Information
-
Patent Grant
-
6199632
-
Patent Number
6,199,632
-
Date Filed
Monday, November 23, 199825 years ago
-
Date Issued
Tuesday, March 13, 200123 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Will; Thomas B.
- Petravick; Meredith C.
Agents
- Herman; Paul I.
- Youst; Lawrence R.
-
CPC
-
US Classifications
Field of Search
US
- 166 2426
- 166 243
- 166 212
- 166 213
- 166 214
- 166 282
-
International Classifications
-
Abstract
A locator device (50) that is selectively lockable within a nipple profile (40) disposed within a wellbore (32). The locator device (50) comprises a locator key (106) disposed between a housing (104) and a mandrel (102) that is radially extendable through a window (108) of the housing (104). The locator key (106) has an engageable position and a retracted position with respect to nipple profile (40). A support ring (110) is disposed between the housing (104) and the mandrel (102) that maintains the locator key (106) in the engageable position until the support ring (110) is axially displaced relative to the mandrel (102). A engagement mechanism (116, 118) is disposed within a radial bore (114) of the mandrel (102) that is selectively engageable with the support ring (110) in response to a differential pressure such that axial force from the support ring (110) is transferred to the mandrel (102), thereby preventing axial displacement of the support ring (110) relative to the mandrel (102) and preventing the passage of the locator device (50) in a first direction relative to the nipple profile (40).
Description
TECHNICAL FIELD OF THE INVENTION
This invention relates, in general, to tools used during the completion and operation of a subterranean wellbore and, in particular to, a selectively locking locator used to selectively prevent the passage of the locator through a landing nipple once the locator is locked in place within the subterranean wellbore.
BACKGROUND OF THE INVENTION
Without limiting the scope of the present invention, its background will be described with reference to perforating and fracturing a subterranean formation, as an example.
Heretofore in this field, a potentially productive geological formation beneath the earth's surface which contains a sufficient volume of valuable fluids, such as hydrocarbons, may have a very low permeability. As the valuable fluids are contained within pores in the potentially productive subterranean formation, if the pores are not interconnected, the fluids cannot move about and, thus, cannot be brought to the earth's surface without a structural modification of the production zone.
In such a formation having a very low permeability, but a sufficient quantity of valuable fluids in its pores, it becomes necessary to artificially increase the formation's permeability. This is typically accomplished by fracturing the formation, a practice that is well known in the art. Basically, fracturing is achieved by applying sufficient pressure to the formation to cause it to crack or fracture. The desired result of this process is that the cracks interconnect the formation's pores and allow the valuable fluids to be brought out of the formation and to the surface.
In conventional fracturing, the general sequence of steps needed to stimulate a production zone through which a wellbore extends is as follows. First, a plug is set in the well casing at a predetermined depth in the well, proximate the subterranean production zone requiring stimulation. Next, a perforating trip is made by lowering a perforation assembly into the wellbore on a lower end portion of a work string. The gun assembly is then detonated to create a spaced series of perforations extending outwardly through the casing, the cement and into the production zone. The discharged gun assembly is then pulled up with the work string to complete the perforating trip.
Next, the spent gun assembly may be replaced on the work string with a proppant discharge member having a spaced series of discharge openings formed therein. The proppant discharge member is then lowered into the wellbore such that the discharge openings are, at least theoretically, aligned with the gun-created perforations. Proppant slurry is then pumped down the work string so that proppant slurry is discharged through the discharge member openings and then flowed outwardly through the casing and cement perforations into the corresponding perforations in the surrounding production zone. The work string is then pulled out again to complete the stimulation trip and ready the casing for the installation therein of production tubing and its associated production packer structures.
Alternatively, attempts have been made to design a single trip apparatus and method to perforate and stimulate a hydrocarbon formation. In this case, the work string carries a drop-off type perforating gun and a locator installed thereon above the perforating gun. The gun is operatively positioned within the casing by lowering the locator through an internal profile within the nipple to a location below the nipple. The work string is then pulled upwardly to engage the key of the locator in the nipple profile. Once in place, the guns may be fired to create a spaced series of perforations extending outwardly through the work string, the casing, the cement and into the production zone. The gun is now dropped to a location below the perforations. The proppant slurry is then pumped down the work string. The proppant slurry is discharged through the openings in the work string, the casing and the cement into the corresponding perforations in the surrounding production zone.
It has been found, however, the even when the proppant slurry is pumped down the work string on the same trip as the perforation, the alignment, both axial and circumferential, of the gun-created perforations in the work string and in the casing is not maintained unless a substantial overpull tension force is exerted on the portion of the work string above the locator and maintained during the firing of the gun. The desired overpull force, however, may sheer the sheer pins in the locator causing disengagement of the locator from the nipple profile.
A need has therefore arisen for a locator device that may be used during a single trip perforating and fracturing operation. A need has also arisen for such a locating device that may be locked into a nipple profile and support substantial tensile load within the work string without sheering internal sheer pins or releasing from the nipple profile. A need has further arisen for such a locating device that is simple to disengage from the nipple profile once the perforating and fracturing operation has been completed.
SUMMARY OF THE INVENTION
The present invention disclosed herein comprises a locator device that may be used during a variety of downhole operation. The locating device of the present invention may be locked into a nipple profile and support a tensile force in the work string without sheering internal sheer pins or releasing from the nipple profile. The locating device of the present invention is also simple to disengage from the nipple profile once the wellbore operation has been completed.
