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Description  |
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FIELD OF THE INVENTION
This invention relates generally to blow out preventers for use with oil
and gas wells, and, more particularly, relates to a system for modifying a
ram type preventer from a remote location to permit sealing engagement of
the preventer about pipe of varying diameters.
BACKGROUND OF THE INVENTION
In the drilling of oil or gas wells apparatus is employed to prevent such
wells from blowing out of control during the drilling operations. Such
apparatus conventionally comprises a plurality of devices known in the art
as blow out preventers which are attached to the well head.
It is further conventional to provide at least two such preventers of the
ram type, a typical example of one being manufactured by Cameron Iron
Works and depicted on page 1435 of the Composite Catalog 1980-1981
published by World Oil. Such preventers typically include a pressure
vessel housing enclosing hydraulically or mechanically actuated opposing
pistons which are attached to corresponding ram blocks for puroses of
urging the ram blocks in radial directions into and out of the wellbore.
The ram blocks, in turn, carry faces of varying design, each having a
semicircularly shaped sealing surface formed of a resilient packing
material whereby when the faces are forced radially inwards by the pistons
sufficiently, a cylindrical sealing surface of this resilient material is
thereby formed for sealing engagement about pipe traversing the preventer
bore and borehole. The closing of these ram blocks about the pipe thereby
effectively seals off the preventer bore transversely about the pipe,
thereby preventing undesirable escape of pressurized fluid from the
wellbore.
During the drilling of hydrocarbon wells, it is necessary at various times
to suspend pipe of varying outside diameters through these blow out
preventers into the wellbore for purposes well known in the art.
Accordingly, it is concomitantly necessary to change out the ram blocks in
the preventers to accommodate these differing pipe diameters, inasmuch as
for a given pair of ram blocks installed within a preventer, the radius of
curvature of the sealing faces thereof define a single bore diameter
adapted for sealing engagement only with pipe of a correlative outer
diameter. Moreover, in order to accommodate the wide range of pipe
diameters and provide correlative ram openings encountered in the art,
which may typically range from 23/8 to 95/8 inches o.d., it has been
conventional to disassemble the preventers and install different ram
blocks with faces having sealing surfaces of a different radius of
curvature to accomodate the o.d. of the particular pipe traversing the
wellbore.
Unfortunately, the aforementioned blow out preventers are frequently
disposed in inaccessible or hazardous locations as, for example, below the
drilling rig floor, or, in the case of offshore wells, adjacent to the sea
bed. It may thus be readily appreciated that such changing out of ram
blocks to accomodate pipe of differing diameters is not only time
consuming but frequently a dangerous and expensive operation. For example,
in the case of the aforesaid preventers located on the ocean floor, as for
example with a floating drilling rig, the change-out operation
necessitates detaching the preventers and riser from the wellhead, lifting
the preventers, which are frequently quite bulky and heavy, and their
attached riser to the drilling rig, disassembling the preventers to remove
the ram blocks, installing different blocks and reassembling and pressure
testing the preventers, and thence returning the preventers and riser to
the sea bed wellhead and reattaching them. Such operations are thus as
stated extremely difficult, dangerous, time consuming and expensive, with
several days of unproductive rig drilling down time being required to
effect such changes.
For the foregoing reasons, methods and apparatus were long sought for
effecting the modification of such preventers from remote locations to
accomodate pipe of varying diameters. Thus, it has become known in the art
as shown in U.S. Pat. Nos. 4,133,342 and 4,003,430 to provide various
drill pipe conveyed mechanisms which were lowered proximally to the ram
faces for cutting out and flushing away the resilient packing material
carried by the ram blocks. Additional apparatus as shown in U.S. Pat. Nos.
3,737,974 and 3,821,838 has further been provided, also conveyed by the
drill string, for transferring replacement seals from a remote location to
the preventer and thence installing and securing such seals in the recess
resulting from the previous operation of removing the pliable packer
material in the rams.
