Note: Descriptions are shown in the official language in which they were submitted.
6V~
APPARATUS FOR USE IN DRILLING
~ his invention relates to apparatus for use in
drilling.
It has previously been the practice in
drilling operations to rotate the drill string or other
tubular members being worked by mear.s of a rotary table
drive or an electric motor top drive. Rotary table
drives are inefficient and costly. Electric top drives
have had numerous problems; for example, to move and
support drill strings weighing up to 500 tons, the
direct current traction motors used must be very large,
consequently they require a large and effective motor
cooling system. Above all, there are considerable
potential safety hazards associated with the use of an
electric top drive. ~ecause of these potential hazards
obtaining compliance with accepted safety codes and
insurance certification for use of electric top drives
has been a tedious, expensive, and time-consuming
process. There are also numerous structural and
functional disadvantages associated with the use of
electric top drives. Thus, one prior art electric top
drive utilizes an expensive thrust bearing to support
the drill string. Another prior art electric top drive
has an electric motor which is offset from the shaft
supporting the drill string which results in an
inbalance in the distribution of the reactive torque
applied.
According to one aspect of the present
invention there is provided, in or for use in a drilling
rig having at least two upwardly extending guide rails,
apparatus comprising:-
~a) a support frame which can be mounted on
said guide rails and which can be moved
B 35 therealong;
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(b) a top drive mounted on the support frame
and comprising a hydraulically actuable motor
having a single central drive shaft
connectable either to mating intermediaries or
connectable direc'ly to drill pipe so that the
drive shaft aligns axially with lntermediaries
or drill pipe connected thereto, the drive
shaft being hollow along its length for
receiving well fluids and conducting the
fluids into the drill pipe;
pivot means connecting the top drive to the
support frame so that, in use, it can be
pivoted in a generally horizontal plane
between an operative position and a
maintenance position; and
pipe handling means pivotally connected to the
frame independently of the top drive so that
in use the pipe handling means is displaceable
in a generally horizontal plane.
Advantageously, said pipe handling means
includes pipe positioning means mounted on said support
frame and operable to lift pipe into position beneath
said top drive. The pipe positioning means may comprise
a) a positioning arm,
b) a bowl in said positioning arm for
supporting a pipe,
c) a lateral opening in said bowl for allowing
a pipe to enter said bowl, and
d) retractable latch means disposed across0 said opening.
Preferably said apparatus includes means for,
in use, raising and lowering said positioning arm.
Advantageously, the pipe handling means
includes a pipe wrenching device mounted beneath the top
drive for making and breaking pipe connections.
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For a better understancling of the invention and
to show how the same may be carried into effect reference
will now be made by way of example to the accompanying
drawings in which:-
~ igure 1 is a schematic elevation of a drillingrig provided with apparatus accordin~ to the present
invention;
Figure 2 is a top plan view of the pipe
positioning apparatus taken on line II-II of Fi~ure l;
Figure 3 is a sectional view of a bail link;
Figure ~ is a sectional view of a splined quick
disconnect;
Figure 5 is a section on line V-V of Figure 4;
Figure 6 is a top view, partially in section, of
a breakout/makeup wrenching device assembly;
Figure 7 is a side view of the assembly of
Figure 6;
Figure 8 shows, on an enlarged scale, a detail
of the assembly shown in Figure 7;
Figure 9 is a bottom view, partially in section,
of the lower section of the assembly of Figure 7;
Figure 10 is a section on line X-X of Figure 9;
and
Figure 11 is a section on line XI-XI of Fig.9.
Referring now to Figure 1, a top drive 10 is
suspended from a commercially available swivel 11 fitted
with optional bail links 12. The bail links 12 are, in
turn, attached to a travelling block 13 which is attached
by cables to a crown block 14 in the derrick 15. The top
drive 10 is attached to a support frame 16 which is
51inably mounted on guide rails 17 which are mounted on
the derrick 15. The attachment of the top drive 10 to the
shaft of swivel 11 may be made through a one piece
threaded hollow shaft or by using a splined quick
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disconnect 18. The hydraulic fluid which operates the top
drive 10 is conducted through pipes 19 and hoses 20 from
a power unit 21 located at a convenient point. The top
drive 10 has a hollow shaft 30 with a threaded top end
30a for connection to the splined quick disconnect 18.
