I would like to make a distinction between the application of state-of-the-art aeromagnetics for geologic interpretation and micromagnetics as a hydrocarbon direct-detection method. Very few people promote micromagnetics as a directdetection method anymore. High-resolution aeromagnetics (HRAM) for structural interpretation, on the other hand, is enjoying something of a renaissance. Not only did magnetic methods survive last decade's industry slump, but they actually advanced through the period.
HRAM is descriptive of an exploration methodology targeted at very detailed high-resolution interpretation of the full geologic section. HRAM surveys are standard today because of an increased interest during the 1980s in sampling high-frequency, low-amplitude magnetic anomalies that many people thought were direct hydrocarbon indicators. The magnetic field was sampled at a 1/10-second increment, from an altitude of 80.150 m, along lines spaced 250. 500 m apart. The striking new data shook conventional wisdom, and caused a reevaluation of rules of thumb. Today, aeromagnetic contractors are busier than ever.
The conventional use of aeromagnetics, to map basement structure, has had to make room for new concepts. An explorationist now thinks of using highresolution aeromagnetics when: