DOWNHOLE DRIVING UNIT HAVING A HYDRAULIC MOTOR IN A WHEEL
Field of the invention
The present invention relates to a downhole driving unit for insertion into a well,
comprising a driving unit housing, an arm assembly movable between a retracted
position and a projecting position in relation to the driving unit housing, an arm
activation assembly arranged in the driving unit housing for moving the arm
assembly between the retracted position and the projecting position and a wheel
assembly comprising a stationary part and a rotational part, the stationary part
being connected with or forming part of the arm assembly and being rotatably
connected with a rotational part. Furthermore, the present invention relates to a
downhole system comprising said driving unit and to use of such driving unit.
Background art
When operating in a downhole well, tools used for the operation may not be
submergible themselves. Some tools are positioned at the front of coiled tubing
and are driven forward by pushing the tubing further down the well. Other tools
are lowered into the well by means of a wireline, and gravity will thus ensure that
the tool submerges. Hence, not all tools are capable of moving in the well and
thus need to be moved forward in the well by an additional tool. In particular,
this is the case in the horizontal part of the well, as gravity cannot aid in the
movement.
Several tools have been developed for this purpose, inter alia one running on a
caterpillar track. However, this tool has the disadvantage that it cannot always
hold its footing in the more uneven parts of the well, and in some cases it is
impossible for such a tool to pass a place where two well pipes meet but do not
abut hence leaving a gap. Another tool has wheels driven by means of a roller
chain and all driven by one motor. However, if the motor is unable to drive all
wheels, the tool is unable to drive itself any further. This may be the case if the
well has an obstacle and one wheel is unable to be driven across the obstacle.
Summary of the invention
It is an object of the present invention to wholly or partly overcome the above
disadvantages and drawbacks of the prior art. More specifically, it is an object to
provide an improved downhole tool for moving an operational tool forward in all
parts of a well.
The above objects, together with numerous other objects, advantages, and
features, which will become evident from the below description, are accomplished
by a solution in accordance with the present invention by a downhole driving unit
for insertion into a well, comprising:
- a driving unit housing,
- an arm assembly movable between a retracted position and a projecting
position in relation to the driving unit housing,
- an arm activation assembly arranged in the driving unit housing for moving the
arm assembly between the retracted position and the projecting position, and
- a wheel assembly for driving the driving unit forward in the well, comprising a
stationary part and a rotational part, the stationary part being connected with or
forming part of the arm assembly and being rotatably connected with a rotational
part,
wherein the wheel assembly comprises a hydraulic motor comprising a hydraulic
motor housing and a rotatable section connected with the rotational part for
rotating part of the wheel assembly.
By having a motor enclosed in a hydraulic motor housing in the wheel assembly,
roller chains or caterpillar tracks can be avoided. By having a closed housing, dirt
from the well fluid in which the driving unit propels itself does not get stuck in the
chain or caterpillar track, destroying the function of the wheel.
In one embodiment, the driving unit comprises several arm assemblies, each
connected in one end with the driving unit housing and in another end with a
wheel assembly.
By having the motor directly in the wheel, each wheel can drive the driving unit
forward independently of the other wheels of the driving unit. When passing an
obstacle, the arm assembly nearest to the obstacle is pressed towards the driving
unit housing as the other wheels drive the driving unit forward. Thus, the driving
unit is capable of passing most obstacles in the well or casing. Furthermore,
when passing a gap, e.g. between two tubular casings, the wheels not situated in
the gap drive the driving unit forward and thus, the driving unit is able to propel
itself in almost all parts of the well.
By having movable arm assemblies which may be retracted into the driving unit
housing, the driving unit is capable of passing an obstacle as earlier described
and the driving unit is capable of propelling itself forward in wells having an inner
diameter varying within a larger range than if the arms were not movable. When
the operation is performed, the arm assemblies are retracted into the housing
and the driving unit is removed from the well by dragging a wireline connected to
the driving unit.
In one embodiment, the stationary part and the rotational part may constitute
the hydraulic motor housing.
In another embodiment, the wheel assembly may further comprise a planetary
gearing system.
In one embodiment, the planetary gearing system may be comprised in the
hydraulic motor housing.
Also, the wheel assembly may comprise a wheel ring.
Furthermore, the rotatable section of the hydraulic motor may be connected with
a sun gear of the planetary gearing system.
Said planetary gearing system may be comprised in the hydraulic motor housing.
