Initially I regarded this chapter as one for specialists interested mainly in devising new processes. Then I realized that in dealing with things that don't seem to work as they are expected to, we are really, for the first time, struggling to contend with reality, not with what theory predicts. This can hold much interest for skilled interpreters.
The heart of petroleum prospecting is the interpretation of reflection seismic data. What is seismic interpretation? To be a ``routine interpreter'' you must know everything on which theory and practice generally agree. To be a good interpreter you must know the ``noise level'' of alternate phenomena with similar effects. Anomalies in seismic data can arise from the complexity of the earth itself, from seismic wave propagation in the earth (deep, near surface, or out of plane), or from imperfections in recording and imaging techniques. To make realistic judgements in so wide a realm, you must be a seismologist who is part geologist, part engineer, and part mathematician. This chapter will not teach you to be a good interpreter, but it will offer you a chance to observe some critical thinking about the relationship of seismic theory to seismic data.