Are geophysical information on subsurface rock formations gathered by means of a seismograph; the investigation of underground strata by recording and analyzing shock waves artificially produced and reflected from the subsurface bodies of the rock
A surface separating rocks that transmit seismic waves at different velocities.
The data acquired during the seismic survey is processed, partly on board and partly in a computer centre, using a variety of techniques until the final seismic section is obtained. At this stage the data may also be loaded onto an interpretative workstation rather than the traditional paper. The section is then “interpreted”, i.e. “read” by geologists to determine the most fruitful area to drill an exploratory (wildcat) well.
Data acquired by the use of an explosive sound source and a geophones or hydrophones (offshore) to detect sound waves reflected from the underlying rock strata
These are various physical measurements of the nature of the reflected event which may be used for predicting rock properties or hydrocarbon presence. The attributes can be related to reflection of strength, phase, frequency or ratios/relationships with neighboring seismic traces. Advanced attributes include inversion, AVO, coherency and spectral decomposition. Attributes can give indications of: hydrocarbons especially natural gas, faults/fractures (coherency), drilling hazards, porous vs. non porous rock (sandstone vs. shale).