The top drive 10 is attached to the support
frame 16 in such a manner that it may be rotated in a
horizontal plane about pivots 22 on the wheeled support
frame 16 for maintenance or removal from service. A drill
pipe positioning arm 23 is also pivoted from the support
frame 16 in such a manner that it may be rotated in a
horizontal plane to a drill pipe pick-up point using
cylinders 24 (Figure 2). The drill pipe positioning arm
23 may be moved to a point which positions the drill pipe
66 directly over the centerline of the well being
drilled. Additional cylinder(s) 25 (Figure 1) then
elevate the drill pipe 66 to allow a screwed connection
to be made to ~ither: the threaded bottom end 30b of
hollow shaft 30, the threaded bottom end of an elevator
link adapter 27 (when it is used), or to the threaded end
of the saver sub 67 when it is used. Since the motive
force of the top drive 10 is centered about the hollow
shaft 30, the reactive forces are substantially balanced
and a substantially concentric balanced force is imparted
to the drill string.
A wrenching device having an upper section 26
and a lower section 31, is also pivotably connected to
the support frame 16 in such a manner that it may be
rotated aside in a horizontal plane to allow access for
maintenance or removal.
Referring again to Figure 1, the positioning arm
23 is provided with a bowl 33 which has a tapered seat to
match the drill pipe tool joint. A lateral opening 35a
is provided across which extends a latch 35. The latch 35
can be displaced to allow the entry of a drill pipe. The
12L~5~21
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latch 35 is spring loaded to the closed position. Drill
pipe may be loaded by pushing into the opening 35a. A
cylinder 36 is used to move the latch 35 to the open
position. Cylinder 2~, when actuated, moves the drill
pipe 66 into contact with the mating thread on the saver
sub 67. The latch 35 may also be actuated manually.
Referring now to Figure 3, each bail link 12 has
a piston 34 which is biased upward in a cylinder barrel
34a as a result of fluid under pressure entering the
interior of the barrel 34a from an accumulator 38. The
internal force acts like a compression spring. When the
piston 34 is actuated downward by a load the potential
energy is stored within the hydraulic accumulator 38.
When the load is next reduced, such as when a sec~ion of
the drill string is being unscrewed, the distance between
the attaching holes 43a and 43b will decrease, the
drill string proper will remain stationary in the hole
and the swivel 11 will move upward as the threaded
members of the drill string are separated. When the
sections are unscrewed the upper section is raised clear
of the drill string proper by the action of the piston 34
within the barrel 34a. When the load is entirely
removed, the distance between the attaching holes 43a
and 43b will be at minimum. Packing seals 37 are
provided circumjacent the piston 34.
Referring to Figures 4 and 5, the splined quick
disconnect 18 comprises (a) a tubular member 40 provided
with a male spline and an extension bearing a sealing
element 42, and (b) a section 41 provided with a female
spline which co-operates with the male spline. A threaded
collar 39 mates with the threads on the section 41. An
inside shoulder 45 on collar 39 abuts a projection 44 on
member 40 and thereby locks the assembly as a splined and
sealed unit. Torque is transmitted through the splines.
Referring to Figure 6, the upper section 26 of
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the wrenching device has a box section 56 securely
attached to support members 50. A die block 52 is
attached to inner die carrier 53 by pins 58. Die blocks
51 and 52 are able to move inward or outward on guides
57. Cylinder 60, when press~rized in chamber 65, moves
die block 51 into contact with tubular workpiece 62. As
die block 51 engages workpiece 62 a reac.ion force moves
inner die carrier 53 in a direction away from workpiece
62 until die block 52 which is attached to inner die
carrier 53 is forced to engage workpiece 62. In
operation, pressure in chamber 65 creates a gripping
force which firmly engages serrated dies 64 against the
workpiece 62. In the reverse action, cylinder 60 is
pressurized in chamber 63 causing die block 51 to move
away from workpiece 62. A~ter partial travel, die block
51 will contact stops 54 which will cause the body of
cylinder 60 and the inner die carrier 53 to move inward
toward the workpiece 62. This action forces the die block
52 away from workpiece 62.
