Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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METHOD OF PRODUCING HYDROCARBONS THROUGH A SMART WELL
BACKGROUND OF THE INVENTION
The invention relates to a method of producing
hydrocarbons through a smart well in which one or more
well tubulars and an assembly of power, sensing and/or
signal transmission cables is arranged.
A smart well is a well in which one or more
instruments, such as valves, motors, pumps and/or sensors
are arranged downhole and electrical and/or hydraulic
power and/or fiber optical, acoustic or other signals are
transmitted between a power source or control unit at the
earth surface and the downhole instruments.
Installation, connection and protection of a fragile
power and/or signal transmission cable assembly in a well
is a complex and expensive operation.
UK patent application GB 2433080 discloses a drill
pipe, wherein a wire is bonded to an inner surface of the
pipe, which requires a complex procedure to insert the
wire to the possibly 9 meters long pipe and to firmly
bond the wire to the pipe such that it is not detached
during the drilling operations.
It is an object of the present invention to provide a
method of producing hydrocarbons through a smart well in
which installation, connection, protection and/or removal
of the power and/or signal transmission cable assembly is
less complex and the cable assembly is adequately
protected.
SUMMARY OF THE INVENTION
In accordance with the invention there is provided a
method of producing hydrocarbons through a smart well
containing a well tubular and a power, sensing and/or
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signal transmission cable assembly comprising at least one
power, sensing and/or signal transmission cable, which is
bonded along at least part of its length to an outer surface of
the well tubular.
The present invention further relates to a method of
producing hydrocarbons through a smart well containing a well
tubular and a power, sensing and/or signal transmission cable
assembly comprising: providing in the well at least one power,
sensing and/or signal transmission cable, which is bonded along
at least part of its length to an outer surface of the well
tubular; and producing hydrocarbons from the well, wherein the
power, sensing and/or signal transmission cable assembly is
encapsulated in a protective layer, which is bonded along at
least part of its length to the well tubular by an adhesive
which is reusable.
Preferably, the power, sensor and/or signal
transmission cable assembly is encapsulated in a protective
layer, which is bonded along at least part of its length to the
well tubular by an adhesive, which is reusable and/or has a
thermal conductive of at least 3 W/mK or at most 0.2 W/mK.
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Optionally,the assembly comprises a plurality of
power, sensor and/or signal transmission cables is
encapsulated in a common protective layer with an outer
substantially flat side which is bonded along at least
5 part of its length to the well tubular.
The protective layer may be configured as a substantially
flat hollow strip with an outer surface having a pair of
substantially flat opposite sides with a larger width
than other sides of the strip.
10 The protective layer may furthermore at selected
intervals be attached to the outer surface of the well
tubular by releasable and/or elastic straps, such that
one of the flat sides is pressed against the well
tubular.
15 The well tubular may be radially expanded after
insertion into the wellbore and one of the substantially
flat sides of the protective layer is along at least part
of its length bonded to the outer surface of the well
tubular by a reusable adhesive, which is detached from
20 the outer surface of the well tubular during the
expansion process and which is induced to be rebonded to
the outer surface of the well tubular after the expansion
= process.
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The well tubular may be radially expanded such that
one of the flat sides of the protective layer is pressed
against along at least part of its length against the
outer surface of the expanded tubing and an opposite flat
side is pressed along at least part of its length against
the inner surface of the surrounding wellbore or well
casing and/or against the inner surface of at least one
elastic strap.
The power, sensing and/or signal transmission cable
assembly may comprise a plurality of electrical power
cables and a plurality of fiber optical sensing and/or
transmission cables and extend between at least two nodes
that are longitudinally spaced along the length of the
length of the cable assembly, which nodes comprise
switches for switching power and/or optical signal
transmission to another power, sensing and/or optical
cable if a cable is damaged or for another reason.
It is preferred that at or near at least one node a
wireless power and/or signal transmission device is
arranged which is configured to transmit wireless power
and/or signals to one or more electrical devices and/or
sensors arranged downhole in the well tubular and/or in
the space between the tubing and the surrounding wellbore
or well casing, and/or in the formation surrounding the
wellbore, and/or in a branch wellbore that is connected
to the wellbore in which the tubing is arranged.
When used in this specification and claims the term well
tubular shall encompass any tubular element in a well,
such as a production tubing, well casing, well liner,
liner hanger, well packer, well screen and/or an
intrumented sleeve.
