Preliminary Study on Relations between Methane Carbon Isotopic Fractionation and Accumulation of Natural Gas of Lower Paleozoic in the Center of Ordos Basin, China

2013 ◽  
Vol 318 ◽  
pp. 477-481
Author(s):  
Yun Feng Zhang
Keyword(s):  
Thermal Evolution ◽  
Ordos Basin ◽  
Isotopic Fractionation ◽  
Source Rocks ◽  
Gas Migration ◽  
Lower Paleozoic ◽  
Carbon Isotopic ◽  
Physical And Chemical ◽  
Methane Carbon ◽  
Carbon Isotopic Fractionation

Carbon isotopic fractionation frequently occurs during the process of source rocks generating hydrocarbon and its migration through the pore media. Conversely, the recorded isotopic information reflects some physical and chemical characteristics of the rocks, such as porosity, permeability and thermal evolution, etc. In this paper, based on the preliminary analysis of methane carbon isotopic fractionation of Lower Paleozoic in the center of Ordos Basin, China, some reservoir-forming factors like thermal evolution centers, gas pool margins, gas migration directions and the favorable accumulation zones were roughly identified. The results show the hydrocarbon-generating centers located in the Yanan-Jingbian area, the gas migrating direction from southeast to northwest, and the gas reservoir bounded by the lower permeable zone of Wuqi-Suligemiao-Yulin-Jiaxian. Finally, the isotopic results are supported by the otherss special research conclusions of source rock maturity and lithofacies palaeogeography. Therefore, the suggested viewpoints about carbon isotope in this paper have higher reliability.

Evidence from the Changing Carbon Isotopic of Kerogen, Oil, and Gas during Hydrous Pyrolysis from Pinghu Formation, the Xihu Sag, East China Sea Basin

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8317
Author(s):  
Qiang Cao ◽  
Jiaren Ye ◽  
Yongchao Lu ◽  
Yang Tian ◽  
Jinshui Liu ◽  
...  
Keyword(s):  
Carbon Isotopes ◽  
Oil And Gas ◽  
Thermal Evolution ◽  
Vitrinite Reflectance ◽  
Heating Time ◽  
Source Rocks ◽  
Evolution Process ◽  
Carbon Isotopic ◽  
Hydrous Pyrolysis ◽  
Increasing Temperature

Semi-open hydrous pyrolysis experiments on coal-measure source rocks in the Xihu Sag were conducted to investigate the carbon isotope evolution of kerogen, bitumen, generated expelled oil, and gases with increasing thermal maturity. Seven corresponding experiments were conducted at 335 °C, 360 °C, 400 °C, 455 °C, 480 °C, 525 °C, and 575 °C, while other experimental factors, such as the heating time and rate, lithostatic and hydrodynamic pressures, and columnar original samples were kept the same. The results show that the simulated temperatures were positive for the measured vitrinite reflectance (Ro), with a correlation coefficient (R2) of 0.9861. With increasing temperatures, lower maturity, maturity, higher maturity, and post-maturity stages occurred at simulated temperatures (Ts) of 335–360 °C, 360–400 °C, 400–480 °C, and 480–575 °C, respectively. The increasing gas hydrocarbons with increasing temperature reflected the higher gas potential. Moreover, the carbon isotopes of kerogen, bitumen, expelled oil, and gases were associated with increased temperatures; among gases, methane was the most sensitive to maturity. Ignoring the intermediate reaction process, the thermal evolution process can be summarized as kerogen0(original) + bitumen0(original)→kerogenr (residual kerogen) + expelled oil (generated) + bitumenn+r (generated + residual) + C2+(generated + residual) + CH4(generated). Among these, bitumen, expelled oil, and C2-5 acted as reactants and products, whereas kerogen and methane were the reactants and products, respectively. Furthermore, the order of the carbon isotopes during the thermal evolution process was identified as: δ13C1 < 13C2-5 < δ13Cexpelled oil < δ13Cbitumen < δ13Ckerogen. Thus, the reaction and production mechanisms of carbon isotopes can be obtained based on their changing degree and yields in kerogen, bitumen, expelled oil, and gases. Furthermore, combining the analysis of the geochemical characteristics of the Pinghu Formation coal–oil-type gas in actual strata with these pyrolysis experiments, it was identified that this area also had substantial development potential. Therefore, this study provides theoretical support and guidance for the formation mechanism and exploration of oil and gas based on changing carbon isotopes.

scholarly journals Lower Paleozoic source rocks and natural gas origins in Ordos Basin, NW China

2016 ◽  
Vol 43 (4) ◽  
pp. 591-601 ◽  
Author(s):  
Dan LIU ◽  
Wenzheng ZHANG ◽  
Qingfen KONG ◽  
Ziqi FENG ◽  
Chenchen FANG ◽  
...  
Keyword(s):  
Natural Gas ◽  
Ordos Basin ◽  
Source Rocks ◽  
Lower Paleozoic ◽  
Nw China

Carbon isotopic fractionation associated with lipid biosynthesis by a cyanobacterium: Relevance for interpretation of biomarker records

1997 ◽  
Vol 61 (24) ◽  
pp. 5379-5389 ◽  
Author(s):  
Susumu Sakata ◽  
John M. Hayes ◽  
Andrew R. McTaggart ◽  
Ronald A. Evans ◽  
Kristen J. Leckrone ◽  
...  
Keyword(s):  
Isotopic Fractionation ◽  
Lipid Biosynthesis ◽  
Carbon Isotopic ◽  
Carbon Isotopic Fractionation
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