While such technology has met with some success in certain applications,
several problems were nevertheless still associated with attempts to
effect the modification of ram shoe bores from a situs remotely of the
preventer. For example, in the aforementioned approach, it will be
recalled that one step comprised the cutting out and thus destruction of
the prior packing material which was thus obviously not retrieved intact
at the remote location. Moreover, such a cutting operation required that
mechanisms be provided for insuring that material thus cut away was
sufficiently removed from the recess in order to permit installation of
the new packer material. Still further, provision was further required for
insuring that such spent material was flushed from the preventer itself.
However, an even more serious problem with the prior technology related to
the limitations in bore diameter of the resultant replacement seals which
might thus be installed. More particularly, in such technology, it will be
recalled that primarily it was the sealing material that was cut away from
ram blocks which carried metalic pipe faces of a fixed radius of curvature
and which could thus not be remotely varied during the seal member
changing operation. Such pipe faces defined a portion of the cylindrical
surface of the preventer rams adapted to circumscribe pipe of a diameter
correlative to the radius of curvature of the pipe faces.
Accordingly, the portion of the replacement seals intended to sealing
engage the outer periphery of the pipe could have a radius of curvature
substantially equal to that of the pipe faces of the ram shoes in order to
accomodate pipe of the same diameter sealed by the prior seal.
Alternatively, the replacement seal could even have a portion intended to
sealingly engage pipe having an even smaller radius of curvature to
accomodate pipe of a correlative smaller o.d. than that previously sealed
about by the preventer.
However, inasmuch as the radius of curvature of the metallic faces of the
ram blocks could not be enlargened from a remote location, this
effectively limited the ability to modify the preventer from a remote
location so as to accomodate pipe having an o.d.TM.greater than that
corresponding to this radius of curvature of the pipe faces. In other
words, means were provided for remotely modifying a preventer so as to
accomodate pipe o.d.'s equal to or smaller than those corresponding to the
radius of curvature of the ram faces, but the pipe face o.d. of the rams
first installed in the preventer when first deployed effectively limited
the maximum pipe o.d. which might be accomodated and sealingly engaged by
the preventer.
Still further problems were associated with prior attempts to remotely
modify preventers to accomodate widely ranging pipe o.d.'s in order to
sealingly engage therewith. In the removal of prior sealing material and
replacement of a seal having a differing radius of curvature from a remote
location, it is necessary to establish with some precision both the radial
and axial position of the preventer relative to the tool performing these
functions. More reliable means were sought for establishing this spatial
interrelationship between the running tool relative to the preventer
components. Moreover, means were also sought for more reliably and
precisely establishing such radial and axial positioning of ram shoes
relative to the conveying running tool both when such shoes are withdrawn
from the preventer by the tool and installed within the preventer by the
running tool.
Still further, a conventional replacement ram shoe adapted to replace
another such shoe transported and under control from a remote location to
the preventer was typically releasably attached to the ram by means of a
plurality of pins and apertures in the seal and ram. When such apertures
were brought in registry, they could be matingly received by such pins to
releasably and retainedly interconnect the seal and the ram. Particularly
in the application of the instant invention wherein it is desirable to
control from a location remotely of the preventer both the removal of the
prior seal as well as replacement by a new seal, the provision of such a
plurality of fastening pins provided great difficulty both in effecting
release of the seal from the ram block for removal as well as in reliably
effecting a subsequent interconnection between the replacement seal and
the ram block with the necessary integrity under the adverse conditions of
the borehole environment.
Accordingly, technology was also sought in the art for providing a
releasable interconnection between a ram shoe and ram block which was
simpler in design and operation, reliable, and effective in controlling
both such release and interconnection from a remote location.
The present invention overcomes the hereinbefore described problems as well
as others, providing a novel system for effecting replacement of ram shoes
in a preventer from a remote location.
SUMMARY OF THE INVENTION
In one aspect of the invention a novel ram is provided for use in pairs
within a ram-type blowout preventer. Each ram has a ram block body which
releasably receives one of a plurality of novel ram shoes. The ram
includes means for releasably interconnecting a shoe to and disconnecting
a shoe from a respective ram block body while the ram block body is
disposed functionally within the preventer.
