Information
-
Patent Grant
-
6450541
-
Patent Number
6,450,541
-
Date Filed
Thursday, August 31, 200023 years ago
-
Date Issued
Tuesday, September 17, 200221 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Browne; Lynne H.
- Bochna; David E.
Agents
- Knobbe Martens Olson & Bear LLP
-
CPC
-
US Classifications
Field of Search
US
- 285 1
- 285 2
- 285 34
- 285 83
- 285 306
- 285 33
- 285 35
- 285 102
- 285 900
- 285 924
-
International Classifications
-
Abstract
A releasable connector connects between coiled tubing, a pipe string or similar tubular string and a tool/piece of equipment. Two sleeve-shaped inter-connectable parts are configured to be releasable, wherein one is connected to the coiled tubing, and the other is connected to the tool/equipment. A locking device holds the two sleeve-shaped parts of the connector in a blocked non-released position, and a retaining sleeve keeps the locking device in its locking position. The retaining sleeve is axially displaceable for releasing the connector by a sufficient, axial displacing movement. A coaxial displaceable piston body with a transversal end surface can be influenced by fluid pressure in order to start a releasing process. The piston body has a spring, which resists the displacement of the piston and is arranged in a spring chamber. In an initial position of the connector, the spring chamber is filled with a medium which can be forced out through a cavity and an opening. Forcing the medium through the opening provides for a delay on the displacement of the piston body and the compression of the spring and, thus, a release delay.
Description
FIELD OF THE INVENTION
This invention relates to a releasable connector arranged to be inserted between coiled tubing, a pipe string or similar tubular string and a tool/piece of equipment, and arranged to release and be divided into two sleeve-shaped interconnectable parts, of which one is connected to the coiled tubing, and the other is connected to said tool/equipment, and in which the two sleeve-shaped parts of the connector are held together in a blocked non-released position by means of a locking device which is kept in its locked position by means of a retaining sleeve, which is axially displaceable on release, or the initial release, of the connector, said retaining sleeve releasing said locking device by a sufficient axial displacing movement, said locking device thereby initiating the release, said connector comprising internally a coaxial displaceable piston body with a transversal end surface, which can be actuated by fluid pressure in order to start the release process, and which influences, when being displaced, the locking device to release its locking effect and allow division of the connector into said two interconnectable parts.
When released intentionally, the connector is divided between its connecting ends, whereby the coiled tubing etc. is separated from the downhole tool.
BACKGROUND OF THE INVENTION
Such connectors are generally known in several embodiments, and are brought to function, i.e. brought to release, should, for example, the downhole tool jam and become stuck and resist withdrawal together with the coiled tubing/pipe string and the connector in undivided condition.
An example of a connector of this kind is disclosed in NO 180.552. The releasable locking means holding together two separable parts of the connector, here consists of a radially expandable locking ring, which is in a compressed, non-expanded condition in its locking position, blocking the two separable parts of the connector. In its locking position, the locking ring engages a lock mandrel included in the connector, and is surrounded by an axially displaceable retaining sleeve, which is shear-pinned in a non-displaceable position in the active position of the connector. Whenever it is desirable to release the connector for division into an upstream part, which may be extracted together with intact coiled tubing (pipe string), and a downstream part, which will remain in its position downhole together with the tool, an internal seat formed in a piston sleeve is used in a well-known manner, whereby a ball is released from a surface position to settle sealingly on the seat, after which drilling mud/drilling fluid or other fluid is pumped down under pressure from the surface to exert a considerable pressure on the reaction surface of the piston sleeve opposite the pressure, consisting of the ball surface of the ball and the seat surface opposite the direction of flow of the pressure fluid. By a certain pressure build-up upstream of the ball-/sphere-like sealing body cooperating with the seat of the piston sleeve, the piston sleeve is put into a displacing movement, whereby said retaining sleeve is subjected to an axial compressive force. The shear pins are sized to shear by for example the compressive force (e.g. equalling 70.3 kg/cm
2
—1000 psi) achieved thereby. When the shear pins have been shorn, the piston sleeve and thereby the retaining sleeve are displaced until the latter is no longer surrounding the locking ring, but releases it. In its released condition the locking ring expands and releases the connector.
