fig. 1, with and without the setting tool assembly. More
specifically:
Figure 2a illustrates setting the bridge plug and junk basket, using the
11 junk basket as a setting sleeve;
12 Figure 2b illustrates the junk basket on the bridge plug after removal
13 of the setting tool;
14 Figure 3a is a cross-sectional view illustrating the collection of debris
in the junk basket, including ball sealers, the bridge plug detail is omitted
to clarify
16 the junk basket components;
17 Figure 3b is a close-up of the slot area according to Fig. 3a illustrating
18 packing of sand between the sleeve and casing;
19 Figure 4a is a cross-sectional view illustrating a retrieval tool inserted
into a well bore, just above the junk basket (no debris is shown);
21 Figure 4b is a cross-sectional view illustrating the retrieval tool with
the
22 mandrel engaging the shoulders of the junk basket while collapsing the
latch fingers
23 radially inwardly, before actually latching (no debris is shown);
7
CA 02291991 2003-04-22
1 Figures 5a - 5c are detail partial views of the latching of the retrieving
2 tool with the top sub before, after setting down with tubing weight and
during lifting
3 respectively;
4 Figure 6 is a cross-sectional view illustrating a debris-filled junk basket
with the basket's ball in place in the basket floor's port. Cleanout fluid
flow is shown
6 lifting fine debris upwardly past the retrieving tool's lower centralizer;
7 Figure 7a is a cross-sectional view illustrating the retrieval tool
8 positively engaged with the junk basket having upward facing, outside
shoulders of
9 the latch finger's shoulders catching inside shoulders of the basket's top
sub (no
debris is shown);
11 Figure 7b is a cross-sectional view illustrating commencement of
12 retrieval by shearing of the junk basket from the bridge plug, dropping the
basket
13 floor of the basket for rapid loosening of the debris therein and packed
therearound
14 (no debris is shown);
Figure 8 is a cross-sectional view illustrating the loosened, yet still
16 debris-filled junk basket after shearing from the bridge plug and in the
process of
17 being retrieved from the well bore;
18 Figure 9a is a cross-sectional view of the retrieval device complete
19 with upper and lower centralizer subs, a cleanout nozzle and collet
supporting latch
fingers;
21 Figure 9b is a cross-sectional view along section lines B-B of Fig. 9a
22 illustrating the hollow mandrel having a fluid bore and annular cleanout
passages;
8
CA 02291991 2003-04-22
1 Figure 9c is a cross-sectional view along section lines C-C of Fig. 9a
2 illustrating the individual finger latches of the collet; and
3 Figure 9d is a partial cross-sectional view of the tip of a finger latch.
4
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
6 Having reference to Figs. 1 and 2a, a well bore 10 is shown which is
7 going to have some sort of workover pertormed intermediate along the well
bore.
8 The well bore 10 has a casing 11, a bridge plug 50 (Fig. 2A) and a junk
basket 12
9 installed for collecting debris above the plug 50. The term "well bore" is
sometimes
used herein as a more general term for the bore of the casing 11. The
preferred
11 embodiment is described in the context of a workover comprising a hydraulic
12 fracturing operation which utilizes ball sealers. The presence of ball
sealers is
13 instructive in illustrating the ability of the invention to deal with a
variety of debris.
14 Applicant is not restricting use of the invention to fracturing operations,
but the
operation is merely used for best illustrating the present invention.
16 The junk basket 12 is positioned above the bridge plug 50 using a
17 process described later. The basket 12 comprises a cylindrical sleeve 13
having a
18 top end 14a and a bottom end 15a. The sleeve 13 fits closely within the
casing 11,
19 forming a narrow casing/sleeve annulus 16. A top sub 14b is threaded onto
the
sleeve's top end 14a and a bottom sub 15b is threaded onto the sleeve's bottom
21 end 15a. A contiguous bore 19 extends through the top sub 14b, sleeve 13
and
22 bottom sub 15b.
9
CA 02291991 1999-12-10
1 At the top of the sleeve 13, adjacent to the top sub 14b, axial slots 29
2 (four shown) are provided for permitting fluid communication between the
sleeve's
3 bore 19 and the casing annulus 16. The slots are sized to permit fluid
4 communication but exclude large debris.
