Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS AND METHOD FOR RAISING AND LOWERING A PISTON IN A PISTON-CYLINDER
ARRANGEMENT IN A DERRICK
The present invention relates to an apparatus for a derrick,
comprising two or more hydraulic piston/cylinder arrangements
for raising and lowering a yoke which travels on guide rails
in the derrick itself, where two or more wire lines are
strung over sheaves rotatably attached to the yoke, said
wire lines being at one end attached to the top drive and at
the other end to an attachment point adjacent to a drill
floor, said two or more wire lines being run in two sets of
lines, the attachment points of which are spaced apart.
~s
A derrick structure, developed by the present inventor in
1987, that has shown great promise is the RamRigTM concept.
Two or more hydraulic piston/cylinder arrangements are used
in the derrick for raising and lowering the drill string.
zo The cylinders operate between the drill floor and a yoke
which travels on guide rails in the derrick itself. The
advantages of this concept are numerous, some of the most
important being that it is possible to place the drill floor
at,a higher level than the platform floor, that a derrick
Zs having significantly lower air resistance can be constructed,
and that the most expensive components of the derrick attain
higher safety and a longer lifetime.
Since it is possible to position the drill floor higher than
3o the platform floor, pipe handling is significantly sim-
plified. There is no longer any need to arrange the pipe
handling equipment at a high level in the derrick. All pipe
handling equipment can be placed on the platform floor and
the drill floor.
The object of the present invention is to solve important,
practical problems in the realization of the RamRigTM
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2
concept. This object is achieved by means of the features
apparent from the characterizing clause of the subsequently
disclosed claim 1.
The invention will now be explained in greater detail with
reference to the enclosed drawings, where
Figure I shows a RamRigTM derrick in every essential detail;
Figure 2 shows the derrick schematically, viewed from the
side;
Figure 3 shows the derrick schematically, viewed from the
front, with the top drive in its lowest position;
Figure 4 shows the derrick schematically, viewed from the
front, with the top drive in its highest position;
Figures 5 - 13 show the drive means of the piston/cylinder
arrangements in various modes of operation.
Figure 1 shows a derrick I positioned on a drill floor 2.
The drill floor is positioned at a higher level than the
platform floor 3, so that the pipe handling equipment 4 can
be placed, in the main, between the platform floor 3 and the
drill floor 2. The derrick 1 is substantially gantry-shaped,
with gantry legs 5, 6. Guide rails 7 for a yoke 8 and a top-
drive 9 run along each gantry leg 5, 6. Hydraulic piston/cyl-
inder arrangements 10, il are positioned so that they extend
3o along each gantry leg 5, b and operate between the drill
floor 2 and the yoke 8, for moving the yoke 8 vertically
along the guide rails 7. ,
The yoke 8 is provided with a plurality of sheaves 12, pre- ,
35 ferably four, for running wire lines 13. The wire lines 13
run from the drill floor 2 along each gantry leg 5, b, over
the sheaves 12 and down to the top drive 9. By retracting and
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3
extending the piston/cylinder arrangement 10, 11, it is thus
possible to raise and lower the top drive 9.
n
In Figures 2, 3 and 4, the function of the lift system is
seen most clearly. In Figures 2 and 3, the piston/cylinder
arrangement 10, 11 is shown in a completely retracted
condition. The top drive 9 is then in its lowest position,
quite close to the drill floor. The yoke 8 is at the upper
end of the piston/cylinder arrangement.
to
When the pistons in the piston/cylinder arrangement are
extended, the yoke 8 is lifted along the guide rails 7 up to
the top of the derrick 1. The top drive is then lifted, as a
result of the exchange created by the wire lines 13 being run
over the sheaves 12, from its position adjacent to the drill
floor 2 to a position directly below the yoke 8. The height
to which the top drive 9 is lifted is thus the double of that
to which the yoke 8 is lifted.
ao There may, for example, be as much as eight wire lines 13
arranged in the lift means described above, where two and two
are strung in their own separate tracks over the same sheave
I2. Four sheaves are arranged in pairs at each end of the
yoke 8. The wire lines 13 are thus arranged in two sets 13a
25 and 13b, extending from attachment points 14a and 14b at the
drill floor 2, over the sheaves 12 and down to the top drive
9. The attachment points 14a and 14b are horizontally spaced
apart by a distance approximately like the length of the yoke
8.
3o
In Figure 5 the piston/cylinder arrangements 10, 11 are
schematically illustrated. Here the yoke 8 is also shown,
together with the sheaves 12 and the top drive 9. The drill
floor 2 is also indicated. From the drill floor 2 each of the
wire lines 13 runs over its own sheave 12 and down to the
top drive 9.