This known connector can release on unintentional pressure build-up inside the connector.
Unintentional pressure build-up, which may make the connector release, may occur during so-called underbalanced perforation. The formation pressure is lower than the hydrostatic pressure of the well before perforation.
A hydraulically releasable connector of the kind initially mentioned, is known from the Norwegian patent document No. 305.715. This known connector is arranged for the releasable connection of a tool to the end of coiled tubing. The casing of the connector is formed with two or more hydraulic channels for the transfer of hydraulic fluid from hydraulic lines run through the coiled tubing to said tool. The connector is retained in its connected position by means of a locking device which is secured by means of an axially displaceable sleeve, which again is retained in its securing position by means of transversal shear pins. The retaining sleeve is arranged as a piston-like hydraulically manoeuvrable means, and is provided with annular seals of different sealing diameters. These seals define annular areas on the piston-like retaining sleeve, and these piston areas each have a hydraulic channel arranged thereto. The retaining sleeve is subjected to an axial force, equalling the sum of the product of the pressure in each of the hydraulic channels and the respective annular piston area. The shear pins are sized to be brought to break, whenever both annular piston areas are subjected to hydraulic working pressure. This connector also has not got any delaying means (such as a spring and/or viscous liquid) on the underside of the piston-like retaining sleeve.
SUMMARY OF THE INVENTION
Thus, the object of this invention has been to arrange it so that a brief pressure increase inside the connector will not necessarily result in full release and division of the connector into two separate parts.
The object is realized, according to the invention, by means of a connector of the kind specified in the introductory part of Claim 1, which distinguishes itself through the features appearing from the characterizing part of Claim 1.
On undesirable pressure build-up in the connector, the return spring of the piston may be compressed somewhat, and the shear pin(s) may shear, but the release-delaying device according to the invention prevents the complete compression of the return spring, which is necessary for the release of the locking mechanism.
The release-delaying device consists of a spring chamber filled with lubricating grease, in which the piston forces, during its displacement and compression of the spring, the lubricating grease (or other particularly viscous liquid or pumpable substance) out through a choked opening, preferably adjustable in size, which resists accelerated rate of extrusion, thus delaying the displacement of the piston, and thereby the compression of the spring, for a period of time, during which the locking ring or other locking mechanism still has not been brought completely out of its locking position when the unintentional pressure increase ceases. When all of the lubricating grease/liquid has been forced out of the spring chamber, the delaying means has been spent, whereby there is nothing else but the return spring attempting to hold back the piston. If the compressive force, acting axially on the piston, exceeds the counter-force of the spring, the piston is displaced during the compression of the spring, and completes its stroke to release the locking ring/mechanism.
If it is desired to release the connector intentionally and consciously, the reaction surface of the piston is exposed to high pressure, e.g. 70.3 kg/cm
2
(1000 psi), for a period of time, which is known, from experience, to exceed the time for the forcing out of the lubricating grease from the spring chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
A non-limiting example of a preferred embodiment will be explained in further detail in the following with reference to the drawings, in which:
FIGS. 1-3
show axial sections through a connector in various functional positions thereof;
FIG. 1
illustrating the connector in an active position, in which its two connected parts are locked to each other;
FIG. 2
illustrating an intermediate position, in which the shear pins are broken, and the displacement of the piston and compression of the return spring has been initiated;
FIG. 3
showing an end position, in which the locking mechanism (the locking ring) has been released, and in which the release of the connector cannot be postponed any longer. The connected condition cannot be re-established.
FIG. 4
shows the two main parts of the connector separated.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings, a straight, elongate connector, generally identified by the reference numeral
10
, is formed with a passage
12
for liquid, extending axially therethrough. The connector comprises two sleeve-shaped parts
14
and
16
, held together by means of a releasable locking ring
17
, whose locking effect may be brought to cease in the manner explained in further detail below.