Each shoe has a shoe body defining a pair of pipe faces with
half-cylindrical surfaces. A recess circumscribing the body receives a
resilient seal which includes a half-cylindrical packer face surface in
vertical registry with and disposed between the pipe faces. The half
cylindrical surfaces of the shoes of a pair, when in opposing engagement,
define a cylindrical bore therethrough for sealing engagement about the
periphery of pipe. A plurality of pairs of shoes is provided, each with a
different such bore adapted to engage pipe of a different o.d. when
installed in a pair of ram block bodies.
Each shoe has load shoulders slidingly receivable by a mating recess within
each ram block body. Means are provided for releasably interconnecting
each shoe to its respective ram block body while disposed within the
preventer. In a preferred embodiment such means comprises a vertical pin
hole in an upper load shoulder, a vertical locking pin hole substantially
centrally located in the upper surface of the ram block body, and a
locking pin. When load shoulders of a shoe are within the recess of the
ram block body, the holes are in vertical registry so as to receive an
extractable locking pin. With the pin in place, the shoe and ram block
body are integrally interconnected to form a ram of the preventer and,
with the pin removed while the ram is within the preventer, the shoe may
thence be removed from the ram block body and a replacement shoe
installed.
The recess within the ram block body and an outer peripheral edge of the
shoes are of mating general U shapes wherein the sides of the U's diverge.
Sliding contact between the surfaces defining the sides of the U's as the
load shoulder is slid into the ram block body recess serves as an
alignment guide to insure a proper final preselected radial orientation
between the shoe and its respective ram block body when installed therein.
A running tool to be disposed on a drill string and conveyed between a
first location and a ram-type blowout preventer disposed at a second
location is provided. The tool sequentially performs the functions of
releasing an old shoe pair from ram block bodies while within the
preventer in situ at the remote second location, conveying these shoes
from the second to the first location, conveying replacement shoes from
the first to the second location which have a bore either smaller, the
same, or larger than that of the old shoe pair as desired in functional
relation to the pipe o.d. to be sealingly engaged, and thence releasably
installing the replacement shoes on the ram block bodies while within the
preventer.
The tool comprises means for radially and vertically positioning said tool
relative to said ram block bodies for said releasing and installing of
said shoes; means for disconnecting said old shoes from said ram block
bodies; means for releasably connecting said disconnected old shoes to
said tool; means for releasably connecting said replacement shoes to said
tool; and means for connecting said replacement shoes to said ram block
bodies.
In a preferred embodiment, each ram block body includes in its upper
surface an upper orientation slot for matingly receiving an orientation
slot pin on the lower carrier flange of the tool. The tool is lowered
until the slot pin contacts the upper ram block bodies which is detected
at the rig floor, thereby establishing relative vertical position of the
tool with respect to the ram block bodies. The tool is then rotated by the
drill string until the slot pin engages the orientation slot, also
detected at the rig floor, thereby establishing relative radial position
of the tool with respect to the ram block bodies.
In some applications of the invention, first and second sets of rams are
disposed at correlative first and second locations in known relative
spatial orientation. In an alternate embodiment of the invention,
positioner means on the drill string is provided in known spatial
orientation relative to the running tool for determining orientation of
the positioner means relative to the second set of rams. The running tool
is thereby properly positioned adjacent the first set of rams for shoe
installation and/or retrieval in functional response to this determined
orientation of the positioner means relative to the second set of rams.
These and other features of the present invention may be better understood
from the following detailed description in conjunction with the drawings,
wherein:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partially sectioned front elevational view of a ram rype blow
out preventer with ram assemblies thereof of the present invention
withdrawn from the preventer bore.
FIG. 2 is a pespective view of a ram shoe according to the invention.
FIG. 3 is a partially sectioned perspective view of a lock pin for
releasably securing the shoe within the preventer to a ram block.
FIG. 4 is a perspective view of a ram block with a shoe of FIG. 2 wherein
the shoe and block are disposed to receive the locking pin of FIG. 3.
FIG. 5 is a partially sectioned front elevational view of a ram shoe
carrier according to the invention.
FIG. 6 is a partially sectioned front elevational view of the running tool
assembly of the present invention including the ram shoe carrier of FIG. 5
with two shoes of FIG. 2 and two locking pins of FIG. 3 prior to
installation of the shoes in the preventer of FIG. 1.
