Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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WIRELESS COMMUNICATION BETWEEN TOOLS
Field of the invention
The present invention relates to a downhole tool system for being submerged
into a casing, comprising at least three tools having a tool axis.
Furthermore, the
present invention relates to a downhole tool system for being submerged into a
casing, comprising at least three tools, and finally the invention relates to
communication methods for communicating wirelessly between a first and a third
tool separated by a second tool.
Background art
Communication between surface and a tool in a well via acoustic signals in the
well fluid is known. However, well fluid is most often very inhomogeneous as
it
comprises mud, scales, both oil and water, and gas bubbles. Therefore, the
communication sometimes fails.
Sometimes, two operators work together to perform a well operation in the
sense
that a tool of one operator is arranged between the tools of another operator.
However, when this is the case, communication between the tools of the other
operator is hindered as these tools are separated by the tool of the one
operator,
through which communication is not possible. This is due to the fact that the
one
operator uses a different communication system than the other operator and
that
it is not possible to pull wires through the intermediate tool.
Since prior art acoustic communication through well fluid does not always
function successfully, there is a need for an alternative communication form.
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 tool string enabling successful communication between two
tools separated by an intermediate tool.
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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 tool
system
for being submerged into a casing, comprising at least three tools having a
tool
axis:
- a first tool having a first and a second end and comprising a first
communication device arranged at the second end,
- a second tool having a first end, which is connected with the second end
of the
first tool, and a second end, the second tool comprising a housing, and
- a third tool comprising a second communication device and a first end, the
first
end of the third tool being connected with the second end of the second tool,
the first and second communication devices comprising an antenna for
communicating with each other by sending and receiving radio waves.
In an embodiment, the antennas may transmit radio waves having a wavelength
which is lower than 200 m, preferably lower than 1 m, more preferably lower
than 10 cm, even more preferably lower than 2.5 cm.
Moreover, the antenna may comprise one or more ferrite rods.
Further, the antenna may be wound around one or more ferrite rods.
By having ferrite rods or even by the antenna being wound around the ferrite
rods, the inductance is increased without increasing the size of the antenna
substantially.
Said ferrite rods may extend parallel to the tool axis.
Also, the ferrite rods may be arranged in a circular loop.
In an embodiment, orthogonal frequency-division multiplexing (OFDM)
modulation may be used for transmitting encoding digital data on multiple
carrier
frequencies between the antennas.
Furthermore, the antenna may send and receive at different frequencies with
one
frequency for each rod.
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In one embodiment, the antenna may be a loop antenna.
In another embodiment, the antenna may be a small loop antenna.
In yet another embodiment, the antenna may be a loop stick antenna.
Moreover, the waves may be transmitted at a frequency of 520-1610 kHz.
The present invention further relates to a downhole tool system for being
submerged into a casing, comprising at least three tools:
- a first tool having a first and a second end and comprising a first
communication device arranged at the second end,
- a second tool having a first end, which is connected with the second end
of the
first tool, and a second end, the second tool comprising a housing, and
- a third tool comprising a second communication device arranged at a first
end,
the first end of the third tool being connected with the second end of the
second
tool,
the first and second communication devices being a first and a second acoustic
device, respectively,
wherein the second tool is arranged between the first tool and the third tool,
and
the first acoustic device arranged at the first end of the second tool sends
and
receives acoustic signals to and from the second acoustic device which is
arranged at the first end of the third tool.
During a well operation, two operators may be forced to work together in the
sense that one operator provides one tool and the other operator provides two
tools, and the three tools are to be connected into one tool string where the
tool
of the one operator is arranged between the two tools of the second operator.
In
such a situation, the second operator must be able to communicate from one
tool
to the other through the intermediate tool. However, operators often use
different communication systems, and sometimes, the second operator is not
able to get communication cables into and through the intermediate tool.
Therefore, there is a need for a tool system facilitating communication from
one
tool to another through an intermediate tool.
