f Geological Expression: Using geophysical data to understand structural geology

Geophysical data such as seismic reflectivity, inversion, and well data contain a wealth of information about the subsurface geology, but often in a form that is hard to understand or interpret. To compensate for this, the information extracted is often in a simplified form, and therefore information is lost. We present some easy to use workflows which directly translate the geophysical data into geological information allowing the interpretation of complex structure using all the information available. Attribute analysis of reflectivity data for the purposes of fault interpretation is usually limited to some form of discontinuity or coherence measure, and usually only one volume is used. This can be an effective first pass, however one volume does not show you the subtle changes in the fault expression. Using different attributes which are sensitive to different geophysical expressions, and combining those attributes together in an easy to view way, we can extract geological information such as throw, drag, damage zones, and lithology changes down the faults. This technique has been effective in both exploration areas where there is limited well data, and mature fields where more is known about the geology. We present the results of a structural analysis of data from NW Australia, in a complex fault zone where the detail of the faults was hard to determine. Using these Geological Expression techniques we have been able to understand the fault behaviour and the structural setting of the area.