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Marine Gravity and Magnetic Services

     Since its founding in 1970, EDCON-PRJ has continued to advance the science of measuring gravity and magnetic fields at sea by developing and applying creative and innovative technology. Among its accomplishments are development of improved instrumentation and data recording. These enhancements have led to the acquisition of higher-resolution data. The improved field data have driven EDCON-PRJ’s data processing advancement.

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We use the best gravity and magnetic instrumentation available in combination with advanced data processing techniques to yield the optimum geologic information for every project. EDCON-PRJ has developed specifications for the acquisition and processing of marine gravity and magnetic data which have been adopted by many client companies world-wide.

EDCON-PRJ’s experience in the two primary modes of marine gravity and magnetic data acquisition, operations aboard client seismic vessels and stand-alone surveys, is unparalleled: .

Stand-Alone


 Operating in stand-alone mode on a dedicated gravity and/or magnetic survey vessel or working in concert with seismic, EM, ROV or other types of hydrographic surveys on client vessels, EDCON-PRJ provides personnel and equipment worldwide to meet the unique requirements of every marine survey situation. In the Gulf of Mexico, EDCON-PRJ has acquired over 115,000 line-km of stand-alone surface-ship gravity and magnetic data. EDCON-PRJ has also completed stand-alone marine gravity and magnetic surveys in many other parts of the world, including:

  • Albania

  • Alaska

  • Gabon

  • Indonesia

  • Oman

  • Western Australia

    Advantages of stand-alone surveys include:

1. Survey Design: The survey layout is specifically created to optimize survey results. The density of primary survey lines is chosen to match the geologic goals of the program with sufficient tie-lines to allow effective data leveling during processing. The line orientation is chosen with a view to both geologic goals and efficient data acquisition.

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2. Vessel opertation :
speed and heading) and survey line layout  are selected to yield optimum gravity and magnetic results, considering sea direction and weather conditions.

3. Rapid Results: The speed of data collection on a stand-alone survey is generally much greater when the vessel speed is not limited by requirements of other survey methods. Gravity and/or magnetic stand-alone surveys are typically acquired at vessel speeds of 8-10 knots with rapid line changes. In comparison, seismic operations are generally limited to 5-knot or slower vessel speeds with long line-change times.

4. On-the-fly Data Evaluation: On our stand-alone surveys, preliminary processing (both on the vessel and at the EDCON-PRJ office) identifies line segments that are of sub-standard quality (generally due to heavy sea conditions) so that the lines may be re-acquired efficiently.

Client Vessel Survey


The majority of marine gravity and/or magnetic data are collected in conjunction with other survey methods. Most marine gravity and magnetic survey work takes place as an addition to seismic surveys, but marine gravity and/or magnetic data are also collected on EM surveys, ROV projects, multi-beam bathymetric surveys, and other hydrographic projects. Advantages of having the gravity and/or magnetic data acquired in conjunction with other projects include the following:

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  1. Economy: The cost for adding the marine gravity and/or magnetic services to an existing survey is relatively low. In the stand-alone mode, the additional cost for a dedicated vessel with a positioning and bathymetry system can be substantial.

  2. Regulatory Issues: Generally, adding marine gravity and/or magnetic services to an existing survey does not involve any significant additional permitting or licensing issues with the governing legal authorities.

  3. Co-located Survey Lines: Having the gravity and/or magnetic data acquired along the same survey tracks as the seismic or other survey methods can be beneficial in certain multi-discipline enhanced processing and interpretation methods