Over a longitudinal portion the sleeve-shaped
16
is screwed by threads
18
together with a third sleeve part
20
, and the parts
16
,
20
appear and are considered as one functional unit
16
,
20
, in which the free (left-hand) end portion
20
a
forms an externally threaded connecting pin of reduced diameter, for the connection of a replaceable tool/piece of equipment (not shown).
The upstream, sleeve-shaped part of the connector
10
has an internally threaded, widened box cavity
22
for the connection of the threaded extremity of coiled tubing or of a pipe string (not shown).
A piston
23
with a longitudinal, tubular piston rod
23
a
is displaceably mounted in an axial cylinder chamber defined by an inner surface of the sleeve-shaped part
16
telescopically overlapping the second sleeve-shaped part
14
extending axially in the extension thereof.
Within this area, in which the two interconnected disconnectable sleeve-shaped parts
14
and
16
,
20
of the connector overlap telescopically, there is arranged, between the two, a locking ring
17
which is split and is formed of a resilient material, so that the ring
17
will expand radially when it is not influenced by radial inward forces.
In internal/external circumferential grooves in the relatively displaceable individual parts of the device, there are inserted, for sealing purposes, gaskets/seals
24
, for example in the form of O-rings.
At its internal circumferential portion, the radially expandable locking ring
17
is formed with waved ridges
26
and intervening grooves
28
, which engage corresponding grooves
30
, or which are matchingly engaged, in a position-fixing manner, by ridge-shaped portion formed externally on the sleeve part
14
.
Round the locking ring
17
there is an annulus
32
, defined between the external surface of the first (right-hand) sleeve part
14
, and the opposite internal surface portion of the second sleeve part
16
,
20
.
The outer, free box-shaped end portion of the first sleeve part
14
is connected to a narrower sleeve-shaped portion, in which the waved grooves
30
are formed, through a shoulder portion
14
a,
which is an annular stop portion on which the end surface
16
b,
FIG. 3
, of the second sleeve part
16
,
20
rests supportingly,
FIGS. 1 and 2
, when the connector
10
is fitted together and is in use, or is in an intermediate position (FIG.
2
).
When the connector
10
is fitted together,
FIG. 1
, an axially projecting (towards the right) peripheral, annular end portion
23
b
of the piston
23
essentially occupies the space inside the annulus
32
, thereby keeping the locking ring
17
pressed radially inwards, so that it adopts the non-expanded stand-by/locking position, in which the locking ring
17
keeps the sleeve parts
14
and
16
,
20
of the connector
10
in an axially fixated, locking position, the locking ring
17
bearing supportingly, in a manner so as to block axial movement, by its right-hand end on an internal shoulder surface
34
formed in the second sleeve-shaped part
16
,
20
, while at the same time the circumferential ridges
26
of the locking ring
17
are matchingly bearing in the corresponding, complementarily formed grooves
30
of the sleeve part
14
.
The longitudinal axis of the releasable connector is identified by A—A, and the direction of flow of drilling fluid or other pumpable fluid is identified by P. Thus, the box cavity
22
is the upstream connecting portion of the connector and the end portion
20
a
its downstream connecting portion.
Through the piston
23
and the piston rod
23
a
thereof, the through bore
12
is formed with end portions different from the its general extent. Thus, there is a relatively short upstream bore portion
12
a,
tapering conically in the direction of flow P, and an even shorter downstream bore portion
12
b,
widening conically in the direction of flow P. Otherwise there are several bore sections differing from one another in diameter.
From the narrowest bore portion within the first sleeve part
14
, there is a radial port
36
to allow pressurized fluid to influence the reaction surface
38
of the piston
23
.
Between the annular surface
40
of the piston
23
, which is parallel to and opposite the reaction surface
38
, and an annular end surface
20
b
at a distance therefrom, there is inserted a helical compression spring
42
pressing against the piston head
23
, opposite the arrow P, to retain it in the position shown in FIG.
