IMPROVED INTERPRETATION OF AN INCISED VALLEY SYSTEM - CHANNEL DELINEATION AND THICKNESS ESTIMATION USING SPECTRAL INVERSION, BLACKFOOT FIELD, ALBERTA, CANADA

Following P-P inversion processes using a constrained model-based inversion and spectral inversion methods for a 3C-3D dataset in the Blackfoot field, the spectral inversion volume achieved better resolution than the original data and the model-based inversion result, increasing the spectrum bandwidth, with the dominant frequency improving from 35 Hz to 90 Hz.

Well ties to the spectral inversion reflectivity volume showed superior correlation to well ties to the conventional seismic data, improving the correlation coefficient from about 0.31 to 0.67 in some wells. After depth conversion, interpretation using this spectral inversion volume produced estimates of Glauconitic channel sand thickness with less than 5% error in 4 out of 5 wells. This sand unit was below the previously held resolution limit (<23m) for the original seismic data volume.

Both the model-based inversion and the spectral inversion results correctly predicted a relatively higher impedance zone at the shale-filled test well 12-16 compared to surrounding channel sand impedances. However, optimal lithology discrimination was achieved using the spectral inversion result, revealing the channel morphology and at least one dry hole in the field (test well 14-09).