Moreover, the sun gear of the planetary gearing system may drive a plurality of
planet gears which are connected through a carrier member for driving a ring
gear of the planetary gearing system.
In an embodiment, the wheel ring may comprise the ring gear, enabling the
planet gears to engage and drive the wheel ring.
In addition, the wheel ring may be closed from one end by a closing member.
Additionally, the wheel ring may comprise the closing member.
Also, the aforementioned planetary gearing system may comprise a ring gear
constituted by the wheel ring or the closing member.
Furthermore, the rotatable section may comprise a first sun gear of the planetary
gearing system driving a plurality of planet gears which are connected through a
carrier member being connected with or comprised in the wheel ring, the
stationary part may comprise a ring gear of the planetary gearing system, and
the ring gear may engage the planet gears.
Said the rotatable section of the hydraulic motor may be connected with the
planet gears and the planet gears may be driven by the rotatable section.
In one embodiment, the stationary part may comprise the sun gear of the
planetary gearing system.
In another embodiment, the rotational part may comprise the wheel ring and
may be driven by the planet gears.
The rotatable section of the hydraulic motor may comprise a first sun gear of the
planetary gearing system and the first sun gear may drive a plurality of first
planet gears which are connected through a carrier member.
Also, the carrier member of the planetary gearing system may drive a plurality of
second planet gears and the carrier member may comprise the sun gear
engaging and driving the second planet gears.
Moreover, the second planet gears may be connected by means of a second
carrier member being part of the rotational part for rotating part of the wheel
assembly.
In an embodiment, the second carrier member may be connected with the
rotational part of the wheel assembly or may be part of the rotational part.
The stationary part may comprise the ring gear of the planetary gearing system
engaging the first planet gears and the second planet gears.
Additionally, the arm assembly may comprise a wheel arm and the wheel arm
may comprise fluid channels for providing fluid to and from the hydraulic motor
through the stationary part.
Further, the hydraulic cylinder block may comprise fluid channels arranged in
alignment with the fluid channels in the wheel arm so that fluid may be led from
the wheel arm to cylinders in the hydraulic cylinder block.
The downhole driving unit according to the present invention may further
comprise a pump for providing fluid to the hydraulic motor.
In one embodiment, the hydraulic motor may be a radial piston motor.
Said hydraulic motor may comprise a cam ring connected with or forming part of
the stationary part of the wheel assembly.
Additionally, the rotatable section may be a hydraulic cylinder block.
Also, the hydraulic motor may comprise pistons movable within cylinders in the
hydraulic cylinder block.
Furthermore, the driving unit having several arm assemblies may have a
longitudinal centre axis and the arm assemblies may be connected with the
driving unit housing having a distance to the centre axis and opposite side of the
centre axis. When having at least three arm assemblies, they are arranged in a
zigzag pattern along the centre axis in a plane.
In addition, the driving unit may be connected to a wireline and the arm
assemblies may project from the driving unit housing having an angle less than
90° from the longitudinal axis of the driving unit. The arm assemblies may face
backwards in relation to the wireline.
The present invention further relates to a downhole system comprising a driving
unit and an operational tool connected with the driving unit for being moved
forward in a well or borehole.
Said operational tool may be a stroker tool, a key tool, a milling tool, a drilling
tool, a logging tool, etc.
Moreover, the present invention relates to a use of the driving unit according to
the invention in a well or borehole for moving itself and/or an operational tool
forward in a well or borehole.
Brief description of the drawings
The invention and its many advantages will be described in more detail below
with reference to the accompanying schematic drawings, which for the purpose of
illustration show some non-limiting embodiments and in which
Fig. 1 shows a downhole tool such as a driving unit in a well,
Fig. 2 shows a wheel arranged on a wheel arm,
Fig. 3 shows an arm activation assembly,
Fig. 4A shows a cross-sectional view of the wheel,
Fig. 4B shows another cross-sectional view of the wheel of Fig. 4A,
Fig. 5A shows a cross-sectional view of another embodiment of the wheel,
Fig. 5B shows another cross-sectional view of the wheel of Fig. 5A,
Fig. 6A shows a cross-sectional view of another embodiment of the wheel,
Fig. 6B shows a cross-sectional view of yet another embodiment of the wheel,
Fig. 7 shows a downhole system,
Fig. 8 shows a cross-sectional view of part of another embodiment of the wheel,
Fig. 9 shows a cross-sectional view of another embodiment of the wheel,
Fig. 10 shows a cross-sectional view of another embodiment of the wheel
comprising a double gear,
Fig. 11 shows a cross-sectional view of yet another embodiment of the wheel,
and
Fig. 12 shows another partly cross-sectional view of the hydraulic motor within
the wheel.
