Advancements in Experimental Studies on the Tectonic Physical-chemical Mechanisms of Coal Metamorphism
Coal is an organic rock that is highly sensitive to geological conditions such as temperature and pres-sure.Various tectono-thermal events during geological evolution inevitably result in a series of changes in the physics,chemistry,texture,and structure of coal.Physical simulation experiments are essential to reveal the mechanisms of coal metamorphism.Based on previous thermal simulation experiments and high-temperature,high-pressure simulation studies of coal metamorphism,this paper reviews the previous research on the metamor-phism processes,evolutionary stages,applications,and simulation experiments of coal.Coal metamorphism in-cludes coalification and graphitization,which manifest as multi-scale and multi-stage physical and chemical structural evolution.Its basic characteristics involve a progressive simplification of chemical constituents and structural ordering.Temperature is the dominant factor in coal metamorphism,while the mode of force also in-fluences coal metamorphism.The thermal simulation experiment is based on the"time-temperature compensa-tion principle"and utilizes various experimental systems,such as open,semi-open,and closed,to simulate the pyrolysis process under different temperature and pressure conditions,and tectono-thermal environments.Ac-cording to the principle of similarity,high-temperature and high-pressure experiments include pressure as a vari-able in addition to thermal simulation.These experiments were conducted under varying temperature and pres-sure conditions,and stress-strain conditions to comprehensively simulate the physical and chemical changes of coal across different physicochemical environments.The mechanism,influencing factors,and evolutionary pathway of coal metamorphism under different coupling conditions of temperature and pressure have been investi-gated.Thermal simulation and high-temperature,high-pressure experiments of coal metamorphism have been widely used in various fields such as oil and gas generation,coal reservoir evaluation,coal-forming graphitiza-tion,and strategic migration of metal elements in coal.In the future,these experiments will evolve towards multidisciplinary cross-integration and multi-field coupling simulation,aiming to more accurately simulate the complex geological conditions influenced by stratigraphic structure.It provides a more effective technical means for the in-depth exploration of the tectonic-physicochemical mechanisms of coal metamorphism.
coal metamorphismtectonic-physicochemical mechanismthermal simulation experimenthigh-temperature and high-pressure simulation experiment