Transcript for Wrestling with Uncertainty, segment 08 of 16
Rocks exposed at the surface frequently provide a clue to what exists thousands of feet below so the search for petroleum commonly begins here. These outcrops and others like them may be our only glimpse of the character of the rocks that lie buried beneath.
We can get a pretty good view of what's present beneath the surface through seismology. Seismic waves generated at the surface move through the crust, reflecting from different rock layers. The records of these reflections appear chaotic, but they contain information that lets us build a picture of what exists below the surface. They don't actually show us where oil and gas occur, but they do indicate where geologic conditions are favorable. We can prove that petroleum is present only by drilling a well. If it hits oil or gas, an exploration play is set in motion.