EP1368510B1 - Subsea pipeline power transmission - Google Patents

Subsea pipeline power transmission Download PDF

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Publication number
EP1368510B1
EP1368510B1 EP01272502A EP01272502A EP1368510B1 EP 1368510 B1 EP1368510 B1 EP 1368510B1 EP 01272502 A EP01272502 A EP 01272502A EP 01272502 A EP01272502 A EP 01272502A EP 1368510 B1 EP1368510 B1 EP 1368510B1
Authority
EP
European Patent Office
Prior art keywords
pipeline
filter means
selected range
power supply
location
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP01272502A
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German (de)
French (fr)
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EP1368510A1 (en
Inventor
Steven Martin Hudson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Expro North Sea Ltd
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Expro North Sea Ltd
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Publication date
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Publication of EP1368510A1 publication Critical patent/EP1368510A1/en
Application granted granted Critical
Publication of EP1368510B1 publication Critical patent/EP1368510B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
    • C23F13/02—Inhibiting corrosion of metals by anodic or cathodic protection cathodic; Selection of conditions, parameters or procedures for cathodic protection, e.g. of electrical conditions
    • C23F13/06—Constructional parts, or assemblies of cathodic-protection apparatus
    • C23F13/08—Electrodes specially adapted for inhibiting corrosion by cathodic protection; Manufacture thereof; Conducting electric current thereto
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
    • C23F13/02—Inhibiting corrosion of metals by anodic or cathodic protection cathodic; Selection of conditions, parameters or procedures for cathodic protection, e.g. of electrical conditions
    • C23F13/06—Constructional parts, or assemblies of cathodic-protection apparatus
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
    • C23F13/02—Inhibiting corrosion of metals by anodic or cathodic protection cathodic; Selection of conditions, parameters or procedures for cathodic protection, e.g. of electrical conditions
    • C23F13/06—Constructional parts, or assemblies of cathodic-protection apparatus
    • C23F13/08—Electrodes specially adapted for inhibiting corrosion by cathodic protection; Manufacture thereof; Conducting electric current thereto
    • C23F13/20—Conducting electric current to electrodes
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F2213/00—Aspects of inhibiting corrosion of metals by anodic or cathodic protection
    • C23F2213/30—Anodic or cathodic protection specially adapted for a specific object
    • C23F2213/31—Immersed structures, e.g. submarine structures
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F2213/00—Aspects of inhibiting corrosion of metals by anodic or cathodic protection
    • C23F2213/30—Anodic or cathodic protection specially adapted for a specific object
    • C23F2213/32—Pipes

