--> De-Risking Subsalt Exploration by Integrated Depth Imaging, Oliver K. Geisler and Markus H. Krieger, #90093 (2009)
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De-Risking Subsalt Exploration by Integrated Depth Imaging
 

Oliver K. Geisler1 and Markus H. Krieger2
 

1TERRASYS Geophysics, 3000 Wilcrest Dr., Ste. 155, Houston, Texas  77042 

2TERRASYS Geophysics, Baumeisterstr. 2, 20099 Hamburg, Germany

   

ABSTRACT

 

Salt structures are challenging geophysical interpretation issues and need to be addressed properly.  In this paper we discuss how non-seismic data can be integrated in the cycle of iterative depth migration and model updating leading to better seismic imaging results and a more reliable prospect evaluation.

 

Especially areas involving complex salt geometries as in the Gulf of Mexico are affected by issues limiting the success of pre-stack depth migrations (PreSDM), e.g., reduced data quality, incorrect structural concepts, unresolved geometries or inaccurate velocities.  Our approach to tackle these problems is the integration of data from independent geophysical techniques that are linked to the same lithological model but respond to different geophysical properties like density, susceptibility, or resistivity.

 

Key ingredients for a successful application of this concept—besides a reasonable seismic coverage—are adequate high-resolution non-seismic databases, geological boundary conditions, a flexible software environment for integrated 3D modeling and inversion, experienced interpreters with excellent interdisciplinary communication skills, and a proven workflow, adjustable to the specific project requirements.

 

Gravity, gravity gradient, magnetic, or Previous HitmagnetotelluricTop datasets are often available.  Initially, a coarse evaluation of their usability for these applications is necessary, especially with regard to the availability of constraining information.  Further workflow steps include qualitative data analysis, primary model building with respective sensitivity tests, and geostatistics on property relationships.  The main project phase usually consists of one or more joint seismic (e.g., PreSDM) and potential field interpretation cycles, leading to an improved, integrated model, increased geological reliability, and reduced exploration risk.

 

We will present some examples from different regions where 3D gravity modeling helped to delineate the allochthonous salt distribution.  As in most cases the base of salt could not be clearly identified from seismic data alone, the integrated approach reveals its geometry and thickness:  a major step for better imaging of target structures below salt.

 

Geisler, O. K., and M. H. Krieger, 2009, De-risking subsalt exploration by integrated depth imaging:  Gulf Coast Association of Geological Societies Transactions, v. 59, p. 297-303.

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AAPG Search and Discover Article #90093 © 2009 GCAGS 59th Annual Meeting, Shreveport, Louisiana