The locator device of the present invention comprises a mandrel having one or more radial bores through the sidewall thereof. A housing is partially disposed exteriorily around the mandrel. A set of locator keys is disposed between the housing and the mandrel. The locator keys are radially extendable through a window in the housing. The locator keys have a first position wherein the locator keys are engageable with the landing nipple and a second position wherein the locator keys are retracted from the nipple profile. A support ring is disposed between the housing and the mandrel. The support ring prevents movement of the locator key from the first position to the second position until the support ring is axially displaced relative to the mandrel. Disposed within each of the radial bores are pistons that are selectively engagable with the support ring in response to a differential pressure between the interior and the exterior of the locator device. When the pistons are operably engaged with the support ring, axial displacement of the support ring relative to the mandrel is prevented as is retraction of the locator keys from the nipple profile. As such, upward passage of the locator device through the nipple profile is also prevented.
The locator device may include one or more sheerable members extending between the mandrel and the support ring that sheer in response to a predetermined axial force between the support ring and the mandrel. The sheerable members will not sheer, however, when the pistons are operably engaged with the support ring as the axial force from the support ring is transferred to the mandrel through the piston.
A c-ring may be disposed between the pistons and the support ring. The c-ring may include a plurality of teeth that engage a plurality of teeth on the support ring to selectively prevent axial displacement of the support ring relative to the mandrel. The c-ring radially biases the pistons to disengage the pistons from the support ring when the differential pressure between the interior and exterior of the locator device is reduced below a predetermined level. Alternatively, a differential pressure having a gradient opposite that of the prior differential pressure may be acted on the pistons to disengage the pistons from the support ring. For example, if the differential pressure used to engage the pistons requires a higher pressure on the interior of the locator device than on the exterior of the locator device, the differential pressure used to disengage the pistons will require a higher pressure on the exterior of the locator device than the interior of the locator device.
Once the pistons has been disengaged from the support ring, the axial force between the support ring and the mandrel caused by upward pulling on the locator device will sheer the sheerable members. A shoulder on the window of the housing then engages the locator key as the support ring is axially displaced relative to the mandrel such that the locator key disengages from the nipple profile. After the locator key has disengaged from the nipple profile, upward passage of the locator device through the nipple profile is allowed.
Viewed more broadly, the present invention may be applied to a variety of downhole tools when it is desirable to selectively prevent the relative axial movement between first and second tubular members. The second tubular member, whether located on the interior or the exterior of the first tubular member, has one or more radial bores in the sidewall thereof wherein pistons are disposed. The pistons selectively engage the first tubular member in response to a differential pressure between the interior and the exterior of the tubular members. Axial movement of the tubular members relative to one another is selectively prevented while the pistons are engaged.
When the second tubular member is disposed within the interior of the first tubular member, the piston is shifted radially outwardly in response to the differential pressure. When the second tubular member is disposed exteriorily about the tubular member, the piston is shifted radially inwardly in response to the differential pressure.
A c-ring may be disposed between the piston and the first tubular member. When the second tubular member is disposed within the interior of the first tubular member, the c-ring radially inwardly biases the piston to disengage the piston from the first tubular member. When the second tubular member is disposed exteriorily about the first tubular member, the c-ring radially outwardly biases the piston to disengage the piston from the first tubular member.
Alternatively, the piston may be disengaged from the first tubular member in response to a differential pressure having a gradient opposite to that of the differential pressure that engages the pistons with the first tubular number. When the second tubular member is disposed within the interior of the first tubular member, this differential pressure radially inwardly shifts the piston to disengage the piston from the first tubular member. When the second tubular member is disposed exteriorily about the first tubular member, this differential pressure radially outwardly shifts the piston to disengage the piston from the first tubular member.
In operation, the present invention may, for example, comprise selectively preventing passage of a locator device through a nipple profile once the locator device is locked within the nipple profile by engaging a set of locator keys with the nipple profile, providing a differential pressure to the locator device to act on the pistons disposed within radial bores in the sidewall of the mandrel, radially shifting the pistons to engage the support ring to transfer axial force from the support ring to the mandrel and to prevent axial displacement of the support ring relative to the mandrel, thereby preventing retraction of the locator key from the nipple profile and passage of the locator device through the nipple profile.
To disengage the support ring from the mandrel, a c-ring may be used to bias the pistons after the differential pressure within the locator device drops below a predetermined level. Alternatively, differential pressure having a gradient opposite that of the differential pressure that engages the pistons with the support ring may be applied to the locator device to radially shift the pistons to disengage the pistons from the support ring. Once the pistons are disengaged, the locator may be passed through the nipple profile.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which:
FIG. 1
is schematic illustration of an offshore oil and gas platform operating a selectively locking locator device of the present invention;
FIG. 2
is schematic illustration of a downhole formation traversed by a wellbore having a selectively locking locator device of the present invention disposed therein;
FIGS. 3A-3C
are cross sectional views of a selectively locking locator device of the present invention in its various operating positions;
FIGS. 4A-4B
are cross sectional views of a selectively locking locator device of the present invention;
FIGS. 5A-5B
are cross sectional views of a selectively locking locator device of the present invention;
FIGS. 6A-6B
are cross sectional views of the locking mechanism of two embodiments of a selectively locking locator device of the present invention; and
FIGS. 7A-7C
are cross sectional views of a selectively locking locator device of the present invention in its various operating positions.
