scholarly journals Combination of Methyl from Methane Early Cracking: A Possible Mechanism for Carbon Isotopic Reversal of Overmature Natural Gas

Geofluids ◽  
2022 ◽  
Vol 2022 ◽  
pp. 1-9
Author(s):  
Jingkui Mi ◽  
Kun He ◽  
Yanhuan Shuai ◽  
Jinhao Guo
Keyword(s):  
Natural Gas ◽  
Bond Cleavage ◽  
Experimental Result ◽  
Maturity Stage ◽  
Solid Carbon ◽  
Gas Generation ◽  
Carbon Isotopic ◽  
Hydrocarbon Gas ◽  
Heavy Gas ◽  
Increasing Temperature

In this study, a methane (CH4) cracking experiment in the temperature range of 425–800°C is presented. The experimental result shows that there are some alkane and alkene generation during CH4 cracking, in addition to hydrogen (H2). Moreover, the hydrocarbon gas displays carbon isotopic reversal ( δ 13 C 1 > δ 13 C 2 ) below 700°C, while solid carbon appears on the inner wall of the gold tube above 700°C. The variation in experimental products (including gas and solid carbon) with increasing temperature suggests that CH4 does not crack into carbon and H2 directly during its cracking, but first cracks into methyl (CH3⋅) and proton (H+) groups. CH3⋅ shares depleted 13C for preferential bond cleavage in 12C–H rather than 13C–H. CH3⋅ combination leads to depletion of 13C in heavy gas and further causes the carbon isotopic reversal ( δ 13 C 1 > δ 13 C 2 ) of hydrocarbon gas. Geological analysis of the experimental data indicates that the amount of heavy gas formed by the combination of CH3⋅ from CH4 early cracking and with depleted 13C is so little that can be masked by the bulk heavy gas from organic matter (OM) and with enriched 13C at R o < 2.5 % . Thus, natural gas shows normal isotope distribution ( δ 13 C 1 < δ 13 C 2 ) in this maturity stage. CH3⋅ combination (or CH4 polymerization) intensifies on exhaustion gas generation from OM in the maturity range of R o > 2.5 % . Therefore, the carbon isotopic reversal of natural gas appears at the overmature stage. CH4 polymerization is a possible mechanism for carbon isotopic reversal of overmature natural gas. The experimental results indicate that although CH4 might have start cracking at R o > 2.5 % , but it cracks substantially above 6.0% R o in actual geological settings.

The Research of Origin of Deep Natural Gas of Qianbei Sub-Sag in the South of Songliao Basin

2014 ◽  
Vol 675-677 ◽  
pp. 1341-1346
Author(s):  
Wu Yi ◽  
Wei Chao Tian
Keyword(s):  
Natural Gas ◽  
Analytical Data ◽  
Parent Material ◽  
Source Rocks ◽  
Gas Content ◽  
Carbon Isotopic ◽  
Hydrocarbon Source Rocks ◽  
Study Results ◽  
Humus Type ◽  
Hydrocarbon Gas

This paper analyses the origins of deep natural gas in Qianbei Subsag using a variety of analytical data such as the natural gas components, the isotope and the light hydrocarbon analysis combining with the development characteristics of hydrocarbon source rocks. The study results show as the following: The abundance of organic matter from hydrocarbon source rocks in Qianbei Subsag is high and dominated by humus type. Part of good hydrocarbon source rocks of Type II1 and Type II2 are developed in Yingcheng Formation and these are the major gas source rocks that is in the stage of postmaturity in evolution degree. The natural gas component is dominated by methane and non-hydrocarbon gas content is low. The isotope values of ethane are lighter and methane and ethane have an obvious phenomenon of carbon isotopic reversal. Parent material types of methane and ethane are from different sources. The sources of methane are biased to humic parent material while the sources of ethane are biased to sapropelic parent material.

scholarly journals Emissions Effects of Energy Storage for Frequency Regulation: Comparing Battery and Flywheel Storage to Natural Gas

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 549
Author(s):  
Eric Pareis ◽  
Eric Hittinger
Keyword(s):  
Energy Storage ◽  
Natural Gas ◽  
Fossil Fuels ◽  
Storage Systems ◽  
Storage System ◽  
The United States ◽  
Frequency Regulation ◽  
So2 Emissions ◽  
Gas Generation ◽  
Electrical Generation

With an increase in renewable energy generation in the United States, there is a growing need for more frequency regulation to ensure the stability of the electric grid. Fast ramping natural gas plants are often used for frequency regulation, but this creates emissions associated with the burning of fossil fuels. Energy storage systems (ESSs), such as batteries and flywheels, provide an alternative frequency regulation service. However, the efficiency losses of charging and discharging a storage system cause additional electrical generation requirements and associated emissions. There is not a good understanding of these indirect emissions from charging and discharging ESSs in the literature, with most sources stating that ESSs for frequency regulation have lower emissions, without quantification of these emissions. We created a model to estimate three types of emissions (CO2, NOX, and SO2) from ESSs providing frequency regulation, and compare them to emissions from a natural gas plant providing the same service. When the natural gas plant is credited for the generated electricity, storage systems have 33% to 68% lower CO2 emissions than the gas turbine, depending on the US eGRID subregion, but higher NOX and SO2 emissions. However, different plausible assumptions about the framing of the analysis can make ESSs a worse choice so the true difference depends on the nature of the substitution between storage and natural gas generation.

