Skip to main content
Article thumbnail
Location of Repository

Low-temperature gas from marine shales

By Frank D Mango and Daniel M Jarvie

Abstract

Thermal cracking of kerogens and bitumens is widely accepted as the major source of natural gas (thermal gas). Decomposition is believed to occur at high temperatures, between 100 and 200°C in the subsurface and generally above 300°C in the laboratory. Although there are examples of gas deposits possibly generated at lower temperatures, and reports of gas generation over long periods of time at 100°C, robust gas generation below 100°C under ordinary laboratory conditions is unprecedented. Here we report gas generation under anoxic helium flow at temperatures 300° below thermal cracking temperatures. Gas is generated discontinuously, in distinct aperiodic episodes of near equal intensity. In one three-hour episode at 50°C, six percent of the hydrocarbons (kerogen & bitumen) in a Mississippian marine shale decomposed to gas (C1–C5). The same shale generated 72% less gas with helium flow containing 10 ppm O2 and the two gases were compositionally distinct. In sequential isothermal heating cycles (~1 hour), nearly five times more gas was generated at 50°C (57.4 μg C1–C5/g rock) than at 350°C by thermal cracking (12 μg C1–C5/g rock)

Topics: Research Article
Publisher: BioMed Central
OAI identifier: oai:pubmedcentral.nih.gov:2654466
Provided by: PubMed Central
Download PDF:
Sorry, we are unable to provide the full text but you may find it at the following location(s):
  • http://www.pubmedcentral.nih.g... (external link)
  • Suggested articles

    Citations

    1. (2007). 5-year, 100–240°C heating of oils and source rocks in water with different D content: CF-IRMS of C1–C4 hydrocarbon gases record H-isotope exchange with H2O.
    2. Africa; Abstract .
    3. (1994). AT: Role of transition metal catalysis in the formation of natural gas.
    4. (1985). Braun RL: General kinetic model of oil shale pyrolysis. In Situ
    5. (1997). Carbon and nitrogen isotopics in hydrocarbon research and exploration. Chemical Geology
    6. (2000). Carbon isotopic evidence for the catalytic origin of light hydrocarbons. Geochemical Transactions
    7. (1980). Cassou AM: Properties of gases and petroleum liquids derived from terrestrial kerogen at various maturation levels. Geochimica et Cosmochimica Acta
    8. (1993). Chaos in surface-catalyzed reactions.
    9. (1982). Covalent effects in the Effective-Medium Theory of Chemical Binding: Hydrogen heats of solution in the 3d metals. Physical Review B
    10. (1978). Determination of subnanogram per gram quantities of light hydrocarbons (C2-C9) in rock samples by hydrogen stripping in the flow system of a capillary gas chromatograph. Analytical Chemistry
    11. (1999). Elrod LW: The carbon isotopic composition of catalytic gas: A comparative analysis with natural gas. Geochimica et Cosmochimica Acta
    12. (2006). Enhanced late gas generation potential of petroleum source rocks via recombination reactions: Evidence from the Norwegian North Sea. Geochimica et Cosmochimica Acta
    13. (2003). et al.: Oscillatory thermomechanical instability of an ultrathin catalyst. Science
    14. (1985). Evaluation of petroleum generation by hydrous pyrolysis. Philosophical Transactions Royal Society,
    15. (1992). Experimental simulation in a confined system and kinetic modeling of kerogen and oil cracking. Organic Geochemistry
    16. (2003). Field evidence for mineral-catalyzed formation of gas during coal maturation.
    17. (1993). Gyórgyi L: Chaos in Chemistry & Biochemistry River Edge,
    18. (1997). Hightower JW: The catalytic decomposition of petroleum into natural gas. Geochimica et Cosmochimica Acta
    19. (2007). Introduction to Geomicrobiology
    20. (1994). Introduction to Surface Chemistry and Catalysis
    21. (1993). IR: Mixing of thermogenic natural gases in Northern Appalachian Basin. American Association Petroleum Geologists,
    22. (1985). IR: Role of minerals in the thermal alteration of organic matter – I. Generation of gases and condensate. Geochimica Cosmochimica Acta
    23. (1980). Kerogen Technip,
    24. (1993). Laboratory simulation of petroleum formation – hydrous pyrolysis. I n Organic Geochemistry Edited by: Engle
    25. McCrossan RG: Identification of petroleum source rocks using hydrocarbon gas and organic carbon content. Geological Survey Canada,
    26. MD: A laboratory study of petroleum generation by hydrous pyrolysis.
    27. (2001). Methane concentrations in natural gas: the genetic implications. Organic Geochemistry
    28. (1999). Muhlenbachs A: Low temperature thermal generation of hydrocarbons gases in shallow shales. Nature
    29. (1987). Pelet R: Extrapolation of oil and gas formation kinetics from laboratory experiments to sedimentary basins. Nature
    30. Petroleum Geochemistry and Geology Freeman,
    31. (2002). Ruble TE: Composition of petroleum generation kinetics by isothermal hydrous and non-isothermal open-system pyrolysis. Organic Geochemistry
    32. (1969). Sinke GC: The chemical thermodynamics of organic compounds
    33. (1979). Somorjai GA: Heats of chemisorption of O2, H2, CO, CO2, and N2, on polycrystalline and single crystal transition metal surfaces. Catalysis Reviews, Science and Engineering
    34. (1989). Stroppa F: Thermal degradation of kerogen by hydrous pyrolysis. A kinetic study.
    35. (1989). The micro-scale simulation of maturation: outline of a new technique and its potential applications. Geologische Rundschau
    36. (2000). The origin of light hydrocarbons.
    37. (1996). Transition metal catalysis in the generation of natural gas. Organic Geochemistry
    38. (1992). Transition metal catalysis in the generation of petroleum and natural gas. Geochimica et Cosmochimica Acta
    39. (1998). Two-tier symmetry-breaking model of patterns on a catalytic surface. Physical Review E
    40. (1994). Welte DH: Occurrence of thermogenic gas in the immature zone – implications from the Bakken insource reservoir system. Organic Geochemistry
    41. (1984). Welte DH: Petroleum Formation and Occurrence

    To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.