Patent ID: 7912649

Claim:
A computer apparatus loaded with machine executable instructions for implementing a method of characterising a hydrocarbon reservoir contained in a region of interest, the method comprising: providing the computer apparatus with a set of measured controlled source electromagnetic (CSEM) data of the region of interest; providing the computer apparatus with a set of measured seismic data of the region of interest; defining in the computer apparatus an earth model of the region of interest by setting values of a plurality of earth model parameters; defining in the computer apparatus a rock physics model with a plurality of interdependent relations linking rock property parameters of the region of interest, including porosity, elasticity moduli, water saturation level and hydrocarbon saturation level, with elastic and electrical parameters of the region of interest, including P-wave velocity, S-wave velocity and electrical conductivity; setting in the computer apparatus values for the rock property parameters; computing in the computer apparatus a set of synthetic CSEM data of the region of interest with said values of the rock property parameters and using survey equipment parameters for a CSEM transmitter and CSEM receivers matched to those used when collecting said measured CSEM data; computing in the computer apparatus a set of synthetic seismic data of the region of interest with said values of the rock property parameters and using survey equipment parameters for a seismic transmitter and seismic receivers matched to those used when collecting said measured seismic data; and perturbing in the computer apparatus the values of at least a subset of the rock property parameters in order to find a fit of the synthetic CSEM and seismic data to the measured CSEM and seismic data respectively, thereby to determine the hydrocarbon saturation level of the hydrocarbon reservoir.