DETAILED DESCRIPTION OF THE INVENTION
While the making and using of various embodiments of the present invention is discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the invention.
Referring to
FIG. 1
, a single trip perforating and fracturing apparatus including a selectively locking locator in use on an offshore oil and gas platform is schematically illustrated and generally designated
10
. A semi-submersible platform
12
is centered over a submerged oil and gas formation
14
located below sea floor
16
. A subsea conduit
18
extends from deck
20
of platform
12
to wellhead installation
22
including blowout preventers
24
. Platform
12
has a hoisting apparatus
26
and a derrick
28
and for raising and lowering pipe strings such as work sting
30
.
A wellbore
32
extends through the various earth strata including formation
14
. A casing
34
is cemented within wellbore
32
by cement
36
. As best seen in
FIG. 2
, casing
34
includes a nipple
38
that has, from top to bottom along its interior, an annular locator profile
40
, a reduced diameter top annular seal surface
42
, a radially thinned tubular perforatable side wall area
44
and a reduced diameter bottom annular seal surface
46
.
Work string assembly
48
includes a length of work string
30
which is extendable downwardly through casing
34
and its nipple
38
. Work string assembly
48
includes, from top to bottom, a selectively locking locator
50
exteriorly mounted on work string
30
, upper annular seal structure
52
, a longitudinal gun carrying portion
54
, a lower annular seal structure
56
, a locator
58
, a conventional screened tubular sliding side door assembly
60
having upper and lower external annual end seals
62
and
64
and installed in its closed position and an open lower end
66
.
The selectively locking locator
50
may be passed downwardly through annular locator profile
40
. As will be discussed in detail below, once selectively locking locator
50
is returned upwardly into profile
40
, selectively locking locator
50
may be locked within profile
40
to selectively prevent upward passage of locator
50
through profile
40
until such time when it is desired to remove locator
50
from profile
40
.
A drop-off type perforating gun
76
is operatively supported within an upper end section of the gun carrying potion
54
of the work string
30
. The lower end of gun carrying portion
54
is connected to the portion of the work string
30
therebelow by a suitable releasable connection
70
such as, for example, that typically used in a lock mandrel running tool. Directly above the releasable connection
70
, within the work string
30
, is a check valve
72
that functions to permit upward fluid flow therethrough and preclude downward fluid flow therethrough. The check valve
72
is directly below an internal no-go structure
74
which, as later described herein, functions to catch perforating gun
76
after it has been fired and drops off its mounting structure within the work string
30
.
When it is desired to perforate and stimulate formation
14
, work string assembly
48
is lowered through casing
34
until locator
50
is positioned beneath profile
40
. Work string assembly
48
is then raised until locator
50
is operatively engaged by profile
40
. Work string
30
is then internally pressurized to lock locator
50
within profile
40
to stop further upward movement of the work string assembly
48
, as will be more fully described below. Perforating gun
76
is disposed between the upper and lower internal nipple seal areas
42
and
46
, with the side of gun
76
facing the perforatable side wall area
44
of the nipple
38
. Upper and lower tubing seals
52
and
56
respectively engaging the upper and lower nipple areas
42
and
46
, thereby sealing off the interior of the perforatable side wall area
44
from the rest of the interior of work string
30
.
Next, the pressure within work string
30
is elevated placing work string
30
in tension, representatively about 250,000 pounds of upward force, which must be supported by locator
50
. The gun
76
is then fired to create a spaced series of first perforations
78
in the side wall of the gun carrying portion
54
, and a spaced series of second perforations
80
aligned with the first perforations
78
and extending outwardly through the perforatable side wall area
44
, the cement
36
and into formation
14
.
Alternatively, the first perforations
78
may be preformed in the gun carrying portion
54
, before it is lowered into casing
34
, and appropriately aligned with the series of detonation portions on the perforating gun
76
. When gun
76
is later fired, it fires directly outwardly through the preformed perforations
78
, thereby reducing the overall metal wall thickness which gun
76
must perforate.
After the firing thereof, and the resulting circumferentially and axially aligned sets of perforations
78
and
80
, the gun
76
is automatically released from its mounting structure within work string
30
and falls downwardly through work string
30
to the dotted line position of the gun
76
in which it is caught within a lower end section of gun carrying portion
54
by the no-go structure
74
. In this position, dropped gun
76
is disposed beneath the lowermost aligned perforation set.
After the perforation gun
76
drops, and while still maintaining the tension force on work string
30
above locator
50
, formation
14
is stimulated by pumping stimulation fluid, such as a suitable proppant slurry, downwardly through work string
30
, outwardly through perforations
78
and into formation
14
through perforations
80
which are aligned with perforations
78
both circumferentially and axially.