The acoustic devices arranged at each end of the intermediate tool are able to
send acoustic signals propagating along the housing of the intermediate and
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second tool. The housing is often made of a solid material, increasing its
transmitting ability compared to the transmitting ability in the surrounding
well
fluid which may be inhomogeneous and thereby be a poor transmitting media
compared to a metal housing.
The three tools are most often connected by means of threaded connections
providing a sufficiently firm connection for transmitting acoustic signals
from the
first or third tool to the second tool.
In an embodiment of the invention, the first and second acoustic devices may
comprise means for converting data parameters into electric signals and
transducers for receiving the electrical signal and generating acoustic
signals
propagating along the housing of the second tool.
Furthermore, the transducers may abut the ends of the second tool.
Moreover, the transducers of the first and second acoustic devices may face
the
second tool, causing the acoustic signals to propagate axially along the
housing
of the second tool.
In another embodiment, the first and second communication devices may be
antennas instead of acoustic devices, sending and receiving radio waves.
Moreover, the antennas may transmit signals having a wavelength of 1-2 cm.
The third tool may be a logging tool.
Furthermore, the first tool may comprise an electronic motor.
In addition, the first and/or second communication device(s) may comprise a
memory.
Also, the first and/or second communication device(s) may comprise a
processing
unit for processing data before converting the data into acoustic signals.
Moreover, the transducer may be a magnetostrictive transducer.
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Additionally, the acoustic devices may comprise piezoelectric microphones.
Furthermore, the first tool may be connected with a wireline.
5 Moreover, the first or third tool may comprise a driving unit, such as a
downhole
tractor.
In addition, the communication device may comprise a battery.
Also, the acoustic devices may comprise mechanical or electronic filters.
The present invention furthermore relates to a communication method for
communicating wirelessly between a first and a third tool separated by a
second
tool, comprising the steps of:
- connecting the first tool with the second tool, the first tool comprising a
first
communication device having an antenna and the second tool comprising a tool
housing,
- connecting the third tool with the second tool, the third tool comprising
a
second communication device having an antenna,
- sending radio waves from the first communication device to the second
communication device.
The communication method described above may further comprise the step of
using orthogonal frequency-division multiplexing (OFDM) modulation for
transmitting encoding digital data on multiple carrier frequencies between the
antennas.
Finally, the present invention relates to a communication method for
communicating wirelessly between a first and a third tool separated by a
second
tool, comprising the steps of:
- connecting the first tool with the second tool, the first tool comprising
a first
acoustic device and the second tool comprising a tool housing,
- connecting the third tool with the second tool, the third tool comprising
a
second acoustic device,
- sending acoustic signals from the first acoustic device to the second
acoustic
device, the signals propagating along the housing of the tool.
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This communication method may further comprise the step of converting data
parameters into electric signals.
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 partial cross-sectional view of a downhole tool system,
Fig. 2 shows another embodiment of the downhole tool system, and
Fig. 3 shows yet another embodiment of the downhole tool system.
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 system 1 comprising three tools; a first 1, a
second
2 and a third 3 tool, arranged as a tool string. The first tool 1 is connected
to a
wireline at its first end 11 to power the tool string. In its second end 12,
the first
tool 1 is connected to a first end 21 of the second tool 2 by means of a
threaded
connection firmly connecting the first 1 and second 2 tools. In its second end
22,
the second tool 2 is connected to a first end 31 of the third tool 3, also by
means
of a threaded connection.
Two operators may work together to perform a well operation in the sense that
a
tool of one operator is arranged between the tools of another operator. Thus,
the
first 1 and the third tool 3 come from a first operator and the second tool 2
comes from a second operator. Since the first 1 and third 3 tools are
separated
by the second tool 2, communication between the tools of the first operator
cannot take place inside the tools in the conventional way since it is not
possible
to communicate through the second tool 2. This is due to the fact that the
second
operator uses a different communication system than the first operator and
that
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it is not possible to pull wires through the intermediate tool without having
to
substantially reconstruct this tool.