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Each piston/cylinder arrangement 10, 11 consists of a
cylinder and a piston 21 having a piston rod 22. The
cylinder 20 is at one end attached to the drill floor 2,
whereas the piston rod 22 is attached to the yoke 8. The
piston 21 divides the cylinder into two chambers, a lower
chamber 23 and an upper chamber 24. The lower chamber 23 is
circular/cylindrical and only delimited by the walls of the
cylinder 20 and the lower end surface 25 of the piston 21.
The upper chamber 24 is also delimited by the walls of the
is cylinder 20, but is in addition delimited by the piston rod
22 and the upper annular surface 26 of the piston 21. It
will thus be seen that hydraulic fluid in the Iower chamber
23 has a larger operating surface with respect to the piston
21 than hydraulic fluid in the upper chamber 24, since the
~5 lower end surface 25 of the piston is larger than its upper
annular surface 26.
The drive system which is here generally designated by
reference numeral 30, consists of a reservoir 31, a feed pump
zo 32 driven by a motor 33, one or more main pumps 34 driven by
one or more motors 35, a control valve 36, an accumulator/-
valve plate 37, a cylinder valve 38 for each cylinder 20,
one or more accumulators 39 and one or more pressure tanks
40.
From each side of the main pumps 34 lines 41, respectively
42, lead to a separate port a, b for each, in the control
valve 36. A line 43 Ieads from the reservoir 31, via the
feed pump 38 to a third port c in the control valve 36. From
3o a fourth port d in the control valve 36 a line 44 leads to
the accumulatar/vaive plate 37. From a fifth port a in the
control valve 36 a line 45 leads via a ramification 46, -
where the line 45 branches so as to create one line for each
cylinder 20 leading into a port f in each cylinder valve 38. .
The line 44 which Ieads into a port g in the accumula-
tor/valve plate 37, splits here into branches which lead from
a number of ports h to the control valve 38 of each cylinder
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20 into a port i for each control valve 3b. The accumulators
39 are connected to the accumulator valve plate 37 via ports
It must be understood that both ports h and ports
respectively may represent a plurality of ports or optionally
5 one port branching outside the accumulator/valve plate 37.
The accumulators 39 are connected to the pressure tanks 40
via a line 47.
A line 48, connected with the upper chamber 24 of the
cylinder 20, extends from a port k in each cylinder valve 38.
From a port 1 in each cylinder valve a line 49 leads to the
chamber 23 of the cylinder 20. A Tine 50 connects ports m in
each cylinder valve 38.
Now, since the construction of the drive means 30 of the
pi,ston/cylinder arrangements 10, 11 has been explained, the
mode of operation of this drive means 30 shall be explained
by means of Figures 5 - 13, as follows.
zo In Figure 5, the piston/cylinder arrangements 10, 11 are in a
locked position. The main pump 34 is set for zero dis-
placement volume, and the connection between the ports k and
the ports f and i is closed. Thus, there is no flow of
hydraulic fluid in the system.
In figure b the piston/cylinder arrangements are extended
for maximum thrust power, but at low velocity. Now the
displacement volume of the main pump 34 is adjusted so that
hydraulic fluid flows from the reservoir 31, via the feed
3a pump 32 and the line 43, in through the port c in the
control valve 36, out through the port b, through the line 42
via the main pump 34 and the line 41 to port a of the
control valve 36, out through the port e, via the line 44 to
port g of the accumulator valve plate and from this via the
j5 ports h to the ports i in the cylinder valves 38 and further
out through the ports 1 and the lines 49 to the chamber 23 of
the cylinder 20. Hydraulic fluid, displaced from the chamber
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b
24 of the cylinder 20, flows via the Lines 48, via the
cylinder valves 38 and the line 45 back to the control valve
36 and main pump 34. The ports ~ in the accumulator valve '
plate 37 are closed. The connection 50 between the ports m
of the cylinder valves 38 is open, however, in order to
Pn~p_re? that t_h_P_rP i_c enpal_ prPfi~~rg~ ~~a~nrripr~~eip 2r~n~
the pistons 21. In this mode the piston/cylinder arrange-
ments 10, 11 would be extended at a comparatively low
velocity, but with a relatively high thrust power.
io
In Figure 7 another mode is shown which, with respect to
hydraulic fluid circulation, is quite in accordance with the
mode shown in figure 6. However, here the ports ~ in the
accumulator valve plate 37 have been opened up so that the
accumulators 39, which are influenced by pressure from
pressure tanks 4 via the line 47, increase the pressure in
the hydraulic fluid which flows through the line 44 to the
lower chamber 23 of the cylinders 20. The velocity of the
pistons 21 is then somewhat increased at the same time as
zo the thrust power is maintained at a high level.