At this point it is important to note that the stimulation process for formation
14
has been completed not with the usual plurality of downhole trips, but instead with but a single trip of work string
30
. Additionally, during the pumping and work string discharge of the proppant slurry, work string perforations
78
are kept in their initial firing alignment with casing, cement and production perforations
80
as a result of the continuing tension force exerted on work string
30
above locator
50
. The high pressure streams of proppant slurry exiting the work string discharge perforations
78
are jetted essentially directly into their corresponding aligned perforations
80
, thereby eliminating the conventional tortuous path, and resulting abrasion wear problems, of discharged proppant slurry resulting from misalignments occurring in conventional multi-trip stimulation operations.
The maintenance of the desirable, abrasion reducing alignment between perforations sets
78
and
80
during the proppant slurry phase of the overall stimulation process is facilitated by the previously mentioned tension force maintained during slurry pumping. Such overpull force, coupled with the forcible upward engagement of the locator
50
with the corresponding locator profile
40
, automatically builds into work string
30
compensation for thermal and pressure forces imposed on work string
30
during proppant slurry delivery that otherwise might shift perforations
78
relative to their directly facing perforations
80
.
While the axial force used to maintain the alignment between the perforations
78
and
80
is preferably a tension force, it could alternatively be an axial compression force maintained on the portion of the work string
30
above locator
50
. To use this alternate compression force it is simply necessary to reconfigure locator
50
so that it will pass upwardly through profile
40
but is releasably precluded from passing downwardly therethrough.
If desired, after the proppant slurry pumping step is completed, a cleanout step may be carried out to remove residual proppant slurry from the interior of nipple
38
. After this optional clean out step is performed, the internal pressure within work string
30
is reduced so that locator
50
may be disengaged from profile
40
as will be discussed in detail below. Work string
30
is then pulled upwardly with a force sufficient to shear out and disable locator
50
, thereby permitting locator
50
to pass upwardly through profile
40
, and then further pulled upwardly until locator
58
engages profile
40
to halt further upward movement of work string
30
. At this point, the annular upper and lower sliding side door end seals
62
and
64
sealingly engage the annular internal nipple sealing surface areas
42
and
46
, respectively, with the screened tubular sliding side door structure
60
longitudinally extending between the sealing surfaces
42
and
46
.
Finally, an upward pull is exerted on the portion of the work string
30
above locator
58
with sufficient force to separate work string assembly
48
at the releasable connection
70
, thereby leaving the lower portion of the work string assembly
48
in place within nipple
38
.
It should be noted that with the use of locator
50
to achieve the one trip method described above, the spent perforating gun
76
is automatically retrieved with the upper work string portion upon completion of the method instead of being simply dropped into the well's rat hole as is typically the case when a drop-off type perforating gun is used in conventional multi-trip perforation and stimulation methods.
Also, it should be noted that the screened sliding side door structure
60
was initially installed in its closed position in work string assembly
48
. Accordingly, the sliding side door structure
60
, when left in place within the nipple
38
at the end of the one-trip perforation and stimulation process, serves to isolate formation
14
from the balance of the well system by blocking inflow of production fluid from formation
14
through perforations
80
and then upwardly through either work string
30
or casing
34
.
The overall method just described is thus utilized, in a single downhole trip, to sequentially carry out in a unique fashion a perforation function, a stimulation function and a subsequent production zone isolation function. As will be readily appreciated, similar one-trip methods may be subsequently performed on upwardly successive formations (not shown) to perforate, stimulate, and isolate them in readiness for later well fluid delivery therefrom.
After each formation has been readied for well fluid delivery in this manner, any zone, such as formation
14
, may be selectively recommunicated with the interior of its associated work string section simply by running a conventional shifting tool down wellbore
32
and using it to downwardly shift the door portion of sliding side door structure
60
, to thereby permit production fluid to flow from formation
14
inwardly through perforations
80
, into the now opened screened sliding side door structure
60
, and then upwardly through work string
30
to the surface. Alternatively, of course, the sliding side door structure could be rotationally shiftable between its open and closed positions instead of axially shiftable therebetween.
Even though
FIGS. 1 and 2
depict a vertical well, it should be note by one skilled in the art that the selectively locking locator of the present invention is equally well-suited for deviated wells, inclined wells or horizontal wells. As such, it should be apparent to those skilled in the art that the use of directional terms such as above, below, upper, lower, upward, downward and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward direction being towards the top of the corresponding figure and the downward direction being toward the bottom of the corresponding figure. It is to be understood that the selectively locking locator of the present invention may be operated in vertical, horizontal, inverted or inclined orientations without deviating from the principles of the present invention.
Referring now to
FIGS. 3A-3C
, therein is depicted a selectively locking locator of the present invention that is generally designated
100
. Locator
100
includes a generally cylindrical axially extending mandrel
102
. Securably and sealingly coupled to mandrel
102
is a housing
104
. Housing
104
extends upwardly from mandrel
102
and is partially disposed exteriorily around mandrel
102
forming a receiving area for a locator key
106
such that locator key
106
is disposed between housing
104
and mandrel
102
. Locator key
106
is radially extendable through a window
108
of housing
104
. As best seen in
FIG. 3A
, locator key
106
has a first position wherein locator key
106
is engagable with a matching profile of a nipple such as profile
40
of FIG.
2
. As best seen in
FIG. 3C
, locator key
106
has a second position wherein locator key
106
is retracted within the receiving area between mandrel
102
and housing
104
and away from profile
40
.
