Method for interpreting events of seismic records to yield indications of gaseous hydrocarbons

摘要

The present invention indicates that gas-containing strata of an earth formation have low Poisson's ratios and that the acoustic contrast with the overburden rock has a surprising effect as a function of the angle of incidence on a seismic wave associated with an array of sources and detectors: viz., a significant--and progressive--change in P- wave reflection coefficient as a function of the angle of incidence occurs. Thus, differentiating between high-intensity amplitude annomalies of nongas- and gas-containing media is simplified: progressive change in amplitude intensity of resulting traces generated by the field array as a function of offset between each source-detector pair, is associated with the last-mentioned medium only.