The basket 12 has a movable floor 20 preferably formed of a funnel-
6 shaped body which fits closely within the sleeve's bore 19. The basket floor
20 is
7 axially slidable within the bore 19 for varying the volume V within the bore
19 of the
8 sleeve 13. An internal upset within the bottom sub 15b forms an inward
internal
9 shoulder 21 which projects sufficiently into the sleeve's bore 19 to prevent
exit of
the basket floor 20. In Fig. 1, the basket floor 20 is shown resting on the
bottom
11 sub's internal shoulder 21. In Fig. 2a, the basket floor 20 is shown spaced
upwardly
12 intermediate the sleeve's bore.
13 The basket floor 20 has an axial, centralized port 25 and ball seat 26.
14 A ball 27 is provided which is movable within the sleeve's bore 19 and
which is
operative to seat on the ball seat 26 and block the axial port 25. The ball 27
is only
16 operative at a defined point in the operation of the junk basket as
described in
17 greater detail later.
18 The top sub 14b (Fig. 1 ) is adapted for engaging a retrieving tool 70
19 (Figs. 9a-9d). The retrieving tool 70 is provided for the eventual
retrieval of the junk
basket 12 (See sequential Figs. 4a,4b,7a and 7b).
21 Referring then to Figs. 1, 5a-5c, and 9d, the top sub 14b and retrieving
22 tool 70 have complementary latching shoulders 32, 132. For enabling the
23 engagement of the retrieving tool 70, the top sub 14b comprises a wide
mouth 19a.
CA 02291991 1999-12-10
1 Downhole from the mouth 19a, the top sub's bore 19 progressively narrows for
2 forming an internal shoulder 31. The uphole end of the shoulder 31 forms a
ramp
3 33 for guiding and easing the entry of the complementary retrieving tool 70.
A
4 bottom face of the shoulder 31 is angled perpendicularly for forming the top
sub's
internal latch 32.
6 As an assembly, the sleeve 13, bottom sub 15b, basket floor 20 and
7 ball 27 form the volume V for the collection of debris.
8 Accordingly, referring to Figs. 2a, 2b, the junk basket 12 is supported
9 in the well bore 10 by the bridge plug 50. The bridge plug 50 is utilized to
separate
the well bore into a lower isolated zone and an upper working zone. Preferably
the
11 bridge plug is retrievable, providing maximum flexibility in the resumption
of well
12 operations after the workover. The bridge plug 50 is anchored in the well
bore 10
13 and actuated for sealing the casing 11. Besides anchoring slips and sealing
14 elements (not shown), the plug 50 comprises a mandrel 51 having an axially
extending protuberance 52 which incorporates a central shear stud 53 having a
16 weakened neck portion 54. Positioned near the top of the plug's mandrel 51
are
17 laterally projecting setting and retrieving load-bearing lugs 55.
18 The junk basket 12 is connected to the plug's top protuberance 52.
19 The bridge plug's top protuberance 52 extends into the bore 19 of the
bottom sub
15b until the bottom sub bears against the retrieval lugs 55. The bottom sub
15b is
21 retained to the bridge plug using two brass set shear pins 59 having a
known shear
22 load - typically 1000 Ibs. each. To decouple the basket 12 and plug 50, the
basket
11
CA 02291991 1999-12-10
1 12 is loaded in tension relative to the anchored plug 50 until the brass
pins 59
2 shear.
3 When coupled, the basket floor 20 rests against the plug's
4 protuberance 52 under its own weight. The protuberance 52 causes the floor
to be
spaced upwardly in the sleeve's bore 19, above the top protuberance 52. The
axial
6 port 25 in the floor 20 is sized to accept and pass the plug's shear stud 53
7 therethrough.
8 The structure of the junk basket 12 enables unique setting, debris
9 collection and retrieval.
11 Setting Tool Assembly
12 Best seen in Fig. 2a, a setting tool assembly 60 is provided comprising
13 both a setting tool 61 and a slender insertion rod 62. The setting tool
assembly 60
14 is used for conveying the bridge plug 50 into the well bore 10 and then
setting or
deploying it in the casing 11. The assembly 60 is typically connected to the
end of
16 coiled tubing or electric wireline (neither shown) which is run in the well
bore 10.
17 The assembly's insertion rod 62 is positioned at the lower end of the
setting tool
18 assembly 60 and projects through the bore 19 of the junk basket's top sub
14b and
19 through the sleeve 13 to connect to a rod connection of the plug, such as
the shear
stud 53, typically by threaded connection.
