Direct indication of hydrocarbons by airborne and ground magnetic survey
It has been proposed that high frequency, low amplitude magnetic anomalies are sometimes found over hydrocarbon deposits. To test this, aerogeophysical data sets, comprising both magnetic and gamma-ray spectrometer measurements, over two known and one prospective hydrocarbon deposits in the United Kingdom, are examined and detailed surface magnetometer traverses are investigated. No hydrocarbon induced magnetic anomalies have been detected. The majority of the high frequency events occurring in the aeromagnetic data correlate with cultural features, others are attributed to artefacts of the data processing. In particular there are no areas of extensive high frequency, low amplitude anomalies. None of the oil fields investigated possess a characteristic spectrometric signature. Anomalies are found to be related to hydrological conditions and to the distribution of superficial deposits. When borehole chippings from the two known hydrocarbon deposits are examined, high magnetic susceptibilities are found to be due to contamination from the drilling. Magnetite, identified by mineralogical analysis, is found to be of detrital origin. It is very unlikely that high resolution aeromagnetic surveys can be used for hydrocarbon exploration in the European context of high levels of cultural noise. In particular, an anomaly found over one of the hydrocarbon prospects is caused by the cumulative effect of borehole casing. This cultural contaminaton from oilfield equipment may explain some of the anomalies discovered over hydrocarbon deposits in North America.
Bibliographic Reference: EUR 12837 EN (1990) 154 pp., MF, ECU 8
Record Number: 199010756 / Last updated on: 1994-12-01
Original language: en
Available languages: en