The August 2014 edition of Elements Magazine focuses on the global impact of unconventional hydrocarbons. The edition was guest edited by David Cole (DCO Deep Energy Chair; Ohio State University, USA) and Michael Arthur (Pennsylvania State University, USA), and contains three articles contributed by DCO scientists.
In “Unconventional Hydrocarbon Resources: Prospects and Problems,” Arthur and Cole introduce the need for this in-depth and scientific review of the issues surrounding the use of unconventional hydrocarbons as an extensive energy source . Unlike free-flowing conventional sources of oil and gas, unconventional hydrocarbons are trapped as tight-gas sandstones, oil shales, and other formations. Extraction of unconventional hydrocarbons is therefore challenging, and presents technical, practical, and environmental concerns. But, with oil and gas production from conventional sources declining and the ubiquitous global distribution of unconventional sources, international government and industry interest in these resources is intensifying. With such interest unlikely to wane, a fundamental understanding of the geologic processes underlying the formation and exploitation of unconventional hydrocarbons is critical.
Taras Bryndzia (DCO Executive Committee; Shell International Exploration & Production, Inc., USA) and Neil Braunsdorf (Shell International Exploration & Production, Inc., USA) delve into the formation of hydrocarbon source rock formation in “From Source Rock to Reservoir: The Evolution of Self-Sourced Unconventional Resource Plays” . Such source rocks are generally marine and continental sedimentary formations, including clays, quartz, and carbonate, with variable concentrations of organic matter. Trapped in these low-porosity matrices, organic matter matures over time to form hydrocarbon products including oil and gas. Such formation conditions result in source rocks containing oil and gas trapped under pressure in the presence of little to no water. While these features are attractive for exploitation by hydraulic fracturing, associated high concentrations of ions can contaminate ground water during extraction.
In “Abiotic Gas: Atypical, But Not Rare,” DCO’S Giuseppe Etiope (INGV, Italy) and Martin Schoell (GasConsult International Inc., USA) discuss the fascinating contribution of abiotic genesis to unconventional natural gas deposits . Natural gas from conventional sources is generally biotic in origin (i.e., it is produced through breakdown of organic matter). However, methane can also be made abiotically via reactions between inorganically derived gases such as carbon dioxide and molecular hydrogen. Such abiotic genesis is usually the result of magmatic processes (such as hydrolysis or hydrogenation of metal carbides) or gas-water-rock reactions (such as serpentinization and subsequent catalytic hydrogenation of carbon dioxide).
The full table of contents for this edition of Elements can be found here.