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.

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

A method of seismic analysis is disclosed for determining geopressures or seismic velocities or other formation attributes. In one embodiment, a frequency related attribute is determined from seismic data by analysis of the frequency content of one or more signal traces. Geopressure or velocity may then be derived from the frequency related attribute without reliance on moveout techniques. In another embodiment, a derivative of a maximum value of pore pressure is utilized to determine a transition zone whereby the derivative peaks and then recedes. The lithology is then examined to determine a formation directly below the transition zone at which an overpressure may exist

Method of seismic signal processing

A model for simulating the behaviour of an underground reservoir is defined from initial geologic knowledge and available data. It allows production forecasts to be achieved from parameters representative of the initial data. The method notably consists in defining one or several possible production evolution scenarios by creating, for each of these scenarios, new production data corresponding to hypotheses on the future states of the reservoir. For each scenario considered, it is checked whether it is possible to adjust the available parameters of the simulation model, considering the constraints of the initial geologic model, so that the simulation model reproduces both the production data measured and the data added. The method can be used to quantify uncertainties on the production forecasts by seeking the min/max extremes of the future production values. Application : production of hydrocarbons for example.

Method for predicting, by means of an inversion technique, the evolution of the production of an underground reservoir

In an exemplary embodiment, a method and system is disclosed for developing a subterranean geomechanics model of a complex geological environment The method can include estimating a pore pressure field, a stress field, a geomechanics property field, and a geological structure field from a geological concept model; geostatistically interpolating vectors and tensors from the estimated fields; and combining the results from the estimated fields and the geostatistically interpolated vectors and tensors to derive a geostatistical geomechanical model of the geological environment

Methods and systems for constructing and using a subterranean geomechanics model spanning local to zonal scale in complex geological environments

Seismic data is combined with well log data to generate a two-dimensional geopressure prediction display; this permits deviated and horizontal well planning plus lithology detection. Shale fraction analysis, compaction trend, and seismic velocity may be automatically or interactively generated on a computer work station with graphics displays to avoid anomalous results. Corrections to velocity predictions by check shots or VSP, and translation of trend curves for laterally offset areas increases accuracy of the geopressure predictions. Multiple wells' logs in a basin permits analysis fluid migrations.

Geopressure analysis system

A method of predicting pore pressures at a proposed drilling location using Interval Transit Times derived from seismic data and Interval Transit Times from a calibrated normal geopressure trend. Seismic Interval Transit Times derived pore pressures and actual pore pressures derived from logs in a drilled well at an offset location are used to correlate graphically or analytically the seismic Interval Transit Times to normal geopressure interval transit times from a proposed drilling location to be used in the prediction of pore pressures at the proposed location.

Robert R. Weakley

Papers

Pore pressure prediction method