In conventional utilization of the seismic reflection method, it has traditionally been assumed that seismic signals can be viewed as a band-limited normal incidence reflection coefficient series with appropriate traveltime and amplitude variation due to propagation through an overburden. Ostrander (1982) demon strated that gas sand reflection coefficients vary in an anomalous fashion with increasing offset and showed how to utilize this anomalous behavior as a direct hy?rocarbon indicator on real data. This work populanzed the methodology which has come to be known as amplitude variation with offset analysis (A VO). In addition to being a "seismic lithology" tool, AVO provides an improved model of the reflection seismogram which allows us to better stimate both normal incidence reflection coefficients and "background" velocities. Exploration geophysics is, to a large extent, a science of anomalies. It is probably safe to assume that most hydrocarbons found in the past fifty years have been associated with some kind of geophysical anomaly. Explorationists routinely utilize deviations from expected gravity, seismic traveltime, and seismic amplitude, without recovering uniquely determined absolute density, depth, or reflectivity. Consequently, significant risk is associated with drilling a well, even when all the technology and analysis available have been thrown at the problem. Experience has shown that geophysical anomalies can be used to reduce risk and consequently, to identify new prospects.

Tidak tersedia versi lain

Tidak Ada Data