Note: Descriptions are shown in the official language in which they were submitted.
Varicus types of hole enlargement arrangements have been
heretofore employed and are currently in use. In the devices with
which applicant is familiar, a body structure formed of inner and
outer body sections has cutter arms pivotally secured on the outer
body section and a piston and cylinder means de-fined between the
inner and outer body sections receive hydraulic fluid to effect
telesccpic movement of the body sections in one relative direction
whereupon a cam surface mechanically engages and forces the cutter
arms out to underreaming or bore hole enlarging position.
After the underreaming operation is completed, the cutter arms
of the prior art devices are generally then retracted by raisiny the
operating string on which the body structure is supported so that the
expanded or projecting arms engage the shoulder fonned at the
juncture of the upper end of the enlarged underreamed portion with
the smaller bore. Continued raising of the operating string exerts a
force on the extended cutter arms to endeavor to fcrce the arms
inwardly to retracted position relative to the body structure.
If mud or some other obstruction prevents relative longitudinal
telescopic movement between the inner and outer body sections so that
the cutter arms can retract, then it has been generally custcmary in
such circumstances to merely continue exerting a pull on the operat-
ing string until some portion of the bore hole enlarging structure
breaks so that it then may be withdrawn from the well bore. Also, it
can be appreciated that iE the structure of the prior art malfunc-
if 0~
tions or breaks so that the inner and if bodies are locked against
telescopic movement while the arms are in extended position, then the
arms again are forced to collapsed position by pulling up on the
operating string to try to force them to retracted position, or to
break whatever structure may be necessary to enable the prior art
bore hole enlarging arrangement to be withdrawn from the bore hole.
~2'~
hen the arms of the bore hole enlarger are extended during
drilling operations to underream or drill an enlarged portion in a
bore hole, there are various forces that act upon the cutter arms
during the bore hole enlarging operations. Some of such forces
include an upwardly directed force on the outer projecting end of the
arm due to the reaction from the weight oE the operating string
during drilling operations. There also are other forces. For
example, there is a force which tends to move the cutter arms back
towards retracted position due to the angle of the hole, a force due
to the reaction from rotation while drilling the formation which
tends to retract the cutter arms inwardly, and a force which arises
from rotation during bore hole enlarging operations so that formation
pressure against the leading edge of the arm along its axial extent
tends to flex the cutter arm.
In prior art devices, these forces are transmitted frcm the
cutter arms to the pivot arrangement of the cutter arms on the body
structure and cam surface relied upon to move and maintain the cutter
arms in extended cutting position. In sone circumstances these
forces may be substantial and in some instances damage or break
components of the bore hole enlarger.
The present invention provides an arrangement that assists in
overcoming the above and other problems. The cutter arms are pivot-
ally mounted on the inner body structure and a cooperative support
arrangement on the outer body section and cutter arms is employed to
assist in moving or expanding the cutter arms to expanded cutter
position and to assist in retracting the arms when the cutting
operation is over. The cooperatiny support arrangement also assists
in better distributing the loads and forces employed during the bore
hole enlarging operation and also increases the mechanical advantage
2~
tending to maintain the cutter arms in expanded position during bore
hole enlarging operations
Other objects and advantages of the present invention will
become apparent from a consideration of the following description and
drawings.
Fig. 1 is a lonyitudinal sectional view illustrating a preferred
embodiment of the bore hole enlarger with the cutter arms in
retracted position;
Fig. 2 is a sectional view on the line 2-2 of Fig. 1 to better
illustrate certain structural details;
Fig. 3 is a sectional view on the line 3-3 of Fig. 2 to illus-
trate an embodiment of the cooperative means on the outer body
section and the cutter arms;
Fig. 4 is a longitudinal sectional view, partly in elevation,
illustrating the relationship of the bore hole expander arrangement
when the cutter arms are extended; and
Fig. 5 is an end view on the line 5-5 of Fig. I.