In Figure 8 a mode is shown where the travelling speed of the
pistons 21 has been further increased. At the same time the
thrust force is reduced. This mode is thus well suited for
z5 raising the unloaded top drive 9. In this mode the connection
is opened between the ports i, k, 1 and m in the control
valves 38, so that the Lower chamber 23 and the upper
chamber 24 of the cylinders 20 are short circuited. Hence,
the hydraulic pressure acts on a differential area which is
so equal to the difference between the area of the underside 25
of the piston 21 and the top side 26 of the piston 21, i.e.,
the cross-sectional area of the piston rod 22. Thus the =
piston 21 obtains a greater travelling speed at the same
hydraulic pressure. In this mode the ports ~ in the accumuia-
for valve plate 37 are closed so that the accumulators 39 do
not function.
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In Figure 9 a further mode is shown, where the ports ~ of
the accumulator valve plate 37 are opened so that the
accumulators 39 supply an additional pressure into the line
44. As in Figure 8, the connection between ports i, k and 1
in the cylinder valves 38 is open. The ports m may also be
open in this mode, although this is not shown here. In this
mode, the travelling speed of the piston 21 will be further
increased because of the increased pressure in the line 44.
The thrust force will still be comparatively low, however.
1D
In Figure 10 there is shown a lowering mode at maximum load
and controlled speed. The main pump 34 is now readjusted so
that the hydraulic fluid flows into the pump through the
line 42 and out of the pump through the line 42. In this
case the connection between the ports k of the lines 48 in
the cylinder valves 38 and the port f of the line 45 in the
cylinder valves 38 is open so that the hydraulic fluid flows
into the upper chamber 24 of the cylinder. At the same time
the connection between the port 1 and the port i in the
zo cylinder valves 38 is open so that the hydraulic fluid in
chamber 23 of the cylinder 20 flows out in the line 44. A
part of the hydraulic fluid will flow back to the reservoir
31 for the very reason that the chamber 24 of the cylinder 20
has a smaller cross sectional area than the chamber 23.
In Figure 11 a lowering mode is shown where the lowering is
carried out at up to maximum load and up to maximum velocity.
Here the ports f, i, k and I in the cylinder valves 38 are
connected with each other. Thus hydraulic fluid can freely
3o flow out of the chamber 23 of the cylinder 20. Some of this
fluid will flow back to the cylinder and into the chamber 24,
. whereas the remainder will flow through the lines 44 and 45
and further, to the reservoir 31. The lowering speed can be
. controlled to a certain degree by means of the main pump 34,
but because of the fact that the connection between the
cylinder valves 38 and the reservoir 31 via the line 45 is
completely open, it wi31 be expedient to control the lowering
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speed by means of a throttling 51, which, as shown here, may
1 ie in the connection between the port 1 and the ports f , i
and k in the cylinder valves 38. This mode will be well
suited for carrying out hard thrusts with the drill string,
if the need should arise.
Figure 12 shows a mode of operation where constant load is
maintained during the movement of the piston/cylinder
arrangements 10, 11. This mode is used, for ezample, for the
drilling itself. In this mode the fluid flow goes back and
forth in the system, and the displacement volume of the main
pump 34 is adjusted in both directions in accordance with
signals given from a load distributor (not shown). The
connection between the ports f and k in the cylinder valve 38
is open, as is the connection between the ports i and 1. The
hydraulic fluid thus flows between the main pump 34 and the
cylinder valve 38 via the line 44 and the line 45, respec-
tively. The directions of the flow of fluid in these two
lines will at all times be opposite to each other. A certain
~ exchange of hydraulic fluid with the reservoir 31 will also
occur, since the cross-sectional areas of the lower chamber
23 of the cylinder 20 and of the upper chamber 24 are
different.
z5 Figure 13 shows a similar mode of operation, where the
purpose is~to maintain a constant load while the pistons 21
are moved. In this mode, however, a greater velocity is
achieved with respect to the travel of the piston. The port
f in the valve 38 is now closed, so that there no longer will
3o be any fluid flow in the line 45. The ports i, k and 1 in
the cylinder valve 38 are connected with each other, however.
Thus , in the same manner as in the mode according to Figure -
9, the area of piston 21 activity will be the dffferential
area between the area of the lower surface 25 of the piston
35 and the area of the upper annular surface 26 of the piston.
This corresponds to the cross-sectional area of the piston
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rod 22. A faster move of the piston 2I will then be obtained
even if the pressure in the system is unchanged.
Even though the use of the accumulators 39 to provide
increased pressure in the system has been shown in only a few
of the modes shown in Figures 5-9, it must nevertheless be
understood that the accumulators may be used in any one of
the modes shown, for increasing the pressure in the system
and thus increase either the velocity of the piston movement,
the force by which the piston 21 is moved or both. In the
lowering of the pistons 21, it will be expedient to open the
ports ~ in the accumulator valve plate 37 in order to
transfer some of the pressure created hereby into the
accumulators 39, which thereby charge the pressure tanks 40
via the Line 47. Hence, it will be ensured that there is
extra power available from the accumulators 39 when this is
needed. Even in the modes for constant loads it may be
expedient to use the accumulators 39.
25
35
