煤变质作用的构造物理化学机理实验研究进展

Advancements in ExperimentalStudies on the Tectonic Physical-chemical Mechanisms of Coal Metamorphi

煤作为对温度、压力等地质环境条件极敏感的有机岩,地质历史演化过程中各种构造-热事件必然导致煤发生一系列物理、化学、结构和构造变化,物理模拟实验则是揭示煤变质作用机理的重要手段。本文基于煤变质热模拟实验、高温高压模拟实验方面的研究成果,着重对煤变质作用机理、演化进程及煤变质作用模拟实验的应用和发展趋势进行阐述。煤变质作用包含煤化作用和石墨化作用两个阶段,体现为多尺度、多阶段的物理化学结构演化,基本特征趋向于分子结构有序化和化学成分单一化。温度是煤变质的主导因素,而力的作用方式同样约束着煤变质作用。热模拟实验基于“时间-温度补偿原理”,采用开放、半开放和封闭等不同实验体系,模拟不同温压条件和构造-热环境下的热解过程。高温高压模拟实验基于相似性原理,在热模拟基础上加入压力变量,模拟不同温压条件和应力-应变环境,以全面模拟煤在各种构造物理化学条件下所发生的物理化学变化,探究不同温压耦合条件下煤变质作用机理、影响因素与演化途径。煤变质的热模拟及高温高压模拟实验在油气生成、煤储层评价、煤成石墨化及煤中战略性金属元素迁移等多个领域得到广泛应用,今后将朝多学科交叉融合和多场耦合模拟实验方向发展,以期更精确地模拟地层构造作用下的复杂地质条件,为深入探究煤变质作用的构造物理化学机理提供更有效的技术手段。

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.