Attention is first directed to Fig. 1 ox the drawings wherein
the rearer or hole enlarger of the present invention is referred to
generally by the numeral 9. A body structure referred to generally
at 10 is fonned by a longitudinally extending outer body section 11
which receives therein an inner body section referred to generally at
20.
The outer body section 11 is provided with a threaded pin end 12
and a threaded box end 13 at the c~posite end of the body structure
10 whereby the body structure 10 may be threadedly engaged with a
rotary well striny S for lowering in a well bore to enlarge, or
underream a portion of the well bore.
The inner body section 20 includes a tube 21 extending longitudinally
of the outer body section 10 as shcwn. The tube 21 includes a bore
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22 therethrough which co~lmunicates with the bore l in the outer body
structure for forming a fluid flcw path that communica-tes with the
connected well string for supplying drilling fluid to actuate the
underreamer 9 as will be described.
The tube 21 is received within the counterbore 23 at toe upper
end of the outer body section 11 and is provided with seal means 2~
for sealably engaging therewith. A chamber 16 is formed in the outer
body section 11 and extends from the lower end of the counterbore 23
to the upper end of the longitudinal passage 15 in which is received
the lower extension 21a of the tube 21 as shown. A seal bushing 25
is mounted on the tube extension 21a in any suitable manner such as
by the annular shoulder or projection 26 on the tube 21a and the snap
ring 27 which abuts the lower end of the seal bushing 25 to secure it
with the tube extension 21a. The seal bushing 25 seals between the
tube extension 21a and the passage 15.
The outer body section 11 is provided with passages 16a for
communicating the well bore with the interior oE chamber 16 for
equalization of pressure therebetween. A cylindrical member 17 is
secured with the outer wall section of outer body section 11 with
chamber 16 as illustrated in any suitable manner such as by the
threads 17a which threadedly engage the cylindrical walls of the
cylindrical member 17 to the outer body section 10 wi-thin chamber 16.
The lower end 17b ox cylindrical number 17 is closed as shown.
The longitudinal tube 21 forming part of inner body section 20
extends through the closed end 17b of cylindrical member 17 as shown
and is sealably engaged as shown at 28 with the lcwer closed end 17b
of the cylindrical member 17. A piston member 29 is threadedly
secured -to the tube 21 and is thereby positioned within the
cylindrical member 17. Annular seal 30 on piston member 29 engages
the cylindrical walls of the cylindrical member 17 and seal 30a
1 sealably engages piston member 29 on -tube 21. This defines
a means including the piston arrangement 29 and cylinder
means 17 to cfEect telescopic movement of said body sec-
tions in one relative direction. More particularly, the
space between -the lower end of pis-ton member 29 and the
closed end 17b of cylindrical member 17 defines between
the inner body sec-tion 20 and outer body section 11 a
chamber 35 for receiving prom the well striny pressured
drilling fluid which flows through passage 14 in body
l structure 10, passage 22 and port 36 in tube 21 to act on
the piston and cylinder means to effec-t telescopic movement
of the outer body section 11 and inner body section 2~ in
one relative direction to move the cutter arms 40 from the
retracted position shown in Fig. 1 -to the expanded position
shown in Fig. JO
Suitable spring means 37' abut at its upper end
against the shoulder wormed by the junc-ture o the chamber
16 with the counterbore 23. The lower end of spring 37'
rests on the top side of -the piston means 2~ to iend to
JO urge the inner body section 20 and piston means downwardly
to a position to tend to main-tain the cutter arms ~0 in
re-tracted position. Stated differently, such spring meclns
37' inhibits telescopic movement be-tween the inner body
sec-tion 20 and outer body section 10 in said one relative
direction.
To assist in maintaining alignment as well as
providing other func-tions, a yoke member 37 is -threadedly
secured to the tube 21 as shown in the drawings and extends
longi-tudinally in the lower part of -the chamber 16 to ac-
commoda-te relative longitudinal movement between the inner
if
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.
