Interpretation of Potential Field Data

Multi-Physics

Many interpretive methods are used. Each interpretation is unique. Factors influencing the interpretation workflow include: quality and quantity of geological and geophysical constraints, the anomalous character of the potential field data, project timing and economics.

Interpretation and modeling are performed using CGG’s comprehensive suite of Potential Field software.

ApplicationsGravity and magnetic studies are cost-effective reconnaissance tools and can be used in seismic survey design. They are particularly suited for tectonic reconstructions, to investigate continental oceanic crustal boundaries (COB) and to test regional models. In challenging environments for advanced seismic imaging, such as salt provinces, areas characterized by near-vertical structures, or in the presence of basalt and volcanics, carefully interpreted potential field data help define essential features such as salt bodies, basalts and volcanic intrusions, and basement architecture.

Tectonic and structural elements with continental oceanic crustal boundaries (COB).

All environments from regional frontier studies to the prospect levelOur internationally known and respected interpretation geoscientists tightly integrate gravity and magnetic data with geological, seismic and well data to add insight into the resource evaluation process in most of the world’s petroleum basins.

Interpretation of Potential Field DataMulti-Physics

Spectral decomposition attributes and monogenic signal enhancements are used to define lineaments and faults (Hassan and Yalamanchili, 2013. Monogenic signal decomposition: A new approach to enhance magnetic data, SEG Houston 2013 Annual Meeting).

Various filtering techniques are used to enhance anomalies through certain spectral aspects of observed gravity and magnetic data. These products are called “enhancements” and are useful for the qualitative interpretation of anomalies related to bodies assumed to be associated with a specific depth range, or for removing spectral energy associated with noise or geological features that are not of interest. These enhancements are widely used in the industry for mapping lineaments and faults.

Service includes:•Proprietary and multi-client integrated geological

and geophysical studies

•Salt and subsalt interpretation

•Gravity-constrained velocity modeling

•Seismic imaging support

•Basement/volcanic mapping

•Regional structure and tectonics

•GIS-based studies

•Geological model of petroleum provinces

•Geological interpretation with remote sensing

Two-dimensional earth modelingCGG Multi-Physics uses 2MODTM, the exploration industry’s premier 2/2.5D gravity/magnetic modeling application. 2MOD is unique in its ability to display seismic data (image raster or SEGY trace data), perform on-the-fly time-to-depth conversion and viewing between model results in depth and seismic data in time, and easily import client-interpreted seismic horizons (as grids or horizons), in standard industry formats.

In the example shown in the figure below the combination of gravity and magnetic data with seismic data has refined not only the large-scale features such as Moho and basement surfaces but also helped the identification of igneous sources and carbonates within the sedimentary section.

2.5D gravity and magnetic modeling to validate seismic interpretation. The goal is to derive a unified interpretation from all available data sets; a) Initial forward model based on the seismic interpretation; b) Final forward model consistent with the potential field and seismic data.

Three-dimensional earth modeling3D gravity/magnetic modeling is accomplished using CGG’s 3MODTM, an interactive forward and inverse 3D gravity and magnetic modeling application. Geological constraints may be imposed in a variety of different ways. Applications range from project oriented subsalt modeling to regional studies involving mapping of basin/sub-basin architecture and trends.

The 3D model is developed through both inverse and forward modeling techniques resulting in realistic geological models that satisfy known geology, seismic, gravity and magnetic data. The results from 3D inversion modeling include interpreted 3D horizons highlighting specific geological structures and apparent lithological properties.

Interpretation of the potential field and seismic data allows definition of the base of the salt geometry.

Interpreted 3D horizons.

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b)

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Interpretation of Potential Field DataMulti-Physics

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General ContactRao Yalamanchilirao.yalamanchili@cgg.com+1 832 351 4824

Local ContactAPAC David Moore david.moore@cgg.com +6189 273 6470 EAME James Andrew james.andrew@cgg.com +44 (0)1293 683219 NAM David Schwartz david.schwartz@cgg.com +1 832 351 4806SAM Andre Rabelo andre.rabelo@cgg.com +55 21 3501 7720

CGG Worldwide Headquarters - Tour Maine-Montparnasse - 33, avenue du Maine - B.P. 191 - 75755 Paris Cedex 15, FRANCE +33 1 64 47 45 00

Benefits of our experienced interpretation services include:•Extensive knowledge of the various

tectonic provinces

•Fast delivery of resource evaluation to the explorationist

•Use of multiple interpretive methods to derive a unified interpretation from available gravity, magnetic, seismic and geologic data

•Access to sophisticated computer algorithms increase the accuracy of the output model

•Powerful complement to seismic imaging in salt provinces, in the presence of basalt and volcanics and in areas characterized by near-vertical structures

3D view of basement surface and interpreted intrusives from magnetic data.

Basement and volcanic mappingCGG Multi-Physics utilize MAGPROBETM, the undisputed flagship magnetic depth estimation application. MAGPROBE exploits many semi-automatic algorithms (including Werner and Euler deconvolution), as well as multiple manual techniques such as the Peters half-slope and the straight-slope methods. Depth estimate results can be compared with other geospatial data sets through dynamic real-time links to other CGG software applications. Applications of this technique include basin mapping (sediment thickness) and delineation of volcanics and intrusions (including sub-volcanic mapping).