Lesson No. 25: The Three-Dimensional Seismic Path Problem—Single Layer
Published:January 01, 1959
The seismic energy released at the shot-point by the explosion of the charge is transmitted over a three-dimensional region. The full interpretation of the data obtained must be considered therefore from that standpoint. Up to now we have reduced the problems in hand to two-dimensional ones by assuming that the profiles shot were at right angles to the strike of a dipping interface; in other words, that our vertical “section” of the subsurface included the direction of true dip of the bed involved.
If the interface involved in the problem is horizontal or, at worst, of very gentle dip as is quite often the case, the methods we have discussed apply. In fact, these methods are very often used even when the dip involved is sizeable, the questions of applicability of the methods being evaded. This, however, is not always as serious a matter as one might suspect since the “flat” areas, like tops of anticlines and bottoms of synclines, which enter the picture, ought to be mapped reasonably well in any case. It is at the adjacent dips that the two-dimensional interpretation would misplace the bed.
With the present greater need for higher accuracy in subsurface delineation, we shall have to pay more attention to the three-dimensional aspects of interpretation. It is the purpose of the next few lessons to lay the groundwork for an understanding of these problems and to indicate the methods of solving them.
Figures & Tables
Lessons in Seismic Computing
“An elementary text and problem book containing 44 lessons in seismology arranged for selection or combination to cover the normal 36-week course, or for condensation into an 18-week course. The lessons begin without assuming more than secondary school mathematics. An elementary knowledge of calculus is desirable, though not required, for the last half of the book.”