All the figures are highly schematic and not necessarily to scale, and they show
only those parts which are necessary in order to elucidate the invention, other
parts being omitted or merely suggested.
Detailed description of the invention
Fig. 1 shows a downhole tool 10, such as driving unit 11 arranged in a casing 6,
having an inside 4, in a well or borehole 5 in the formation 2. The downhole tool
is powered through a wireline 9 which is connected with the tool via a top
connector 13. The downhole tool further comprises an electronic section having
mode shift electronics 15 and control electronics 16 before the electricity is
supplied to an electrical motor 17 driving a hydraulic pump 18. In Fig. 1, the
downhole tool is a driving unit 11 having a driving unit housing 5 1 in which arm
assemblies 60 are moved between a retracted position and projecting position in
relation to the driving unit housing 5 1 along a longitudinal axis of driving unit 11
by means of fluid from the hydraulic pump 18. In Fig. 1, the arm assembly is
shown in its projecting position. The driving unit 11 is divided in several sections
54 and is connected with a compensating device 20 for compensating the
pressure within the driving unit so that a high pressure does not result in the
driving unit housing bulging outwards or collapsing inwards.
The arm assemblies 60 are moved in and out of the driving unit housing between
the projecting and retracted position by means of an arm activation assembly 4 1
arranged in the driving unit housing 5 1 as indicated by the dotted lines. The arm
activation assemblies 4 1 are driven by the hydraulic pump for moving the arm
assemblies 60 through a hydraulic cylinder. The downhole driving unit 11 is most
often used for moving an operational tool into a specific position in the well or
just forward in the well while an operation is performed, such as moving a
logging tool forward while logging fluid and formation data in order to optimise
the production of oil fluid from the well. Another operational tool could be a
stroker tool providing an axial force in one or more strokes, a key tool opening or
closing valves in the well, positioning tools such as a casing collar locator (CCL),
a milling tool or drilling tool, etc. The operational tool is connected through a
connector 14.
The driving unit 11 is insertable into a well and propels itself forward and is thus
capable of moving an operational tool forward in the well. To be able to propel
itself and the operational tool 12, the driving unit comprises several wheel
assemblies 90, each arranged in a first end of the arm assembly 60 furthest away
from the driving unit housing 5 1 when the arm is in its projecting position, as
shown in Fig. 2. The wheel assembly comprises a stationary part 9 1 and a
rotational part 92. The stationary part 9 1 is fixedly connected with the arm
assembly or forms part of the arm assembly and is rotatably connected with the
rotational part. The rotational part 92 is connected with or forms part of a wheel
ring 99, which is the outermost part of the wheel assembly 90 contacting an
inner surface of the casing 6 or borehole 5. The wheel assembly rotates around a
wheel rotation axis 33. In order to propel itself forward in the well, each wheel
assembly 90 comprises a hydraulic motor 23. The hydraulic motor 23 has a
hydraulic motor housing 93 and a rotatable section 84 connected with the
rotational part 92 for rotating part of the wheel assembly 90 and thus drive the
wheel ring 99 and the driving unit 11 forward in the well. On its outside, the
wheel ring 99 has indentations 110 to obtain a better grip in the casing wall or
the borehole wall as shown in Fig. 2. The wheel ring 99 may also have any other
friction enhancing means, such as spikes or grooves, and the wheel ring may
comprise friction enhancing means made of rubber, elastomer, etc.
In Fig. 3, the arm activation assembly is shown arranged in the driving unit
housing 5 1 as indicated in Fig. 1 for moving the arm assemblies between a
retracted position and a projecting position. The arm assembly is fastened to one
end of a crank member 7 1 which is rotated around a rotation axis 32 as indicated
by arrows. This end is rotationally connected in relation to the housing, and the
other end of the crank member is moved along the longitudinal axis of the driving
unit 11 by means of a piston 47 moving in a piston housing 45. The piston is
moved in a first direction by means of hydraulic fluid supplied through channel 80
by mea ns of the pump and in an opposite and second direction by mea ns of a
spri ng member 44.
