Seismic modeling with minicomputers

The energy crisis has created increased interest in petroleum exploration. Discoveries of major deposits are increasingly rare and difficult to locate. The geophysicist requires more accurate knowledge to assist him in locating deeper and smaller hydrocarbon deposits. While gravity, magnetic, and electrical methods are also used, the predominant exploration tool is the seismic method and provides a wealth of subsurface information. Geophysicists continue to increase their seismic proficiency by using such things as modeling. The concern of this paper is the ability to model the seismic response of a known subsurface. The practicality and usefulness of a modeling technique is determined by how accurately, routinely, and economically it may be used to simulate realistic cases. Modeling techniques, such as numerical solutions to the wave equation and ray tracing, are possible and offer distinct advantages and disadvantages. The method presented in this paper is a numerical solution to the wave equation obtained by finite difference techniques. A brief background in seismic methods and theory is presented. The numerical modeling technique is described, and a typical example is given. Also discussed is a minicomputer system which makes the method economically feasible for routine use.