Bulk and molecular composition variations of gold-tube pyrolysates from severely biodegraded Athabasca bitumen
- PDF / 1,399,095 Bytes
- 13 Pages / 595.276 x 790.866 pts Page_size
- 68 Downloads / 132 Views
ORIGINAL PAPER
Bulk and molecular composition variations of gold‑tube pyrolysates from severely biodegraded Athabasca bitumen Zhong‑Xuan Li1 · Hai‑Ping Huang1,2,3 Received: 14 October 2019 © The Author(s) 2020
Abstract Gold-tube pyrolysis experiments were performed on two Athabasca oil sand bitumens at 300 °C to 525 °C with 2 °C/h rate and 25 °C step under 50 MPa. Pyrolysis temperature of 425 °C is critical for weight loss of bulk bitumen and hydrocarbon generation and destruction. Polar compounds are the main source of saturated and aromatic hydrocarbon, gas and coke fractions. Molecular compositions in pyrolyzates vary systematically with increasing pyrolysis temperatures. High molecular weight n-alkanes (C26+) are gradually destructed during pyrolysis due to thermal cracking. Moderate molecular weight n-alkanes (C21–C25) show the highest thermal stability in designed pyrolysis temperatures. The loss of low molecular weight n-alkanes (C20−) might be caused by volatilization during pyrolysis, which may alter commonly used molecular parameters such as ∑n-C20−/∑n-C21+, Pr/n-C17 and Ph/n-C18. Aromatic hydrocarbons were generated from 300 to 425 °C, then condensation and dealkylation have been initiated at 425 °C as evidenced by decreased summed alkylnaphthalenes to alkylphenanthrenes ratios and increased unsubstituted aromatics to substituted homologs ratios in higher temperatures. The occurrence of anthracene and benz[a]anthracene in pyrolysates indicates pyrogenic origin, while fluoranthene shows unexpected behaviors during pyrolysis. Ratios derived from them are not always reliable for pyrogenic source input diagnosis in environmental samples. Keywords Oil sand bitumen · Gold-tube Pyrolysis · GC–MS · Molecular compositions · Athabasca
1 Introduction Oil sand bitumen (OSB) is one of the most important energy resources in the world. The largest OSB deposit in the Western Canada Sedimentary Basin contains about 1.7 trillion barrels of heavy oil and bitumen. Three major deposits are situated at Athabasca, Cold Lake and Peace River in Alberta, which are hosted in the reservoirs of varying age, ranging from the Devonian (Grosmont Formation) to Early Edited by Jie Hao * Hai‑Ping Huang [email protected] 1
School of Energy Resources, China University of Geosciences (Beijing), 29 Xueyuan Road, Beijing 100083, China
2
School of Geosciences, Yangtze University, Wuhan 430100, Hubei, China
3
Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada
Cretaceous (Mannville Group) (ST98-2018). These bitumens are originated from matured source rocks with initial API gravity about 28° in the southwest Alberta and migrated to the north and east for over 100 km during the Laramide Orogeny (Larter et al. 2006; Yin et al. 2013). Biodegradation is the main alteration process to transform conventional oil to current API gravity about of 8°‒12° bitumen by preferentially removal of light components (Head et al. 2003; Zhou et al. 2008). OSB is commonly enriched in heavy and bas
Data Loading...
