US 5,583,825 A · Method for deriving reservoir lithology and fluid content from pre-stack inversion of seismic data

Abstract

A method for deriving reservoir lithology and fluid content for a target location from pre-stack seismic reflection data. The method uses inversion of pre-stack seismic reflection data for both the target location and a calibration location having known subsurface lithology and fluid content to derive the subsurface lithology and fluid content at the target location. The inversion process is preferably a viscoelastic inversion to account for the effects of friction on seismic wave propagation. The results of the inversion process are a set of subsurface elastic parameters for both the target and calibration locations. Relative magnitudes of these subsurface elastic parameters are compared, together with the known subsurface lithology and fluid content at the calibration location, to derive the subsurface lithology and fluid content at the target location.

Claims35

Dependent claims

A method for deriving the lithology and fluid content at a subsurface target location from pre-stack seismic reflection data obtained at both said subsurface target location and a subsurface calibration location having known lithology and fluid content, said method comprising the steps of:

(a) creating computer models of said subsurface target and calibration locations;
(b) selecting a set of elastic parameters representative of said known lithology and fluid content at said subsurface calibration location;
(c) performing an inversion of said pre-stack seismic reflection data to determine the values of said set of elastic parameters at each of a plurality of points in said models of said subsurface target and calibration locations;
(d) comparing relative magnitudes of said elastic parameter values for said subsurface target and calibration locations;
and
(e) using the results of said comparison and said known lithology and fluid content at said subsurface calibration location to derive said lithology and fluid content at said subsurface target location.

3 more elements

A method for deriving the subsurface lithology and fluid content at a target location, said method comprising the steps of:

(a) selecting a calibration location having a well drilled thereon;
(b) obtaining wellbore measurements from said well and determining the subsurface lithology and fluid content at said calibration location from said wellbore measurements;
(c) obtaining pre-stack seismic reflection data for both said target and calibration locations;
(d) creating computer models of the subsurface at both said target and calibration locations;
(e) selecting a set of elastic parameters representative of said subsurface lithology and fluid content at said calibration location, said set of elastic parameters being selected from the group consisting of the elastic reflection factors for P-wave velocity, S-wave velocity, density, P-wave impedance, S-wave impedance, and ratio of P-wave velocity to S-wave velocity;
(f) performing an inversion of said pre-stack seismic reflection data to determine the values of said set of elastic parameters at each of a plurality of points in said models of the subsurface at said target and calibration locations;
(g) comparing relative magnitudes of said elastic parameter values for said target and calibration locations;
and
(h) deriving said subsurface lithology and fluid content at said target location from the results of said comparison and said subsurface lithology and fluid content at said calibration location.

6 more elements

A method for analyzing pre-stack seismic reflection data for a subsurface target location to determine the presence or absence of significant hydrocarbon accumulations in said subsurface target location, comprising the steps of:

(a) obtaining pre-stack seismic reflection data for a subsurface calibration location having a known hydrocarbon saturation;
(b) creating computer models of both said subsurface target location and said subsurface calibration location;
(c) selecting a set of elastic parameters representative of said known hydrocarbon saturation at said subsurface calibration location, said set of elastic parameters being selected from the group consisting of the elastic reflection factors for P-wave velocity, S-wave velocity, density, P-wave impedance, S-wave impedance, and ratio of P-wave velocity to S-wave velocity;
(d) performing an inversion of said pre-stack seismic reflection data for both said subsurface target location and said subsurface calibration location to determine arithmetic values of said selected set of elastic parameters at each of a plurality of points in said computer models of said subsurface target and calibration locations;
and
(e) comparing said arithmetic vales of said selected elastic parameters at said subsurface target and calibration locations, together with said known hydrocarbon saturation at said subsurface calibration location, to predict the hydrocarbon saturation at said subsurface target location.

3 more elements

Dependencies are inferred from the claim text.

Method for deriving reservoir lithology and fluid content from pre-stack inversion of seismic data

Life of this patent

Method for deriving reservoir lithology and fluid content from pre-stack inversion of seismic data

Life of this patent

Abstract

Claims35