Aletho News

Natural Gas and Oil

Thomas Gold | January 1997

Natural gas and oil are widely considered to originate on Earth from the chemical evolution of biological debris. A view, widespread in earlier times and entertained by Mendeleev among others, was instead that these substances originated in materials laid down in the formation process of the Earth, and later percolated towards the surface.

Similar hydrocarbons are widespread on many other planetary bodies, as well as on comets and generally in deep galactic space, clearly not related to biological materials there.

Thermodynamic considerations show that in the high-pressure, high-temperature regime of the outer mantle of the Earth, hydrogen and carbon will readily form hydrocarbon molecules, and some of those will be stable during ascent into the outer crust. There is no reason now for invoking the unique origin of biology for the Earth’s hydrocarbons, different from the origin of similar materials on the other planetary bodies.

The many molecules of unquestionably biological origin in petroleum – hopanes, pristine, phytane, steranes, certain porphyrins – can all be produced by bacteria, and such microbial life at depth is indeed now seen to be widespread. The presence of these molecules can no longer be taken to be indicative of a biological origin of petroleum, but merely of the widespread presence of a microflora at depth. The presence of helium and of numerous trace metals, often in far higher concentrations in petroleum than in its present host rock, has then an explanation in the scavenging action of hydrocarbon fluids on their long way up. Many mineral deposits may be due to the formation and transportation of organo-metallic compounds in such streams, often interacting with microbial life in the outer crust.

A 6.6 km deep well drilled in the granite of Sweden shows petroleum and gas, and bacteria that can be cultured, all in the complete absence of any sediments, and hence of any biological debris. Combustible gas in large sample containers has been brought to the surface from a depth of more than 6.5 km. It will readily burn, and it shows a composition which includes methane and heavier hydrocarbons up to C-7, as well as free hydrogen. The greatest concentrations of this gas are in and close to the various intrusions of volcanic rocks (dolerite), indicating that the gases have used the pathways from depth that the volcanic rock created or used in its ascent.

The Origin of Methane (and Oil) in the Crust of the Earth

Thomas Gold

U.S.G.S. Professional Paper 1570, The Future of Energy Gases, 1993

Abstract

The deposits of hydrocarbons in the crust of the Earth have long been regarded by many investigators as deriving from materials incorporated in the mantle at the time of the Earth’s formation. Outgassing processes, active in all geological epochs, then transported the liquids and gases liberated there into porous rocks of the crust. The alternative viewpoint, that biological debris was the source material for all crustal hydrocarbons, gained widespread acceptance when molecules of clearly biological origin were found to be present in most commercial crude oils.
Modern information re-directs attention to the theories of a non-biological, primeval origin. Among this information is the prominence of hydrocarbons—gases, liquids and solids—on many other bodies of the solar system, as well as in interstellar space. Advances in high-pressure thermodynamics have shown that the pressure-temperature regime of the Earth would allow hydrocarbon molecules to be formed and to survive between the surface and a depth of 100 to 300 km. Outgassing from such depth would bring up other gases present in trace amounts in the rocks, thus accounting for the well known association of hydrocarbons with helium. Recent discoveries of the widespread presence of bacterial life at depth point to this as the origin of the biological content of petroleum. The carbon budget of the crust requires an outgassing process to have been active throughout the geologic record, and information from planets and meteorites, as well as from mantle samples, would suggest that methane rather than CO2 could be the major souce of surface carbon. Isotopic fractionation of methane in its migration through rocks is indicated by numerous observations, providing an alternative to biological processes that have been held responsible for such fractionation. Information from deep boreholes in granitic and volcanic rock of Sweden has given support to the theory of the migration of gas and oil from depth, to the occurrence of isotopic fractionation in migration, to an association with helium, and to the presence of microbiology below 4 km depth.

Introduction

The gas methane, CH4, the principal component of natural gas, does not contain sufficient evidence in itself from which to deduce its origin on the Earth. There is some evidence from its isotopic composition, but interpretations of that are not unique. Information, however, exists in the mode of occurrence of natural gas reservoirs, in the geographic and geological relationships, in associated chemicals, and, above all, in the frequent association with other hydrocarbons, specifically crude petroleum and bituminous coal. Although there are numerous occurrences of natural gas without the heavier hydrocarbons, the association is generally so clear that one cannot contemplate an origin for the natural gas deposits independent of those of petroleum. We shall therefore first consider the origin of the whole set of hydrocarbons, including natural gas, and then discuss aspects that are specific to methane. … continue

December 15, 2014 - Posted by aletho | Economics, Malthusian Ideology, Phony Scarcity, Science and Pseudo-Science, Timeless or most popular