THE IMPORTANCE OF REFLECTED REFRACTIONS IN SEISMIC INTERPRETING

Abstract

Even under excellent recording conditions, the interpretation of seismic data is often complicated by the presence of energy not attributable to simple subsurface reflection sources. One type of extraneous energy, more prevalent than commonly realized, is reflected refractions which often complicate seismic results in many areas of the San Joaquin and Sacramento Valleys of California. In localities where the subsurface layering is nearly flat, reflected refractions, because of their steeply dipping alignments, can be readily recognized, although not all of these steeply dipping alignments will be reflected refractions. The geophysicist’s real identification problem comes in areas of steeply dipping geological beds, especially when record quality is poor. His failure to recognize reflected refractions can result in a seismic interpretation having little or no relationship to the true subsurface geological picture.