Disposed between housing
104
and mandrel
102
is a support ring
110
. One or more sheerable members
112
friably prevent support ring
110
from axial moving with respect to mandrel
102
. As best seen in
FIG. 3A
, support ring
110
is positioned to prevent the movement of locator key
106
from the first position as long as sheerable members
112
are unsheered. As best seen in
FIG. 3C
, once sheerable members
112
are sheered in response to a predetermined axial force between support ring
110
and mandrel
102
, support ring
110
is axially shifted with respect to mandrel
102
such that locator key
106
may be operated to the second position to disengage profile
40
.
Mandrel
102
includes one or more radially bores
114
. At least partially disposed within each radial bore
114
is an engagement mechanism such as piston
116
and engagement member
118
. As explained in more detail below, each piston
116
may be integral with an engagement member
118
or each piston
116
and engagement member
118
may be separate parts. It should be noted by one skilled in the art that the relative size of each piston
116
and engagement member
118
will depend on such factors as the expected force to be supported by piston
116
and engagement member
118
of the engagement mechanism.
In the illustrated embodiment, piston
116
moves radially outwardly within radial bore
114
in response to internal pressure within mandrel
102
. Piston
116
has an engagement member
118
operably extending therefrom. As best seen in
FIG. 3A
, engagement member
118
has a spaced apart relationship with support ring
110
when locator
100
is run into the wellbore. The spaced apart relationship between support ring
110
and engagement member
118
is maintained as locator
100
is passed downwardly through profile
40
. Once locator
100
is returned upwardly into profile
40
, locator key
106
is engaged with profile
40
. As best seen in
FIG. 3B
, once an internal pressure is applied to mandrel
102
, piston
116
along with engagement member
118
are outwardly radially shifted such that engagement member
118
contacts support ring
110
. This internal pressure may be in the range of 50 to 200 psi or other suitable pressure depending on the size and number of pistons
116
. When engagement member
118
contacts support ring
110
, upward passage of locator
100
through profile
40
is disallowed.
As the pressure within the work string
30
is further elevated, the work string
30
is placed in tension which is supported by locator
100
without the possibility of sheering the sheerable members
112
. This is achieved by transferring the axial force between support ring
110
and mandrel
102
to piston
116
through the contact between engagement member
118
and support ring
110
. Thus, as long as the internal pressure is maintained within mandrel
102
, piston
116
supports the axial load between support ring
110
and mandrel
102
, sheerable members
112
remain unsheered, axial displacement of support ring
110
relative to mandrel
102
is prevented, retraction of locator key
106
from profile
40
is prevented and upward passage of locator
100
through profile
40
is disallowed.
When it is desired to remove locator
100
from profile
40
, piston
116
is radially inwardly shifted to disengage engagement member
118
from support ring
110
by reducing the internal pressure within mandrel
102
, by increasing the external pressure around housing
104
or both. As best seen in
FIG. 3C
, once piston
116
is radially inwardly shifted to disengage engagement member
118
from support ring
110
, an upwardly acting tensioning force delivered to housing
104
and mandrel
102
is transmitted to support ring
110
via locator key
106
when locator key
106
is engaged with profile
40
. When the tensioning force reached a predetermined level, the axial force between support ring
110
and mandrel
102
, which is no longer carried by piston
116
, sheers sheerable members
112
, thereby allowing the axially displacement of support ring
110
relative to mandrel
102
. For example, if there are ten sheerable members
112
each capable of carrying 5000 pounds extending between support ring
110
and mandrel
102
, it would require 50,000 pounds of axial force to separate support ring
110
from mandrel
102
. It should be noted that this sheer force is significantly less than the tension force during the perforation and stimulation steps described above. It should also be noted that this sheer force delivered to housing
104
radially inwardly biases locator key
106
due to the interaction between shoulders
120
and
122
of window
108
with surfaces
124
and
126
of locator key
106
.
Referring now to
FIGS. 4A-4B
, therein are depicted cross sectional views of a selectively locking locator of the present invention in its various positions that is generally designated
130
. Locator
130
includes mandrel
102
having four radial bores
114
each of which has a piston
116
disposed therein. Received around mandrel
102
and pistons
116
is a c-ring
132
that serves as engagement member
118
described above with reference to
FIGS. 3A-3C
. Dispose about c-ring
132
is support ring
110
. Housing
104
encircles support ring
110
.
When locator
130
is run into the wellbore and as best seen in
FIG. 4A
, c-ring
132
has a spaced apart relationship with support ring
110
. The spaced apart relationship between support ring
110
and c-ring
132
is maintained as locator
130
is passed downwardly through the nipple profile. Once locator
130
is returned upwardly into the profile, the locator key engages the profile. As best seen in
FIG. 4B
, once an internal pressure is applied to mandrel
102
, pistons
116
are outwardly radially shifted such that c-ring
132
is radially expanded to engage support ring
110
. When c-ring
132
engages support ring
110
, upward passage of locator
130
through the profile of the nipple profile is disallowed.
When it is desired to remove locator
130
from the nipple profile, the internal pressure within mandrel
102
is reduced below a predetermined level such that the spring action of c-ring
132
radially inwardly shifts pistons
116
within radial bores
114
. C-ring
132
then disengages support ring
110
, as best seen in FIG.
4
A.
