Evaluation of the timedip, correlation and coherence maps for structural interpretation of seismic data

In recent years, seismic attribute maps have become important tools in the structural interpretation of seismic data (e.g. Buchanan et al. 1988; Flint et al. 1988; Dalley et al. 1989; Voggenreiter 1991, 1993; Hoetz & Watters 1992; Rye-Larsen 1994; Dorn et al. 1995; Eggink et al. 1996; Jones & Knipe 1996, Hesthammer & Fossen 1997a,b). The attribute maps have proven especially valuable for identifying minor structures such as faults close to or below seismic resolution. Such faults may have a dramatic effect on reservoir performance (e.g. Antonellini & Aydin 1994), particularly for thin reservoir units separated by impermeable shales, but also for thicker sandstone units where deformation structures may drastically decrease permeability. The importance of being able to identify minor faults has led to a marked increase in the focus on seismic attribute maps as the interpreter is challenged to provide more accurate and detailed structure maps. But the increased attention also contains pitfalls that may lead to erroneous interpretation unless the seismic interpreter is aware of the dangers and knows how to quality control the seismic observations (Hesthammer, in press). This paper will focus on the use of the timedip, coherence and correlation maps for structural interpretation of seismic data. Special focus is paid to the problem of seismic noise and how well data may help separate noise features from real structures. A direct comparison of the different attribute maps will help to critically evaluate some of the new, and increasingly popular, methods of attribute analysis for structural interpretation.