These and other features and embodiments
of the method according to the present invention are
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described in the accompanying claims, abstract and the
following detailed description of preferred embodiments
in which reference is made to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG.1 is a schematic longitudinal sectional view of a
smart well in which a power transmission and/or sensing
cable assembly is bonded along at least part of its
length to the outer surface of a well tubular;
FIG.2 is a schematic longitudinal sectional view of a
smart multilateral well in which a series of mutually
interconnected power transmission and/or sensing
assemblies are bonded along at least part of their length
to the outer or inner surfaces of various well tubulars;
FIG.3 is a schematic cross-sectional view of an
expandable well tubular to which a power strip is bonded
along at least part of its length; and
FIG.4 is a schematic longitudinal sectional view of a
power strip which is at selected intervals along its
length bonded to the outer surface of a well tubular by
an swellable elastomer.
DETAILED DESCRTIPTION OF THE DEPICTED EMBODIMENTS
FIG.1 shows a crude oil, natural gas and/or other
hydrocarbon fluid production well 1, which traverses a
crude oil, natural gas and/or other hydrocarbon fluid
containing formation 2.
The well 1 comprises a well casing 3 which is fixed
within an overburden formation 4 by a cement sheeth 5.
A production tubing 6 is suspended within the well 1
from a wellhead 7 and is sealingly secured to a lower
portion of the well casing 3 by a production packer 8.
The production tubing comprises a perforated lower inflow
section 6A, which comprises perforations 9 and which
traverses the hydrocarbon fluid containing formation 2
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such that hydrocarbon fluid is induced to flow from the
formation 2 through the perforations 9 into the
production tubing 6 towards the wellhead 7 as illustrated
by arrows 10 and 11. The perforated lower inflow section
6A of the production tubing 6 is surrounded by a gravel
pack 12 to protect caving in of the formation 2.
A power and/or signal transmission cable assembly 13
comprising at least one power and/or signal transmission
cable is bonded to the outer surface of the production
tubing 6. The assembly 13 comprises at least one fiber
optical Distributed Temperature Sensor (DTS) which is
bonded along a substantial part of its length to the
outer surface of the production tubing 6 by an adhesive,
such as a fast curing high-tack 1K polyurethane adhesive
designed for industrial bonding, for example TEROSON ISR
70-03 (TEROSON is a trade mark).
The assembly 13 is connected to a fiber optical
signal transmission, reception and interpretation
assembly 14, which transmits a pulsed optical signals
into the fiber optical DTS and detects the time of
arrival and spectrum of the optical reflections that are
reflected back when the light pulses travel along the
length of the fiber optical DTS and which spectrum
contains information about the temperature of the wall of
the DTS sensor at the reflection point. It will be
understood that by bonding the assembly 13 to the tubing
6 using a thermally conductive adhesive the fiber optical
DTS will have a temperature which closely matches that of
the wall of the production tubing 6. Since the
temperature of the perforated lower section 6A of the
tubing 6 in a region with a relatively large influx of
hydrocarbon and/or other fluids will be different from
the temperature in a region with a relatively small
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influx of hydrocarbons and other fluids the temperature
profile measured by the fiber optical DTS along the
length of the inflow zone along the length of the
perforated lower section 6A will give information about
the fluid influx. Furthermore influx of gaseous
components will result in adiabatic expansion of these
components and consequently in a temperature drop, so
that the temperature profile measured by the fiber
optical DTS will also provide information about the gas
content and/or heat capacity of the well effluents, so
that information is provided regarding the composition of
well effluents flowing into the well 1 and where which
well effluents flow into the well 1 along the length of
the perforated lower section 6A of the production tubing
6.
FIG.2 shows a multilateral well 20, which comprises a
substantially vertical main wellbore 21 and a pair of
substantially horizontal well branches 22 and 23, which
traverse different crude oil, natural gas and/or other
hydrocarbon fluid containing formations 24 and 25. The
main wellbore 21 comprises a well casing 26 which is
sealingly secured within the overburden 27 and
hydrocarbon fluid containing formations 24 and 25 by
means of an annular cement sheets 28. The well casing 26
comprises two openings into which curved elbow liners 29
and 30 extend. The curved elbow liners 29 and 30 are
connected to horizontal liners 31 and 32 that extend
through the horizontal well branches 22 and 23 and that
are perforated by e.g. a perforating gun to provide a
series of perforations 33 through which hydrocarbon
fluids flow from the formations 24 and 24 into the
horizontal well branches 22 and 23.