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.

Hydrocarbon gas generation from pyrolysis of extracts and residues of low maturity solid bitumens from the Sichuan Basin, China

2017 ◽  
Vol 103 ◽  
pp. 51-62 ◽  
Author(s):  
Zixiang Wang ◽  
Yongli Wang ◽  
Baoxiang Wu ◽  
Gen Wang ◽  
Zepeng Sun ◽  
...  
Keyword(s):  
Sichuan Basin ◽  
Gas Generation ◽  
Hydrocarbon Gas ◽  
The Sichuan Basin

Composition of Mixtures of Natural Gas Components Determined by Raman Spectrometry

1980 ◽  
Vol 34 (4) ◽  
pp. 411-414 ◽  
Author(s):  
Dwain E. Diller ◽  
Ren Fang Chang
Keyword(s):  
Natural Gas ◽  
Mole Fraction ◽  
Gas Mixtures ◽  
Spectrometric Method ◽  
Gas Mixture ◽  
Raman Intensity ◽  
Raman Spectrometry ◽  
Intensity Measurements ◽  
Hydrocarbon Gas ◽  
Related Line

The feasibility of using Raman spectrometry for determining the composition of mixtures of natural gas components was examined. Raman intensity measurements were carried out on eight, gravimetrically prepared, binary gas mixtures containing methane, nitrogen, and isobutane at ambient temperature and at pressures to 0.8 MPa. The repeatability of the molar intensity ratio, ( I2/ y2)/( I1/ y1), where y1 is the concentration of component 1 in the mixture, and I1 is the intensity of the related line in the mixture spectrum, was examined. The compositions of two gravimetrically prepared methane-nitrogen-isobutane gas mixtures were determined spectrometrically with an estimated precision of about 0.001 in the mole fraction. Typical differences from the gravimetric concentrations were less than 0.002 in the mole fraction. The Raman spectrum of a gravimetrically prepared, eight component, hydrocarbon gas mixture was obtained to show that the Raman spectrometric method has potential for being applicable to natural gas type mixtures.

Using natural gas generation to improve power system efficiency in China

Energy Policy ◽  
2013 ◽  
Vol 60 ◽  
pp. 116-121 ◽  
Author(s):  
Junfeng Hu ◽  
Gabe Kwok ◽  
Wang Xuan ◽  
James H. Williams ◽  
Fredrich Kahrl
Keyword(s):  
Natural Gas ◽  
Power System ◽  
System Efficiency ◽  
Gas Generation

Comparison of isotopic compositions of hydrocarbon gas in shallow groundwater and a deep oil and natural gas reservoir in southeastern New Brunswick, Canada

2020 ◽  
Vol 56 ◽  
pp. 207-229
Author(s):  
Diana B. Loomer ◽  
Kerry T.B. MacQuarrie ◽  
Tom A. Al
Keyword(s):  
Natural Gas ◽  
New Brunswick ◽  
Shallow Groundwater ◽  
Isotopic Signature ◽  
Oil Field ◽  
Hydrocarbon Gases ◽  
Gas Field ◽  
Isotopic Analyses ◽  
Oil And Natural Gas ◽  
Hydrocarbon Gas

Isotopic analyses of natural gas from the Stoney Creek oil field in New Brunswick indicate carbon (δ13C) and hydrogen (δ2H) values in methane (C1) of -42.4 ± 0.7‰ VPDB and -220.9 ± 3.2‰ VSMOW, respectively. Isotopic data and a gas molecular ratio of 12 ± 1 indicate a wet thermogenic gas formed with oil near the onset of the oil-gas transition zone. The isotopic profiles of the C1–C5 hydrocarbon gases are consistent with kinetic isotope effect models. The Albert Formation of the Horton Group hosts the Stoney Creek oil field (SCOF) and the McCully gas field (MCGF) the only other gas-producing field in the province. Both are thermogenic in origin; however, the SCOF gas has a lower thermal maturity than the MCGS. Hydrocarbon gas composition in shallow aquifers across southeastern New Brunswick was also evaluated. Gas source interpretations based on δ13C and δ2H values are uncertain; oxidation and biogenic overprinting are common and complicate interpretation. The effect of oxidation on δ13C and δ2H values was apparent when C1 concentrations were ≤1 mg/L. In some samples with C1 concentrations >5 mg/L, isotopic discrimination methods point to a biogenic origin. However, the molecular ratios <75 and the presence of >C3 fractions, indicate a thermogenic origin. This suggests a thermogenic isotopic signature has been overprinted by biological activity.

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