U.S. patent application number 12/866897 was filed with the patent office on 2011-01-27 for method of producing hydrocarbons through a smart well.
Invention is credited to William Birch, Johannis Josephus Den Boer, Daniel Joinson.
Application Number | 20110017468 12/866897 |
Document ID | / |
Family ID | 39495166 |
Filed Date | 2011-01-27 |
United States Patent
Application |
20110017468 |
Kind Code |
A1 |
Birch; William ; et
al. |
January 27, 2011 |
METHOD OF PRODUCING HYDROCARBONS THROUGH A SMART WELL
Abstract
A method is disclosed for producing hydrocarbons through an
instrumented smart well containing a well tubular (6,29-32) and an
assembly of power, DTS and/or other sensing and/or signal
transmission cables (13,40-44) comprising at least one power and/or
signal transmission cable, which is bonded along at least part of
its length to an outer surface of the well tubular (6,29-32) by an
adhesive, which preferably is reusable and/or has a thermal
conductive of at least 3 W/mK or at most 0.2 W/mK.
Inventors: |
Birch; William; (Aberdeen
Aberdeenshire, GB) ; Den Boer; Johannis Josephus;
(Rijswijk, NL) ; Joinson; Daniel; (Rijswijk,
NL) |
Correspondence
Address: |
SHELL OIL COMPANY
P O BOX 2463
HOUSTON
TX
772522463
US
|
Family ID: |
39495166 |
Appl. No.: |
12/866897 |
Filed: |
February 12, 2009 |
PCT Filed: |
February 12, 2009 |
PCT NO: |
PCT/EP2009/051618 |
371 Date: |
October 7, 2010 |
Current U.S.
Class: |
166/369 |
Current CPC
Class: |
E21B 17/026 20130101;
E21B 43/103 20130101 |
Class at
Publication: |
166/369 |
International
Class: |
E21B 43/00 20060101
E21B043/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 15, 2008 |
EP |
08101691.7 |
Claims
1. 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 that is
bonded by a reusable adhesive along at least part of its length to
an outer surface of the well tubular; and producing hydrocarbons
from the well.
2. The method of claim 1, wherein the power, sensing and/or signal
transmission cable assembly is encapsulated in a protective layer
that is bonded along at least part of its length to the well
tubular by an adhesive that has a thermal conductivity of at least
3 W/mK or at most 0.2 W/mK.
3. The method of claim 2, wherein the assembly comprises a
plurality of power, sensing and/or signal transmission cables that
are encapsulated in a common protective layer with an outer
substantially flat side which is bonded along at least part of its
length to the well tubular.
4. The method of claim 3, wherein the protective layer is
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.
5. The method of claim 3, wherein the protective layer is
furthermore at selected intervals 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.
6. The method of claim 3, wherein the well tubular is 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 the outer surface of
the well tubular during the expansion process and which is induced
to re-bond to the outer surface of the well tubular after the
expansion process.
7. The method of claim 6, wherein the well tubular is 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.
8. The method of claim 6 wherein the tubing is expanded by pushing
an expansion cone therethrough and a reusable bonding agent is
used, wherein the bonding agent is detached from the tubing during
the expansion process and bonds itself again against the expanded
tubing.
9. The method of claim 2, wherein the power, sensing and/or signal
transmission cable assembly comprises at least one electrical power
cable and at least one fiber optical sensing and/or signal
transmission cable.
10. The method of claim 9, wherein the power, sensing and/or signal
transmission cable assembly comprises a plurality of electrical
power cables and a plurality of fiber optical sensing and/or
transmission cables and the assembly extends 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 and/or
optical cable if a cable is damaged or for another reason.
11. The method of claim 10, wherein 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.
12. The method of claim 11, wherein at least one wireless
electrical transmission device that is connected to one of the
electrical cables is an inductive coupler that is arranged in the
vicinity of an inductive coupler that is connected to the downhole
electrical device and/or sensor.
