Experiences With cable faults located at metallic screen connections

Overheating of metallic ground screen connections at accessories of single core cables are the root cause of severe insulation failures in the distribution network. The overheating is due to a high transition resistance of the connections combined with high induced currents in the ground screens during operation. For copper screened cables equipped with a metallic laminate, overheating causing failures are also observed randomly along the cables often at locations close to cable straps or cleats. Currently there are no international standards with complete tests to determine the ampacity of ground screen connections for different cable system designs making future installations more reliable. Furthermore, product information from the suppliers indicates that basis for design and test criteria is not uniform, and tests are not performed concerning relevant operation and fault scenarios. A research project is launched in Norway, to test different ground screen connections and then to provide guidelines to ensure proper future installations. A new CIRED working group is proposed to provide recommendations for complete tests of ground screen connections lacking in current international standards and brochures.publishedVersio

Next Generation Heating of Subsea Oil Production Pipelines

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Optimizing Electrical Heating System of Subsea Oil Production Pipelines

Direct Electrical Heating (DEH) is a field-proven technology for hydrate and wax management of subsea production pipelines. DEH has been in use for nearly 20 years and is installed on approximately 30 pipelines/flowlines with length up to 43 km and on 1000 m depth, Studies indicate significant cost-reductions and improved utility by going from the present DEH-systems operating at normal power frequency of 50/60 Hz to a system operating at a frequency ranging between 100 and 200 Hz. Increased frequency reduces the size and weight of the cables, reduces electrical currents in seawater, reduces AC corrosion and is favourable regarding development of ultra-deep fields as well as continuous operation. Copyright © 2018 by the International Society of Offshore and Polar Engineers (ISOPE)acceptedVersio

AC Corrosion of Electrically Heated Pipelines

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Next Generation Heating of Subsea Oil Production Pipelines

acceptedVersio

AC Corrosion of Electrically Heated Pipelines

acceptedVersio

Prediction of Heating Power in Magnetic Pipe Conducting Large AC Current With High Frequencies Up to 200Hz

In direct electrical heating system (DEHs), which is developed for subsea process to safeguard well stream through pipelines to topside process platform or shore, the production pipeline is also acts as an active conductor conducting large AC current to generate heat. The heating source is conductive and hysteresis power losses in the pipe. Currently, the all implemented DEHs operate at 50Hz. There is a potential to further improve the heating capacity of the DEHs by operating the system at higher frequency so that the same power can be achieved at lower current. Consequently, the cross-session of the power cable can be reduced. Furthermore, operation in higher frequency directly results in better system utilization and less AC corrosion of the pipeline. This will further reduce the installation and operational cost and increase the system lifetime. For DEHs design it is critical to predict the heating power as function of input current and frequency so that proper frequency and current can be selected correspondingly. This paper analytically evaluate the heating power as functions of current and frequency based on experimentally measured material properties such as mass density, conductivity, B-H curve and hysteresis

Experiences With cable faults located at metallic screen connections

Overheating of metallic ground screen connections at accessories of single core cables are the root cause of severe insulation failures in the distribution network. The overheating is due to a high transition resistance of the connections combined with high induced currents in the ground screens during operation. For copper screened cables equipped with a metallic laminate, overheating causing failures are also observed randomly along the cables often at locations close to cable straps or cleats. Currently there are no international standards with complete tests to determine the ampacity of ground screen connections for different cable system designs making future installations more reliable. Furthermore, product information from the suppliers indicates that basis for design and test criteria is not uniform, and tests are not performed concerning relevant operation and fault scenarios. A research project is launched in Norway, to test different ground screen connections and then to provide guidelines to ensure proper future installations. A new CIRED working group is proposed to provide recommendations for complete tests of ground screen connections lacking in current international standards and brochures