U.S. patent application number 15/756769 was filed with the patent office on 2018-08-23 for arrangement and method for heave compensation of tools provided with vertical rack gearing in a derrick.
This patent application is currently assigned to West Drilling Products AS. The applicant listed for this patent is West Drilling Products AS. Invention is credited to Bjorn Eilertsen, Odd B. Skjaerseth.
Application Number | 20180238125 15/756769 |
Document ID | / |
Family ID | 58240298 |
Filed Date | 2018-08-23 |
United States Patent
Application |
20180238125 |
Kind Code |
A1 |
Skjaerseth; Odd B. ; et
al. |
August 23, 2018 |
Arrangement and Method for Heave Compensation of Tools Provided
with Vertical Rack Gearing in a Derrick
Abstract
An arrangement and a method is for heave compensation of a
working unit. At least one driving unit is arranged in a vertically
displaceable manner in a tower by the driving unit being in
engagement with a pitch rack arranged vertically in the tower, the
pitch rack being hung off in a vertically displaceable manner in a
heave compensator.
Inventors: |
Skjaerseth; Odd B.;
(Stavanger, NO) ; Eilertsen; Bjorn; (Hundvag,
NO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
West Drilling Products AS |
Stavanger |
|
NO |
|
|
Assignee: |
West Drilling Products AS
Stavanger
NO
|
Family ID: |
58240298 |
Appl. No.: |
15/756769 |
Filed: |
September 7, 2016 |
PCT Filed: |
September 7, 2016 |
PCT NO: |
PCT/NO2016/050184 |
371 Date: |
March 1, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 15/02 20130101;
E21B 19/09 20130101 |
International
Class: |
E21B 19/09 20060101
E21B019/09; E21B 15/02 20060101 E21B015/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 8, 2015 |
NO |
20151153 |
Claims
1. An arrangement for heave compensation of a working unit, thereby
compensating heave motion of a floating surface installation on
which the working unit is installed, the working unit comprising at
least one driving unit and being arranged in a vertically
displaceable manner in a tower by said at least one driving unit
being in engagement with a pitch rack arranged vertically in the
tower, wherein the pitch rack is hung off in a vertically
displaceable manner in a heave compensator arranged in an upper
tower portion, the pitch rack depending from the heave
compensator.
2. The arrangement according to claim 1, wherein the heave
compensator comprises at least one rotary actuator taken from a
group comprising hydraulic motors and electric motors.
3. The arrangement according to claim 1, wherein the pitch rack is
provided with two opposite rows of teeth, and the heave compensator
comprises at least one rotary actuator in engagement with each of
the rows of teeth.
4. The arrangement according to claim 1, wherein a rotary actuator
is connected to a mechanical or hydraulic transmission via a
remote-operated clutch.
5. The arrangement according to claim 1, wherein the tower
comprises several parallel pitch racks, whose vertical
displacements are synchronized by the pitch racks being
interconnected by a mechanical or hydraulic transmission for
generating the cooperating displacements of the pitch racks via at
least one associated rotary actuator.
6. The arrangement according to claim 1, wherein the tower
comprises several parallel pitch racks whose vertical displacements
are synchronized by each pitch rack being connected to an
electronic position-monitoring system connected to a control system
for the heave compensator for the generation of displacement of
each pitch rack via at least one rotary actuator connected to each
pitch rack or group of pitch racks.
7. A method of heave-compensating a working unit, thereby
compensating heave motion of a floating surface installation on
which the working unit is installed, the working unit comprising at
least one driving unit and being arranged in a vertically
displaceable manner in a tower by said at least one driving unit
being in engagement with a pitch rack arranged vertically in the
tower, the method comprises the steps: a) arranging a heave
compensator in an upper portion of the tower; b) hanging off the
pitch rack in the heave compensator; c) registering a heave
movement in the tower via a control system connected to the heave
compensator; d) displacing the pitch rack vertically via the heave
compensator in order thereby to neutralize the heave movement of
the tower.
8. The method according to claim 7, wherein the method further
comprises: e) hanging off several pitch racks in the same heave
compensator; and f) moving the pitch racks synchronously by f1)
connecting the pitch racks to a mechanical or hydraulic
transmission, and moving the pitch racks collectively, or f2)
connecting each pitch rack to an electronic position-monitoring
system connected to a control system for the heave compensator, and
displacing each pitch rack individually.
