U.S. patent number 3,888,318 [Application Number 05/283,334] was granted by the patent office on 1975-06-10 for well drilling apparatus.
Invention is credited to Cicero C. Brown.
United States Patent |
3,888,318 |
Brown |
June 10, 1975 |
Well drilling apparatus
Abstract
A portable well drilling unit comprising: a support skid; a
snubber mounted on the support skid for rotation and reciprocation
of a drill string; a mast mounted on the support skid; swivel
apparatus suspended by cables from the mast for handling pipe
joints to be added to or taken from the drill string; and powered
apparatus connected to the cable for raising and lowering the
swivel apparatus. The swivel apparatus may comprise an upper
stationary section and a lower rotatable tubular section adapted to
receive one end of a pipe joint and having a radially moveable
latch assembly for engagement therewith. The lower section is
provided with cam apparatus movable, relative to the latch
assembly, from an inoperative position to an operative position
camming the latch assembly from a first position, permitting free
entry of the pipe joint end into the lower section, to a second
position, latching the pipe joint end in the lower section.
Inventors: |
Brown; Cicero C. (Houston,
TX) |
Family
ID: |
26876853 |
Appl.
No.: |
05/283,334 |
Filed: |
August 24, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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181067 |
Sep 16, 1971 |
3722603 |
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Current U.S.
Class: |
173/149; 52/115;
52/116; 285/315; 166/77.51; 173/164; 285/362 |
Current CPC
Class: |
E21B
19/10 (20130101); E21B 19/08 (20130101); E21B
19/00 (20130101); E21B 19/16 (20130101) |
Current International
Class: |
E21B
19/08 (20060101); E21B 19/16 (20060101); E21B
19/00 (20060101); E21B 19/10 (20060101); E21b
019/08 () |
Field of
Search: |
;175/85,170 ;166/77.5
;52/115,116 ;173/57,149 ;285/164,168,281,280,314,315
;254/29R,30,31 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Abbott; Frank L.
Assistant Examiner: Pate, III; William F.
Attorney, Agent or Firm: Torres & Berryhill
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
The present application is a continuation-in-part of application
Ser. No. 181,067 filed Sept. 16, 1971 by C. C. Brown now U.S. Pat.
No. 3,722,603.
Claims
I claim:
1. A portable well drilling unit comprising:
a. support means;
b. snubber means mounted on said support means having a fixed head,
selectively engageable with a drill string for support thereof, and
a rotating head, selectively and non-threadedly engageable with
said drill string and reciprocally movable relative to said fixed
head power means operatively connected to said rotating head for
simultaneous driving rotation and reciprocation of a drill string
during drilling operations, said rotating head surrounding upper
joints of said drill string and being reciprocal thereon when not
in engagement therewith so as to permit the upper portion of said
drill string to extend through and vertically above said rotating
head;
c. mast means mounted on said support means;
d. non driven swivel means suspended by cable means from said mast
means for handling pipe joints to be added to or taken from said
drill string and for supporting the upper end of the last joint of
said drill string in a non-driving relationship during said
drilling operations; and
e. power means connected to said cable means for reciprocation of
said swivel means.
2. A well drilling unit as set forth in claim 1 in which at least a
portion of said mast means is pivotable between an upright position
and a substantially horizontal position for ease of
transportation.
3. A well drilling unit as set forth in claim 2 comprising
hydraulic piston and cylinder means connected to said pivotable
portion of said mast means for moving said mast means between said
upright and horizontal positions.
4. A well drilling unit as set forth in claim 1 comprising a mud
line attached to said swivel means for delivering drilling fluid to
said drill string.
5. A well drilling unit as set forth in claim 1 in which said
swivel means comprises a swivel assembly having an upper
non-rotatable section and a lower rotatable section, said lower
rotatable section being adapted for non-threaded engagement with
one end of a pipe joint.
6. A well drilling unit as set forth in claim 5 comprising a pair
of said swivel assemblies operable independently of each other to
permit engagement of one end of said drill string by one of said
swivel members simultaneously with the engagement of a separated
pipe joint by the other swivel assembly.
