Comparison of pyrolysis products from different subbituminous coals

Conference · Fri May 01 00:00:00 EDT 1987 · AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States)

OSTI ID:6193316

Lu, S; Ruth, E; Kaplan, I R

Two different immature subbituminous coals (Australia, Gippsland, Latrobe, an oil-prone coal, and Rocky Mountain Upper Cretaceous, a gas-prone coal) were selected to conduct pyrolysis at 300/sup 0/C from 2 to 1000 hours. The liquid hydrocarbon and aromatic hydrocarbons generated in the Australia Gippsland Coal (AGC), was up to four times higher than those formed from Rocky Mountain coal (RMC), although the amount of gaseous hydrocarbon and starting H/C ratio is similar for both coals. Furthermore, in the extracts the distribution of n-alkane is similar; both have high OEP in the range of n-C/sub 25/ to n-/sub 34/. Pristane/phytane ratios are 5.01 and 4.51, and delta/sup 13/C is -25.7 per thousand and -24.9 per thousand in RMC and AGC, respectively. However, the amount of diterpenoid hydrocarbon was unusually high in the original bitumen of the RMS, whereas triterpane was the major component in that of AGC. Hopane distribution obtained from both the bitumen and pyrolysates of both coals shows that C/sub 31/ ..cap alpha.. ..beta.. 22R homohopane was released at very early stages of diagenesis. It is also possible that the C/sub 31/ ..cap alpha.. ..beta.. homohopane precursor was unbound to kerogen because it predominated in the original bitumen but occurs only to a small extent in the pyrolysates. Surprisingly, the distribution of biomarkers in the pyrolysates of RMC look more immature than those of AGC, although the vitrinite reflectance values (R/sub 0/) of the starting and residual coal kerogen were consistently higher in the RMC than those in the AGC. Nevertheless, the maturation index, e.g., C/sub 29/ ..cap alpha cap alpha cap alpha.. 20 S/S + R and C/sub 31/ and C/sub 32/ ..cap alpha.. ..beta.. 22 S/S + R, increased with maturity (increased with the R/sub 0/ of vitrinite reflectance) and heating time during pyrolysis. This suggests that although biomarkers may give consistent maturation trends in a given basin, these trends can vary significantly with different types of humic coals.

• Research Organization: Univ. of California, Los Angeles
• OSTI ID: 6193316
• Report Number(s): CONF-870606-
• Journal Information: AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States), Vol. 71:5; Conference: American Association of Petroleum Geologists annual meeting, Los Angeles, CA, USA, 7 Jun 1987
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
SUBBITUMINOUS COAL
MATURATION
PYROLYSIS
MACERALS
OPTICAL PROPERTIES
SOURCE ROCKS
CARBONACEOUS MATERIALS
CHEMICAL REACTIONS
COAL
DECOMPOSITION
ENERGY SOURCES
FOSSIL FUELS
FUELS
MATERIALS
PHYSICAL PROPERTIES
THERMOCHEMICAL PROCESSES
010600* - Coal
Lignite
& Peat- Properties & Composition