Definitions

  • This invention relates to subsea pipeline power transmission systems, methods and apparatus.
  • WO 01/04381 which has an earlier filing date but later publication date than the earliest priority date of the present application describes an anode monitoring system in which notch filters are provided between respective anodes and a pipeline which the anodes protect.
  • the filters provide a high impedance which can be signaled across but do not interfere with the cathodic protection system.
  • a subsea pipeline power transmission system comprising a pipeline, an electrical power supply connected to the pipeline at a first location, and connection means provided on the pipeline at a second location for connection of a load to the pipeline to allow the load to receive electrical power from the power supply via the pipeline, wherein the pipeline has a plurality of cathodic protection anodes, each of which is electrically connected via respective filter means to the pipeline, the respective filter means being arranged to give a high impedance to time varying signals within at least one selected range of frequencies and a low impedance to signals outside the selected range and the electrical power supply being arranged to apply, to the pipeline, alternating current signals having a frequency within said at least one selected range.
  • a method of subsea pipeline power transmission along a pipeline having a plurality of cathodic protection anodes comprising the steps of:
  • the filter means can be arranged so that the real part of the impedance is substantially zero. This means that there is little or no attenuation of the dc components of signals passing through the filter means.
  • filter means has advantages when the metallic structure is used to carry power currents because these means can be chosen to offer high impedance to the time varying signals used for power supply thereby reducing losses, whilst offering low impedance to the currents used for cathodic protection. Minimising losses is particularly important when transmitting power rather than merely trying to detect a signal. Limiting loss to a realistic level is necessary to give a practical system.
  • the drawing shows a subsea pipeline system which comprises a pipeline 1 provided with a plurality of anodes 2 which are electrically connected to the pipeline 1 via respective filter means 3.
  • a power supply 4 is electrically connected to the pipeline 1 towards one end. This location will typically be at a main facility or some other place provided with good infrastructure such that the provision of a power supply 4 is not problematic.
  • the pipeline system is provided with a cathodic protection system of which the anodes 2 form an essential part.
  • Cathodic protection currents flowing in the pipeline 1 to improve corrosion resistance will be dc currents.
  • the filter means 3 provided at each anode are arranged to have substantially zero impedance to dc currents.
  • the filter means 3 are arranged to have a very high impedance to the power supply currents delivered by the power supply means 4.
  • the power supply means applies a current typically having a frequency in the order of 30 to 100 Hz.
  • the filter means 3 are arranged to have a high impedance to signals having the appropriate frequencies in this range.
  • the filter means 3 may be designed so that at the transmission frequency it gives an impedance of at least two orders of magnitude greater than the characteristic impedance of the pipeline (with anodes removed) when acting as a transmission system. This means that whilst the cathodic protection currents can flow to the anode substantially unimpeded, the losses from the pipeline 1 as far as the power supply current is concerned are greatly reduced.
  • the frequency of current used to transmit power is chosen with regard to two main factors. Lower frequencies call for more bulky and expensive components in the filter means whereas as frequency is increased, skin effect in the pipeline becomes problematic.
  • the frequency at which skin effect begins to compromise performance may be determined empirically on a test length of pipe but can be expected to be in the range of 50 to 100 Hz for most typical pipes.
  • loads 5 i.e., pieces of equipment which need electrical power
  • a load 5 may, for example, be connected directly to the pipeline 1 and provided with a separate earth terminal E, or may be connected directly across one of the filter means 3 associated with a particular anode 2 where the equipment to be driven is located at or near an anode 2.
  • filter means 3 between the pipeline 1 and the anode 2 makes a power supply system of this type feasible.
  • power supply in this manner might be possible in a subsea pipeline over a distance of say only 300 to 400 metres.
  • the filter means included it can be possible to transmit power over a distance of say 10 kilometres.
  • the loss of power might typically be in the order of 0.5 to 1dB per kilometre and as such, if the power supply 4 applies 150 watts to the pipeline 1 then a load at a 10 kilometre distance from the power supply 4 should be able to draw a power in the order of 50 to 15watts. It has been determined that effectively stopping leakage from the anodes gives a 10 4 improvement in power transmission capabilities over 10 kilometre subsea pipelines.
  • this signal may be locally converted into a dc signal using known techniques if this is required.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Prevention Of Electric Corrosion (AREA)
  • Pipeline Systems (AREA)
  • Laying Of Electric Cables Or Lines Outside (AREA)

Abstract

A subsea pipeline power transmission system comprasing a pipeline (1), an electoral power supply (4) connected to the pipeline at a first location, and connection means provided on the pipeline at a second location for connection of a load (5) to the pipeline. Once connected the load 5 can receive electoral power from the power supply (4) via the pipeline (1). The pipeline has a plurality of cathodic protection anodes (2), each of which is electrically connected via respective impedance means to the pipeline.

