Abstract

This paper, the SEG Research Committee's second annual review of current developments in exploration geophysics, will emphasize research activities at universities and other non-commercial institutions which relate closely to geophysical exploration.Industry developments worth noting in the seismic field include the considerable increase in use of magnetic recording, use of pressure-sensitive geophones with preamplifiers in the bay and marsh areas of the Gulf Coast, use of fathometer-type instruments to obtain near bottom layering in marine areas, and use of nonphotographic methods of reproducing seismic data. Considerable experimentation with weight dropping techniques, and with use of higher frequencies to get better resolution has continued during the past year. Use of models, particularly two dimensional models, is increasing.There have been significant innovations in logging techniques, particularly in the use of in-hole accelerators for neutron generation, and in the development of in-hole equipment for measuring gamma ray spectra. The use of continuous velocity logs is increasing.Academic research has been of two kinds. First, there are studies of basic physical principles underlying current or prospective exploration methods which could lead to improvements and new applications. Secondly, geophysical methods originally developed for petroleum exploration are being employed for large-scale investigations of the earth's crustal structure. These studies should contribute important information on the geology of such features as continental shelves, geosynclines, and mountain systems, information potentially useful to geologists for developing new concepts in exploration thinking. The two kinds of research illustrate the current interdependence between 'pure' and 'applied' geophysics.Important research projects on scattering, statistical improvement of signal-to-noise, explosion-wave generation in the earth, and surface waves exemplify the activity going on in university laboratories today which may result in improved seismic exploration techniques tomorrow. Conversely, university-sponsored seismic and gravity investigations of the deep oceans, the continental margins and various western mountain chains illustrate how geophysics is contributing basic geologic information on a regional to global scale.

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