It should be noted that c-ring
132
may be free to rotate about mandrel
102
and pistons
116
. Alternatively, the rotation of c-ring
132
relative to mandrel
102
may be prevented by, for example, a set screw. In this case, it is preferable the open portion of c-ring
132
not be aligned with one of the pistons
116
.
Referring now to
FIGS. 5A-5B
, therein are depicted cross sectional views of a selectively locking locator of the present invention in its various positions that is generally designated
140
. Locator
140
includes mandrel
102
having four radial bores
114
each of which has a piston
116
disposed therein. Each of the pistons
116
has a piston extension
142
that is disposed about mandrel
142
. The piston extensions
142
serve as engagement member
118
described above with reference to
FIGS. 3A-3C
. Dispose about piston extensions
142
is support ring
110
. Housing
104
encircles support ring
110
.
When locator
140
is run into the wellbore and as best seen in
FIG. 5A
, piston extensions
142
have a spaced apart relationship with support ring
110
. The spaced apart relationship between support ring
110
and piston extensions
142
is maintained as locator
140
is passed downwardly through the nipple profile. Once locator
140
is returned upwardly into the profile, the locator key engages the profile. As best seen in
FIG. 5B
, once an internal pressure is applied to mandrel
102
, pistons
116
are outwardly radially shifted such that piston extensions
142
are outwardly radially shifted to engage support ring
110
. When piston extensions
142
engage support ring
110
, upward passage of locator
140
through the nipple profile is disallowed.
When it is desired to remove locator
140
from the nipple profile, the internal pressure within mandrel
102
is reduced. In addition or alternatively, the external pressure around housing
104
is increased such that piston
116
and piston extensions
142
are radially inwardly shifted to disengage piston extensions
142
from support ring
110
, as best seen in FIG.
5
A.
Even though
FIGS. 4A
,
4
B,
5
A and
5
B have been described with reference to four pistons
116
, it should be noted by one skilled in the art that the exact number of pistons and the size of the pistons will depend on such factors as the diameter of the locator and the expected force that the pistons will operate under. As such, the exact number of pistons may be less than or greater than that describe above without departing from the principles of the present invention, such number including, but not limited to, one piston, two pistons, six pistons or eight pistons.
Referring next to
FIGS. 6A-6B
, the locking mechanisms of two embodiments of a selectively locking locator of the present invention are depicted in cross section. In
FIG. 6A
, engagement member
118
includes a plurality of gear teeth
150
. Gear teeth
150
of engagement member
118
mesh with gear teeth
152
of support ring
110
when an internal pressure is applied to mandrel
102
that outwardly radially shifts pistons
116
. When gear teeth
150
of engagement member
118
mesh with gear teeth
152
of support ring
110
, upward passage of the locator through the nipple profile is disallowed. Similarly, as depicted in
FIG. 6B
, engagement member
118
may alternatively include one or more projections
154
. Projections
154
of engagement member
118
are inserted into a corresponding number of slots
156
of support ring
110
when an internal pressure is applied to mandrel
102
that outwardly radially shifts pistons
116
. When projections
154
of engagement member
118
are inserted into slots
156
of support ring
110
, upward passage of the locator through the nipple profile is disallowed.
Even though the present invention has been describe with reference to a selectively locking locator, it is to be understood by those skilled in the art that the present invention is broadly applicable to a variety of downhole tools when it is desirable to selective prevent the axial movement of two tubular members relative to one another. For example, one of the tubular member, the interior or exterior member, has a radial bore in the sidewall thereof wherein a piston is disposed. The piston selectively engages the other tubular member in response to a differential pressure between the interior and the exterior of the tubular members. As such, axial movement of the tubular members relative to one another is selectively prevented while the piston is engaged.
Referring now to
FIGS. 7A-7C
, therein is depicted another embodiment of a selectively locking locator of the present invention that is generally designated
200
. Locator
200
includes a generally cylindrical axially extending mandrel
202
. Securably and sealingly coupled to mandrel
202
is a housing
204
. Housing
204
extends upwardly from mandrel
202
and is partially disposed exteriorily around mandrel
202
forming a receiving area for a locator key
206
such that locator key
206
is disposed between housing
204
and mandrel
202
. Locator key
206
is radially extendable through a window
208
of housing
204
. As best seen in
FIG. 7A
, locator key
206
has a first position wherein locator key
206
is engagable with a matching profile of a nipple such as profile
40
of FIG.
2
. As best seen in
FIG. 7C
, locator key
206
has a second position wherein locator key
206
is retracted within the receiving area between mandrel
202
and housing
204
and away from profile
40
.
Disposed between housing
204
and mandrel
202
is a support ring
210
. One or more sheerable members
212
friably prevent support ring
210
from axial moving with respect to mandrel
202
. As best seen in
FIG. 7A
, support ring
210
is positioned to prevent the movement of locator key
206
from the first position as long as sheerable members
212
are unsheered. As best seen in
FIG. 7C
, once sheerable members
212
are sheered in response to a predetermined axial force between support ring
210
and mandrel
202
, support ring
210
is axially shifted with respect to mandrel
202
such that locator key
206
may be operated to the second position to disengage profile
40
.