FIG. 7 is an enlarged sectioned front elevational view of a portion of the
running tool of FIG. 6 depicting a portion of one of the lock pin
inserter/extractor assemblies thereof and further illustrating a lock pin
of FIG. 2 after removal from the preventer of FIG. 1 and ram block and
shoes of FIG. 4.
FIG. 8 is a sectioned plan view taken along line A--A of the shoe carrier
of FIG. 5 illustrating the position of the lock pin guides, holding pins
and taper leads of the upper carrier flange.
FIG. 9 is a perspective view of the underside of the ram shoe of FIG. 2.
FIG. 10 is a perspective view illustrating a positioner sub assembly for
use in the drill string with and either above or below the running tool of
the present invention to establish vertical and radial positioning thereof
with respect to rams in need of shoe replacement.
FIG. 11 is a pictorial and schematic view of a typical subsea blowout
preventer stack consisting of two double ram preventers illustrating one
mode of use of the assembly of FIG. 9 and a running tool in accordance
with the present invention wherein the tool is positioned for use with the
bottom preventer and with the assembly of FIG. 10 engaging one of the
middle sets of rams.
FIG. 12 is a pictorial and schematic view of the preventer stack of FIG. 11
illustrating another mode of use of the assembly of FIG. 9 and a running
tool in accordance with the present invention wherein the too is
positioned for use with the middle preventer and with the assembly of FIG.
10 engaging the bottom set of rams.
FIG. 13 is a schematic representation of the running tool of FIG. 6 and
assembly of FIG. 10 illustrating interconnectnion of the assembly to
either the top or bottom of the tool.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
First a general description will be given of a ram type flow out preventer
60 depicted generally in FIG. 1. Next, a more detailed description of a
ram assembly 10 will be given with reference to FIGS. 2-4. This will be
followed by a more detailed description with reference to FIGS. 5-8 of the
apparatus whereby modification of the ram assembly 10 may be effected in
preventer 60 and controlled from a location remotely of the preventer 60
to accomodate pipe of varying outside diameters. Finally, this will be
followed with a description of the method of use of the apparatus depicted
in FIGS. 1-8 for achieving the hereinbefore recited purposes of the
subject invention.
First, with respect to FIG. 1, a preventer is shown employing the novel ram
assemblies 10 of the present invention shown in FIG. 4. The typical
preventer 60 is secured to other preventers and the wellhead by means of
bolts 7. Extending through the pressure housing of the preventer 60 is a
bore 6 for purposes of providing fluid communication through the preventer
along the borehole, as well as for permitting pipe 5 ,used for various
purposes known in the art and having varying outside diameters, to extend
therethrough. In general, the preventer includes a pair of opposing ram
assemblies 10 which may be urged radially inwards into and outwards from
the bore 6.
Although the ram assemblies 10 will be described in greater detail with
reference to FIGS. 2-4, for present purposes it will be appreciated that
each assembly includes a resilient member providing a semicircularly
curved packer surface portion 27. When the ram assemblies 10 are urged
radially inwards by hydraulic or mechanical actuating means 1 and 2
through thrust rods 13 having longitudinal axes 94, these packer surfaces
27 will sealingly and matingly engage about the outer circumferential
periphery of the pipe 5. Additionally, radially inward portions of the
packets 27 on sealing surface 9 will engage one another whereby such
sealing engagement in combination with the portions of the ram assemblies
10 extending into the bore 6 will effectively seal off vertical fluid flow
and pressure differentials within the bore 6. It is conventional in the
art to provide top and side seals 12 and 25, respectively, for purposes of
sealing off the area between the outer periphery of the ram assembly and
the bore in the preventer housing through which the assemblies travel.
Thus flow is prevented between the bore 6 and portions of the preventer 60
radially outwards of the ram assemblies 10 and the bore through which they
travel.
With reference now to FIGS. 2-4, a novel ram shoe 8 of FIG. 2, locking pins
11 of FIG. 3, and block body 76 with ram shoe 8 of FIG. 4 of the present
invention may be seen illustrated. For purposes herein when the shoe 8 of
FIG. 2 is installed in the body 76 as shown in FIG. 4 with or without the
locking pin 11, such assembly may be variously referred to herein as the
ram assembly 10 or for purposes of convenience, "rams".
First, with respect to FIG. 2, the shoe 8 depicted therein may be seen as
having a shoe body 70 of metallic or like strong and durable material and
a seal 82. The shoe body 70 includes a pair of load shoulders 14 and a
pair of semicircular pipe faces 18 and 18a, the body further defining a
seal receiving recess which circumscribes the body and carries a seal 82
disposed therewithin of a resilient material. The upper and lower
shoulders have respective upper and lower shoulder surfaces which are
substantially flat and lie in corresponding parallel planes which are
normal to a shoe body vertical axis of symmetry 64. It will be noted that
the shoe is of a generally symmetrical configuration about this axis. A
pin hole 15 extends into, but not through load shoulder 14.
With more particular reference to the seal 82, in a preferred embodiment,
it will in part be comprised of an inside seal portion for mating and
sealing engagement with portions of the block body 76 defined by an
internal recess therein of the same general U shape defined by the
combination of the outer surface 68 of the inside seal portion 16 and the
outer edges 29 of the load shoulders 14, the latter two being referred to
collectively as a surface means. The block body is generally symmetrical
about its vertical axis 80. By providing mating U shapes of the recess in
the block body 76 and the outer peripheral edge or surface means of the
shoe, proper radial positioning and alignment of the shoe relative to the
body is insured during insertion of the shoe into the body 76. More
particularly, the two sides of these respective U shapes preferably are
substantially flat and diverge outwards, i.e. are non-parallel.
With reference to FIG. 4, the seal 82 will further comprise the curved
packer surface portion 27 intended to engage the outer periphery of the
pipe 5 and a generally flat packer portion 72 intended to engage a like
portion of the opposing ram assembly 10. The radius of curvature of the
pipe faces 18 and 18a is preferably substantially the same as that
defining the curved packer surface portion 27. The pipe faces 18 and 18a
and curved packer surface portions 27 may thereby in vertical registry
form a generally semicircular half-cylinder shape of the same approximate
radius of curvature of the pipe 5 about which the ram assemblies 10 are to
seal.
It is contemplated by the present invention to provide a plurality of shoe
pairs (individual shoes of which are of the form shown in FIG. 2) whereby
when the shoes of each pair are disposed in opposing relation in contact,
each pair defines a bore therethrough of a predetermined diameter for
receiving pipe of a corresponding o.d. More particularly, the bore
diameter of a particular pair will be defined by the radius of curvature
of the pipe faces and curved packer surface portions (which are preferably
substantially equal) of the shoes comprising the pair.
A pair of ram shoes 8 will be provided for each o.d. of pipe to be
sealingly engaged by the preventer wherein the bore and radius for each
such shoe pair will be functionally related to the o.d. of the pipe for
which it is provided and intended to seal about. The remainder of each ram
assembly when a shoe is removed is of a universal design and thus adapted
so as to receive in the manner shown in FIG. 4 any such shoe. The shoe of
a ram assembly of the present invention may thus be replaced or
interchanged with any remaining shoe of the plurality of pairs.
In this manner to sealingly engage pipe of a given o.d., an appropriate
particular pair of shoes 8 from the plurality of shoe pairs may be
selected corresponding to this o.d. Shoes previously in place in each ram
assembly of the preventer are removed and replaced with respective ones of
the selected replacement shoes whereby ram assemblies 10 are thereby
created which are custom fit to accomodate any desired o.d. pipe 5.
As aforestated, it is a further feature of the invention to provide a
system for remotely controlling the replacement of such pairs of shoes
within the preventer while the block bodies 76 are present therein,
thereby accomodating any desired pipe o.d.
With further reference to FIG. 4, it will be noted that a holding pin
recess 17 may preferably be provided in the upper portion of the shoe body
70. The purpose of this recess is generally to insure that when a shoe is
retrieved from a block body 76 it is securely and retainedly held by the
running tool of the present invention when this shoe is transported away
from the preventer and conversely to insure that a new replacement shoe
will, in like manner, be reliably retained by the running tool as it is
being transported from a remote location to the preventer for subsequent
installation in the ram block body 76.