In Figs. 4A and 4B, the hydraulic motor 23 is a rad ia l piston motor in which the
rotata ble section 84 is a hydraulic cyl inder block havi ng cyl inders 83 in which at
least fou r pistons 82 move rad ia lly in relation to a wheel rotationa l axis 34 of the
wheel assembly 90. The arm assembly 60 comprises a wheel arm 81 and the
wheel arm 81 comprises f luid cha nnels 85 for provid ing f luid to and from the
hydraulic motor 23 t hroug h the stationa ry part 91 of the wheel assembly 90. The
hydraulic motor housi ng 93 of the hydraulic motor 23 is constituted by the
stationa ry part 91 and the rotationa l part 92 of the wheel assembly 90. The
wheel assembly 90 comprises a closi ng member 26 closing the wheel ring 99
from one end 111, and the hydraulic motor 23 is t hus enclosed by the wheel arm
81, the wheel r ing 99, the closi ng member 26 and sea ling members 27
therebetween to provide a sea led con nection and a substa ntia lly tig ht hydraulic
motor housi ng . In this way, wel l fluid surrou nd ing the drivi ng unit 11 is kept out
of the hyd raulic motor housi ng 93. The hydraulic motor 23 is thus comprised in
the same housi ng as the wheel assembly so that the motor housi ng and the
wheel housi ng are the same housi ng and thus the same f luid cha mber. The
solution of the present invention is thus very compact in order that the arm
assembly 60 with the wheel assembly 90, when retracted in the drivi ng unit
housing, only takes up little space, so that the diameter of the drivi ng unit 11
and thus of the downhole tool is not substa ntia lly increased when there are
wheels at the end of the arms 60 of the drivi ng unit 11.
The drivi ng unit 11 has a unit diameter DU as shown in Fig . 1, and the wheel
assembly 90 has a wheel diameter Dw and a width W, as shown in Fig . 2, the
width W being less tha n V the unit dia meter, prefera bly less tha n 1/3 the unit
dia meter, more prefera bly less tha n /4 the unit dia meter.
The hyd raulic motor 23 comprises a cam r ing 24 formi ng part of the stationa ry
part 91 of the wheel assembly 90. In Figs. 4A and 5A, the pistons move in the
cyli nders and are forced outwa rds by the hydraulic f luid from the f luid cha nnel 86
in the hydraulic cyl inder block 84. This is due to the fact that the f luid cha nnels
85 in the stationa ry part 91 in Figs. 4A and 5A are arra nged opposite f luid
cha nnels 86 in the hydraulic cyli nder block 84 so that f luid flows into the back of
the cyl inder and forces the piston outwa rds. Other pistons in the hydraulic
cylinder block 84 are moved in the opposite direction by lobes in the cam ring
forcing the pistons back into the cylinder as shown in Figs. 4B and 5B. In Figs. 4B
and 5B, other fluid channels 85 in the stationary part 9 1 are arranged opposite
the front of the cylinder so that fluid in the cylinder can be emptied and the
piston moved towards the centre of the hydraulic cylinder block 84. In this way,
the hydraulic cylinder block rotates. The cam ring 24 is thus stationary and the
hydraulic cylinder block rotates the rotational part 92 of the wheel assembly 90.
A ball bearing 36A is arranged between the wheel ring 99 and the stationary part
9 1 on the outside of the cam ring 24, enabling the wheel ring 99 to rotate.
Furthermore, a ball bearing 36B is arranged between a projecting shaft 112 of
the stationary part 9 1 of the wheel assembly 90 and the rotatable section 84 of
the hydraulic motor 23. The shaft is stationarily arranged inside the hydraulic
cylinder block and forms part of the wheel arm 8 1 or is connected with the wheel
arm 81. The ball bearing 36B is arranged around the shaft and in a recess in the
hydraulic motor block.
In Figs. 4A-5B, the closing member 26 is fastened to the wheel ring 99 by means
of a screw but may be fastened in any other suitable manner. The closing
member 26 has indentations matching recesses in the hydraulic cylinder block for
transmitting the rotational force from the hydraulic cylinder block to the wheel
ring 99. In figs. 4A and 4B, the hydraulic cylinder block drives the wheel ring via
the closing member 26. The closing member 26 may be fastened in any other
suitable manner for transmitting the rotational force from the hydraulic cylinder
block. In Fig. 6A, the closing member 26 is fastened to the wheel ring 99 by
means of a snap ring 113 arranged in a groove 114 of the wheel ring 99 to keep
a projecting flange 115 of the closing member firmly fastened to the wheel ring
99. Between the flange of the closing member 26 and the wheel ring 99, a
sealing member 116 is arranged for sealing the motor housing 93.