Referring now to Figure 9, which is a bottom
view of the lower section 31 of the wrenching device, a
box section 56' is securely attached to a circular guide
plate 55. Die block 52' is attached to an inner die
carrier 53' with pins 58'. Die blocks 51' and 52' are
able to move inwardly and outwardly, being aligned by
guides 57'. Cylinder 60', when pressurized in chamber
65', moves die block 51' to contact tubular workpiece 62.
As die block 51' engages workpiece 62, a reaction force
moves inner die carrier 53' in a direction away from the
workpiece 62 until die block 52' engages workpiece 62. In
operation, pressure in chamber 65' creates a gripping
force which firmly engages serrated dies 64' against
workpiece 62.
In the reverse action, the cylinder 60' is
presurized in chamber 61l causing die block 51' to move
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away from workpiece 62. After partial travel, die block
51' will contact stops 54' which causes the body of
cylinder 60' to move towa~d the workpiece 62. Since inner
die carrier 53' is attached to cylinder 60', inner die
carrier 53' will move toward worlcpiece 62 and force die
block 52' away from the workpiece 62, the force being
transferred through pins 58' which attach die block 52'
to inner die carrier 53'. Torque arms 68 are securely
attached to box section 56'.
Referring to Figures 8 and 10, the circular
guide plate 55 features a guide lip 69 which will be used
in attaching the assembly of Figure 9 to the u2per
section of the wrenching device shown in Figure 6.
Referring now to Figure 11, a typical section
through either the top wrenching section or the lower
wrenching section is shown illustrating the method of
attaching an inner die carrier (53, 53') to a die block
(52, 52') using a pin (58, 58').
Referring now to Figure 7, cylinders 70 are
affixed to respective torque arms 68 of the wrenching
device through a clevis at the rod end. The barrel end is
connected to the upper section through a hinged joint 71
and the reaction is restrained by the upper section. When
the cylinders 70 are energized, the lower section will
rotate the centerline of the lower die blocks about axis
y. The guide lip 69 rotates in annular groove 72 (Figure
8). When the bolts 73 are removed the wrenching device is
free to pivot in a horizontal plane on support frame 16.
With this embodiment well drilling fluids enter
the drill string through a conventional flexible hose
connected to the swivel 11 shown in Figure 1. The swivel
11 has a hollow shaft through which fluids pass into the
hollow shaft 30 of the top drive 10 and on through the
hollow sections of the remaining subs or devices into the
interior of the drill string.
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The following chart compares certain features
(but not all) of the embodiment described with reference
to the drawings with the embodiments disclosed in U.S.
Patent 4,4~3,596 and with the Bowen ES-7 Eiectric
Drilling Swivel:
In the following comparison Prior Art is
identified by the letters PA and Preferred Embodiment by
the letters PE.
Bowen ES-7 Electric Drillinq Swivel
PA~ Electrical power is conducted from the
generating room to the unit through rubber covered
electrical cables. Danger of damaging and sparking is
ever present. An accident at a time when well head gasses
are present could be disasterous.
PE: Operated by hydraulic fluid. There is no
danger of sparking. The hydraulic power unit is located
in a safe area.
PA: Complete drilling system weighs
approximately 18,000 kg.
PE: Complete system weighs 9,000 kg or less.
PA: In the event of mechanical failure requires
complete "rig down"; the replacement of the electric top
drive is complex and time consuming.
PE: Unit is designed to accommodate rapid
replacement of the hydraulic top drive. Recause of this
feature several hours of down time are saved.
PA: All installations are equipped with a
conventional (rotary table) drive system on "standby"
because of high down time if replacement of electric top
drive required.
PE: Reliability of this system and ease of
replacement would allow users to eliminate the rotary
table drive systems, spare hydraulic motors and
9 ~5~
components are the only "back-up" equipment. This saves
hundreds of thousand dollars rig cost.
PA: Hazardous area certificates are required for
the numerous safety devices used to monitor systems
designed to render this unit safe for use in a hazardous
location. This is time consuming and expensive.
PE: Electrical devices are located below the
drill floor in a pressured safe room which would, in any
event normally already exist. The multitude of monitoring
devices used on the electric drive are not required.
PA: During drilling, excessive bit weight or
hole friction and stops the drill bit and stalls the
electric motor. Common practice is to reduce bit weight.