1
.
The spring
42
is arranged in an annulus
44
defined by the two opposed annular radial surfaces
20
b
and
40
and the internal surface of a longitudinal portion of the second sleeve-shaped part
16
,
20
of the connector and the external surface of the tubular piston rod
23
a.
Between the tubular piston rod
23
a
and the sleeve portion
20
leading downstream, a shear pin connection
46
is established, depending on the applied force and comprising one or more radial shear pins
46
, which engage the tubular walls of the sleeve part portion
20
and the piston rod
23
a,
and which are illustrated in a shorn condition in
FIGS. 2 and 3
, where the two separate non-connectable shear pin pieces are identified by
46
a
and
46
b.
Over a longitudinal section of the downstream portion
20
of the second sleeve-shaped part
16
,
20
, the piston rod
23
a
is sized with a somewhat reduced external diameter, so that over said section of its length there is formed an annulus
48
, which places the spring chamber
44
in fluid communication with an angled channel
50
in the tubular wall of the sleeve part portion
20
, and which leads to a choke valve
52
, whose outlet opening is directed radially out from the tubular body
10
of the connector.
According to the present invention, the spring chamber is filled with lubricating grease or liquid, preferably viscous liquid, for which it will take a certain period of time to be forced out of the spring chamber
44
through the choke valve
52
via the annulus
48
and the channel
50
. Such forcing out of lubricating grease/liquid will take place on displacement of the piston/piston rod unit
23
,
23
a
in the direction of flow P.
Such a linear displacing movement may be brought about intentionally by the supply, initiated from a surface position, of pressurized fluid, acting on the end surface
38
of the piston
23
, opposite said direction of flow P, against the action of the compression spring
42
.
The shear pin
46
may be sized to shear by an axial compressive force communicated by the piston rod
23
a
relative to the second (downstream) sleeve part
16
,
20
of the connector
10
. The shearing force may correspond, with respect to the axial compressive force of the piston
23
and the piston rod
23
a,
to the force that the compressive spring
42
can resist before it starts to yield elastically and become compressed,
FIG. 2
, showing an intermediate position, in which the spring
42
has not been compressed to its maximum, and in which the locking ring
17
has not reached its radially expandable position, so that the locking effect is still maintained. Then it is possible to avoid unintentional release of the connector, so that intact string of coiled tubing, connector, in addition to connected tool/equipment (at
20
a
) can be recovered and brought up to the surface after a brief, great pressure build-up has been observed.
The pumping out of, for example, lubricating grease through the choke valve
52
slowing down the pump rate, will delay the displacement of the piston/piston rod unit
23
,
23
a
towards its end position (FIG.
3
), which is favourable as regards unintentional shearing of the shear pins, piston displacement and compression of the spring. When the shearing of the shear pins and the displacement of the piston is brought about intentionally by the pumping down of pressurized drilling fluid, the compressive action on the piston
23
is maintained until the delaying device
44
,
48
,
50
,
52
has ceased its action (lubricating grease has been forced out of the spring chamber
44
), and the compression spring
42
has been maximally compressed, and the releasable connection of the two main parts of the connector, the sleeve-shaped parts
14
and
16
,
20
, has been released.
The choke opening or any hole of a reduced area of through-put relative to the size of the channel, may be adjustable in size.
By intentional release of the connector
10
and irremediable division thereof into separate sleeve parts
14
and
16
,
20
, operation at a fluid pressure of 70.3 kg/cm
2
(1000 psi) should be maintained for a somewhat prolonged period of time, so that the shear pin(s)
46
is (are) brought to break first, after which the piston/piston rod unit
23
,
23
a
is allowed to be displaced, to concurrently press out lubricating grease etc. and compress the spring
42
into the releasing position in
FIG. 3
, in which the locking ring
17
has expanded radially. In this releasing position the compressed spring
42
cannot force the peripheral annular extension
23
b
of the piston
23
radially inwards immediately outside the outer jacket of the locking ring
17
. Through the relative positioning of the peripheral annular extension
23
b
of the piston
23
, the locking ring
17
and the engaging portion
30
of the sleeve part
14
opposite the locking ring
17
, as shown in
FIG. 2
, the restoring of the active position of the connector
10
is made possible, because the locking ring
17
has not expanded radially and adopted its inactive position. Thus, when a brief, great pressure build-up is over, the position of the connector
10
will be as shown in
FIG. 2
, with the exception, however, that the shear pin(s)
46
is (are) broken.
