UPDATED Venue: Departamento de Engenharia Eletrica, Sala L401-1*, PUC - Rio de Janeiro, Brazil (*Sala Multimeios, Departamento de Engenharia Electrica - Ed. Cardeal Leme, Quarto Andar, PUC)
UPDATED Date: 9am, Wednesday October 26th, 2016
Applications for established deep sea geophysical methods used in mineral exploration for the subsea inspection of pipeline infrastructure
Peter Kowalczyk, Chief Technical Officer, Ocean Floor Geophysics Inc. As subsea pipeline are placed in deeper and deeper waters and the installed infrastructure ages, the necessity to inspect these pipes efficiently is becoming urgent. Present methods rely upon visual inspection using remotely operated vehicles (ROVs) and intervention using these same ROVs. This is costly, and these costs are increasing as inspection requirements become more stringent and the depth of water that the pipelines sit in also increases. Autonomous Underwater Vehicles (AUVs) can dramatically lower the cost of routine inspections and allow timely and appropriate intervention. This strategy of using AUVs to inspect on a regular basis, followed by targeted interventions at problem areas using ROVs will result in lower costs overall, with a higher success ratio at interventions due to the early recognition of problems and an outcome of reduced adverse environmental impacts. The OFG AUV "Chercheur" is an fully equipped survey and pipeline inspection AUV with an unsurpassed suite of sensors including HiSAS (Synthetic Aperture Sonar), EM2040 multibeam echo-sounder, high resolution camera and on-board pipeline tracking software. These systems can be used to map as-built positions, buckling, movement, supports, mat positions, scours and free spans. There exists an opportunity to further extend the capabilities offered by Chercheur for the detection of invisible flaws such as cracking, pipeline erosion and corrosion (internal and external), and fractures through the use of technologies proven in the arena of subsea minerals.
Three technologies have particular application and can be readily adapted to use in AUV pipeline inspections. These are E-field monitoring of galvanic protection systems, magnetic monitoring of impressed current cathodic protection (ICCP) systems and the measurement of the electromagnetic time decay constant of the pipe itself using a time domain electromagnetic (TEM) system. (1) E-field monitoring implies measurement of the ambient electric field around a pipe using detection electrodes on an AUV. The electric gradient in seawater is a measure of the cathodic current flowing from the pipeline, and the activity of active or passive cathodic protection electrodes. Anomalous reading will indicate a failure in the pipeline covering, or wastage of the cathodic electrodes. (2) Magnetic measurements along the pipeline made with high frequency magnetometers can measure the amplitude of the cathodic protection current in the pipeline for ICCP systems. If the current along the pipeline changes, this indicates leakage of current from the pipeline to the sea. A correlating E-field anomaly may be expected at this location. (3) TEM measurements will require a transmitter on the AUV, and then an appropriate high speed and very sensitive vector magnetometer to measure the secondary field from the induced secondary current in the pipeline caused by the TEM transmitter pulse. The measurement of the time decay constant (tau) is important as this is a property of the pipe, and is independent of the transmitter and receiver geometry. A change in tau will indicate a change in the physical condition of the pipe. In particular, a reduced tau can be expected to correlate with damaged regions of the pipe.
All three methods are used in subsea mineral exploration, and equipment to make these measurements has been developed and is proven to work in the subsea environment. The technology risk here is small, and the challenge is to demonstrate these technologies from the subsea mineral exploration world in the world of industrial subsea pipeline inspections.
About Peter Kowalczyk, BSc, P. Geo.
Chief Technical Officer, Ocean Floor Geophysics, Vancouver
Peter is a founder of Ocean Floor Geophysics (OFG), a company started in 2007 to provide geophysical services for seafloor exploration for minerals and gas hydrates. Prior to starting Ocean Floor Geophysics he was chief geophysicist for Placer Dome Inc. Following graduation with a BSc degree in geophysics from the University of British Columbia, Peter joined Placer Dome as a project geophysicist in 1970 and worked on geophysical surveys around the world forporphyry copper, uranium, base metal and gold exploration, becoming chief geophysicist in 1992 that role Peter coordinated Placer's geophysical research and was heavily involved in the introduction and implementation of digital processing, visualization and geophysical inversion methods into the exploration practices at Placer Dome. In 2005 and 2006 Peter managed the geophysical component of Placer Dome's leading-edge exploration program for sea bottom massive sulphidesAn exploration generalist, he has particular experience in the processing and interpretation of airborne, ground and marine electromagnetic and electrical survey data. Since leaving Placer following its purchase by Barrick Gold and starting OFG in 2007, Peter has been the chief scientific officer managing multiple cruises to explore for and map seafloor massive sulfide deposits, and in particular has directed or carried out a variety of recent marine projects including: Submarine Massive Sulfide (SMS) exploration projects in the South Pacific and around Japan, · Very high precision bathymetric mapping using ROVs and AUVs, and · Mapping offshore gas hydrate deposits using the Scripps Institute Vulcan CSEM system. He is the inventor of the patented Ocean Floor Geophysics submarine electromagnetic system, and has also been part of a team that has developed a magnetometer system that provides automatic and highly accurate heading-compensated data when mounted on AUVs and ROVs that have not been degaussed or specially prepared as magnetometer survey platforms.
Peter has presented and published a wide variety of talks and papers on both land and marine geophysical projects. Peter has long been involved in pro-bono efforts in the geophysical community in BC, including serving a multi-year stint as President of the BC Geophysical Society. Strongly committed to supporting and advancing geophysical education, Peter is also a long-serving Director of the KEGS Foundation and has guided fund-raising in the Lower Mainland community in support of the Foundation’s geophysical scholarship program.
Selected talks and publications:
Mapping SMS deposits during exploration and exploitation. Using Sonar, Magnetic, Electromagnetic & Seismic methods effectively, EAGE Munster, Mar 2016
CSEM for gas hydrate exploration - a new approach using the Scripps Institute of Oceanography CSEM Vulcan system, Gas Hydrate Workshop, Taiwan, Mar 2015
Geophysical Methods for the Mapping of Submarine Massive Sulphide Deposits, OTC, May 2015
Geophysical prelude to first exploitation of submarine massive sulphides, First Break, Nov 2008
Interactive geophysical inversion using qualitative geological constraints, Exploration Geophysics, Jan 2007
Theta Map: Edge detection in magnetic data, Geophysics, Jul 2005
What if your inversion has no numerical target?, ASEG mtg, Jan 2003
3 component borehole magnetometry in and around magnetic orebodies, SEG meeting, Jan 1999
3D inversion of resistivity and IP data, two case studies from mineral exploration, SEG meeting, Jan 1999
Applications of geophysical inversions in mineral exploration, Leading Edge, Apr 1998
Geophysics of the Big Bell gold deposit, Western Australia, ASEG, Jan 1994