US 6,977,866 B2 · Method and process for prediction of subsurface fluid and rock pressures in the earth

Abstract

A method of determination of fluid pressures in a subsurface region of the earth uses seismic velocities and calibrations relating the seismic velocities to the effective stress on the subsurface sediments. The seismic velocities may be keyed to defined seismic horizons and may be obtained from many methods, including velocity spectra, post-stack inversion, pre-stack inversion, VSP or tomography. Overburden stresses may be obtained from density logs, relations between density and velocity, or from inversion of potential fields data. The seismic data may be P-P, P-S, or S-S data. The calibrations may be predetermined or may be derived from well information including well logs and well pressure measurements. The calibrations may also include the effect of unloading. The determined pressures may be used in the analysis of fluid flow in reservoirs, basin and prospect modeling and in fault integrity analysis.

Claims46

Dependent claims

In a method for determining a fracture pressure gradient of a subsurface region of earth formations comprising:

(a) obtaining seismic survey information about the subsurface region;
(b) identifying a plurality of seismic horizons from the obtained survey information;
(c) obtaining estimated seismic velocities corresponding to at least one interval between at least one pair of said plurality of seismic horizons;
(d) calibrating the estimated seismic velocities to the parameter of interest
(e) using the results of said calibration and the obtained seismic velocities to obtain said fracture pressure gradient at any location within the seismic survey;
further comprising displaying the parameter of interest on one of:
(i) P- or S-wave velocity displays;
(ii) P-wave impedance displays;
(iii) S-wave impedance displays;
(iv) P-wave frequency attribute displays;
(v) S-wave frequency attribute displays;
(vi) P-wave phase attribute displays;
(vii) S-wave phase attribute displays;
(viii) density displays;
(ix) P-wave amplitude attribute displays;
(x) S-wave amplitude attribute displays.

13 more elements

A computer system implementing a computer program comprising instructions for:

(a) accessing subsurface seismic data that is at least one of:
(A) a 2-D seismic line, and
(B) a 3-D seismic volume,
corresponding to a subsurface region;
(b) displaying, editing and datuming a well log associated with the subsurface region and fitting a calibration curve to the log;
(c) predicting fluid and rock pressures in the subsurface region based at least in part on the subsurface seismic data and results of the fitting;
and
(d) displaying results of the prediction.

5 more elements

A machine readable medium comprising instructions for:

(a) accessing subsurface seismic data that is at least one of:
(A) a 2-D seismic line, and
(B) a 3-D seismic volume,
corresponding to a subsurface region;
(b) displaying, editing and datuming a well log associated with the subsurface region and fitting a calibration curve to the log;
(c) predicting fluid and rock pressures in the subsurface region based at least in part on the subsurface seismic data and results of the fitting;
and
(d) displaying results of the prediction.

5 more elements

Dependencies are inferred from the claim text.

Method and process for prediction of subsurface fluid and rock pressures in the earth

Life of this patent

Method and process for prediction of subsurface fluid and rock pressures in the earth

Life of this patent

Abstract

Claims46