Structure sometimes creates fracture networks that can be important in conventional plays, but are often key elements of unconventional plays. Likewise, lineaments can be sources of fluid migration in a basin such as petroleum, gas, or water. If water moving through a system is hot enough due to nearby volcanism or has unusual components such as acids (sometimes formed during petroleum generation), or perhaps high levels of occluding minerals like anhydrite, these fluids can increase maturity with heat, open up porosity with dissolution, or alternatively occlude porosity by precipitating minerals. Structure is one of the primary tools for predicting fluid migration paths. If the timing of the fluid movement is understood (often with clues from structural history) the changes it may have rendered to the source rock or reservoir rock before or after petroleum migration can be hypothesized. In unconventional exploration in shales, these sources of heat often lead to identification of "sweet spots." Without understanding structure, none of these ideas could even be conceived.
Spindletop, the famous well in Texas that was drilled in 1901 on a structure that was visible at the surface. http://www.history.com/topics/oil-indust…