Integrated Geological and Geophysical Analysis by Hierarchical Classification: Combining Seismic Stratigraphic and AVO Attributes

Seismic attributes analysis and classification for exploration and reservoir characterization have been widely published. Applications vary from standard horizon-based facies classification maps to more recent 3D multi-attribute facies classification volumes. The approach is usually the same and run in a two-step procedure. First, an unsupervised classification aims at revealing the natural clustering of the data, and second, a supervised scheme is applied where training and validation data are used to redefine the class cloud point centers based on well log data flagging a specific fluid or lithology. The limitations of these approaches are that they are focused on one aspect of the seismic response, usually fluid, and tend to neglect the geological framework. In these workflows, more attention is put on the reservoir facies for fluid and potential lithology detection, while the seismic seismostratigraphic signature is overlooked or not used as a constrain in the attribute analysis. We present a case study in which both texture facies and fluid prediction are linked by performing a hierarchical classification and estimation scheme whereby a multiattributes volume, which captures seismic stratigraphy and texture information, is combined with AVO attributes to map fluid response into a single, coherent seismostratigraphic and reservoir facies volume. This methodology is applied for exploration data screening in offshore Borneo in the Greater Samarang sub-block (East Baram Delta, offshore Sabah, Malaysia). In this case study, geological framework, seismic geomorphology, seismic stratigraphy, and combined fluid response from AVO data calibrated with well data facilitate the development of new play concepts in the highstand system tracts and in the morphology generated by incisions in the shoreface deposits during the low stands.