Feasibility Studies

Based on well logs or elastic velocity models, we calibrate rock physics models and  construct forward what-if scenarios. We provide a thorough assessment of CO2 detectability and information content that can be retrieved under various acquisition geometries and scenarios. Our comprehensive anisotropic 2d and 3d true viscoelastic (frequency-dependent elastic constants) finite difference solver, coupled to moment-tensor sources is particularly suited to the task and can handle reflection, VSP as well as passive seismic with traditional or DAS receivers.

We perform fluid/fracture identification using extracted prestack amplitudes along azimuthal and angle gathers over horizons. We use our rock physics-modelling preprocessor coupled to a full anisotropic Zoeppritz exploration tool to find scenarios that best match the data corresponding to regional circumstances. Likewise, we incorporate the frequency-dependent attenuation in these analyses, in order to assess sensitivities of angle gathers to fluid content from frequency-dependent AVO attributes.

Our proprietary PWI method uses dictionary learning techniques to jointly invert data for reflectivity and instantaneous phase which is directly related to intrinsic attenuation. The method improves estimates of the thickness of the injected CO2 layers and enhances the interpretation of pay/no-pay zones. The method is potentially applicable in areas where estimation of gas saturations is of interest. Projects typically involve seismic and well log data from which we run the inversion technique alongside traditional impedance inversions and then interpret the results on the basis of rock physics models calibrated to regional circumstances. From  these we deliver thickness and intrinsic attenuation maps which can be interpreted with our extensive rock physics library. In the example from Sleipner above (data courtesy of Equinor/CO2datashare),  the PWI result on the right highlights the area of the horizon where there is discrepancy between traditional impedance inversion and phased inversion due to wavelet phase.

Our many years' expertise in anisotropic seismic data analysis and interpretation can be used to assess fluid pathways, permeability and fracture orientation. Using established rock physics models, we have performed analyses on walkaround VSP, wide and narrow azimuth reflection seismic data obtained with OBS, as well as converted waves with emphasis on shear wave splitting analysis for fluid identification.