One reason why pretroleum structure discovery may accelerate in the coming decade.
(Note the adaptability of the methods outlined herein to mineral structures. There are now three aerogravity techniques including one from Russia, that may have efficacy in finding mineral bodies. The point that can be inferred is that aerogravity may have fewer interferences and perhaps better positivity than electrical methods. Strangely the ground gravity techniques often laborious and slow and in mineral exploration often ambiguous and not positive, have proven themselves for decades in oil exploration and now from aerial techniques fairly efficacious. A recent example of this has been the technical successes of Far West Mining in Argentina. farwestmining.com The only drawback to what Far West was doing was what it owed BHP for the technique allowed too quick and too cheap a back-in by the major. A better system might be to try a less proprietary technique in an area known to be productive of such orebodies as may respond to this, which has already some other positive indication. This sort of approach would be "at the cutting edge" of strategy, and such an independent exploration technique may prove to have much better success than has been had by the "shotgun systems" of the past regional TDEM surveys by companies and government.
In other words when you know three criteria related to an anomaly, positivity may increase by an order of magnitude or better, serving to filter thousands of anomalies to mere dozens of probabilities. Older EM systems, reported on to this respondent, and referred to in past posts may have had similar effects in that they were more discriminatory due to their greater power, simplicity and magnetic rejection. TDEM has a poor record of rejecting magnetic horizons and shear zones. Ditto AFMAG.)
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Airborne Gravity and Magnetic Survey in the Volcan Auca Mahuida and Senal Cerro Bayo Fields of the Neuquen Basin, Argentina in 2001 by PATRICK HARBORD of the Aerogravity Division of Carson Services Inc, USA. (Thur 7 Feb 2002)
Carson Services, Inc. Aerogravity Division conducted an aerogravity and magnetic survey of the Volcan Auca Mahuida and Senal Cerro Bayo Exploration Lots in the country of Argentina in early 2001. Data were collected at a one second sample rate in a 2 by 2 kilometer and a 500 by 500 meter flight grid in the central part of the block. The data were collected at a flight elevation of 2830 meters and flown at a ground speed of 80 kilometers per hour. The patented Carson system was used for the survey. This system uses a three axes Lacoste and Romberg gravity meter specially modified by the Carson gravity meter company, dual frequency and multi channel GPS receivers and an optically pumped Cesium magnetometer. All data are compressed and encrypted and sent via satellite communication link on a daily basis to the main Carson processing centre in Pennsylvania. Quality control and survey progression are monitored efficiently in this manner.
An integrated geologically constrained interpretation was made from the data. This interpretation defined structural information and depth to structure calculations, which were verified to within 30 to 80 meters during drilling. The geology of the area was complicated with interlaying zones of basaltic material found at several levels. These basaltic layers were found at different depths and can be related to mineral ore bodies in the modeling software. In essence the survey, while for a petroleum prospect also defined very well potential mineral bodies. The total well depths were in the 3000 meters range. In this complex area where seismic procedures would not work, the Aerogravity data provided a fast and economical method to define the drilling prospects with a high degree of accuracy.
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