A lock pin hole 23 will also be disposed vertically within the block body
76 in such a manner that when the shoe 8 is in mating engagement with the
block body to form the ram assembly 10, this lock pin hole 23 and pin hole
15 of the shoe will be in vertical registry so as to receive the lower
portion of the lock pin 11 of FIG. 3.
Also with respect to FIG. 4, an orientation slot means 26 is provided in
the upper surface 78 of the block body 76. In general the purpose of this
slot is to establish a desired preselected radial orientation of the
running tool relative to the block bodies when disposed in the preventer
housing. Further with reference to FIGS. 2 and 4, a guide slot 66 is
provided in the lower portion of the shoe body 70. The purpose of slot 66
is to insure proper radial positioning of each shoe as it is being
disposed onto the running tool for removal from the preventer to the
remote location and, conversely, to insure again such proper radial
positioning of a new replacement shoe with respect to the running tool
during removal of the shoe from the running tool for installation at a
remote location of the shoe within the block body 76. The guide slot 66
may preferably form a portion of a conventional mud slot 19 also disposed
in the lower surface of the shoe and traversing the block body 76 which is
used for conventional purposes well known in the art.
Regarding the locking pin 11 depicted in FIG. 3, from the sectional wall
view portion thereof, an annular collet shoulder 22 may be seen defining a
portion of the collet hole 21 disposed axially in the upper portion of the
pin. Further, a snap ring 20 will be provided about the outer periphery of
the upper portion of the pin 11. The purposes of such collet hole, snap
ring, and shoulders will be hereinafter described with reference to the
overall operation of the system.
With reference now to FIG. 5, a ram shoe carrier 28 is shown depicted
therein generally which forms a portion of the assembled running tool of
FIG. 6. The basic purpose of the carrier 28 is to carry away from the
preventer a first pair of shoes already disposed within the preventer to a
remote location and to further transport a replacement pair of shoes (such
as those defining in combination a sealing bore different from that of the
pair of shoes thus removed) to the preventer for installation in response
to remote control actions transmitted through the drill string and running
tool.
Accordingly, it will be appreciated that such a carrier 28 must be designed
whereby these shoes may be (1) securedly affixed to the running tool when
it is desired to transfer them away from and into the preventer while at
other times the shoes must be (2) readily, easily, and reliably released
from the running tool for installation in the preventer. Moreover, such a
carrier 28 must further provide the function of (1) easily and reliably
removing the locking pins 11 from the prior ram assemblies 10 while
disposed in the bore of the preventer so as to release these shoes from
the ram bodies for removal by the carrier while at other times providing
the function of (2) installing the locking pins within the locking pin
holes and pin holes of the ram body and shoe when in mating vertical
registry to rigidly secure the new replacement shoes to their respective
block bodies.
FIG. 8, a sectional view through the ram face carrier 28 of FIG. 5,
illustrates the upper carrier flange 30 with the relative positions of the
tapered holding pins 37 and locking pin guides 38 depicted
Thus, with continued reference to FIG. 5, a lower carrier flange 29, upper
carrier flange 30, and carrier sleeve 31 are provided. The carrier sleeve
31 has a keyway 32 to engage a key 33 shown in FIG. 6 for purposes to be
hereinafter described. The upper carrier flange 30 has a tapered lead 36
and the previously mentioned spring-loaded holding pins 37, and locking
pin guides 38. The lower carrier flange, in like manner to the upper
flange, has a taper face 39 interupted by a radial guides 40, orientation
slot pins 41, and pipe thread 42 from which guide pipe is suspended below
the running tool. The purpose and operation of these components will be
made more clear with reference to discussion hereinafter of the running
tool itself.
