Evidence for Deep-Earth Gas

Abstract

The abiogenic theory of petroleum formation presumes that an enormous source of pri-mordial hydrocarbons resides in the upper mantle and lower crust—far deeper than can be drilled and sampled directly. Consequently, we must search for evidence in the regions of crust that our drilling equipment can penetrate. What empirical evidence in the shallow crust or at the earth’s surface favors the theory that a substantial source of hydrocarbons exists at great depth?