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1. (WO1999008131) METHOD FOR DETERMINING THE PRESENCE OF FLUIDS IN A SUBTERRANEAN FORMATION

Pub. No.:    WO/1999/008131    International Application No.:    PCT/US1998/016676
Publication Date: Feb 18, 1999 International Filing Date: Aug 11, 1998
IPC: G01V 1/28
G01V 1/30
Applicants: TRANS SEISMIC INTERNATIONAL, INC.
PISETSKI, Vladimir, B.
Inventors: PISETSKI, Vladimir, B.
Title: METHOD FOR DETERMINING THE PRESENCE OF FLUIDS IN A SUBTERRANEAN FORMATION
Abstract:
A method for seismic data interpretation for the purposes of identification of oil, gas and water accumulation locations and delineation of their contours uses a model of discrete media with inhomogeneous stresses. For a selected reflection horizon, the relative value of overall pressure gradient is calculated on the basis of instantaneous amplitudes and frequencies of seismic signals using a derived relationship between the reflection coefficients of elastic waves and the stress condition parameter. The calculation technique uses estimates of instantaneous amplitudes and frequencies smoothed over the entire seismic horizon or its fragment. A generalized model of normal (lithostatic) pressure is excluded, and the final interpreted parameters have the sense of relative estimates of anomalous pressure caused by basin dynamics. Maps of anomalous relative pressure and isochronal maps corrected for signal frequency variations along the reflection horizon are constructed using tracking of one or more seismic horizons. The regions of low anomalous pressure within the analyzed fragment of a time section coincident with favorable geometry and specific patterns of the reflection time map are the most probable locations of the accumulation of fluids.