Gaseous hydrocarbons generated during pyrolysis of petroleum source rocks using unconventional grain-size: Implications for natural gas composition

Sedat Inan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)

Abstract

Open-system pyrolysis experiments were performed on a suite of immature to marginally mature source rocks to investigate the influence of kerogen type on primary gas composition and the effect of grain size on gas expulsion characteristics. The pyrolysis of rock powders confirmed that hydrogen-rich kerogens yielded wetter gases than did hydrogen-poor kerogens. Gases detected from the pyrolysis of rock chips were drier than those from powders of equivalent samples. This was due to two processes: the retention and secondary cracking of higher molecular weight pyrolysis products and the preferential expulsion of methane from the rock matrix. These two effects, one chemical the other physical, could be distinguished using a novel approach involving multi-step pyrolysis of rock chips followed by on-line crushing of the residues. The enrichment of methane in natural gas attributed, by earlier workers, to be a consequence of fractionation during secondary migration (post-expulsion) has been proven to be real also during expulsion from source rocks at least for pyrolysis conditions.

Original languageEnglish
Pages (from-to)1409-1418
Number of pages10
JournalOrganic Geochemistry
Volume31
Issue number12
DOIs
Publication statusPublished - 2000
Externally publishedYes

Keywords

  • Expulsion
  • Gas dryness
  • Gaseous hydrocarbons
  • Migration fractionation
  • Natural gas composition
  • Open system
  • Pyrolysis
  • Restricted system
  • Retention
  • Secondary cracking
  • Unconventional grain size

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