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Furthermore a production tubing 34 is suspended from
a wellhead 35 within an upper part of the well casing 26
and sealingly secured to the casing 26 by an expandable
well packer 36.
Each of the horizontal well branches 22 and 23 is
provided with pressure, temperature, composition, seismic
and/or other sensors 37 and a pair of inflow control
valves (ICV's) 38 which monitor the composition of the
hydrocarbon and/or other fluids and control the fluid
influx into the different well effluent inflow regions
upstream of the inflow control valves 38. The sensors 37
and valves 38 are connected to well monitoring and
control equipment 39 near the wellhead 35 by a series of
backbone cable assemblies 40-44 that are interconnected
by four inductive and fiber optical coupler assemblies
45A-D - 47A-D. The backbone cable assemblies 40-44
comprise a primary backbone electrical power and fiber
optical sensing cable assembly 40 which is bonded to the
outer surface of the well casing 26 and is embedded in
the cement sheets 28 and which is connected to a pair of
outer annular electrical inductive couplers 45A, 47A and
fiber optical couplers 45C, 47C that are also embedded in
the cement sheets 28. These outer annular electrical
inductive couplers 45A, 47A and fiber optical couplers
45C, 47C are co-axially arranged around a pair of inner
electrical inductive couplers 45B, 47B and fiber optical
couplers 45D, 47D that are arranged in the interior of
the curved elbow liners 29 and 30 and that are connected
to a pair of curved secondary electrical and fiber
optical power and communication backbone cable assemblies
41 and 43 that are bonded to the inner walls of these
elbow liners 29 and 30. Each of the curved secondary
electrical power and fiber optical communication cable
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assembly 41,43 is at its lower end connected to a
tertiary electrical power and fiber optical communication
cable assembly 42,44 which extends through each of the
horizontal well branches 22,23 by means of pairs of
coaxial electrical inductive couplers 46A,46B and 48A and
48B and fiber optical couplers 46C, 46D and 48C, 48D.
These four inductive and fiber optical coupler assemblies
45A-D - 48A-D allow repair and or replacement of the
secondary and tertiary backbone cable assemblies 41-44 in
case of damage of these assemblies 41-44 and or of the
ICV's 38 and or sensors 36, which may also be connected
by releasable inductive and/or fiber optical couplers to
these assemblies 41-44. Thus it will be understood that
by bonding the primary, secondary and tertiary cable
assemblies 40-44 to the inner or outer walls of the well
casing 26 and liners 29-32 a versatile and at least
partially replacable power and communication backbone
cable assembly is provided which enable to install an
efficient and powerful electrical power and fiber optical
communication network within the main wellbore 21 and
well branches 22 and 23.
Currently, smart wells often include a plurality of
sensing and control systems including gauges, optical
sensors and valves. It is common for multiple vendors to
be used to provide the sensing and control systems and
for the associated cabling to be unique, proprietary and
specific to the system in question. This commonly leads
to the requirement for each sensing or control component
of the full smart well system to have individual cabling
or pipework containing, but not limited to, electrical or
optical cables and hydraulic working fluids. The number
of cables required causes increased complexity in
pressure control and other well construction components,
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increased costs associated with the procurement and
installation of the cables and increased risk of failure
of one or more components during installation due to
increased component numbers. Current methods are also
inflexible in the sense that the systems (instrumentation
and control) are installed when the well is built and
that their configuration cannot be altered or systems
augmented or serviced without well intervention, which is
typically logistically difficult and financially
expensive.
In accordance with the invention there is provided a
method of producing hydrocarbons through a smart well
containing well tubulars and one or more instruments,
such as valves, motors, pumps and/or sensors are arranged
downhole whereby the instruments are connected to the
surface control systems using one or more common backbone
cable assemblies 40-44 comprising power and/or electrical
communications and/or optical fiber communications and/or
sensing (e.g DTS, FBG or other fiber-optic sensing
method) capability.
The physical embodiment of each backbone cable
assembly 40-44 includes an assembly of power and/or
signal transmission cables, which cables are encapsulated
in a common protective layer that is releasably secured
to the outer or inner surface of a well tubular and has
an outer circumference with a larger width than
thickness.
FIG.3 illustrates an assembly of power and/or signal
transmission cables 31 that is arranged in a common
protective layer, which is configured as a substantially
flat hollow power strip 32 with an outer surface having a
pair of substantially flat opposite sides 32A-B with a
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larger width than other sides 32 C-D of the power strip
32.
