The application of surface geochemical methods to finding petroleum is based on the detection of hydrocarbons in the soil that have leaked from a petroleum reservoir at depth. While the "seal" over the deposit was once considered impermeable, surface geochemistry data now show that such leakage is a common occurrence. Despite its simplicity and low costs, surface geochemistry remains controversial because, until now, there was no objective and in-depth treatment of the various methods of surface geochemistry for oil exploration. Written by a successful oil finder, this practical guide: surveys a broad array of surface geochemistry techniques, from soil gases to microbiology, and provides clear strategies for applying them to the high-stakes art of petroleum exploration; offers numerous case studies, both successes and failures, to show the strengths and weaknesses of different approaches; examines statistical and spatial variation, surveys, and models in surface geochemistry, demonstrating how each analytical tool can be used to optimize accuracy; integrates surface geochemistry data interpretation with data from conventional methods of oil exploration, and considers the economics of surface geochemical approaches; and discusses key topics that have been neglected in the literature, such as grid design and the effects of soils.