7. A well drilling unit as set forth in claim 5 in which said lower
rotatable section is provided with latch means radially movable
between a first position, permitting free entry of one end of a
pipe joint into said rotatable section, and a second position
engaging said one end of a pipe joint and preventing said joint
from being displaced therefrom.
8. A well drilling unit as set forth in claim 7 comprising cam
means carried by said lower rotatable section and movable from an
inoperative position to an operative position camming said latch
means into said second position.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to apparatus for drilling oil and/or
gas wells. In particular it concerns portable well drilling units
and special apparatus designed therefor.
2. Description of the Prior Art
In conventional rotary drilling, a power driven rotary table
operating through a so-called "Kelly joint" connected to the upper
end of the drill pipe string is employed for rotating the drill
string. High-powered drawwork systems, including derricks with
multiple-strand, cable-connected crown and traveling blocks, are
also employed for running the drill string into and out of the well
and for otherwise performing drilling and pipe handling operations.
Conventionally, the rotary table and the drawworks and the power
units for driving and operating the same constitute massive,
relatively, complicated and expensive structures, particularly
those designed for deep drilling.
In the aforementioned copending patent application, Ser. No.
181,067, a fluid pressure operated snubber device is disclosed for
use in drilling wells, which generally takes the place of the
rotary table and drawwork systems conventionally heretofore
employed. The device comprises a stationary lower snubbing head and
a rotatable and vertically reciprocable upper snubbing head for
rotating drill pipe when drilling a well and for running the drill
pipe into and out of the well. Each of the snubbing heads includes
a set of pipe gripping wedges movable into and out of pipe gripping
engagement by fluid pressure operated means and a set of cam
acuated shoes for applying torsional forces to the pipe string for
rotating the same in drilling and in making up and breaking out
sections of the pipe string when running into and out of the
well.
Although snubbing devices are known in the prior art, they are
primarily for servicing operations, being used only to pull and
rerun pipe in already completed wells. Such devices eliminate the
need of killing the well and the cost, time and problems associated
with circulating mud, salt water or other kill fluids. They also
eliminate the danger of kill fluids causing permanent damage to the
well bore and formation and the problem of loosing expensive kill
fluids to the formation. However, such units have not heretofore
been designed for, nor capable of, drilling.
SUMMARY OF THE PRESENT INVENTION
The present invention is directed to a well drilling unit or system
utilizing a snubber device, such as is disclosed in the
aofrementioned patent application Ser. No. 181,067, which is
designed for both rotation and reciprocation of a drill string. The
system disclosed includes a support frame or skid on which the
snubber device is mounted, a small mast, at least one swivel
assembly suspended by a cable from the mast for handling pipe
joints to be added to or taken from the drill string, and a power
winch connected to the cable for raising and lowering of the swivel
assembly.
Since the hydraulic snubbing device generally takes the place of
the conventional rotary table and drawwork system, the mast may be
relatively simple and of low capacity. Its major function will be
merely to support relatively low weight elements such as the swivel
assembly and mud hoses and, at the most, only a few sections of
pipe, since the main load of the pipe strings both in drilling and
in running into and out of the well will be taken by the snubber
heads.
A unique swivel assembly is also disclosed which comprises an upper
stationary section and a lower rotatable section adapted to receive
one end of a pipe joint and having a radially movable latch
assembly for engagement therewith. The lower rotatable section also
carries a cam assembly movable from an inoperative position to an
operative position by which the latch assembly is cammed from a
first position, permitting free entry of the pipe joint end into
the lower section, to a second position, latching the pipe joint
end in the lower section. Such swivel apparatus may be operated
manually or hydraulically as will be seen hereafter.