Support ring
210
includes one or more radially bores
214
. At least partially disposed within each radial bore
214
is an engagement mechanism such as piston
216
and engagement member
218
. As explained above, each piston
216
may be integral with an engagement member
218
or each piston
216
and engagement member
218
may be separate parts. It should be noted by one skilled in the art that the relative size of each piston
216
and engagement member
218
will depend on such factors as the expected force to be supported by piston
216
and engagement member
218
of the engagement mechanism.
In the illustrated embodiment, piston
216
moves radially inwardly within radial bore
214
in response to external pressure around support ring
210
. As best seen in
FIG. 7A
, engagement member
218
has a spaced apart relationship with support ring
210
when locator
200
is run into the wellbore. The spaced apart relationship between support ring
210
and engagement member
218
is maintained as locator
200
is passed downwardly through profile
40
. Once locator
200
is returned upwardly into profile
40
, locator key
206
is engaged with profile
40
. As best seen in
FIG. 7B
, once an external pressure is applied to support ring
210
, piston
216
along with engagement member
218
are inwardly radially shifted such that engagement member
218
contacts mandrel
202
. This external pressure may be in the range of 50 to 200 psi or other suitable pressure depending on the size and number of pistons
216
. When engagement member
218
contacts mandrel
202
, upward passage of locator
200
through profile
40
is disallowed.
As the pressure within the work string
30
is further elevated, the work string
30
is placed in tension which is supported by locator
200
without the possibility of sheering the sheerable members
212
. This is achieved by transferring the axial force between support ring
210
and mandrel
202
to piston
216
through the contact between engagement member
218
and mandrel
202
. Thus, as long as the external pressure is maintained around support ring
210
, piston
216
supports the axial load between support ring
210
and mandrel
202
, sheerable members
212
remain unsheered, axial displacement of support ring
210
relative to mandrel
202
is prevented, retraction of locator key
206
from profile
40
is prevented and upward passage of locator
200
through profile
40
is disallowed.
When it is desired to remove locator
200
from profile
40
, piston
216
is radially outwardly shifted to disengage engagement member
218
from mandrel
202
by reducing the external pressure around support ring
210
, by increasing the internal pressure within mandrel
202
which is transmitted via port
228
to engagement member
218
between seals
230
,
232
or both. In addition, if engagement member
218
includes a c-ring as describe above, the spring force of the c-ring assists in the outward movement of piston
216
by outwardly radially biasing piston
216
. As best seen in
FIG. 7C
, once piston
216
is radially outwardly shifted to disengage engagement member
218
from mandrel
202
, an upwardly acting tensioning force delivered to housing
204
and mandrel
202
is transmitted to support ring
210
via locator key
206
when locator key
206
is engaged with profile
40
. When the tensioning force reached a predetermined level, the axial force between support ring
210
and mandrel
202
, which is no longer carried by piston
206
, sheers sheerable members
212
, thereby allowing the axially displacement of support ring
210
relative to mandrel
202
. It should be noted that this sheer force is significantly less than the tension force during the perforation and stimulation steps described above. It should also be noted that this sheer force delivered to housing
204
radially inwardly biases locator key
206
due to the interaction between shoulders
220
and
222
of window
208
with surfaces
224
and
226
of locator key
206
.
While this invention has been described with a reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.
Claims
- 1. A downhole tool comprising:a first tubular member; a second tubular member slidably disposed relative to the first tubular member, the second tubular member having a radial bore in the sidewall thereof; and an engagement mechanism at least partially disposed within the radial bore and including a c-ring, the engagement mechanism selectively engagable with the first tubular member in response to a first differential pressure between the interior and the exterior of the second tubular member, thereby selectively preventing axial displacement of the first tubular member relative to the second tubular member.
- 2. The downhole tool as recited in claim 1 wherein the second tubular member is disposed within the interior of the first tubular member.
- 3. The downhole tool as recited in claim 2 wherein the engagement mechanism is shifted radially outwardly in response to the first differential pressure between the interior and the exterior of the second tubular member.
- 4. The downhole tool as recited in claim 1 wherein the second tubular member is disposed exteriorily about the first tubular member.
- 5. The downhole tool as recited in claim 4 wherein the engagement mechanism is shifted radially inwardly in response to the first differential pressure between the interior and the exterior of the second tubular member.
- 6. The downhole tool as recited in claim 1 wherein the c-ring radially inwardly biases the engagement mechanism to disengage the engagement mechanism from the first tubular member.
- 7. The downhole tool as recited in claim 1 wherein the c-ring radially outwardly biases the engagement mechanism to disengage the engagement mechanism from the first tubular member.
- 8. The downhole tool as recited in claim 1 wherein the engagement mechanism is disengaged from the first tubular member in response to a second differential pressure having a gradient opposite to that of the first differential pressure.
- 9. The downhole tool as recited in claim 8, wherein the second differential pressure radially inwardly shifts the engagement mechanism to disengage the engagement mechanism from the first tubular member.
- 10. The downhole tool as recited in claim 8 wherein the second differential pressure radially outwardly shifts the engagement mechanism to disengage the engagement mechanism from the first tubular member.
- 11. A downhole tool comprising:a locator key disposed between a housing and a mandrel and radially extendable through a window of the housing between an engagable position and a retracted position; a support ring disposed between the housing and the mandrel, the support ring preventing movement of the locator key from the engagable position to the retracted position until the support ring is axially displaced relative to the mandrel; and an engagement mechanism at least partially disposed within a radial bore of the mandrel and including a c-ring, the engagement mechanism selectively engagable with the support ring in response to a first differential pressure between the interior and exterior of the mandrel, thereby selectively preventing axial displacement of the support ring relative to the mandrel and selectively preventing movement of the locator key to the retracted position.
