"On the Fly" Stratigraphic Basin Modelling From Seismic Interpretation Workstations

Abstract

Abstract Seismic intepreters already use the principles of sequence stratigraphy to help interpret the geometry and sedimentary facies of the sedimentary bodies seen on seismic data. Linking seismic interpretation to a well database containing information on bathymetry and lithology, by using ultra-rapid algorithms simulating sediment transport, can help the interpreter to rapidly test and modify the stratigraphic scenario inherently present in the geometry and nature of the surfaces that have been picked. This "on the fly" stratigraphic modelling should make seismic stratigraphic interpretation easier and simpler to perform. Various image-processing techniques can also be of help to the interpreter, both in determining depositional environment from seismic textural analysis and in a more rapid identification of the key toplap, onlap, downlap and truncation surfaces present in the seismic data. Again, linking the textural information with the well database can lead to a better use of both types of data. The above techniques have been applied to seismic and well data of the National Petroleum Reserve Alaska, as a structured workflow involving the construction of a detailed geomodel and time-to-depth conversion cube. For each of the sequences picked on the seismic, the direction and composition of the principal sources of clastic supply are determined, and paleobathymetrical maps are generated, all of which are coherent with the well data (interpreted lithology and depositional environment) and the picked thickness of the sequence on seismic. The interpreter can then choose to view the seismic data of the next sequence in «true stratigraphic position» by shearing to fit the modelled bathymetrical profile of the underlying sequence. He or she may also choose to review and reinterpret the well data or repick the seismic surfaces in the light of the realistic paleogeographical scenario generated by the stratigraphic modelling. Introduction The aim of the present work was to test the application of algorithms designed to assist seismic interpretation for petroleum exploration by using the principles of forward stratigraphic basin modelling. We used a data set from the North Slope, Alaska which is freely available online from the United States Geological Survey (see below). The data to be fitted by the stratigraphic forward modelling included the thickness of stratigraphic intervals between markers picked on seismic data, the bathymetry and the lithological content of these interval identified in wells.