The drilling unit of the present invention is thus very compact,
low in cost, easily transportable and simple to operate. Other and
more specific objects and advantages of the invention will become
readily apparent from the detailed description which follows when
read in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the description which follows reference will be made to the
accompanying drawings in which:
FIG. 1 is an elevation view of a well drilling unit, according to a
preferred embodiment of the invention, utilizing a snubber device,
special swivels and other specially designed apparatus;
FIG. 2 is a longitudinal quarter-sectional view of one of the
swivels of FIG. 1 in which the latch assembly is shown in a
position permitting free entry of the end of a joint of pipe line
into the lower section thereof;
FIG. 3 is a longitudinal quarter-sectional view of the swivel of
FIG. 2, showing the latch assembly in an operative position in
which the joint of pipe is latched in the lower section;
FIG. 4 is a longitudinal quarter-sectional view of a lift plug,
according to a preferred embodiment of the invention, showing a
joint of pipe being received therein;
FIG. 5 is a longitudinal quarter-sectional view of the lift plug of
FIG. 4, showing the pipe joint received therein fully latched into
the bore of the tool;
FIG. 6 is a longitudinal quarter-sectional view of an alternate
embodiment of a lift plug, suitable for use with the present
invention;
FIG. 7, taken along line 7--7 of FIG. 6, is a cross-sectional view
of the lift plug of FIG. 6;
FIG. 8 is a top plan view of the pulley and cable arrangement
installed at the top of the mast of the drilling unit shown in FIG.
1;
FIG. 9 is a partial elevation view of the mast used in the drilling
unit of the present invention, showing stand pipe on each side
thereof;
FIG. 10 taken along line 10--10 of FIG. 3, is a crooss-sectional
view of the swivel of FIGS. 2 and 3, in the latched position;
FIG. 11 is a schematic view of the mast and snubber device of the
present invention showing the mast in an upright position;
FIG. 12 is a schematic view similar to FIG. 11, but showing the
mast in a lowered or traveling position;
FIG. 13, taken along line 13--13 of FIG. 1, is a top plan view of a
portion of the drilling unit of FIG. 1;
FIG. 14, taken along line 14--14 of FIG. 1, is a partial elevation
view of the mast and one of the swivels of the drilling unit shown
in FIG. 1 to illustrate the position of the swivel, the stand pipe,
and the lines for keeping the swivel from rotating;
FIG. 15 is a longitudinal quarter-sectional view of a hydraulically
operated embodiment of the swivel of the present invention, similar
to the manually operated embodiment shown in FIGS. 2 and 3, shown
in the unlatched position;
FIG. 16 is a longitudinal quarter-sectional view of a swivel
according to the alternate embodiment of FIG. 15, shown in the
latched position;
FIGS. 17 and 18 are longitudinal quarter-sectional views of the
swivel shown in FIGS. 15 and 16 illustrating the operation
thereof;
FIGS. 19 and 20 are quarter-sectional views of still another
hydraulically operated embodiment of a swivel of the invention;
FIG. 21, taken along line 21--21 of FIG. 17, is a cross-sectional
view of the swivel of FIG. 17 in the unlatched position;
and FIG. 22, taken along line 22--22 of FIG. 18, is a
cross-sectional view of the swivel of FIG. 18 in the latched
position.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring first to FIG. 1, there is shown a portable well drilling
unit, according to a preferred embodiment of the invention. The
unit may comprise a support frame or skid F on which the entire
unit may be mounted. Attached to the support frame F for
disposition directly above the well hole to be drilled is a
hydraulic snubbing device D. A blowout preventer stack B and
stripper R may also be attached to the frame directly above the
well hole.
Immediately adjacent to the snubbing device D is a mast M, the
purpose of which is to support various apparatus, to be described
hereafter, for handling pipe joints being run into or taken out of
the well hole. As best seen in FIGS. 11 and 12 the mast M may
comrpise a stationary lower section 1 to which an upper section 2
is pivotally attached so that the mast may be moved from the
upright position of FIG. 11 to the horizontal position of FIG. 12.
A structural member 3 may be utilized to provide support for the
pivotal portion of the mast in the lowered or horizontal position.
The lowered position, of course, allows the skid-mounted unit to be
easily transported by truck, rail or whatever without serious
overhead clearance problems. As best seen in FIG. 1, a hydraulic
piston and cylinder assembly 4 may be provided for attachment at
one end to the frame F and at the opposite end to mast M for
raising and lowering the upper portion of the mast 2. The mast may
be firmly maintained in the raised or upper position by a
connection at 5. This connection may be released to permit the
upper mast portion 2 to be lowered.