Description

  • This invention relates to subsea pipeline power transmission systems, methods and apparatus.
  • The term subsea is, used in this application as this is conventional terminology, however, it will be understood that this covers any underwater situation.
  • In many circumstances where subsea pipeline systems are used, there is a desire to operate equipment at locations which, in the general sense, are remote. That is to say, although the equipment is situated adjacent to the pipeline itself it is not near any other facility or infrastructure. Such pieces of equipment might, for example, be sensors which monitor the integrity or operation of the pipeline system.
  • One of the problems with such remote pieces of equipment is providing a suitable power source. Whilst batteries can be used these are unattractive for various reasons including their limited life, their expense and environmental concerns.
  • It is an object of the present invention to provide methods, systems and apparatus which allow the supply of power to remote equipment in subsea pipeline systems.
  • WO 01/04381 which has an earlier filing date but later publication date than the earliest priority date of the present application describes an anode monitoring system in which notch filters are provided between respective anodes and a pipeline which the anodes protect. The filters provide a high impedance which can be signaled across but do not interfere with the cathodic protection system.
  • According to a first aspect of the present invention there is provided a subsea pipeline power transmission system comprising a pipeline, an electrical power supply connected to the pipeline at a first location, and connection means provided on the pipeline at a second location for connection of a load to the pipeline to allow the load to receive electrical power from the power supply via the pipeline, wherein the pipeline has a plurality of cathodic protection anodes, each of which is electrically connected via respective filter means to the pipeline, the respective filter means being arranged to give a high impedance to time varying signals within at least one selected range of frequencies and a low impedance to signals outside the selected range and the electrical power supply being arranged to apply, to the pipeline, alternating current signals having a frequency within said at least one selected range.
  • According to a second aspect of the present invention there is provided a method of subsea pipeline power transmission along a pipeline having a plurality of cathodic protection anodes comprising the steps of:
    • applying alternating current electrical power to the pipeline at a first location; and
    • electrically connecting a load to be supplied to the pipeline at a second location;
    wherein each anode is electrically connected via respective filter means to the pipeline, the respective filter means are arranged to give a high impedance to time varying signals within at least one selected range of frequencies and a low impedance to signals outside the selected range, and the step of applying electrical power comprises the step of applying alternating current having a frequency within said at least one selected range.
  • The filter means can be arranged so that the real part of the impedance is substantially zero. This means that there is little or no attenuation of the dc components of signals passing through the filter means.
  • The use of filter means has advantages when the metallic structure is used to carry power currents because these means can be chosen to offer high impedance to the time varying signals used for power supply thereby reducing losses, whilst offering low impedance to the currents used for cathodic protection. Minimising losses is particularly important when transmitting power rather than merely trying to detect a signal. Limiting loss to a realistic level is necessary to give a practical system.
  • An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawing which schematically shows a pipeline system embodying the invention.
  • The drawing shows a subsea pipeline system which comprises a pipeline 1 provided with a plurality of anodes 2 which are electrically connected to the pipeline 1 via respective filter means 3.
  • A power supply 4 is electrically connected to the pipeline 1 towards one end. This location will typically be at a main facility or some other place provided with good infrastructure such that the provision of a power supply 4 is not problematic.
  • Although not shown in detail, as is common practice in this field, the pipeline system is provided with a cathodic protection system of which the anodes 2 form an essential part. Cathodic protection currents flowing in the pipeline 1 to improve corrosion resistance will be dc currents. Thus, the filter means 3 provided at each anode are arranged to have substantially zero impedance to dc currents.
  • On the other hand, the filter means 3 are arranged to have a very high impedance to the power supply currents delivered by the power supply means 4. In this system the power supply means applies a current typically having a frequency in the order of 30 to 100 Hz. The filter means 3 are arranged to have a high impedance to signals having the appropriate frequencies in this range. The filter means 3 may be designed so that at the transmission frequency it gives an impedance of at least two orders of magnitude greater than the characteristic impedance of the pipeline (with anodes removed) when acting as a transmission system. This means that whilst the cathodic protection currents can flow to the anode substantially unimpeded, the losses from the pipeline 1 as far as the power supply current is concerned are greatly reduced.
  • The frequency of current used to transmit power is chosen with regard to two main factors. Lower frequencies call for more bulky and expensive components in the filter means whereas as frequency is increased, skin effect in the pipeline becomes problematic. The frequency at which skin effect begins to compromise performance may be determined empirically on a test length of pipe but can be expected to be in the range of 50 to 100 Hz for most typical pipes.
  • The above arrangement means that loads 5, i.e., pieces of equipment which need electrical power, can be connected to the pipeline 1 at locations which are remote from the power supply 4. As shown in the drawing, a load 5 may, for example, be connected directly to the pipeline 1 and provided with a separate earth terminal E, or may be connected directly across one of the filter means 3 associated with a particular anode 2 where the equipment to be driven is located at or near an anode 2.
  • The provision of filter means 3, between the pipeline 1 and the anode 2 makes a power supply system of this type feasible. For example, if no filter means 3 are provided, then power supply in this manner might be possible in a subsea pipeline over a distance of say only 300 to 400 metres. However, with the filter means included, it can be possible to transmit power over a distance of say 10 kilometres. In the present system the loss of power might typically be in the order of 0.5 to 1dB per kilometre and as such, if the power supply 4 applies 150 watts to the pipeline 1 then a load at a 10 kilometre distance from the power supply 4 should be able to draw a power in the order of 50 to 15watts. It has been determined that effectively stopping leakage from the anodes gives a 104 improvement in power transmission capabilities over 10 kilometre subsea pipelines.
  • It will be appreciated that although an ac current is applied to the pipeline 1 for transmission, this signal may be locally converted into a dc signal using known techniques if this is required.

