Do natural gas and oil are inexhaustible? 

A revolutionary geological theory that fits the facts of reality
D.Anton
Thomas Gold theory about the origin of oil and natural gas represents a profound change of paradigm. In the mantle of the Earth, maybe at about 200-400 kilometers below the surface the conditions for the formation of methane (CH4) are given. Because methane is less dense it tends to rise when fractures form in the overlying rocky cover.

It is a slow process that can take millions of years (even hundreds of millions) until it approaches the surface. In its rise methane is oxidized. This oxidation takes place taking oxygen from iron oxides (hematite), sulphates (anhydrite) and other oxygenated salts and oxides. Hydrogen is converted into H2O (water) and carbon into CO2 (carbon dioxide). Hydrogen is more easily oxidized so that carbon becomes more concentrated, CH4 turns into C2H6 (ethane), which in turn becomes C3H8 (propane), which turns into C4H10 (butane), and so on, until liquid hydrocarbons (eg naphthas) are formed. The process continues and viscous fluids (tar and bitumen) form followed by solid compounds (lignite, hard coal and anthracite).
This process occurs naturally but at shallower levels (less than 10 km) the metabolic action of hipertermobacterias accelerate it. These bacteria live in the pores of rocks at high pressures and temperatures of 100 degrees Celsius or higher.

The oxidation of metal sulfides generally metal sulfates which are transported by the carbonaceous fluids until precipitate to form metal deposits (eg lead sulphide-galena, iron-pyrite, copper-chalcopyrite, zinc-blende, etc.) .
In their rise hydrocarbons may be retained by rocky mantles or impermeable layers leading to its accumulation forming oil and/or gas deposits.
Thomas Gold offsets orthodox theories, he contends that hydrocarbon deposits are of mineral (abiotic) origin with some bacterial collaboration (but it is not fossil) and many metal deposits are of biotic origin.
According to Gold existing volumes of oil and gas are much more abundant than is generally held (the fall in prices shows in the facts that there is oversupply which in turn is related to hydrocarbon abundance).
Orthodox scientists have a problem: they will have to redesign their hydrocarbon search and exploitation strategies, and of course, rewrite their books. Logically, they oppose that, as often happens in any abrupt change of paradigm. But as usual, the reality is finally imposed and, eventually, the theory of fossil oil (for me an absurd scientific idea) that is supported by the vast majority of geologists, engineers, academics, bureaucrats and politicians, like so many other falsehoods, in the end will collapse.
(To supplement information on this topic should read the book by Thomas Gold, "The Deep Hot Biosphere" or a summarizad version which I published some time ago entitled "Inexhaustible? Petroleum and Natural Gas" D.Anton, 2006, Piriguazú Ediciones).