Claims
- 1. A releasable connector arranged to be connected between coiled tubing, a pipe string or similar tubular string and a tool/piece of equipment, comprising:two sleeve-shaped inter-connectable parts configured to be releaseable, of which one is connected to the coiled tubing, and the other is connected to said tool/equipment; a locking device configured to hold the two sleeve-shaped parts of the connector in a blocked non-released position; a retaining sleeve configured to keep the locking device in its locking position, wherein the retaining sleeve is axially displaceable for releasing the connector, said retaining sleeve releasing said locking device by a sufficient, axial displacing movement, said locking device thereby initiating the release; and a coaxial displaceable piston body with a transversal end surface, which can be influenced by fluid pressure in order to start a releasing process, and which, on displacement, influences the locking device to release its locking effect and allow division of the connector into said two inter-connectable parts, wherein the piston body has a spring arranged thereto, which resists the displacement of said piston, and is arranged in a spring chamber, whose one defining surface forms a transversal surface of the piston body, and wherein the initial position of the connector the spring chamber is filled with a medium for which there is provided a cavity receiving medium forced out and guiding it through an opening, said forcing out of the medium through the opening providing a delay on the displacement of the piston body and the compression of the spring means, and thus a release delay.
- 2. The connector according to claim 1, wherein the medium is selected from a group consisting of lubricating grease and a viscous liquid.
- 3. The connector according to claim 1, wherein extending downstream from the spring chamber, there is an annulus, which extends over part of the axial length of said second sleeve-shaped part, and which communicates with a possibly angled transversal channel ending in a choke opening, choke valve or other hole for the forcing out of the medium, with which the spring chamber is filled.
- 4. A releasable connector arranged to be connected between coiled tubing, a pipe string or similar tubular string and a tool/piece of equipment, comprising:two sleeve-shaped inter-connectable parts configured to be releasable, of which one is connected to the coiled tubing, and the other is connected to said tool/equipment; a locking device configured to hold the two sleeve-shaped parts of the connector in a blocked non-released position; a retaining sleeve configured to keep the locking device in its locking position, wherein the retaining sleeve is axially displaceable for releasing the connector, said retaining sleeve releasing said locking device by a sufficient, axial displacing movement, said locking device thereby initiating the release; and a coaxial displaceable piston body with a transversal end surface, which can be influenced by fluid pressure in order to start a releasing process, and which, on displacement, influences the locking device to release its locking effect and allow division of the connector into said two inter-connectable parts, wherein the piston body has a spring arranged thereto, which resists the displacement of said piston, and is arranged in a spring chamber, whose one defining surface forms a transversal surface of the piston body, and wherein the initial position of the connector the spring chamber is filled with a medium for which there is provided a cavity receiving medium forced out and guiding it through an opening, said forcing out of the medium through the opening providing a delay on the displacement of the piston body and the compression of the spring and thus a release delay, wherein the piston body is connected to one sleeve-shaped part of the connector by at least one transversal shear pin, which is sized to withstand a load preferably corresponding to an axial compressive load, by which the spring arranged to the piston body will start to become compressed.
Priority Claims (1)
Number |
Date |
Country |
Kind |
19994188 |
Aug 1999 |
NO |
|
US Referenced Citations (9)
Foreign Referenced Citations (4)
Number |
Date |
Country |
0 686 753 |
Jun 1995 |
EP |
2 294 714 |
Nov 1994 |
GB |
305715 |
Jul 1999 |
NO |
WO 9729270 |
Feb 1997 |
WO |