1 and outer body sections 20 and 11 while suppor-ting and
stabiliæing the body structure during underreaming, or
well bore enlarging opera-tions. Suitable longitudinal
groove means 33 are provided in the yoke member 37 to
enable fluid pressure ex-teriorly of the body structure
9 to communicate with the chamber immediately above the
yoke member 37 and equalize with -that existing in the
well bore, thus
3~
-5~-
accommodating unrestricted longitudinal movement between the inner
and outer body sections 20 and 11, respectively.
The yoke member 37 also supports the cutter arms 40, three of
which are illustrated in the embodiment in the drawings. Ire cutter
arms 40 are arranged in longitudinal slots 45 which are
circumferencially spaced on the cuter body 10 as shown in Fig. 2 and
3 of the drawings.
The cutter arms 40 are pivotally connected to the inner body 20
by means oE the pivot pins 41 extending through the spaced upper ends
40a of the cutter anns 40 which ends 40a straddle circumferentially
spaced, depending projections 37a formed on the lower end of the yoke
member 37 as better illustrated in Figs. 1 and 2 oE the drawings.
The lower end of each of the cutter arms 40 is provided with a
drill bit 47 rotatable supported on the cutter arm in any manner well
known in the art.
Heretofore, some difficulty has been encountered in conducting
underreaming operations with devices of the prior art due to the
forces and loads imparted to the cutter arms and body structure
during the underreaming operations.
In an attempt to overcome these problems, the cutte-r arms ox the
present invention are not only pivotally mounted and supported on the
inner body section 20, but cooperating means on the outer body
section 11 and cutter arms 40 cooperate to support the cutter arms on
the outer body section 11 and assist in moving the cutter arms
towards expanded and retracted position. Such arrangement also
provides a mechanical advantage which advantage becomes greater as
the cutter arms are moved toward expanded position and which
advantage is maintained during bore hole enlargement operations to
aid in maintaining the tool in open posi-tion, that is, to maintain
the cutter arms 40 expanded during bore hole enlarginy operations and
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to better absorb the loads and forces encountered durlny such
operation.
One arrangement of such cooperating moans is illustrated in the
drawings and is shown as including the arrangement generally referred
to at 60 which enables the outer body 11 to support the cutter arms
arms 40 as they are expanded, and during bore hole enlaryement
operations, as well as assisting the cutter arms 40 in moviny towards
retracted position. After bore hole enlargement operations have been
completed, the body structure 9 is elevated to engage the cutter arms
40 against the ledge formed by the enlargement in the bore hole to
assist in retracting the arms back into the body structure 9 as shcwn
in Fig. 1 oE the drawings. The arrangement 60 provides an interfitt-
ing arrangement and includes suitable means on the outer body section
10 which moveably interfits with each cutter arm 40 and assists in
urging and moving the cutter arms 40 to retracted position, as
opposed to merely breaking the cutter armsO
In the embodiment illustrated in the drawings, such interfitting
arrangement is shown as including projecting means 62 mounted on the
outer body section 11 and which projects inwardly into the longitu-
dinal slots 45 as better illustrated in Fig. 3 of the drawings. Agroove means 63 is formed on each side of and extends diagonally
relative to the longitudinal axis, represented at 40c, of each cutter
arm 40 and receives the projections 62 therein as shown.
When the cutter arms 40 are in retracted position as shcwn in
Fig. 1, the angle represented at 70 between the longitudinal axis of
the body 10a structure 10 and the longitudinal axis 60a of the
arrangement 60 (defined by the longitudinal axis of the groove means
63) is larger than the same angle represented at 70 when the cutter
arms 40 are moved to expanded position as shown in Fig. 4. Since the
angle 70 is smaller when the cutter arms 40 are moved to expanded
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s
position Eor performing underreamer or bore hole enlargement
operations, the mechanical advantage of the present invention becomes
larger when the arms are moved to expanded position and thereby
provides a structure which tends to ~k~intain the cutter arms 40 in
expanded position during well bore enlarying operations.