In Figs. 5A and 5B, the wheel assembly comprises a planetary gearing system
95. The planetary gearing system 95 comprises a sun gear 96 fastened to the
rotatable hydraulic cylinder block by means of screws. The sun gear 96 drives the
planet gears 97 which are connected through a carrier member 37, such as a
carrier plate, enabling the carrier member 37 to drive a ring gear 98 of the
planetary gearing system 95. The wheel ring 99 comprises the ring gear 98
allowing the planet gears 97 to engage and drive the wheel ring 99. The planet
gears 97 rotate around a planet gear rotational axis 34 and are rotatably
connected with the carrier plate 37 through a ball bearing 36C arranged between
a projecting part of the carrier plate and a hole in the planet gear. The planet
gears mesh with the wheel ring 99 functioning as the ring gear 98 of the
planetary gearing system 95. The carrier member 37 is screwed into the
stationary part 9 1 and is thus stationary.
The planetary gearing system 95 is comprised in the hydraulic motor housing 93
and is connected directly to the hydraulic motor block. Thus, the hydraulic fluid
inside the hydraulic cylinder block also surrounds the gears of the planetary
gearing system 95 as they are comprised in the same motor housing. By
arranging the planetary gearing system 95 directly in the hydraulic motor
housing 93, the width of the wheel along the rotational axis 33 of the wheel
assembly 90 is substantially reduced in relation to a solution where a planetary
gearing system is arranged outside the hydraulic motor housing in e.g. a
separate housing comprising the motor housing 93. A small wheel width
provides a smaller diameter of the driving unit 11, enabling the driving unit to
enter also small diameter wells.
The closing member 26 in Figs. 5A and 5B is fastened to the wheel ring 99 by
means of screws 87, and sealing members 27B are provided in a recess in the
wheel ring 99. And when fastening the closing member to the wheel ring, the
sealing member is squeezed in between the closing member 26 and the wheel
ring 99 to provide a fluid-tight connection therebetween. This is also the case
when a snap ring 113 is used for fastening the closing member 26.
In Fig. 6A, the sun gear 96 is provided as part of the hydraulic cylinder block. The
planet gears mesh with the closing member which, accordingly, functions as the
ring gear 98 in the planetary gearing system 95. Thus, the wheel ring 99 is
driven by the hydraulic cylinder block by driving the planet gears which drive the
closing member 26 driving the wheel ring 99. The planet gears 97 are connected
through the carrier plate which is connected to the stationary part 91, thus
making it stationary. Furthermore, four ball bearings 36B are arranged between
the projecting part 112 of the stationary part 9 1 and the rotatable section 84 of
the hydraulic motor 23. In this way, the sun gear 96 can be made as part of the
rotatable section 84.
In Fig. 6B, the fluid channels for providing fluid to the hydralic motor 23 in the
wheel housing are arranged differently than in Fig. 6A to enable radial supply of
the fluid channnel to the hydralic motor block.
The wheel ring 99 rotates around the stationary part 91, and a ball bearing 36A
is arranged therebetween. In Fig. 8, the ball bearing 36A comprises two rows of
balls 120. In another embodiment, the ball bearings 36A, 36B may be replaced
by needle bearings. As can be seen in Fig. 8, the pistons 82 of the hydralic motor
comprise ball bearings 117 arranged in one end opposite the end of the piston 82
moving within the cylinder.
In Fig. 9, the rotatable section comprises the first sun gear 96 of the planetary
gearing system 95 so that the sun gear forms part of the rotatable section 84 of
the hydraulic motor and drive the plurality of planet gears 97 which are
connected through the carrier member 37. The carrier member 37 is connected
with the wheel ring 99, and the stationary part 9 1 comprises the ring gear 98 of
the planetary gearing system 95, enabling the ring gear 98 to engage the planet
gears 97 driving the carier member and thus the closing member of the wheel
ring. The ring gear 98 is fastened to the stationary part 9 1 and is thus stationary.
In Fig. 11, the rotatable section 84 of the hydraulic motor is connected with the
planet gears 97, and the planet gears are thus driven by the rotatable section
around the sun gear 96 fastened to a centre part 112 of the stationary part 91.