The power strip 32 may at selected intervals be
pressed against the outer surface of a well tubular 33 by
releasable straps 34, such that one of the flat sides 32A
of the power strip 32 is pressed against the outer
surface of the well tubular 33 and is bonded to said
surface by an adhesive 35.
The well tubular 33 may be radially expanded after
insertion into the wellbore and one of the flat sides 32A
of the power strip 32 may along at least part of its
length bonded to the outer surface of the well tubular by
a reusable adhesive, such as a fast curing high-tack 1K
polyurethane adhesive 35 designed for industrial bonding,
for example TEROSON ISR 70-03 (TEROSON is a trade mark),
which is detached from the outer surface of the well
tubular 33 during the expansion process and which is
bonded again to the outer surface of the well tubular 33
after the expansion process.
In such case the well tubular 33 may be radially
expanded such that the inner flat side 32A of the power
strip 32 is pressed against along at least part of its
length against the outer surface of the expanded tubing
33 and the outer flat side 32B is pressed along at least
part of its length against the inner surface of the
surrounding wellbore or well casing or of an elastic
strap 34.
In terms of the sensing aspects of the invention, the
use of an adhesive to bond the cable assembly to the well
tubular offers several advantages in the case that the
fiber-optic cable is used for distributed temperature
sensing (DTS). Currently, a DTS cable is clamped
periodically to the well tubular (typically the
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production tubing) and typically the position of the
fiber is ill defined, tending to contact the production
tubing at the clamp points and to bow out and away from,
or around, the production tubing between the clamps, as
is illustrated in FIG.4. This causes observed
fluctuations in the measured temperature along the length
of the DTS fiber. By bonding the fiber on to the
production tubing over it's whole length, or a least over
the minimum length resolvable it is possible to better
define the temperature measurement to be that of the
production tubing and not the temperature of the fluid in
the annular space around the production tubing at an
indeterminate distance from the outer surface of the
production tubing.
The method could be further improved by selecting the
adhesive appropriately, loading the adhesive with
thermally conductive or insulating materials or using an
interstitial insulator (in the sequence: production
tubing - adhesive - interstitial insulator - adhesive -
DTS fiber) such that the thermal condition of the DTS
fiber can be further determined.
The fiber could be, for example, bonded to the
production tubing using an adhesive of high thermal
conductivity to give the best tubing temperature
measurement. Further, the protective layer could have a
lower thermal conductivity, reducing heat flow from the
production tubing through the fiber and providing a
improved measure of the temperature of fluids flowing
inside the production tubing.
In another example, the adhesive bonding the DTS fiber to
the production tubing could be of low thermal
conductivity or include an interstitial insulating layer
which would define the local temperature of the fiber as
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that of the annular space. This example would be
particularly appropriate for temperature monitoring of
inflow from the reservoir into the well tubulars, where
the well tubular is used as the deployment device, but
the required temperature measurement is that of the
fluids exiting the reservoir.
The two previous examples could be used in
combination to best achieve the desired measurement.
Perhaps measuring production tubing temperature over a
portion of the well and annular or inflow temperature
over another portion. It may also be beneficial in wells
which use concentric string production to periodically
measure the temperature in the inner string and outer
string by alternating the adhesive and insulation
arrangement joint by joint.
A further benefit of using an adhesive with a defined
thermal characteristic could be applied to ESP (electric
submersible pump) cables which carry high currents and
are subject to significant heating. An adhesive with high
thermal conductivity bonding the ESP cable to the well
tubular could aid heat removal from the cable, thus
increasing reliability and failures by avoiding 'hot
spots' on the cable, which could occur away from clamp
positions.
In terms of the power and/or signal transmission
aspects of the invention, the cable assembly may comprise
a plurality of electrical power cables and a plurality of
fiber optical transmission or sensing cables and the
assembly may extend between at least two nodes , such as
the couplers 45-48 shown in FIG.2, that are
longitudinally spaced along the length of the length of
the cable assembly 40-44, which nodes 45-48 may comprise
switches or a fusing arrangement for switching power
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and/or optical signal transmission to another power
and/or optical cable if a cable is damaged or for another
reason.It is preferred that several methods can be used
simultaneously, in combination and as required to connect
an instrument to the power and/or signal transmission
and/or optical fiber communications or sensing backbone
cable, including, but not limited to, direct electrical
and/or optical connections, wireless connections and
multiple series wireless connections.
