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Petroleum Origin and Generation
Published in Muhammad Abdul Quddus, Petroleum Science and Technology, 2021
So far the transformation of organic matter is brought about by aerobic and anaerobic oxidation and fermentation processes. Both processes are combinations of multiple reactions, dehydration, hydrolysis, decomposition, cracking, condensation and the removal of functional groups and hetero atoms (S, O and N) under mild conditions. At the end of the diagenesis process, the degraded geopolymer (remaining organic matter) is sparingly soluble and stripped off reactive functional groups. It is a darker, compact, heterogeneous complex solid. The organic solid is given a new name, ‘humic compounds’, a first stage for kerogen formation in subsequent processes. Kerogen is a precursor of oil and gas generation. The total duration of bio-chemical diagenesis transformations of organic matter in the presence of aerobes and anaerobes is very short on a geological time scale.
Fossil Energy Sources
Published in Anco S. Blazev, Power Generation and the Environment, 2021
Initially, the sediments cooked to a waxy substance called kerogen. Kerogen, as in tar and shale oil deposits, is similar to the peat segment of the coal formation process and represents the not-yet completed process of conversion to crude oil. Like peat, it has different (inferior heating) properties than the respective final products, crude oil and coal. As time passed and the cooking processes continued, the sediment was eventually converted into a combination of organic liquids and gases which we call petroleum.
Energy Markets’ Future
Published in Anco S. Blazev, Global Energy Market Trends, 2021
Shale oil, known also as kerogen oil or oil-shale oil, is an unconventional oil produced from oil shale, which is sedimentary rock filled with kerogen. It can be processed by pyrolysis, hydrogenation, or thermal dissolution to convert the organic matter within the kerogen rock into synthetic oil and gas.
Past, present and future of Coal Bed Methane (CBM): a review with special focus on the Indian scenario
Published in International Journal of Coal Preparation and Utilization, 2023
Dev Joshi, Piyush Prajapati, Pushpa Sharma, Anjali Sharma
However, there seem to be two views about the existence of methane that are speculative. The trapped gas could be indicative of the gas’s upward migration distance before it became a hydrate fragment. Despite the fact that Parkes and others (Parkes et al. 1990) unearthed such bacterial motion in residue some few hundred meters beneath the seabed, biogenic hydrocarbon gases (mostly (99%) methane) are generated as a direct result of bacterial action and are normally produced many meters beneath the sea floor. Fine-grained residue is commonly associated with biogenic gas age due to its inherently higher initial natural content. Surprisingly, most thermogenic hydrocarbon gas production occurs at depths more than 1,000 m in the sub-base (Floodgate and Judd 1992). Such hydrocarbon gases are produced by kerogens, which also are obtained from natural matter, under conditions of high temperature and extreme pressure. Methane, being a thermogenic gas, is only observed at the last step of hydrocarbon formation (metagenesis). Thermogenic methane, when found in a hydrate, can exhibit significant upward movement.
Sedimentary environment and facies of the Huagang Formation in the northern central Xihu Depression, East China Sea Basin, China
Published in Australian Journal of Earth Sciences, 2020
Z. X. Zhao, C. M. Dong, C. Y. Lin, X. G. Zhang, X. Huang, B. J. Li, W. Guo, Z. Q. Zhu
Organic geochemistry is another technique for assessing depositional redox conditions with the source of organic matter inferred from the kerogen type and component. Type I kerogen is rare in nature and is generally formed in organic-rich sludge deposited in shallow, oxygenated environments, Type II kerogen is formed under reducing conditions and is mainly composed of a mixture of autochthonous plankton, micro-organisms (mainly bacteria) and organic matter, and Type III kerogen are mainly derived from higher terrestrial plants (Tissot & Welte, 1984). The sapropel is mainly derived from algae-based lower aquatic organisms, whereas the chitin, vitrinite and inertin are mainly derived from terrestrial organisms (Tu, Wang, & Fei, 1998). As described above, the main kerogens are Type I and Type II, and the content of the sapropel ranges from 29.67–93% (mean 64.13%), indicating that the kerogen in the study area was mainly derived from aquatic organisms. Vitrinite and inertinite predominate samples 2 and 5, which suggests that these strata were commonly exposed at the time of deposition.
Activity of hydrothermal fluid at the bottom of a lake and its influence on the development of high-quality source rocks: Triassic Yanchang Formation, southern Ordos Basin, China
Published in Australian Journal of Earth Sciences, 2020
J. You, Y. Liu, D. Zhou, Q. Zheng, K. Vasichenko, Z. Chen
The TOC contents of the Chang 7 samples from the Bawangzhuang section, Z233 well and H269 well range from 1.09 to 27.86, 1.03 to 29.91 and 0.67 to 6.39 wt%, respectively with mean values of 10.05, 11.42, and 1.33 wt%, respectively. In Well H269 a portion of the Chang 7-3 section is an invalid source rock, but a subset is an effective source rock (Figure 4a); kerogen types are mainly type III and type II, which are in the immature–low maturity stage (Figure 4b). The Chang 7 Member in the Bawangzhuang profile and Z233 well are all effective source rocks, and the organic matter (TOC) abundance and source rock potential (S2) are both very good to excellent (Figure 4a). The kerogen type is type I and type II, and is currently in the mature–over mature stage (Figure 4b). Type I kerogen is derived from lake algae, type III kerogen is derived from terrestrial higher plants, and type II kerogen is usually a mixture of the two. Figure 3b shows that the organic matter types in the Yanchang Formation source rocks are consistent with that determined by paleontology (Ji, Yan, Meng, & Zhao, 2010) and indicate that the organic matter precursors in the southern margin of the basin are mainly green algae, such as Chlorella and grape algae, etc. (Bawangzhuang profile and Z233 well), and in the western region of the basin (H269 well) contain a large amount of higher plant debris derived from a terrestrial source.