Abstract
Until the digital processing of seismic data was introduced to Japan in 1968, Japanese geologists had no means but to depend on the seismic depth profiles which displayed very short lines showing inclination of reflection planes picked up by seismologists. There was only a small discovery of the Tuchizaki-oki field those days. After the air-gun and digital processing became available in 1968, offshore exploration activities expanded and led to the discovery of the Aga-oki field in 1972. From the viewpoint of seismology, this discovery was based on stack sections and “hand-made depth sections” which displayed continuous curves indicating prominent reflections. Abnormal reflection patterns such as bright spots, flat spots and pull down began to attract geologists' attention in the mid-1970s, and various processing menus in addition to depth profiles were provided for geologists. In 1981, certain abnormal patterns were found in seismic record sections obtained in 1973, an exploratory well, Iwafune-oki SIM-1 was drilled at the center ofthe distribution area of such anomalies and became the discovery well of the Iwafune-oki field.
Based on these experience, I emphasize the importance of stack sections in conjunction with wide and deep geological knowledge and thought.
-Oil and gas fields are present in geologists' brains-