The mast M also includes a pulley assembly 6, similar to the crown
block of a conventional derrick, but of much less weight and
simpler construction. As seen in FIGS. 1, 8 and 13, the pulley
assembly of the exemplary embodiment comprises a first pair of
pulleys 7 and 8, a second pair of pulleys 9 and 10 and an
intermediate third pair of pulleys 11 and 12 mounted for rotation
on a mounting block 13. Structural bracing 14 is also provided. The
primary purpose of the mast M and pulley assembly 6 is to support a
pair of swivel members S-1 and S-2 for handling pipe joints J.sub.1
and J.sub.2 to be added to or taken from the drill string D.sub.s.
Cables 14 and 15 are attached to each swivel and run over a
corresponding pair of pulleys 7, 8, 9 and 10 to corresponding power
winches W-1 and W-2 about which the ends of the cables 14 and 15
are wound. A lifting plug P may also be suspended by cable 16 from
the pulley assembly. The cable 16 may run over the intermediate
pulleys 11 and 12 to a third power winch W-3.
Drilling fluids may be supplied to the swivels S-1 and S-2 through
vertical stand pipes 17 and 18 and flexible mud lines 19 and 20.
The stand pipes 17 and 18 may be supported alongside mast M by
attachment to the mast with brackets 21 and 22.
The hydraulic snubbing device comprises a stationary lower head H-1
and an upper head H-2, which is both vertically reciprocal and
rotatable relative to the lower head H-1. These snubbing heads
cooperate with the drill string D.sub.s to perform the rotary
drilling functions and the running of the pipe string into and out
of the well. Each of the snubbing heads H-1 and H-2 includes sets
of vertically reciprocal pipe gripping wedges or slips and
angularly rockable, cam-actuated gripping shoes for applying
torsional forces to the pipe string for use both in rotating the
pipe string for drilling and when making and breaking the threaded
pipe joints, as when adding joints to the drill string and when
running the string into and out of the well. The snubbing device D
generally takes the place of the rotary table and drawworks systems
commonly employed on conventional drilling rigs. For purposes of
the present disclosure no further description of the snubbing
device D is necessary. However, for the specific details of
construction and operation of such a snubbing device reference may
be made to the aforementioned copending patent application Ser. No.
181,067, such application being fully incorporated by reference
hereto.
As stated heretofore the purpose of the swivels S-1 and S-2 is to
handle joints of pipe J.sub.1 and J.sub.2 being added to or taken
from the drill string D.sub.s. These swivels are unique in
construction and will be described in detail with reference to
FIGS. 2, 3 and 10. The swivel is generally made up of an upper
stationary section 30 and a lower rotatable section 31. The upper
stationary section 30 may comprise tubular components 32, 33, 34
and 35 for providing a flow passage 36 between a cross member 37
and the interior of rotatable section 31. The cross member 37 is
provided with a suitable connection such as nipple 38 for
connection with a mud line or hose such as 19 in FIG. 1. Thus,
drilling fluids may be passed from the mud hose through the cross
member 37 and passageway 36 into the lower rotatable section 31.
The opposite side of the cross member 37 may be provided with
torque back-up apparatus which may comprise an arm member 40 the
purpose of which is to prevent rotation of the upper section 30 of
the swivel. To accomplish this purpose, suitable support members 41
and a vertical cable 42 are attached to the mast M, as best shown
in FIGS. 13 and 14. The end of arm 40 opposite its connection with
swivel cross 37 is slidingly connected to the cable 42 permitting
up and down movement of the swivel but preventing rotation of the
upper section 30. This provides torque back-up during make-up and
break-out of pipe joints from the drill string D.sub.s, as well as
during the drilling operations. A cable connector 43 is also
attached to the cross member 37 and is the means by which a cable,
such as 14 in FIG. 1, may be attached to the swivel for suspension
from the mast M. The cable connector 43 may be retained in a plug
member 44 by bushing 45.
The lower rotating section 31 of the swivel comprises tubular
members 46, 47 and 48 through which a passageway 49 may communicate
with the pipe joint J.sub.1 which is to be handled by the swivel. A
load carrying thrust bearing 49 and a radial bearing 50 are mounted
between the upper tubular member 46 of rotatable section 31 and
lower tubular members 34 and 35 of non-rotatable section 30.