Therefore, the first 1 and third 3 tools comprise communication devices 13, 33
in
the form of acoustic devices. The acoustic device of the first tool 1 is
arranged in
a housing wall at the second end 12 of the first tool 1, abutting the first
end 21 of
the second tool 2, thereby being able to generate acoustic signals propagating
axially along the housing 23 of the second tool 2. The acoustic device of the
third
tool 3 is arranged in a housing wall at the first end 31 of the third tool 3,
abutting
the second end 22 of the second tool 2, thereby also being able to generate
acoustic signals propagating axially along the housing 23 of the second tool
2.
Each acoustic device comprises a transducer 5 facing the end of the housing 23
of the second tool 2. The transducers 5 may be magnetostrictive transducers
transmitting acoustic signals in the form of longitudinal sonic waves along
the
housing 23 of the second tool 2.
In Fig. 2, the communication devices 13, 33 comprise antennas for sending and
receiving radio waves having wavelengths of 1-2 cm. The antennas are arranged
so that they project only partly from the outer faces of the first 1 and third
3
tools and extend parallel to the longitudinal extension of the tools. By
having
antennas transmitting signals with wavelengths of 1-2 cm, the radio waves
propagate in the well fluid along the tool string without being substantially
destroyed when hitting the wall of the tools 1, 2, 3 or the wall of the
production
casing 10.
The antennas are arranged in the housings of the first 1 and third 3 tools and
are
isolated from the other parts of the tools to improve the quality of the
communication between the first 1 and third 3 tools.
The antennas may also be projecting parts of the tools and be projected as
required and maintained inside the tools when the tool string is submerged
into
the casing 10.
Fig. 3 shows a communication device 13 of the first tool 1 (indicated by
dotted
lines) comprising an antenna 40 for communicating with another antenna 40 of
the third tool 3 by sending and receiving radio waves. The antenna 40 of the
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second tool 3 has the same design as shown in Fig. 3. The antenna 40 comprises
one or more ferrite rods 41. The antenna is a loop antenna wound around one or
more ferrite rods, which increases the inductance without increasing the size
of
the antenna substantially. This is especially useful for downhole tools where
the
space is limited. The ferrite rods extend parallel to the tool axis 43 and
have a
distance to the centre of the tool. The rods are spaced apart along the
circumference of the tool housing and are thus enclosed by the tool housing.
In
another embodiment, the antenna may be arranged in the tool housing. The
ferrite rods are thus arranged in a circular loop connected with a processor
44.
The processor 44, which is also referred to as a CPU, may use orthogonal
frequency-division multiplexing (OFDM) modulation for transmitting encoding
digital data on multiple carrier frequencies between the antennas.
As can be seen from Fig.3, the antennas are arrenged to face the third party
tool
2.
The antenna comprises several rods, of which one half are used as antennas 41a
and the other half are used as back-up antennas 41b. In the centre, an
adaptive
feedback sensor antenna is arranged.
By having rods, the antenna is able to send and receive at different
frequencies -
one frequency for each rod. The antennas transmit radio waves having a
wavelength which is lower than 200 m, preferably lower than 1 m, more
preferably lower than 10 cm, and even more preferably lower than 2.5 cm.
Furthermore, the waves may be transmitted at a frequency of 520-1610 kHz.
Communication over 20 to 40 metres results in data rates between 150 kbps and
680 kbps using linear bandwidth of 1 MHz. If the third party tool being the
second tool is smaller, resulting in communication over a shorter distance,
the
data rates are increased.
Thus, the antennas may be loop antennas, such as small loop antennas, loop
stick antennas, or ferrite rod antennas. The antenna may be a multi-zone
focussed antenna.
By fluid or 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
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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.
In the event that the tools are not submergible all the way into the casing, a
downhole tractor can be used to push the tools all the way into position in
the
well. A downhole tractor is any kind of driving tool capable of pushing or
pulling
tools in a well downhole, such as a Well Tractor .
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.