9. (canceled)
Description
FIELD
[0001] The invention relates to an arrangement and a method for
heave compensation of a working unit which includes at least one
driving unit and is arranged in a vertically displaceable manner in
a derrick by said at least one driving unit being in engagement
with a pitch rack arranged vertically in the derrick.
BACKGROUND
[0002] On floating surface installations that are used for
operations with equipment which is placed on the sea floor or in a
subsea borehole or well, for example for extracting hydrocarbons,
there is often a need to use heave compensation, so that the
equipment depending from the floating surface installation will not
move uncontrolledly because of movement of the surface installation
induced by waves or oceanic currents. The heave compensation is
typically provided by means of winches or hydraulic cylinders,
which are connected to an elongated element to which the equipment
is attached, for example in the form of a wireline or a pipe
string. For example, it is known to hang a top-drive drilling
machine on a complex system of wires, pulleys and winches to
prevent a drill bit from being subjected to uncontrolled vertical
movement owing to the wave-induced movement of a drilling
vessel.
SUMMARY
[0003] The invention has for its object to remedy or reduce at
least one of the drawbacks of the prior art or at least provide a
useful alternative to the prior art.
[0004] The object is achieved through the features that are
specified in the description below and in the claims that
follow.
[0005] The invention provides a tower, especially a derrick, which
includes several guiding tracks for a connected working unit, for
example a pipe winch, a drilling machine, power tongs, a slips
arrangement, a circulation unit for drilling fluid or a work
platform, and combinations of working units, so that said working
unit may be moved up and down the tower to generate a vertical
displacement of an attached tool, for example a pipe string with an
appurtenant downhole tool. The vertical travel of the working unit
is brought about by one or more driving units engaging with at
least one pitch rack arranged vertically in the tower. The position
of the working unit in the horizontal direction may be determined
by the engagement of the working unit in the guiding tracks,
typically provided by supporting means in the form of rollers
and/or guide shoes resting against the guiding tracks.
[0006] The at least one pitch rack is hung off in a heave
compensator. Preferably, the heave compensator is one or more
rotary actuators, typically in the form of electric or hydraulic
motors, engaging with the at least one pitch rack. In a manner
known per se, the heave compensator includes a control system,
which is arranged to register heave movements of the tower and
generate control signals for the rotary actuator(s) so that the
heave movements of the tower are neutralized by the pitch rack
being moved in a vertical direction.
[0007] Advantageously, the pitch rack is provided with toothings on
two opposite sides for abutment against respective gears connected
to the rotary actuator(s) of the heave compensator and to the
driving unit(s) of the working unit. A heave compensator may be
connected to several pitch racks by means of suitable transmission
means, for example mechanical gearboxes and hydraulic systems.
[0008] It is an advantage if the rotary actuators of the heave
compensator are identical.
[0009] It is an advantage if the driving units of the working unit
are identical.
[0010] It is an advantage if the heave compensator is arranged in
an upper tower portion.
[0011] The invention is defined by the independent claims. The
dependent claims define advantageous embodiments of the
invention.
[0012] In a first aspect, the invention relates more specifically
to an arrangement for heave compensation of a working unit which
includes at least one driving unit and is arranged in a vertically
displaceable manner in a tower by said at least one driving unit
being in engagement with a pitch rack arranged vertically in the
tower, characterized by the pitch rack being hung off in a
vertically displaceable manner in a heave compensator.
[0013] The heave compensator may be arranged in an upper tower
portion.
[0014] The heave compensator may include at least one rotary
actuator taken from a group comprising hydraulic motors and
electric motors. Thereby a compact and not very space-demanding
heave compensator is provided.
[0015] The pitch rack may be provided with two opposite rows of
teeth, and the heave compensator may include at least one rotary
actuator in engagement with each of the rows of teeth. Thereby a
plurality of cooperating rotary actuators may be used in the heave
compensator, and, because of that, the size of each of the rotary
actuators may be reduced. Besides, space may be allowed for backup
actuators, which may come into function as soon as a malfunction is
registered in the functioning of a rotary actuator in normal
operation.
[0016] The rotary actuator(s) may be connected to a mechanical or
hydraulic transmission via a remote-controlled clutch. Thereby the
function of the heave compensator may be maintained even if there
should be a malfunction and blocking of one of the rotary
actuators.
[0017] The tower may include several parallel pitch racks, whose
vertical displacements are synchronized by the pitch racks being
interconnected by a mechanical or hydraulic transmission for
generating the cooperating displacements of the pitch racks by
means of at least one rotary actuator connected thereto.