The cylinder means 17 provide a means to adjustably limit the
telescopic movement of the body sections and thereby provides a range
of hole enlargement diameters that may be attained with a particular
body size structure. For example, and by illustration only, assume
that the body structure 10 is 11-3/4 " O.D. This same body size, by
adjusting the lonyitudinal position of the cylinder member 17 in
chamber 16 can be used to underream a 17-1/2 " hole, 20", 22-1/2" or
24" hole, or any desired size from 17-1/2" through 2~" O.D.
Where it is desired to perform a larger diameter underream, a
larger body size would be employed to cover a range of larger under-
ream diameters. This overcomes some of the problems encountered with
prior art devices which require that some co-mponent of the under-
reamer or bore hole enlarger be changed for each hole diameter
desired. In the present invention, merely by threading the cylinder
means 17 longitudinally of the chamber 16 and body structure 10, the
desired underream outer diameter Jay be attained. The longitudinal
position of the cylinder means 17 acts as a stop means Eor the upper
end of the yoke means 37 and thus determines the amount of extension
of the cutter arms 40 and hence the outer diameter of the enlargernent
or underreaming portion to be formed.
The upward end force encountered by the drill cones 47 during
underreaming operations reacts to assist in keeping the arms expanded
during the underreaming operations by reason of the foregoing
construction of the present invention. Also, where the present
invention is used to underream or enlarge in a high angle well bore
hole, and with the arms engaging the low side of the well bore, there
is a tendency Eor the radial load to close or retract the arms of
some prior art devices; however the force acting on the end of the
cones in an upward direction, as the underreaming device moves
dcwnwardly during the underreaming operations and arrangement 60
assists in keeping the arms extended and resists the radial closing
of the arms.
The structural arrangement of the present invention as shown in
the drawings provides as much body support as possible to the arms
since the arms are supported by both the inner and outer body
structures in their extended position which inhibits wobbling as well
as wear on the cc~ponents of the invention, which wear can be
aggravated by the presence of mud encountered during the enlarging
operation that may act to grind or wear den components of some prior
art devices more readily than that which would occur with the present
invention due to the stabilizing effect of the yoke member 37 and of
the interfitting support arrangement 60 between the outer body and
the cutter arms 40.
As previously noted, aEter the underreaming operation is
canpleted, retraction of the cutter arrns 40 is accomplished by
lifting or raising the pipe string in the well bore on which the body
structure 10 is carried so that the cutter arms 40 in their extended
position engage the upper end oE the completed underreamed or
enlarged portion in the well bore. In prior devices where it has
been impossible to effect retraction of the arms by such engagement
and subsequent pulling on the well string, it has been necessary to
break some tool component by exerting a continued upward Eorce on the
well string so that the underreaming device thereaEter might be
recovered from the well bore.
f~L2'~ S
However, in the present invention, even though the body struc-
ture rnay be irnmersed in mud, the Eorce applied to the cutter arms 40
by engaging them with the ledge at the upper end of the enlargement
acts to move the cooperating means 60 between the outer body section
10 and the cutter arms from the position shown in Fig. 4 to the
position sh~7n in Fig. 1. In this instance also, the mechanical
advantage is increased as the cutter anns move from expanded to
retracted position since the angle 70 increases from tha-t shown in
Fig. 4 to that shown in Fig. 1.
A passage 70 in outer body section 11 adjacent the lower end
thereof is provided with a carbide nozzle insert 71 and retained in
position in passage 70 by means well known in the art. This enables
drilling fluid to be conducted from the flow passage in the body
structure 10 and directed against the cones ~7 to assist in removing
cuttings and debris therefrom uring underreaming o-perations.
After underreaming operations are completed, the p~np pressure
acting on the drilling fluid is relieved and when weight of the well
string is removed from body 10 spring 37' tends to move the inner
body section 11 back to the position shown in Fig. l however, the
arms ~0 may be engaged with the shoulder at the top of the underream
section and by applying a pull on the well string, the cooperating
arrangement 60 assists in ving the cutter arms ~0 to retracted
position.
The foreclosing disclosure and description of the invention are
illustrative and explanatory thereof, and various changes in the
size, shape and materials as well as in the details of the illus-
trated construction rnay be made without departing from the spirit of
the invention.
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