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Investigation of the carbonaceous component of gold-bearing ores by means of thermal analysis
Published in Vladimir Litvinenko, Innovation-Based Development of the Mineral Resources Sector: Challenges and Prospects, 2018
T.N. Alexandrova, A.V. Afanasova, Gerhard Heide, Aron Knoblich
Sedimentary rocks usually contain organic matter in two different forms, finely disseminated macromolecular material (kerogen, insoluble in usual organic solvents) and free hydrocarbons, named bitumen which soluble in usual organic solvents (Schmidt 2001). Bitumen may be altered by thermal stress into an insoluble solid form named pyrobitumen (Schmidt 2005).
Genesis of bitumen and high resistivity water layer in Yanchang formation, Ordos Basin, China
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Zhenglu Xiao, Shijia Chen, Xiangdong Yin, Zhanxi Chen, Longxiang Tang, Meimei Han
There are many causes of bitumen formation, mainly including degraded bitumen (formed by water washing, oxidation, and biodegradation), pyrobitumen (formed by thermal alteration), precipitated bitumen (formed by deasphalting due to gas invasion of oil reservoir), and migration bitumen (formed by reservoir differentiation) (Head, Jones, and Larter 2003; Hu, Li, and Wong 2010; Kelemen, Walters, and Kwiatek 2010; Kim, Philp, and Sorenson 2010; Walters, Qian, and Wu 2011). Among them, biodegradation is the most common formation of bitumen. Generally, if the reservoir suffers from severe biodegradation, 25 norhopane will appear on the m/z177 chromatography (2012; Steve et al. 2006; Xiao et al. 2019). In the extracts of Chang 8 reservoir in Yuele area, the total hydrocarbon chromatogram shows double peaks and 25 norhopane appears on the m/z177 chromatogram (Figure 7), indicating that the bitumen in the reservoir is caused by biodegradation.
Characteristics of gaseous hydrocarbons generated from asphaltene pyrolysis and the geochemical significance
Published in Petroleum Science and Technology, 2018
Lei Hou, Guosheng Xu, Shaobo Han, Zonghao Li, Chao Jiang
The characteristics of pyrobitumen generation from asphaltene under high temperature are shown in Figure 4. At the initial stage of pyrolysis (at around 370°C), the mass fraction of the pyrobitumen is up to 500 mg/g. At the final stage of pyrolysis (at around 600°C), the mass fraction of the pyrobitumen is up to the maximum (730 mg/g). During the whole process of asphaltene pyrolysis, the mass fraction of the pyrobitumen is constantly increased, overall. This is because the polycondensation between the asphaltenes is easy to occur during pyrolysis to produce a large amount of pyrobitumen due to the complex macromolecular structure of the asphaltene. According to the analysis results of Figure 2, Figure 3, and Figure 4, the final pyrolyzed products of the asphaltene are methane and pyrobitumen (the mass ratio of the two is about 3: 7). That means the asphaltene in marine crude oil is the key contributors for the pyrobitumen in the reservoirs.
Characterization of hydrocarbon/pores generation and methane adsorption in shale organic matter
Published in Petroleum Science and Technology, 2018
Yanan Miao, Xiangfang Li, John Lee, Yunjian Zhou, Songxia Liu, Yucui Chang, Shan Wang
For thermal catalysis phase of shale, vitrinite reflection, Ro, reaches 1.3% or so. Most kerogen transforms into solid bitumen/pyrobitumen, and the frame is mostly bituminous aromatic compounds. Bitumen is soluble in toluene, and toluene is polar, so according to the “similarity and intermiscibility” principle, bitumen is polar also, and the solid frame will more easily adsorb polar water, and less nonpolar hydrocarbons. Therefore, this phase will also have solid-liquid interface effects. The high-temperature thermal-cracking phase which generates condensate gas and the gas-generation phase are similar as the two phases described above and demonstrate solid-liquid interface effects.