Inversion

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Seismic inversion is the technique of converting seismic survey reflection data into a quantitative rock-property description of a reservoir. Seismic inversion can be applied on pre- or post-stack, using deterministic or stochastic methods.

Inversion incorporates both seismic data and well data – the well data serves to add the frequency below the seismic band and to constrain the inversion.

Low-frequency data is derived from log data, pre-stack depth or time migrated velocities. High frequency can be derived from well control or geostatistical analysis.

Initial inversions can be run, starting with the seismic and then adding limited-trend data from the wells to provide an overview of the reservoir. The accuracy of inversion results to well ties and seismic to synthetics is tested, and wavelets matched to phase and frequency. Wavelet generation can be either via Stochastic or Deterministic techniques.

AVO geostatistical inversion can be used to then incorporate simultaneous AVO inversion into the geostatistical inversion algorithm so high resolution, geostatistics, and AVO may be attained in a single method. The AVO inversion derives elastic properties (P-impedance, S-impedance,Vp/Vs, and density) and lithology volumes.

Output models match input data; therefore, uncertainty can be quantitatively assessed to determine the range of reservoir possibilities within the constraining data.