21 An annular space 64 is formed in the sleeve's bore 19 between the
22 insertion rod 62 and the sleeve 13. The ball 27 is movable within the
annular space
12
CA 02291991 1999-12-10
1 64. The ball 27 cannot achieve a central position over the axial port 26 of
the
2 basket floor 20 due to the presence of the assembly's insertion rod 62.
3 The setting tool 61 causes the basket's sleeve 13 and bottom sub 15b
4 to bear down on the plug's lateral lugs 55, setting the plug's anchoring
slips and
sealing the plug 50 in the casing 11. During setting of the plug, the
insertion rod 62
6 remains fixed to the setting tool 61, resulting in relative movement between
the
7 insertion rod 62 and the lateral lugs 55.
8 Once the plug 50 is set, further downward load on the basket causes
9 an ever increasing tensile load on the insertion rod 62 until the stud 53
shears and
separates at the neck 54 into an upper portion 53a above the neck for removal
from
11 the well bore 10 with the insertion rod and a lower portion 53b which
remains with
12 the plug 50. The top protuberance 52 continues to support the basket floor
20 even
13 after the stud 53 is sheared. Means for actuating the relative movement of
the
14 setting tool 61 and insertion rod 62 are known in the art and have not been
described in detail.
16
17 Retrieving Tool
18 The retrieving tool 70 is connected to the bottom of a coil tubing string
19 (not shown) which is run into the well bore 10 for engaging and retrieving
the junk
basket 12.
21 As detailed in Figs 9a-9d, the retrieving tool 70 comprises a hollow
22 mandrel 71 comprising a fluid bore 72, a cleanout nozzle 73, finger latches
74, a
23 lower centralizer 75, an upper centralizer 76, and lift jets 77. Typically,
air is used
13
CA 02291991 1999-12-10
1 as the cleanout fluid. The fluid bore 72 conducts sufficient air flow for
discharge
2 from the nozzle 73 to fluidize, elutriate and carry light or fine debris,
such as sand,
3 up the casing 11 for removal from the well bore 10 at the surface. As shown
in Fig.
4 9b, the upper and lower centralizers have axial ports 79 formed about their
periphery for passing the cleanout fluid and debris up the well bore 10
6 The lift jets 77 are directed upwardly and outwardly to aid in lifting
7 debris up the well bore 10.
8 The mandrel 71 is an assembly having a top centralizes sub 80 and a
9 lower centralizes sub 81. The top centralizes sub 80 has an upper threaded
socket
for connection to tubing string and a lower male pin end 83a. The upper
centralizes
11 76 is formed onto the top centralizes sub 80. The lower centralizes sub 75
has a
12 female socket 83b for accepting the top centralizes sub's male in end 83a.
A ring
13 seal 84 seals the pin end 83a and socket 83b with shear screws 85 retaining
them
14 together. The shear screws 85 provide a safety disconnect and shear at
loads
greater than the anticipated working loads and those necessary to shear the
sleeve-
16 to-plug pins 59, typically about 10,000 -15,000 Ib. force.
17 The bottom end 86a of the lower centralizes sub 81 is threaded for
18 adapting to a complementary threaded male connection 86b on the cleanout
nozzle
19 73.
Best seen in Figs. 9a and 9c, the finger latches 74 are formed by a
21 collet 87 comprising a ring collar 88 having a plurality of independent
longitudinally
22 extending finger latches 74. The ring collar 88 fits slidably over the
lower centralizes
23 sub 81 forming a latch deflection annulus 89 therebetween. The deflection
annulus
14
CA 02291991 1999-12-10
1 89 has sufficient clearance to permit tips 90 of the finger latches to be
deflected
2 radially inwardly by the basket's top sub shoulder 31, bending elastically
at the
3 collar 88.
4 As detailed in Fig. 9d, the profile of the finger latches 74 is
complementary to that of the basket's top sub 14b. Each finger has an outward
6 facing latch 91 formed at its tip 90. The tip 90 of each finger 74 thickens
upwardly
7 and ramps radially outwardly, forming an outward facing ramp 92 and shoulder
93.
8 At the upper end of the shoulder 93, a top face 132 is angled
perpendicularly inward
9 for complementary latching with the top sub latch 32.
The greatest radial extent of the shoulder 93 in the undeflected state
11 is about that of the bore of the basket's top sub below the top sub
shoulder 31.
12 When engaged, the top face 132 of the finger latches 74 positively engage
the
13 internal latch 32 of the top sub 14b.