The sun gear 96 is fastened to the centre part 112 around which part the
rotatable section 84 of the hydraulic motor rotates. The rotatable section 84 has
projections connected with the planet gears 97 through ball bearings 36C. The
planet gears 97 engage the ring gear 98 which forms part of the closing member
26 connected with the wheel ring 99 through a snap ring 113. The rotatable
section 84 rotates the planet gears 97 rotating around the stationary sun gear 96
engaging the ring gear 98 being comprised in the closing member 26.
In Fig. 10, the wheel assembly 90 comprises a double gearing system. The
rotatable section 84 of the hydraulic motor comprises the first sun gear 96 of the
planetary gearing system 95. Thus, the sun gear 96 is a projecting part of the
rotatable section 84 and drives a plurality of first planet gears 97 which are
connected through a carrier member 37. The carrier member 37 has projections
on one side connected with the first planet gears 97 of the planetary gearing
system 95 through ball bearings 36C. On the other side, the carrier member 37
has one projecting part forming a second sun gear 96 driving a plurality of
second planet gears 97B. The first planet gears 97 and second planet gears 97B
engage a stationary ring gear fixedly connected with the stationary part 9 1 by
means of screws. The ring gear is also used to fasten the ball bearing 36A
between the wheel ring 99 and the stationary part 91.
The second planet gears 97B are connected by means of a second carrier
member 137 which is part of the closing member being connected with the wheel
ring 99 by means of a snap ring 113 for rotating part of the wheel assembly 90.
Thus, the second carrier member 137 is connected with the rotational part 92 of
the wheel assembly 90 or is part of the rotational part 92.
In Fig. 12, the wheel assembly 90 is seen in a partly cross-sectional view showing
the cam ring 24 and the pistons 82 of the hydraulic motor. The closing member
26 has been removed for illustrative purposes. As can be seen, the pistons 82
end in a ball bearing contacting the inner surface of the cam ring 24. When one
piston 82 is forced outwards by hydraulic fluid in the fluid channels 86, another
piston is forced inwards in the cylinder towards the rotational axis of the
rotatable section of the hydraulic motor by the cam ring 24.
Furthermore, the fluid channels 86 in the hydraulic cylinder block supplying fluid
to the motor are substantially parallel with the rotational axis of the wheel. The
wheel arm 8 1 comprises fluid channels 85 aligned with the fluid channels 86 in
the hydraulic cylinder block so that the fluid can flow freely from the arm to the
motor when fluid is supplied to force the piston 82 of the hydraulic piston motor
radially outwards. However, the fluid channels 85, 86 are unaligned when the
piston 82 is no longer moved outwards. Then the fluid channels have moved to
the next piston to be forced outwards in order to drive the rotatable section 84 of
the hydraulic motor to rotate around the rotational axis 34. Only the channels
supplying fluid to the motor are shown. However, other channels are arranged in
the arm in order for the fluid to flow into said other channels when the cylinder is
emptied when the piston 82 moves inwards towards the rotational axis. By
having the fluid channels of the hydraulic cylinder block substantially parallel to
the rotational axis of the wheel, the fluid channels are much easier to
manufacture.
In order to be able to roll along the cam ring 24, the pistons moving in the
cylinders of the hydraulic cylinder block are provided with a ball bearing 117. The
central part of the ball bearing is suspended in a piston body of the piston, and
an outermost part of the ball bearing abuts the cam ring, the ball bearing thus
being capable of rotating in relation to the piston.
The invention further relates to a downhole system as shown in Fig. 7, in which
the driving unit 11 is connected to an operational tool which, in this case, is a
logging tool logging fluid and formation data. The operational tool could also be a
stroker tool providing an axial force in one or more strokes, a key tool opening or
closing valves in the well, positioning tools such as a casing collar locator (CCL),
a milling tool or drilling tool, etc.
By well fluid is meant any kind of fluid that may be present in oil or gas wells
downhole, such as natural gas, oil, oil mud, crude oil, water, etc. By gas is meant
any kind of gas composition present in a well, completion, or open hole, and by
oil is meant any kind of oil composition, such as crude oil, an oil-containing fluid,
etc. Gas, oil, and water fluids may thus all comprise other elements or
substances than gas, oil, and/or water, respectively.
By a casing is meant any kind of pipe, tubing, tubular, liner, string etc. used
downhole in relation to oil or natural gas production.