- 12. The downhole tool as recited in claim 11 further comprising a sheerable member extending between the mandrel and the support ring that sheers in response to a predetermined axial force between the support ring and the mandrel.
- 13. The downhole tool as recited in claim 11 wherein the c-ring radially biases the engagement mechanism to disengage the support ring when the first differential pressure is reduced below a predetermined level.
- 14. The downhole tool as recited in claim 11 wherein a second differential pressure having a gradient opposite of the first differential pressure acts on the engagement mechanism to disengage the engagement mechanism from the support ring.
- 15. The downhole tool as recited in claim 11 wherein the engagement mechanism includes a plurality of teeth and the support ring includes a plurality of teeth, the plurality of teeth of the engagement mechanism engaging the plurality of teeth of the support ring to selectively prevent axial displacement of the support ring relative to the mandrel when the first differential pressure is acting on the engagement mechanism.
- 16. The downhole tool as recited in claim 11 wherein the engagement mechanism includes a projection and the support ring includes a slot, the projection of the engagement mechanism engaging the slot of the support ring to selectively prevent axial displacement of the support ring relative to the mandrel when the first differential pressure is acting on the engagement mechanism.
- 17. A method for selectively preventing relative axial movement between a first tubular member and a second tubular member slidably disposed relative to the first tubular member in a downhole tool, the method comprising the steps of:disposing an engagement mechanism at least partially within a radial bore of the second tubular member, the engagement mechanism including a c-ring; applying a first differential pressure between the interior and the exterior of the second tubular member; and selectively engaging the engagement mechanism with the first tubular member in response to the first differential pressure, thereby selectively preventing axial displacement of the first tubular member relative to the second tubular member.
- 18. The method as recited in claim 17 further comprising the step of disposing the second tubular member within the interior of the first tubular member.
- 19. The method as recited in claim 18 wherein the step of selectively engaging the engagement mechanism with the first tubular member further comprises shifting the engagement mechanism radially outwardly in response to the first differential pressure between the interior and the exterior of the second tubular member.
- 20. The method as recited in claim 17 further comprising the step of disposing the second tubular member exteriorily about the first tubular member.
- 21. The method as recited in claim 20 wherein the step of selectively engaging the engagement mechanism with the first tubular member further comprises shifting the engagement mechanism radially inwardly in response to the first differential pressure between the interior and the exterior of the second tubular member.
- 22. The method as recited in claim 17 further comprising the step of radially inwardly biasing the c-ring to disengage the engagement mechanism from the first tubular member.
- 23. The method as recited in claim 17 further comprising the step of radially outwardly biasing the c-ring to disengage the engagement mechanism from the first tubular member.
- 24. The method as recited in claim 17 further comprising the step of applying a second differential pressure having a gradient opposite to that of the first differential pressure between the interior and exterior of the second tubular member to disengage the engagement mechanism from the first tubular member.
- 25. The method as recited in claim 24 further comprising the step of radially inwardly shifting the engagement mechanism to disengage the engagement mechanism from the first tubular member in response to the second differential pressure.
- 26. The method as recited in claim 24 further comprising the step of radially outwardly shifting the engagement mechanism to disengage the engagement mechanism from the first tubular member in response to the second differential pressure.
- 27. A method for selectively preventing passage of a locator device through a nipple profile within a wellbore comprising the steps of:engaging a locator key of the locator device with the nipple profile; providing a first differential pressure to the locator device to act on an engagement mechanism at least partially disposed within a radial bore in the sidewall of a mandrel and including a c-ring; and radially shifting the engagement mechanism to engage a support ring and prevent axial displacement of the support ring relative to the mandrel, thereby preventing retraction of the locator key from the nipple profile and preventing passage of the locator device through the nipple profile in a first direction.
- 28. The method as recited in claim 27 further comprising the step of extending a sheerable member between the support ring and the mandrel that sheers in response to a predetermined axial force between the support ring and the mandrel.
- 29. The method as recited in claim 27 further comprising the steps of reducing the first differential pressure below a predetermined level and radially biasing the engagement mechanism with the c-ring to disengage the engagement mechanism from the support ring.
- 30. The method as recited in claim 27 further comprising the step of disposing a engagement mechanism extension between the engagement mechanism and the support ring.
- 31. The method as recited in claim 27 further comprising the step of engaging a plurality of teeth on the engagement mechanism with a plurality of teeth on the support ring to selectively prevent axial displacement of the support ring relative to the mandrel.
- 32. The method as recited in claim 27 further comprising the step of engaging a projection on the engagement mechanism with a slot in the support ring to selectively prevent axial displacement of the support ring relative to the mandrel.
- 33. The method as recited in claim 27 further comprising the steps of applying a second different pressure having a gradient opposite of that of the first differential pressure to the locator device and radially shifting the engagement mechanism to disengage the engagement mechanism from the support ring.
US Referenced Citations (9)
Foreign Referenced Citations (1)
Number |
Date |
Country |
WO 9105935 |
May 1991 |
WO |