13. The method of claim 11, wherein at least one wireless
electrical transmission device that is connected to one of the
fiber optical signal transmission cables is 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.
14. The method of claim 11, wherein one or more downhole electrical
devices comprise an electrical motor or generator that is connected
to a downhole valve or pump and one or more downhole sensors
consists of a sensor for monitoring downhole pressure, seismic
vibrations, temperature, the composition of the produced well
fluids and/or movement of fluid in the formation.
15. The method of claim 14, wherein: at least the downhole sensor
is a fiber optical Distributed Temperature Sensor (DTS) cable which
is bonded by an adhesive having a high thermal conductivity to the
well tubular
16. The method of claim 14, wherein an insulating layer is applied
to the outer surface of the fiber optical DTS cable, which layer is
bonded to the well tubular to reduce thermal conduction through the
fiber optical DTS cable and provide a measure of the temperature of
the tubular to which the fiber is bonded and/or the fluids
contained within the tubular.
17. The method of claim 14, wherein the adhesive has a sufficiently
low thermal conductivity to enable accurate temperature measurement
within an annular space surrounding the well tubular to which the
fiber optical DTS cable is bonded; and the fiber optical DTS cable
is used to monitor the temperature of fluids flowing into the well
and/or through the well tubular.
18. The method of claim 14, wherein the adhesive has a sufficiently
low thermal conductivity to enable accurate temperature measurement
within an annular space surrounding the well tubular to which the
fiber optical DTS cable is bonded; and the well tubular comprises
an inner well tubular, which is surrounded by an outer well tubular
through which tubulars well effluents are produced and an assembly
of power and/or signal transmission cables is encapsulated in a
relatively flat encapsulation which is bonded to the outer surface
of the inner well tubular, which strip comprises one fiber optical
DTS cable that is configured to monitor the temperature of the wall
of the inner well tubular and another fiber optical DTS cable that
is configured to monitor the temperature of the well effluents
flowing through the annular space between the inner and outer well
tubular to obtain temperature traces of the fluxes of well
effluents flowing through the interiors of the inner and outer well
tubulars.
Description
BACKGROUND OF THE INVENTION
[0001] 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.
[0002] 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.
[0003] Installation, connection and protection of a fragile power
and/or signal transmission cable assembly in a well is a complex
and expensive operation.
[0004] 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.
[0005] 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
[0006] 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 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.
[0007] 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 a
adhesive, which is reusable and/or has a thermal conductive of at
least 3 W/mK or at most 0.2 W/mK.
[0008] 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 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.
[0009] 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.
[0010] 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 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.
[0011] 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.
[0012] 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.
[0013] 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 instrumented sleeve.
[0014] These and other features, advantages and embodiments of the
method according to the present invention are 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
[0015] 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;
[0016] 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;
[0017] 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
[0018] 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 DESCRIPTION OF THE DEPICTED EMBODIMENTS
[0019] 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.
[0020] The well 1 comprises a well casing 3 which is fixed within
an overburden formation 4 by a cement sheeth 5.
[0021] 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
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.
[0022] 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).
[0023] 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 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.
[0024] 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.
[0025] 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.
[0026] 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 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 replaceable 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.
[0027] 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, 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.
[0028] 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.
[0029] 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.
[0030] 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 larger width than other sides 32 C-D of
the power strip 32.
[0031] 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.
[0032] 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.
[0033] 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.
[0034] 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
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.
[0035] 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.
[0036] 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 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.
[0037] 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.
[0038] 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.
[0039] 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 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.
[0040] 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.
[0041] In the case of wireless connections, the wireless connection
equipment would be connected to the backbone cable much as a
directly connected instrument.
[0042] 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
that is connected to the wellbore in which the tubing is
arranged.
[0043] 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.
[0044] 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.
[0045] 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.
[0046] 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.
[0047] 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.
[0048] 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.
[0049] 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.
[0050] In such case at least one wireless electrical transmission
device that is connected to one of the 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.
[0051] 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.
[0052] 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.
* * * * *