In the case of direct electrical and/or optical
connections, the connection points can be pre-defined and
prepared and utilise standard connector designs or
techniques and/or be established during installation at
any location or at periodic designated connection points.
Also that the electrical and/or optical connection can be
formed by welding, soldering, clamping, piercing or other
means. In this case the design would also include a means
to protect the connection point from the downhole
environmental conditions, including, but not limited to
hydraulic and gas pressures, mechanical shock and loading
and corrosive fluids and gasses, in order to maintain the
long-term integrity and performance of the backbone
cable.
In the case of wireless connections, the wireless
connection equipment would be connected to the backbone
cable much as a directly connected instrument.
The wireless connections would allow the transmission
of electrical power and/or communication signals to one
or more electrical devices and/or sensors arranged
downhole within the well tubular and/or in the annular
space between the production tubing and the surrounding
wellbore or well casing, and/or in the formation
surrounding the wellbore, and/or in a branch wellbore
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that is connected to the wellbore in which the tubing is
arranged.
In the case of multiple wireless connections, more
than one wireless stages would be connected in series to
allow the transmission of electrical power and/or
communication signals to one or more electrical devices
and/or sensors arranged downhole within the well tubular
and/or in the annular space between the production tubing
and the surrounding wellbore or well casing, and/or in
the formation surrounding the wellbore, and/or in a
branch wellbore that is connected to the wellbore in
which the tubing is arranged. This arrangement would be
used in the case that the physical arrangement of the
well did not allow for a single wireless connection to be
used.
It is also preferred that the distribution of direct
and wireless connection points be arranged such and
provide for instruments to be installed, substituted or
recovered for repair using techniques such as slickline,
wireline, coiled tubing, downhole tractors or other means
at any time during the operating life of the well.
It will be recognised that well known electrical
effects such as resistive losses and transfer
efficiencies of wireless connections will ultimately
limit performance of the system.
It is therefore preferred that the power and/or
communications settings be adjustable by manual and/or
automatic means in order to allow for improved and/or
optimised performance in terms of, but not limited to,
power levels, communications data rates and data latency
in response to factors such as range from surface to
connection point and number of wireless steps.
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It is also preferred that a communications protocol
is also provided which conforms to the OSI 7 layer model
and is optimised for use of the communications channel or
channels available. The communications protocol would
also include quality of service (QOS) provisions to
enable suitable sharing of the communications channel or
channels including, but not limited to, the inclusion of
emergency high priority channels for the control of
safety critical instruments such as safety valves.
It is also preferred that the backbone cable design
be such that, where the backbone cable 40 is deployed on
the well casing 26 as illustrated in FIG.2, the long term
pressure integrity of the well structure be maintained to
at least as good a level as it is with current methods.
With the inclusion of the primary backbone cable 40 on
the outside of the well casing 26, there is potential for
the creation of a micro-annulus between the backbone
cable 40 and the cement sheeth 28 and/or the backbone
cable 40 and the well casing 26. The creation of micro-
annuli will be combated by including periodic seal points
positioned along the length of the backbone cable 40.
As illustrated in FIG.4 these seal points 50 could
comprise swellable elastomers 51 formed around the
backbone cable power strip 52 such that these elastomers
would swell once the well to formation annulus 53 had
been cemented or periodic clamp-on devices which provide
metal-ceramic-metal seals along the cable metal cores and
also provide a good bonding surface to ensure a good
cement seal is achieved. Alternatively, the surface
finish of the cable could be designed to provide a good
cement bond through the use of patterning or moulding.
In such case at least one wireless electrical
transmission device that is connected to one of the
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electrical backbone cables may be an inductive coupler
that is arranged in the vicinity of an inductive coupler
that is connected to the downhole electrical device
and/or sensor. The inductive coupler connected to the
backbone cable may be separated from the inductive
coupler connected to the downhole electrical device by
the metallic wall of one or more well tubulars or by a
non-metallic solid, a liquid or a gas.
At least one wireless electrical transmission device
that is connected to one of the fiber optical signal
transmission backbone cables may be an electromagnetic
transmitter and/or receiver which is configured to
transmit and/or receive electromagnetic signals to and/or
from one or more downhole sensors.
One or more downhole electrical devices may consist
of an electrical motor or generator that is connected to
a downhole valve or pump and one or more downhole sensors
may consist of a sensor for monitoring downhole pressure,
seismic vibrations, temperature and/or the composition of
the produced fluids.