Although the invention has been described in the above in connection with
preferred embodiments of the invention, it will be evident for a person skilled in
the art that several modifications are conceivable without departing from the
invention as defined by the following claims.
Claims
1. A downhole driving unit (11) for insertion into a well, comprising:
- a driving unit housing (51),
- an arm assembly (60) movable between a retracted position and a projecting
position in relation to the driving unit housing,
- an arm activation assembly (41) arranged in the driving unit housing for
moving the arm assembly between the retracted position and the projecting
position, and
- a wheel assembly (90) comprising a stationary part (91) and a rotational part
(92), the stationary part being connected with or forming part of the arm
assembly and being rotatably connected with the rotational part,
wherein the wheel assembly comprises a hydraulic motor (23) comprising a
hydraulic motor housing (93) and a rotatable section (84) connected with the
rotational part for rotating part of the wheel assembly.
2. A downhole driving unit according to claim 1, wherein the stationary part
and the rotational part constitute the hydraulic motor housing.
3. A downhole driving unit according to claim 1 or 2, wherein the wheel
assembly further comprises a planetary gearing system (95).
4. A downhole driving unit according to claim 3, wherein the planetary gearing
system is comprised in the hydraulic motor housing.
5. A downhole driving unit according to claim 3 or 4, wherein the wheel
assembly comprises a wheel ring (99).
6. A downhole driving unit according to any of claims 3-5, wherein the
rotatable section of the hydraulic motor is connected with a sun gear (96) of the
planetary gearing system.
7. A downhole driving unit according to claim 4, wherein the sun gear (96) of
the planetary gearing system drives a plurality of planet gears (97) which are
connected through a carrier member (37) for driving a ring gear (98) of the
planetary gearing system.
8. A downhole driving unit according to claim 7, wherein the wheel ring
comprises the ring gear, enabling the planet gears to engage and drive the wheel
ring.
9. A downhole driving unit according to any of the preceding claims, wherein
the wheel ring (99) is closed from one end (111) by a closing member (26).
10. A downhole driving unit according to claim 8, wherein the wheel ring
comprises the closing member.
11. A downhole driving unit according to any of claims 3-10, wherein the
planetary gearing system comprises a ring gear (98) constituted by the wheel
ring or the closing member.
12. A downhole driving unit according to any of claims 3-5, wherein the
rotatable section of the hydraulic motor is connected with the planet gears and
the planet gears are driven by the rotatable section.
13. A downhole driving unit according to any of claims 3-5, wherein the
rotatable section of the hydraulic motor comprises a first sun gear (96) of the
planetary gearing system and the first sun gear drives a plurality of first planet
gears (97) which are connected through a carrier member (37).
14. A downhole driving unit according to claim 13, wherein the carrier member
of the planetary gearing system drives a plurality of second planet gears (97B)
and the carrier member comprises the sun gear engaging and driving the second
planet gears.
15. A downhole driving unit according to claim 14, wherein the second planet
gears are connected by means of a second carrier member (137) being part of
the rotational part (92) for rotating part of the wheel assembly.
16. A downhole driving unit according to any of the preceding claims, wherein
the arm assembly comprises a wheel arm (81) and the wheel arm comprises fluid
channels (85) for providing fluid to and from the hydraulic motor through the
stationary part.
17. A downhole driving unit according to any of the preceding claims, wherein
the hydraulic cylinder block comprises fluid channels (86) arranged in alignment
with the fluid channels in the wheel arm so that fluid is led from the wheel arm to
cylinders in the hydraulic cylinder block.
18. A downhole driving unit according to any of the preceding claims, further
comprising a pump (18) for providing fluid to the hydraulic motor.
19. A downhole driving unit according to any of the preceding claims, wherein
the hydraulic motor is a radial piston motor.
20. A downhole driving unit according to any of the preceding claims, wherein
the hydraulic motor comprises a cam ring (24) connected with or forming part of
the stationary part of the wheel assembly.
21. A downhole driving unit according to any of the preceding claims, wherein
the rotatable section is a hydraulic cylinder block.
22. A downhole system comprising the driving unit according to any of claims
1-21 and an operational tool (12) connected with the driving unit for being
moved forward in a well or borehole.
23. A downhole system according to claim 22, wherein the operational tool is a
stroker tool, a key tool, a milling tool, a drilling tool, a logging tool, etc.
24. Use of the driving unit according to any of claims 1-21 in a well or borehole
for moving itself and/or an operational tool forward in a well or borehole.