Protective seals 51, 52 and 53 are provided above and below the
bearings 49 and 50. A rotating seal 54 may be carried by tubular
member 46 for rotating sealing engagement with a suitable
cylindrical sealing surface 55 on tubular member 35 of the
non-rotating section 30. This seal 54 allows drilling fluid to be
circulated through the swivel into the drill string when the pipe
joint J.sub.1 is properly connected, as will be discussed
hereafter. A relief vent hole 56 may be provided in case drilling
fluids leak past the seal 54.
The lower tubular member 48 may comprise a downwardly depending
sleeve member 57 having radial appertures 58 therethrough in which
are carried a plurality of latches 59. Affixed to the lower end of
the sleeve 57 is a guide collar 60 and a plurality of guide pins or
screws 61. Surrounding the sleeve portion 57 in a sliding
telescopic fit is a cam sleeve 62. The interior of cam sleeve 62
comprises a pair of annular shoulders 63 and 64 between which lies
an annular groove 65. The exterior of latches 59 are provided with
corresponding annular shoulders 66 and 67 having an annular groove
68 there between. In the relaxed or inoperative position of FIG. 2,
the lower shoulder 64 of cam sleeve 62 is disposed between the
shoulder 66 and 67 of latch 59, permitting the latch 59 to assume a
retracted, or first position, permitting free entry of one end of
the pipe joint J.sub.1 into the rotatable section 31 of the swivel.
The relative positions of cam sleeve 62 and latches 59 are
maintained by the engagement of guide pins 61 with the lowermost
horizontal portion of a cam slot 70 in cam sleeve 62.
Once the upper end of pipe joint J.sub.1 is fully received within
rotatable section 31, as shown in FIG. 3, the latches 59 may be
moved to a second position, as in FIG. 3, engaging the pipe joint
and preventing it from being displaced therefrom. This is
accomplished by grasping a circular handle 71 attached to cam
sleeve 62 and rotating the cam sleeve 62 thereby. Rotation of the
sleeve 62 causes the cam slot 70 to follow guide pins 61 displacing
the cam sleeve 62 in a downward axial direction until cam shoulder
63 and 64 register with cam shoulders 66 and 67 of latches 59. This
cams the latches 59 inwardly for engagement with the upset portion
of pipe joint J.sub.1. A spring member 72 biases the cam sleeve 62
downwardly and assures that the latches 59 remain in the second or
locked position of FIG. 3. The length of the bore or passageway 49
is designed to accommodate the upset portion of the pipe joint
J.sub.1 in such a way that the latches 59 engage the joint at the
proper position for engagement therewith. The inner faces of
latches 59 may be slightly tapered to correspond with the tapered
portion of the pipe joint J.sub.1.
A mud seal assembly 73 is provided within rotating section 31 so
that a fluidtight seal may be established between the swivel and
the pipe joint J.sub.1 in the latched in position of FIG. 3. The
mud seal assembly may comprise a resilient annular lip type seal 74
bonded to a carrier ring 75 and maintained in a proper axial
position by spacer ring 76.
The cam and latch mechanisms of the swivel apparatus of FIGS. 2, 3
and 10 are, as previously described, manually operated. However,
such swivel apparatus may be adapted for hydraulic operation and
reference is now made to FIGS. 15-22 which illustrate such
variations. As seen in FIGS. 15 and 16, most of the components of
the hydraulic version of the swivel are identical to the manual
version just described. The hydraulic version contains an upper
non-rotatable section 80 and a lower rotatable section 81
corresponding with said sections 30 and 31, respectively, in the
manual version. Cable connector 82, cross member 83, radial bearing
84, thrust bearing 85, rotating seal 86 and mud seal 87 may be
identical to corresponding components of the manual version.
The primary difference in the hydraulic version lies in the latch
and cam assemblies. As in the previous version a plurality of
radially movable latches 88 are provided. However, these latches 88
are mounted in a slightly different manner. They are carried in
radial appertures 89 of an upwardly projecting sleeve 90 which is
attached to a surrounding cylindrical housing 91. This version also
includes an axially movable cam sleeve 92 as in the manual version.
