Exploration seismology deals with the use of artificially generated elastic waves to locate hydrocarbon deposits, geothermal reservoirs, groundwater, archaelogical sites, and to obtain geological information for engineering. Exploration seismology provides data that, when used in conjunction with other geophysical, borehole and geological data, and with concepts of physics and geology, can provide information about the structure and distribution of rock types.

Marine seismic acquisition

Exploration seismic methods involve measuring seismic waves traveling through the Earth. Explosives and other energy sources are used to generate the seismic waves, and arrays of seismometers or geophones are used to detect the resulting motion of the Earth. The data are usually recorded in digital form on magnetic tape so that computer processing can be used to enhance the signals with respect to the noise, extract the significant information, and display the data in such a form that a geological interpretation can be carried out readily.

The basic technique of seismic exploration consists of generating seismic waves and measuring the time required for the waves to travel from the source to a series of geophones, usually disposed along a straight line directed toward the source. From a knowledge of traveltimes to the various geophones, and the velocity of the waves, one attempts to reconstruct the paths of the seismic waves. Structural information is derived principally from paths that fall into two main categories: refracted paths in which the principal portion of the path is along the interface between two rock layers and hence is approximately horizontal; and reflected paths in which the wave travels downward initially and at some point is reflected back to the surface, the overall path being essentially vertical. For both types of path, the traveltimes depend on the physical properties of the rocks and the attitudes of the beds. The objective of seismic exploration is to deduce information about the rocks from the observed arrival times together with variations in amplitude, frequency and waveform.

Geophone cable for marine seismic acquisition

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