Alternatively, the tower may include several parallel pitch racks
whose vertical displacements are synchronized by each pitch rack
being connected to an electronic position-monitoring system
connected to a control system for the heave compensator for
generating individual displacement of each pitch rack by means of
at least one rotary actuator connected to each pitch rack or group
of pitch racks.
[0018] In a second aspect, the invention relates more specifically
to a method of heave-compensating a working unit which includes at
least one driving unit and is arranged in a vertically displaceable
manner in a tower by said at least one driving unit being in
engagement with a pitch rack arranged vertically in the tower,
characterized by the method comprising the steps:
[0019] a) arranging a heave compensator in association with the
tower;
[0020] b) hanging off the pitch rack in the heave compensator;
[0021] c) registering a heave movement in the tower by means of a
control system connected to the heave compensator;
[0022] d) displacing the pitch rack vertically by means of the
heave compensator in order thereby to neutralize the heave movement
of the tower.
[0023] The method may further include:
[0024] e) hanging off several pitch racks in the same heave
compensator; and
[0025] f) moving the pitch racks synchronously by [0026] f.sub.1)
connecting the pitch racks to a mechanical or hydraulic
transmission, and moving the pitch racks collectively, or [0027]
f.sub.2) connecting each pitch rack to an electronic
position-monitoring system connected to a control system for the
heave compensator, and displacing each pitch rack individually.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] In what follows, an example of a preferred embodiment is
described, which is visualized in the accompanying drawings in
which:
[0029] FIG. 1 shows a side view of a tower with a drilling machine
vertically displaceable along guiding tracks in the tower and in
engagement with a pitch rack hung off in a heave compensator
arranged in an upper portion of the tower;
[0030] FIG. 2 shows, on a larger scale, a side view of an upper
portion of a dual tower with respective pitch racks hung off in a
heave compensator;
[0031] FIG. 3 shows, in perspective, a working unit in the form of
a drilling machine arranged to be vertically displaceable along
guiding tracks in the tower and in engagement with a pitch
rack;
[0032] FIG. 4 shows, in perspective, an upper portion of a dual
tower with respective pitch racks hung off in a heave compensator,
the operation of rotary actuators that are in engagement with the
respective pitch racks being synchronized by them being connected
in pairs to a mechanical transmission; and
[0033] FIG. 5 shows, in perspective, an upper portion of a dual
tower with respective pitch racks hung off in a heave compensator,
the operation of rotary actuators that are in engagement with the
respective pitch racks being synchronized by means of electronic
monitoring of the positions of the
DETAILED DESCRIPTION OF THE DRAWINGS
[0034] A tower 2 projects up from a deck 11 on a floating surface
installation 1 or vessel, shown schematically in FIG. 1. A working
unit 3, shown here as a drilling machine, is vertically
displaceable along guiding tracks 22 on the tower 2, and several
driving units 33, shown here as motors 331, are in engagement with
a pitch rack 23 and are arranged to move, for example, a downhole
tool (not shown) arranged at a remote end of a pipe string or
another elongated body (not shown). The pitch rack 23 is hung off
in a heave compensator 24 connected to the tower, shown in the
exemplary embodiment as arranged in an upper portion 21 of the
tower 2. An upper end portion 235 of the pitch rack 23 projects
freely up above the heave compensator 24. The heave compensator 24
includes several rotary actuators 241, typically in the form of
electric or hydraulic motors that are connected to an energy supply
unit (not shown) and a control system 243 which comprises the
necessary elements (not shown) for registering the heave movements
of the floating installation 1 and generating control instructions
to the rotary actuators 241 of the heave compensator 24.
