Geophysicists are trained mathematicians, physicists and computer specialists.
They all acquire a good grounding in descriptive geology to enable them to work closely with geologists in order to generate images of petroleum traps from the data collected. Geophysicists use a variety of methods, depending on the geological object they wish to visualize. During initial reconnaissance of unexplored terrain, they may detect geological structures that can stretch over several miles, such as a basin's non-visible limits. Once the contours and depth of the sedimentary basin have been ascertained, seismic refraction, and more often seismic reflection techniques, are used. If the point from which the sound wave was generated, and the speed at which it travels through the different rocks are known, then one can deduce the depth of the stratum from which the wave was reflected.