However, the sleeve 92 is provided with an annular piston portion
93 for engagement with inner and outer cylindrical surfaces 94 and
95 forming upper and lower variable pressure chambers 96 and 97.
When pressure is applied to lower pressure chamber 97 through an
appropriate conduit 98 the latch sleeve 92 is displaced upwardly to
the inoperative or joint receiving position of FIG. 15. Once the
pipe joint J.sub.1 is fully received by the lower rotatable section
81 the latch 88 may be moved to the second or engaging position of
FIG. 16 by applying pressure to upper chamber 96 through conduit
99, causing the cam sleeve 92 to move downwardly, camming the
latches 88 to the inner position by the engagement of cam shoulders
100 and 101 with latch shoulders 102 and 103. These operations are
further illustrated by FIGS. 17 and 18, FIG. 17 being the relaxed
or pipe receiving position and FIG. 18 being the pipe engaging
position in which the pipe joint J.sub.1 is locked within the
swivel. As illustrated by the arrows, pressure is applied to lower
chamber 97 through conduit 98 while pressure is relieved from upper
chamber 96 through conduit 99 to maintain the cam sleeve 92 and,
consequently, latches 88 in a pipe receiving position. The
pressures are reversed, as shown in FIG. 18, to move the cam sleeve
92 to an operative position for camming latches 88 into engagement
with pipe joint J.sub.1. Thus, pressure is relieved from lower
chamber 97 through conduit 98. FIGS. 21 and 22 illustrate the
position of latches 88 in the retracted or first position and
engaging or second position, respectively.
FIGS. 19 and 20 illustrate another variation of the hydraulic
version of the swivel apparatus. Latches 103 and cam sleeve 104 are
substantially identical to latches 88 and sleeve 92 in the
previously discussed hydraulic version. However, in the alternate
embodiment only one pressure chamber 105 is provided, the function
of the other pressure chamber being replaced by a spring member 106
which biases the latching sleeve 104 in a downwardly direction. To
maintain the cam sleeve 104 and latches 103 in the pipe receiving
position of FIG. 19 pressure is applied to chamber 105 through
conduit 107 causing the cam sleeve 104 to assume the upwardly
displaced position therein. After the pipe joint is fully received
within this version of the swivel, pressure may be relieved from
chamber 105 through conduit 107 allowing the spring biasing force
of spring 106 to force the cam sleeve 104 in a downwardly direction
and camming latches 103 into the second or pipe latching position
of FIG. 20. A vent hole 108 may be provided to prevent back
pressure against cam sleeve 104 when it is displaced upwardly.
In summary, operation of the snubber device D of the drilling unit
rotates and gradually feeds the drill string D.sub.s (see FIG. 1)
in a downwardly direction as hole is made. The snubbing device
periodically extends itself, as described in the aforementioned
copending patent application Ser. No. 181,067, taking a new bite or
grip on the drill string D.sub.s. From time to time it is necessary
to add joints of pipe to the drill string. Such a joint of pipe
J.sub.1 may be latched into and suspended by a swivel S-1 directly
over the drill string D.sub.s, as shown in FIG. 1. The joint
J.sub.1 is then stabbed into the upper end of drill string D.sub.s
and made up by the proper rotation of snubber head H-2. Then
drilling resumes with the upper end of pipe joint J.sub.1 still
being supported by swivel S-1. Tension may be maintained on the
cable 14 to prevent the pipe joint J.sub.1 from whipping along its
unsupported length. During drilling operations the torque arm 40
prevents rotation of the upper section of the swivel S-1 while the
lower section rotates. As previously described the swivel S-1 is
equipped with a rotating seal which will allow drilling fluids to
be circulated from stand pipe 17 and mud hose 19 through swivel S-1
into the drill string D.sub.s.
While drilling operations proceed, another joint of pipe J.sub.2 is
latched onto with the second swivel S-2 and placed in a
substantially vertical position ready for attachment to the drill
string D.sub.s. When the drill string D.sub.s has advanced a
sufficient amount, swivel S-1 is released from the upper pipe joint
J.sub.1 and the standby pipe joint J.sub.2 is placed in position by
swivel S-2 for making up with the drill string D.sub.s. Then the
swivel S-1 is free for attachment to another pipe joint. This
operation is repeated until the hole is completed.
