The
thermal upgrading of kerogen into fuels has scientific and
industrial importance in oil shale utilization. In this study, multiple
methods were applied to clarify the pyrolysis behaviors of four kerogens
from the Huadian (HD) Basin, Fushun (FS) Basin, Luozigou (LZG) Basin,
and Dachanggou (DCG) Basin oil shales. Two model-free isoconversional
methods and a master plot were utilized to evaluate the kinetic parameters,
and the Coats–Redfern method was used to verify the estimated
kinetic results. The results indicated that all studied oil shales
had very good hydrocarbon generation potential. HD, FS, and LZG oil
shales could be described as type I kerogen, whereas DCG oil shale
was type II1 kerogen with high aromatic content. HD kerogen
featured a stronger polarity and contained more aliphatic structures
compared with the three other samples, which induced the mass loss
of its first stage at ∼38%, even larger than that of its second
pyrolysis stage; the activation energies of the main pyrolysis stage
of HD kerogen could also be divided clearly into two stages and in
accordance with the thermogravimetric results. The thermal cracking
processes of these FS, LZG, and DCG kerogens were mainly concentrated
in the second pyrolysis stage, and the activation energies of FS and
LZG kerogens did not show a considerable variation with conversion
degrees. Moreover, DCG kerogen possessed the largest amount of aromatic
structures which resulted in high yields of char, and the activation
energies of the main pyrolysis stage of DCG kerogen was almost the
largest, especially when the conversation rate was above 0.7. Evolution
behaviors of oil and gas products at different temperatures during
pyrolysis were related to the cleavage of chemical bonds in kerogen.
CH4 and light C2+ aliphatic hydrocarbons were
the typical gaseous products released from the main reaction stages
of all four kerogens, and the evolving behavior of each typical gaseous
product of four kerogens featured good similarity. The results showed
that aliphatic and aromatic carbon contents in kerogen had a remarkable
effect on its thermal characteristic and kinetic parameters, and the
saturated aliphatic bonds and oxygen-containing bonds were easy to
crack and had potentially low activation energy of reaction compared
with those of aromatic bonds. Results of the master plot and Coats–Redfern
methods verified that the Avrami–Erofeev kinetic model was
the optimal model for the pyrolysis of the studied kerogens, thereby
indicating that the four kerogens evolved under a similar genetic
condition.
Gas-bearing volcanic reservoirs have been found in the deep Songliao Basin, China. Choosing proper interpretation parameters for log evaluation is difficult due to complicated mineral compositions and variable mineral contents. Based on the QAPF of volcanic rocks using log data and a genetic algorithm. According to the QAPF scheme,
The energy consumption and carbon footprint of cryptocurrencies have always been a popular topic. However, most of the existing studies only focus on one cryptocurrency, Bitcoin, and there is a lack of long-term monitoring studies that summarize all cryptocurrencies. By constructing a time series hash rate/power model, this research obtained the 10-year time series data on energy consumption dataset of global top-25 cryptocurrencies for the first time. Both the temporal coverage and the spatiotemporal resolution of the data exceed previous studies. The results show that Bitcoin’s power consumption only accounts for 58% of the top-25 cryptocurrencies. After China bans cryptocurrencies, the conservative change in global CO2 emissions from 2020 will be between −0.4% and 4.4%, and Central Asian countries such as Kazakhstan are likely to become areas of rapid growth in carbon emissions from cryptocurrencies.
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