Since full electrical potential remains applied, the
drill suddenly accelerates from zero to up to 250 R.P.M.
in a matter of seconds. This causes over-tightening of
tool joint threads and ruins the drill pipe. Also the
drill string may whip and damage the wall of the hole.
Mechanical reaction is transmitted to the derrick through
the support mechanisms and this vibration damages the
structure and is very noisy.
PE: Hydraulic power, because of its inherent
nature, is much smoother. The mechanism of the moving
fluid are such that acceleration after stall will be
smoother and more uniform. Less damage to drill hole and
equipment are realized.
PA: Air purging the inside of the electric
drilling motor is required at initial start-up and at
every time a safety device actuates. This may require 10
to 30 minutes.
PE: No purging is required because there is no
air cooling system.
PA: ~n units so equipped there is a danger of
water leaking into the electric motor following any
damage or corrosive failure of the water to air heat
5~i2~
exchanger used to cool the motor air. These systems are
required wherever you find stringent safety measures such
as North Sea Platforms. This can cause the motor to fail~
PE: No such system is required.
PA: Making drill pipe connection: The drill pipe
is picked up by the ele-~ator bowl and the lower end
stabbed in the previous pipe. Human skill is then
required to ease the drive shaft down into the thread to
screw it up. Thread damage can occur.
PE: The pipe handling device on this unit has a
hydraulic lift to engage the thread. Proper adjustment
will ensure minimal pressure on the threads. This is much
quicker than when the driller has to execute skill and
judgement making up each joint of pipe.
PA: When picking up a length of drill pipe whose
end is protruding about lm above the drill floor, the
pipe handler must be tilted outward. Since the bowl of
the pickup tool is swivelled, the angle is incorrect for
the pipe. Also the latches on the pickup tool must be
manually closed which takes time.
PE: Substantially perfect alignment and
orientation of the pipe handling mechanism is achieved
via mechanical stops and cylindersto create the necessary
movement. The latch is spring loaded to automatically
lock when the pipe is loaded. A cylinder will actuate the
latch to the open position. This is by remote control
- which is much safer. This system is also much faster than
the manual methoa.
PA: Cost much more.
PE: This system costs much less. This does not
take into account the equipment which an operator does
not have to buy, such as extra swivel and/or rotary table
Zrive which would make the savings se~eral hundred
thousand dollars.
PA: Installing this unit on land rigs or
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retrofitting to offshore rigs is very complicated because
of size and different system.
PE: Retro~it to any existing drilling rig can be
accomplished much easier because of size and weight as
well as simplicity of design.
PA: The closed circult air cooling system
collects carbon dust which eminates from the bushes. This
can lead to internal shorting.
PE: No brushes are used.
PA: Repeated stalling of the main electric motor
especially for more than a few moments, under high
current will damage the armature and subsequent rotation
will lead to failure.
PE: No such stalling problem.
Also, the embodiment described compares
favourably to that disclosed in the prior art U.S. Patent
4,449,596 in the following respects:
PA: Requires two circulating swivels because one
is integral with power sub and one much be used when
unit is rigged down.
PE: Only Gne swivel is required. Current list
price for a 500 ton swivel (Continental Emsco):
$43,290.00.
PA: Requires explosion proof cooling air system.
Present design uses blower mounted on support dolly or
drill floor and air is conducted through 20cm diameter
flexible rubber duct. This lightweight duct is often
windblown and damaged from hanging on the rig structure.
Hot air is exhausted to atmosphere creating a hazardous
condition. Documentation for the alternating current fan
motor and approval for the D.C. drive motor is time
consuming and expensive.
PE: Hydraulic oil is cooled by rig supplied
water being circulated through an oil cooler. This
equipment is located in an existing safe location.
lX~S6~1
-12-
PA: The overall height, width and depth is much
greater; requires approximately 13.8m of vertical derrick
height.
PE: This unit requires less than 10.8m.
PA: The unit does not have a "rise and fall"
mechanism to minimize load on drill stem threads when
unscrewing.
PE: Counterbalance mechanism is provided.
PA: ~nit must be swung back in order to install
well casing.
PE: All normal drilling and casing installion is
done with standard unit.