14 The lower centralizes 75 and latch collet are fitted over the lower
centralizes sub 81 before connection of the Geanout nozzle 73. When the
cleanout
16 nozzle 73 is threaded into the bottom of the hollow mandrel 71, it retains
the lower
17 centralizes and collet 87 onto the mandrel 71.
18 The cleanout nozzle 73 comprises two jets which are contiguous with
19 the fluid bore. The nozzle's jets are directed generally downwardly for
engaging
and loosening debris. Provision of two or more jets avoids complete loss of
21 circulation of one jet becomes blocked.
CA 02291991 2003-04-22
1 The operation of the junk basket 12 can be described as having three
2 basic stages; running in, collection of debris, and retrieval. These three
operations
3 are accomplished in only two trips.
4
RunnincLln
6 To run in the basket 12, it is first assembled with the bridge plug 50,
7 the result being illustrated in Fig. 2a. The basket 12 and plug 50, the
bottom sub
8 15b is inserted over the plug's protuberance 52. Tangs (not shown) depending
from
9 the bottom of the bottom sub engage the lugs 55. The shear stud 53 is
installed
into the plug's protuberance 52. The basket floor 20 is placed over the shear
stud
11 53. The setting tool assembly's insertion rod 62 is threaded onto the shear
stud 53.
12 The sleeve 13 is threaded into the bottom sub 15b. The ball 27 is inserted
into the
13 annulus 64 between the insertion rod 62 and the sleeve 13. The top sub 14b
is
14 threaded onto the sleeve 13. The setting tool 61 is threaded onto the
insertion rod
62. An adjustment on the setting tool 61 takes up slack between the setting
tool 61,
16 the sleeve 13, bottom sub 15b and the plug's lugs 55. When the top sub 14b,
17 sleeve 13 and bottom sub's tangs (not shown) are sandwiched tight between
the
18 setting tool 61 and the plug 50, the brass shear screws 59 are installed
into the
19 sleeve's bottom sub 15b.
The junk basket 12, bridge plug 50 and setting tool assembly 60 are
21 attached to lowering means such as a tubing string (not shown). The tubing
string
22 is inserted into the well bore 10 to the desired setting depth (Fig. 2a).
The setting
23 tool 61 is actuated for setting or anchoring the plug 50 in the well bore
10 by
16
CA 02291991 1999-12-10
1 imparting opposing forces on the plug 50 and shear stud 52, downward through
the
2 basket 12 against the plug's setting lugs 55 and through the shear stud 53.
Once
3 set, the stud 53 is sheared for separating the insertion rod 62 from the
plug 50.
4 The setting tool 61 and insertion rod 62 are removed from the well
bore 10, leaving the basket 12 and bridge plug 50 in the well bore 10 (Fig.
2b). The
6 sleeve's bore 19 is wide open for accepting debris 100 with the basket floor
20
7 spaced somewhat upwards from the bottom of the basket 12 by the plug's top
8 protuberance 52.
9
Collection of Debris
11 As shown in Fig. 3a, during a workover, debris 100 falls through the
12 basket's top sub 14b, into its bore 19 and enters the basket's collection
volume V.
13 The sleeve 13 fits quite closely to the well bore casing 11 and thus most
debris 100
14 enters the basket 12. The debris includes fines, like sand, and larger
debris, like
ball sealers 101. As shown in Fig. 3b, sand can settle in the very small
annulus 102
16 formed between the sleeve 13 and the well bore 10.
17 The amount of debris 100 usually exceeds the volume of the collection
18 volume V, filling it to above the top sub 14b and continuing to pack in the
well bore
19 10 thereabove.
17
CA 02291991 1999-12-10
1 Retrieving
2 Having reference to Figs. 4a - 6, in order to engage and latch the
3 retrieving tool 70 into the basket's top sub 14b, some of the debris 100
which has
4 accumulated on top of the basket 12 - such as packed sand - must be cleared
both
from above and within the upper portion of the top sub 14b of the junk basket
12.
6 Accordingly, the retrieving tool 70 is run into the well bore 10 on a tubing
string.
7 Having reference to Figs. 4a,6 cleanout fluid F is pumped down to the
8 retrieving tool 70 and nozzle 73 for fluidizing lighter gravity debris 100
that may be
9 in the well bore 10 and basket. Fig. 6 illustrates the conclusion of the
debris
cleaning operation. The velocity and viscosity of the fluid F is sufficient to
carry the
11 lighter debris 100 up the well bore 10, past the retrieving tool, through
the
12 centralizer ports 79 and to the surface. Some fluid F will pass through
axial slots
13 and up the casing annulus 16 and around the top sub 14b.