Referring now to the running tool as depicted in FIG. 6, it will be
recalled that it is disposed on the end of a drill pipe string by means of
threads 53 and the ram shoe carrier of FIG. 5 may be seen as a component
thereof. It will further be recalled that the basic purpose of the running
tool is to release a first set of shoes from ram block bodies while within
a preventer, to afix such released shoes reliably to the running tool and
thus transport them away from the preventer to a remote location. Yet a
further purpose of the running tool is to transport a new replacement set
of shoes from this remote location to the preventer and to install such
shoes in these same ram blocks. A pair of block pin inserter/extracter
assemblies 43 and the ram shoe carrier 28 of FIG. 5 are carried by a
mandrel 34. In this view, each inserter/extracter assembly 43 is equiped
with a pin plunger 44 installed in an actuating plunger 45 for insertion
of a lock pin 11 into the lock pin hole 23 and pin hole 15 of the ram
assembly 10 in FIG. 4.
The inserter/extractor assembly 43 contains a restraining spring 47 to bias
the running tool assembly in the extended position depicted in FIG. 6.
Upper and lower stops 48 and 49 are included to limit the travel of the
inserter/extractor assembly 43 when the restraining spring 47 is
compressed and relaxed in response to vertical movement of the drill
string as will be hereinafter described. The mandrel 34 is attached to the
inserter/extracter assembly 43 by threads 50. A key 33 on the
inserter/extracter assembly 43 slidingly received by keyway 32 insures
that the assembly 43 may move in the direction of the longitudinal axis of
the running tool while preventing rotational movement about the tool. The
mandrel 34 further contains signal ports 51 and chevron seals 52 to attach
to the drill pipe that positions and operates the running tool. Four
spring-loaded tapered holding pins 37 are provided disposed about the
longitudinal axis of the running tool, and the pin springs 46 provide
spring biasing for each of the pins 37.
Referring to FIG. 7, this is an enlarged sectioned view of the upper
carrier flange and that portion of the inserter/extractor 43 containing
the actuating plunger 45. The inserter/extractor assembly provides a dual
function. In the installation mode wherein shoes are about to be installed
(as shown in FIG. 6) the running tool has a pin plunger 44 provided in
each assembly 43 for moving a corresponding pin 11 downwards into the
mating holes once the block bodies 76 are brought radially inwards to
engage the shoes 8 carried by the tool. However in the configuration shown
in FIG. 7 the assemblies 43 are adapted to a retrieval mode for extracting
such pins from the block bodies to release the old shoes onto the running
tool which will be hereinafter described.
Obviously, in this retrieval mode, the shoes 8 shown in FIG. 6 will be
omitted from the running tool to provide room for the shoes about to be
extracted from the preventer and transferred to a remote location. Further
regarding this latter retrieval mode for withdrawing the old shoes, the
pin plunger 44 is not employed. Rather the apparatus of FIG. 7 is
substituted in the inserter/extracter assemblies 43 of the running tool.
More particularly, a sleeve 92 is inserted adjacent the actuating plunger
45 and a collet plunger 55 is substituted for the pin plunger 44.
Moreover, a spring collet 54 is further provided. In operation, to extract
a pin 11 from a ram assembly 10, when the plunger 55 is moved downwards by
downward movement of the running tool in a manner to be described, the
lower conically shaped portion of the collet plunger 55 and lower portion
of the spring collet 54 are thereby inserted into the collet hole 21 of
FIG. 1 of the lock pin 11. Moreover, the shoulder of the collet pin 55
contacting the spring collet 54 causes the lower portion thereof to expand
radially outwards into the portion of the collet hole 21 below the collet
shoulder 22. Thereafter, upon subsequent upward movement of the collet
plunger and running tool, the lower conical portion of the plunger 55
moves axially upwards past the collet shoulder 22 to retain the lower
portion of the collet spring below the shoulder 22 whereby the plunger 55,
spring collet 54, and locking pin 11 may thereafter be moved vertically
upwards in integral relation so as to extract pin 11 from the pin holes 23
of the ram assembly 10, thereby permitting release of the shoe from its
block body 76 and subsequent removal therefrom onto the running tool.
It will be noted in FIGS. 6 and 7 that the locking pin preferrably has a
vertical passageway 94 extending axially therethrough communicating with
the collet hole 21. In operation, it is preferable when a locking pin is
installed in the assembly 43 for subsequent insertion into a remotely
located preventer, to fill this collet hole with an appropriate extrudable
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