ISIS Simultaneous Inversion

Find the Best Subsurface Model with Advance
Reservoir Characterization

The ISIS suite of reservoir characterization technologies uses an effective global search for finding the best subsurface model based on simulated annealing; use of trace-to-trace continuity for noise reduction; variable wavelet (both horizontally and vertically); use of low-frequency variation through prior models; and capability of handling very large datasets without segmenting the data. The ISIS simultaneous inversion method can handle AVO converted wave, time-lapse full stack, and time-lapse AVO seismic datasets.

Independent wavelets are estimated for each partial stack and vintage. Any variations in amplitude, frequency, or phase between the different seismic volumes will be captured by the wavelets. Also, there is no need for scaling, phase rotation, or frequency balancing of the seismic data; the wavelets do the balancing in the simultaneous inversion.

ISIS simultaneous inversion is performed directly for

• surface-seismic AVO—it can combine acoustic impedance (AI), Poisson's ratio (PR), and density or AI, shear impedance (SI), and density.
• porosity and saturation (PS) AVO inversion—the parameters are SI and density
• time-lapse, full-stack data—the inversion is done for baseline AI and the changes in AI between each vintage.

For time-lapse AVO inversion, the parameters are the physical properties at the baseline (e.g., AI, PR, and density) and their changes between the different vintages. The ISIS simultaneous inversion can handle any number of vintages and any number of partial stacks for each vintage.

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