Oil and gas exploration is tied to sedimentary rooks being burried and temperature and pressure cracking kerogen to create liquid and gas hydrocarbons. Once a hydrocarbon molecule is created it is driven to reach the surface of the earth because it is lighter than water. If there are ancient beach sands or other reservoir rocks covered by seals like shales, these become upside down reservoirs where hydrocarbons accumulate. 3-D seismic surveys, like shown in the lower right image, have proven to be the best way to image these underground hydrocarbon reservoirs. Interpreting these surveys is like a complex jigsaw puzzle, where the objective is to define the subsurface geology.