Claims (3)

  1. A subsea pipeline power transmission system comprising a pipeline (1), an electrical power supply (4) connected to the pipeline at a first location, and connection means provided on the pipeline at a second location for connection of a load (5) to the pipeline to allow the load to receive electrical power from the power supply via the pipeline, wherein the pipeline has a plurality of cathodic protection anodes (2), each of which is electrically connected via respective filter means (3) to the pipeline, the respective filter means (3) being arranged to give a high impedance to time varying signals within at least one selected range of frequencies and a low impedance to signals outside the selected range and the electrical power supply being arranged to apply, to the pipeline, alternating current signals having a frequency within said at least one selected range.
  2. A power transmission system according to claim 1 in which the filter means (3) is arranged so that the real part of the impedance is substantially zero, such that there is little or no attenuation of dc components of signals passing through the filter means.
  3. A method of subsea pipeline power transmission along a pipeline (1) having a plurality of cathodic protection anodes (2) comprising the steps of:
    applying alternating current electrical power to the pipeline at a first location; and
    electrically connecting a load (5) to be supplied to the pipeline at a second location;
    wherein each anode (2) is electrically connected via respective filter means (3) to the pipeline, the respective filter means (3) are arranged to give a high impedance to time varying signals within at least one selected range of frequencies and a low impedance to signals outside the selected range, and the step of applying electrical power comprises the step of applying alternating current having a frequency within said at least one selected range.
EP01272502A 2001-01-03 2001-12-20 Subsea pipeline power transmission Expired - Lifetime EP1368510B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GBGB0100104.9A GB0100104D0 (en) 2001-01-03 2001-01-03 Subsea pipeline power transmission
GB0100104 2001-01-03
PCT/GB2001/005689 WO2002053804A1 (en) 2001-01-03 2001-12-20 Subsea pipeline power transmission

Publications (2)

Publication Number Publication Date
EP1368510A1 EP1368510A1 (en) 2003-12-10
EP1368510B1 true EP1368510B1 (en) 2012-07-25

Family

ID=9906187

Family Applications (1)

Application Number Title Priority Date Filing Date
EP01272502A Expired - Lifetime EP1368510B1 (en) 2001-01-03 2001-12-20 Subsea pipeline power transmission

Country Status (12)

Country Link
EP (1) EP1368510B1 (en)
JP (1) JP2004517592A (en)
KR (1) KR20030069201A (en)
AP (1) AP2003002777A0 (en)
BR (1) BR0116708A (en)
CA (1) CA2433736C (en)
EA (1) EA200300611A1 (en)
GB (1) GB0100104D0 (en)
MX (1) MXPA03005788A (en)
NO (1) NO336079B1 (en)
OA (1) OA12489A (en)
WO (1) WO2002053804A1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2486687A (en) * 2010-12-20 2012-06-27 Expro North Sea Ltd Impressed current cathodic protection systems and monitoring
EP3340431A1 (en) * 2016-12-20 2018-06-27 Koninklijke Philips N.V. System for impressed current cathodic protection

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE456191B (en) * 1986-02-19 1988-09-12 Kurt Gosta Lange PROCEDURE AND DEVICE FOR AUTOMATIC MONITORING OF ELECTROCHEMICAL CORROSION PROTECTION IN A WATER EXISTING STALL CONSTRUCTION
US5176807A (en) * 1989-02-28 1993-01-05 The United States Of America As Represented By The Secretary Of The Army Expandable coil cathodic protection anode
BR9004940A (en) * 1990-10-02 1992-04-07 Petroleo Brasileiro Sa COUPLING DEVICE FOR PIPE HEATING SYSTEM
US5627414A (en) * 1995-02-14 1997-05-06 Fordyce M. Brown Automatic marine cathodic protection system using galvanic anodes
GB9916410D0 (en) * 1999-07-13 1999-09-15 Flight Refueling Ltd Anode monitoring systems and methods

Also Published As

Publication number Publication date
JP2004517592A (en) 2004-06-10
KR20030069201A (en) 2003-08-25
OA12489A (en) 2006-05-24
BR0116708A (en) 2003-12-23
EA200300611A1 (en) 2003-12-25
NO20033025L (en) 2003-09-03
CA2433736A1 (en) 2002-07-11
AP2003002777A0 (en) 2003-06-30
MXPA03005788A (en) 2003-09-10
GB0100104D0 (en) 2001-02-14
CA2433736C (en) 2010-04-06
WO2002053804A1 (en) 2002-07-11
NO336079B1 (en) 2015-05-04
EP1368510A1 (en) 2003-12-10
NO20033025D0 (en) 2003-07-01

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