In the quest for sustainable energy solutions, researchers are delving into the intricate behaviors of tar-rich coal under stress, unlocking potential pathways to enhance domestic oil and gas production. A groundbreaking study led by Qingmin Shi from the College of Geology and Environment at Xi’an University of Science and Technology has shed light on how overburden stress influences the in-situ pyrolysis of tar-rich coal, offering promising insights for the energy sector.
The study, published in *Meitan xuebao* (which translates to *Journal of China Coal Society*), explores the unique behavior of tar-rich coal when subjected to different levels of stress, a factor often overlooked in conventional pyrolysis experiments. “Understanding how stress affects the pyrolysis process is crucial for optimizing oil and gas extraction,” Shi explained. “Our research reveals that the behavior of tar-rich coal under stress is distinctly different from what we observe in ground pyrolysis, which has significant implications for improving yield and efficiency.”
The research team conducted simulation experiments on tar-rich coal under varying overburden stresses, analyzing the effects on pyrolysis deformation, pore structure evolution, and molecular structure disparities. Using advanced techniques such as low-temperature N2 adsorption, X-ray diffraction, and high-resolution transmission electron microscopy, they uncovered a two-stage process influenced by stress loading.
During the low-stress loading stage (0～10 MPa), the lack of effective radial confining pressure led to the constant fracturing of the coal, enhancing pore connectivity and improving the release of pyrolysis fluids. This stage was characterized by the formation of large pores and a significant increase in the number of > 50 μm pyrolysis macropores. “This enhancement in pore connectivity is conducive to the formation of large pores during convection, which in turn improves the yield of tar and the growth of the coal molecular structure,” Shi noted.
However, as the stress loading increased beyond 10 MPa, the compaction of coal and the closure of fissures inhibited the migration of internal pyrolysis volatiles. This high-stress loading stage led to the formation of smaller pores (2-25 μm) and strengthened the secondary reaction of pyrolysis fluids, resulting in a reduction in tar yield and an increase in gas and semi-coke yields. “The swelling deformation of the coal matrix caused by continuous high-pressure stagnant flow is not favorable to the orderly growth of pyrolysis semi-coke aromatic structure,” Shi added.
The findings of this study have significant commercial implications for the energy sector. By understanding the impact of stress on the pyrolysis process, energy companies can optimize their extraction techniques to maximize oil and gas yields while minimizing environmental impact. This research paves the way for more efficient and sustainable energy production, aligning with global efforts towards green and low-carbon industries.
As the world continues to seek innovative solutions to meet its energy needs, the insights gained from this study could shape the future of coal conversion technologies. “Our research provides a foundation for further exploration into the behavior of tar-rich coal under stress, which could lead to breakthroughs in enhancing the efficiency and sustainability of oil and gas production,” Shi concluded.
With the publication of this study in *Meitan xuebao*, the scientific community and industry professionals alike are poised to benefit from these findings, driving forward the development of advanced energy technologies.