Gravity Data Processing

Fugro-LCT's data processing centers are internationally acclaimed for their role in the continuing development and implementation of state-of-the-art processing technology. We provide clients the benefit of experience and innovation in the processing of potential fields data sets using Fugro-LCT market leading proprietary processing software DATAPRO™.

Fugro-LCT's geoscientists apply their professional knowledge in an interactive computer workstation environment resulting in rapid and accurate processing of geophysical data.

Fugro-LCT offers:

• Rapid and flexible conversion of raw field data into a structured database
• Interactive data processing of marine, land and airborne geophysical data
• Digitizing
• Merging and reprocessing of multiple data sets
• Regional data compilations
• Non-exclusive projects
• Database management services

Fugro-LCT is the only company that can offer the full service for gravity and magnetic data, covering acquisition, processing and interpretation. The company therefore takes responsibility for both data processing and acquisition so simplifying the contractual and project management arrangements, streamlining the service and resulting in faster delivery times for the final products.

Fugro-LCT also offer as standard a fast track data processing service guaranteeing preliminary results from any size survey within two weeks of the completion of data acquisition.

The data processing scheme covers a number of well-documented steps. One of the most important of these is the initial digital recomputation of the gravity meter outputs to allow the processors to start from zero-phase unfiltered primary gravity signal. This is in contrast to a number of processing companies who simply take the data calculated internally by the gravity meter which is heavily filtered and produced only for simple QC purposes by the onboard operator. The following diagram shows the difference between the digitally recomputed gravity (black) and heavily filtered 'meter' gravity (red):

High frequencies removed by the gravity meter filter cannot be recovered later. In this case, these are real events caused by vessel motion and when removed by cross correlation with the Eotvos correction (shown in red) result in retention of a subtle, high frequency gravity anomaly.

In order to correctly level the survey line data, orthogonal tie-lines are required. These are inherently part of a 2D grid but are usually additional to a 3D seismic program and need to be considered during the survey planning stage.

Typical products from a data processing project would be a digital archive of line and gridded data in a variety of formats (including LCT load-and-go format), color-shaded relief maps as hardcopy and digital files in CGM or PDF format and a data processing report as hardcopy and digitally in PDF format.

Final products in Arcview format are also available.

On completion of the data processing, Fugro-LCT will review the results with the client to discuss the processing sequence and recommend how the data may be integrated into the exploration scheme.

Throughout the processing Fugro-LCT have adopted a series of workflow and QA procedures to ensure the quality of the final product. Fugro-LCT uniquely uses the vertical motion monitor (VMON) value, computed by Fugro-LCT from the one-second gravity data, to estimate the final processed gravity data quality expected from different operating conditions encountered during a survey.

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Updated October 2003.