14 Heavier components of the debris 100, like solid ball sealers 101, are
too heavy to be fluid lifted to the surface nor can they pass through axial
slots 29,
16 nor past the lower centralizer, and thus concentrate in the collection
volume V of the
17 basket 12.
18 Having reference more specifically to Figs. 5a - 5c and 9d, as the
19 retrieving tool 70 reaches the top sub 14b, the ramp 92 of the tapered
fingers 74
contact the inside ramp 33 of the top sub 14b (Fig. 5a). Set down weight on
the
21 retrieving tool 70 causes the ramps 92 of the latch fingers 74 to ride on
the top sub
22 ramp 33, collapsing the finger latches radially inwardly, allowing the
latch fingers 74
23 to slide into the top sub 14b until the upward facing, outward facing latch
132 of the
18
CA 02291991 1999-12-10
1 latch fingers pass the downward facing inside shoulder 31 of the top sub
14b. The
2 lower centralizer 75 is seen to contact the top sub, arresting the
retrieving tool (Fig.
3 5b). The finger latches 74 expand inside the top sub 14b and when the
retrieving
4 tool is again lifted (Fig. 5c), the outside shoulders 132 of the finger
latch 74 catch
the top sub's inside shoulder 32, positively engaging the retrieving tool 70
to the
6 basket's top sub 14b. The latched condition is shown in Fig. 6.
7 At any time thereafter, once an operator believes the retrieving tool 70
8 has reached the top sub 14b, the operator can positively determine whether
the tool
9 70 has latched the top sub 14b and a trip out will yield the junk basket 12.
The
operator pulls up on the retrieving tool 70, by pulling up on the tubing
string. The
11 operator observes the pull force and compares that against the weight of
the tubing
12 string. If the pull force climbs significantly, approaching. 2000 Ibs. over
the weight
13 of the tubing, then it is understood that the combination retrieving tool
70 must have
14 latched onto the junk basket 12. If the operator continues to pull up on
the tubing
string to approx. 2000 Ibs., and then the pull force drops sharply to that of
the tubing
16 weight alone, the operator has then confirmed that the junk basket 12 is
latched and
17 that the brass screws 59 have sheared, separating the basket 12 from the
bridge
18 plug 50 as shown in Figs. 7b and 8.
19 As shown in Fig. 8, one of the significant features of the novel junk
basket 12 is demonstrated when the brass screws 59 are sheared. Once sheared,
21 the retrieving tool 70 and latched junk basket immediately and quickly lift
free of the
22 bridge plug. This lifting action quickly spaces the basket 12 from the plug
50 and
23 removes support from the basket floor 20. Accordingly, the basket floor 20
falls
19
CA 02291991 1999-12-10
1 abruptly to the bottom sub's inner shoulder 21 resulting in a sharp increase
in the
2 collection volume V. This increase in the collection volume V causes the
packed
3 debris 100 to loosen as it expands to fill the greater volume. Surprisingly,
the
4 basket is then much easier to retrieve. It is postulated that fine debris,
like packed
sand, has been loosened in the annulus 102 between the sleeve 13 and the
casing
6 11. While the exact mechanism is not clear, it may be that the falling of
the floor
7 acts as a jar, or possible that the sudden increase in volume creates a
localized
8 pressure differential and resulting fluid flow between the basket's bore 19
and the
9 basketlcasing annulus 102 which appears to loosen the grip any packed sand
in the
annulus 102. Having loosened the basket 12 in the casing 11, the basket 12 is
more
11 readily retrieved without binding.
12 Lastly, the retrieving tool 70 and junk basket 12 are pulled out of the
13 well bore 10.
14 To complete the practical aspect of completing the task, the
disassembly of the retrieving tool 70 from the junk basket 12 is described as
follows.
16 The basket's top sub 14b is unscrewed from the sleeve 13. The nozzle 73 is
17 unscrewed from the retrieving tool 70 and the remainder of the retrieving
tool 81,80
18 is slid out of the top sub 14b. The collet 87 is removed through the bottom
end of
19 the top sub 14b. Lastly, the ball 27 and basket floor 20 are removed from
the inside
of the sleeve 13, and the connection between the sleeve 13 and bottom sub 15b
is
21 unscrewed.
22