[0035] The pitch rack 23 is vertically displaceable by means of the
heave compensator 24 as the heave compensator 24 neutralizes the
heave movements of the surface installation 1 in a manner known per
se. The pitch rack 23 is provided with a first row of teeth 231,
which is in engagement with driving gears 332 on the rotary
actuator(s) 331 of the working unit 3 and with corresponding
driving gears 241' connected to the rotary actuator(s) 241 of the
heave compensator 24. Preferably, the pitch rack 23 is double, that
is to say it is provided with two opposite rows of teeth 231, 232
(only one is visible in the figures). It is an advantage if support
is arranged right opposite the driving gears 332 and 241',
respectively, in order to take up the force component that the
displacements of the working unit 3 on the pitch rack 23 and the
pitch rack 23 relative to the heave compensator 24, respectively,
generate normal to the longitudinal axis of the pitch rack 23. When
the pitch rack 23 is provided with two opposite rows of teeth 231,
232, two rotary actuators 241 and 331, respectively, may
appropriately be arranged right opposite each other and on
respective sides of the pitch rack 23 both in the heave compensator
24 and in the working unit 3, as appears clearly from FIGS. 3, 4
and 5, or, possibly, via a suitable transmission (not shown), at
least driving gears 241' and 332, respectively, may be arranged
right opposite each other on respective sides of the pitch rack
23.
[0036] The working unit 3 is provided with several supporting means
32, typically supporting rollers (shown here) and/or guide shoes
resting against respective guiding tracks 22 on the tower 2 and
positioning the working unit 3 accurately in the horizontal plane.
The pitch rack 23 may therefore depend freely from the heave
compensator 24, as it does not contribute in the horizontal
positioning of the working unit 3. On the contrary, the position of
the pitch rack 23 in the horizontal plane is controlled by the
working unit 3.
[0037] Reference is now made particularly to FIGS. 2 and 4, in
which upper portions 21, 21' of first and second towers 2, 2' are
interconnected, and in which the heave compensator 24 includes
several rotary actuators 241, which are connected in pairs via a
mechanical transmission 242. The transmission, which may also be
formed as a hydraulic arrangement, ensures that the heave
compensation of first and second pitch racks 23, 23' is
synchronized. Correspondingly, a tower may include several pitch
racks (not shown) for the suspension of one and the same working
unit, or, possibly, different working units may each be suspended
from a respective pitch rack.
[0038] Reference is now made to FIG. 5, in which the heave
compensation of two pitch racks 23, 23' is synchronized
electronically by the heave compensator 24 being provided with a
system 244 for monitoring the positions of the pitch racks 23, 23',
for example by each pitch rack 23, 23' being provided with position
indicators 234 readable by the position-monitoring system 224 which
then supplies the control system 243 of the heave compensator 24
with control data, and the rotary actuator 241 of each pitch rack
23, 23', possibly sets of several rotary actuators 241, is/are
operated to displace the respective pitch racks 23, 23' in a
synchronous manner.
[0039] When a working unit 3, which is arranged in a tower 2 with
heave compensation like that described above, has been connected to
a pipe string or some other elongated body (not shown) with which
an attached downhole tool (not shown) or the like is to be
displaced or held in position, the working unit 3 is displaced or
positioned relative to the pitch rack 23. Independently of the
travel of the working unit 3 along the pitch rack 23, said pipe
string/elongated body, not shown, may remain unaffected by possible
heave motion in the floating surface installation 1 and the tower 2
by the heave compensator 24 displacing the pitch rack 23 relative
to the tower 2, neutralizing the heave motion. Other working units
(not shown) that are possibly arranged in the tower 2, possibly in
the second, adjacent, tower 2' to cooperate with the working unit 3
shown may be displaced vertically in the same way on the same pitch
rack 23, possibly on the second pitch rack 23' at the same time as
it is heave-compensated synchronously with the working unit 3
shown.
[0040] Even though the exemplary embodiment shows a pitch rack 23
depending from a heave compensator 24 arranged in an upper portion
21 of a tower 2, this does not exclude an arrangement in which the
heave compensator 24 is arranged in a lower portion 25 of the tower
or below the deck 11 from which the tower 2 rises. The advantage of
an arrangement like that not shown is that a heavy element like the
heave compensator 24 will then have a lower centre of gravity,
which increases the stability of the floating surface installation
1. The drawback is that the pitch rack 23 must be secured against
buckling with guides or an increased cross section, which increases
the weight of the pitch rack.
[0041] It should be noted that all the above-mentioned embodiments
illustrate the invention, but do not limit it, and persons skilled
in the art may construct many alternative embodiments without
departing from the scope of the attached claims. In the claims,
reference numbers in parentheses are not to be regarded as
restrictive. The use of the verb "to comprise" and its different
forms does not exclude the presence of elements or steps that are
not mentioned in the claims. The indefinite article "a" or "an"
before an element does not exclude the presence of several such
elements.
[0042] The fact that some features are indicated in mutually
different dependent claims does not indicate that a combination of
these features cannot be used with advantage.
* * * * *