David Cho

Marine source signature estimation for AVO inversion with no well control using a constant Q attenuation model

Summary Amplitude variation with offset inversion can provide insights to reservoir properties that bring uplift to reservoir characterization studies. Typically, well log data is utilized to calibrate the seismic data to well log measurements by the extraction of the seismic wavelet. However, this is not always possible in frontier basins where little or no well control is available. This study documents the wavelet extraction process for a pre-drill AVO inversion for an offshore exploratory well in Eastern Canada. The methodology implemented in this case combines statistical wavelet estimation methods, the water-bottom wavelet and a constant Q attenuation model in the estimation of target level wavelets used in the inversion. All assumptions inherent in the proposed methodology are documented and discussed.

Fractured shale description using isotropic seismic analysis

AbstractDirect methods for fracture detection using P-wave seismic data typically require an azimuthal analysis of the reflected wavefield. However, conventional data acquisition practices often lack sufficient azimuthal coverage for proper application of these techniques. In such cases, alternative methods become necessary. We investigated the use of subsurface properties estimated from seismic data under isotropic assumptions to delineate fracture systems in the Second White Speckled Shale of Alberta, Canada. We implemented two methodologies for fracture detection. (1) Using seismic attributes sensitive to the structure of the seismic image, structural changes such as folds were identified, from which the associated fracture systems can be inferred. (2) For fractures not directly correlated to such structural changes, analysis of the effective elastic properties of fractured media proved useful. In particular, failure criteria and effective-medium theories were used to investigate fracture phenomena and...