Direct Detection of Hydrocarbons Using Seismic Procedures

摘要

The aim of this project was to utilize such information about physical properties of the subsurface for a quantitive lithological interpretation as is contained in amplitude, polarity, and frequency content of seismic signals. Methods for determination of amplitudes and spectra of seismic signals were combined to form a reliable and versatile interpretational system which allows an economical, semiautomatic extraction and a spatial presentation of various seismic parameters for lithological studies. An application of the system to an offshore survey area shows clear correlation between high amplitude anomalies and gas zones. Other indicators of hydrocarbons do not show such significant anomalies. Any quantitative interpretation of the results is impeded by complex layering of sandbeds which cannot be resolved by seismic techniques. The reliable lithological interpretation has to be tested by further experimental application to seismic data and has to be supported by petrophysical studies. A method was developed which allows a reliable determination of frequency-dependent attenuation if clear signals, undistorted by interference, are available and if comparatively high minimal attenuation is present. Problems which occur in the application to seismic data are discussed.