Swivels S-1 and S-2 may also be used for simply pulling and running
pipe and this may be done without stroking the traveling snubber
head H-2 once the pipe string weight becomes less than the capacity
of mast M. However, since the swivels S-1 and S-2 are designed to
permit circulation of drilling fluids certain components therein
are not necessary for merely running and pulling pipe. Thus pulling
apparatus may be designed similarly to swivels S-1 and S-2 but
without the unnecessary components thereof. Such a pulling plug P
is depicted in FIG. 1 as being suspended from the mast M by cable
16 and pulleys 11 and 12. The cable is attached to winch W-3 for
control thereof. As shown in FIG. 1 a receptacle P.sub.r may be
provided for retaining the pulling plug P when not in use.
Referring now to FIGS. 4 and 5, the pulling plug P will be
described in more detail. The plug P may comprise a tubular housing
110 at the upper end of which is a coverplate 111 and a cable
connector ring 112. The ring 112 may have a threaded extension 113
thereon for insertion through a hole in coverplate 111 and for
receiving a nut 114 by which the ring 112 is held thereto. Like the
manual version of the swivel described herein, the pulling plug P
may be provided with a cylindrical sleeve member 115 having
appertures 116 for carrying a plurality of radially movable latch
members 117. The interior of tubular housing 110 is provided with
cam shoulders 118 and 119 which, in the inoperative or pipe
receiving position of FIG. 4, lie immediately adjacent a
corresponding pair of shoulders 120 and 121 on latch 117. In this
retracted or inoperative position the end of a pipe joint J.sub.1
may be received within the pipe plug P. The upper movement of the
pipe joint J.sub.1, relative to pipe plug P, will be arrested by
the upper plate 111, as best seen in FIG. 5.
Attached to the lower end of latch sleeve 115 is a handle member
122 which projects outwardly through a cam slot 123 in tubular
housing 110. Once the end of pipe joint J.sub.1 has been fully
received within pulling plug P, the handle 122 may be rotated along
cam slot 123, finally assuming a downwardly displaced axial
position. The downward movement of sleeve 115 causes the latches
117 to move downwardly and to be cammed inwardly, to the second
position of FIG. 5, engaging the tapered area of the upset tubing
and locking the pipe joint J.sub.1 in the plug P. Spring 124 biases
the sleeve 115 and latches 117 towards such a locked position and
assures that this position is maintained. Since a tool such as plug
P is designed for running and pulling use only no mud seals nor mud
line connections are required. Thus, it is much easier to operate
and would preferably be used in such cases.
An alternate pulling design is shown in FIGS. 6 and 7. Such a plug
P.sub.1 includes a cable connector ring 126 and rod 127. An
externally threaded connection plug 128 is rotatingly mounted on
the lower end of rod 127, permitting the plug 128 to be rotated and
threadingly made up with a pipe joint J.sub.1. The upper portion of
the threaded plug 128 may be provided with an inverted skirt 129
having holes 130 and 131 for gripping by the hand. Thus, the plug
128 may be rotated by hand for making up with the pipe joint
J.sub.1. A bearing 132 may be provided between the lower end of rod
127 and plug 128 to reduce rotating friction. A grease fitting 133
may be provided so that the bearing and the rotating connection may
be lubricated. A seal 134 prevents loss of lubrication fluids.
It can be seen from the foregoing discussion that the drilling unit
of the present invention provides a highly portable, low cost,
easily operated drilling system. The unit is exceptionally light
and can be broken down into easily transportable sections. Because
it is hydraulically powered, the unit does not have to be installed
with support equipment in specific relative psotions. For example,
on offshore locations, auxillary equipment such as the prime mover,
mud system and pipe racks can be installed on a nearby barge or
workboat, as long as the unit pipe hoisting system can conveniently
reach racked tubular goods. Many of the components of the system
are unique in themselves. In addition to the snubber device, the
special swivel assemblies and pulling plug offer many advantages
not possible in the prior art.
Although several variations of the invention have been discussed
herein, there are many others which may be made without departing
from the spirit of the invention. It is therefore intended that the
scope of the invention be limited only by the claims which
follow.
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