Abstract

In this paper, we integrate 3-D seismic and wireline log data to illustrate some modern techniques of seismic stratigraphy. The imaging target is the Lower Cretaceous Mannville Group, traditionally one of the main targets for hydrocarbon exploration and production in Western Canada. The depositional environments for the Mannville Group in our study area were diverse, ranging from fluvial to shallow marine. Mannville Group strata overlie a major unconformity that separates them from predominantly carbonate rocks of the Paleozoic (Devonian).

As a first step, we integrated wireline logs and seismic amplitude data in a qualitative way and gained more stratigraphic insights than could be obtained with either data set alone. We then used seismic inversion and a seismic attribute study to make quantitative lithology predictions. Acoustic impedance inversion proved to be an excellent tool for mapping the unconformity, clearly distinguishing the clastic rocks above from the carbonate-dominated units below it. However, the inversion result did not clearly define stratigraphic features within the Mannville Group. To that end, we generated a pseudo-lithology (gamma-ray) volume for the Mannville Group by integrating wireline logs and seismic attributes using a neural network. This pseudo-lithology volume identified stratigraphic features that were not apparent in either the original seismic amplitude or the inversion volume. The results of this study show how integrating the three different 3-D seismic versions was useful for understanding the stratigraphic complexity of the Mannville Group. The approach presented here can be used for similar purposes in other geological settings.