KIVIOR, IRENA
Archimedes Consulting Pty Ltd., Adelaide, South Australia

Abstract: New Techniques of Interpretation of Aeromagnetic Surveys over Sedimentary Basins

Recent developments in the application of computer technology to the study of the earth's magnetic field have significantly extended the scope of aeromagnetic surveys as a tool in the exploration for hydrocarbons. Aeromagnetic surveys can successfully assist in petroleum exploration by applying new interpretation techniques using automatic and semi-automatic computer methods. Two principal methods are used in the analysis and interpretation of the aeromagnetic survey data: (1) energy spectral analysis applied to the grid data, (ii) automatic curve matching applied to the profile data. An experimental aeromagnetic survey flown over part of the Eromanga/Cooper Basin has recently been interpreted using this new approach. The results obtained show that it is now possible to delineate basement highs and troughs even in a weakly magnetic basement, to follow magnetic horizons within the sedimentary section, to pick out fault and joint patterns within the sedimentary section, establish the thickness of the sediments, and determine the configuration and structure of the underlying basement. The depth to basement estimates computed using the automatic curve matching method are comparable with those derived from seismic survey data. The resolution of structures obtained from interpretation of the aeromagnetic data is limited, however it is clear from comparison that they are consistent with those derived from areas with closely spaced seismic lines. In areas where the basement is weakly magnetic and where the magnetic interpretation is being used to delineate magnetic layers within the sedimentary section, the methods discussed become more effective when they are used to interpolate between widely spaced seismic lines. The new approach to interpretation of aeromagnetic survey data provides petroleum companies with quick, comprehensive and the non-invasive method for firstpass exploration over the sedimentary basins including ones in low latitudes, rugged terrains and volcanic provinces.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas