富油煤原位热解提取煤基油气是弥补我国油气资源短缺、提升煤炭资源利用效率的重要措施，也是富油煤高效开发的新趋势。富油煤在原位热解过程中的油气产出特征及孔裂隙发育情况直接影响到煤体内部传热、热解产物迁移及产出，查明富油煤热解特性及其孔裂隙结构演化规律尤为关键。

利用自主研制的热解实验装置，结合比表面及孔径分析仪、三维显微镜和同步热分析技术，记录富油煤在不同热解温度下的产气规律，测定热解残样的微观孔隙结构及孔径分布特征，分析煤体裂隙演化规律及表面裂隙参数，揭示煤体结构和热解产物对热解温度的响应机制。

结果表明，富油煤热解产气总量和最大产气速率随温度的升高而增大，在温度大于300 ℃时热解反应变得剧烈，产气量增加显著。通过对比不同热解温度下的孔裂隙结构，发现孔隙结构类型以300 ℃为界发生明显改变，低于该温度热解后的孔隙类型以细小瓶颈和缝隙/楔形孔为主，主要为中孔，随着温度升高，孔隙类型以平行狭缝为主，微孔增加，中孔和大孔则进一步发育扩展贯通，形成微裂隙。与低温作用煤样相比，高温作用煤样裂隙开度增加、裂隙网络密度及表面裂隙率相应增大，煤样结构发生宏观破坏，完整性降低。富油煤热解过程中的孔裂隙结构演化是水分蒸发、吸附气体解吸析出、不均匀热膨胀、有机质热解及热解气体逸出等共同作用的结果。研究结果可为富油煤原位热解工艺参数选择提供有益参考。

Extracting coal-based oil and gas from tar-rich coal through in situ pyrolysis plays a significant role in counteracting the shortage of China's oil and gas resources and enhancing the utilization efficiency of coal resources, representing a new trend for the efficient exploitation of tar-rich coals. During the in situ pyrolysis of tar-rich coals, the internal heat transfer, as well as the migration and production of pyrolysis products, is directly influenced by the oil and gas production characteristics and the characteristics of pores and fractures. Hence, it is particularly critical to identify the pyrolysis characteristics and pore-fracture evolutionary patterns of tar-rich coals.

Using a self-developed pyrolysis test device, alongside a specific surface area and pore size analyzer, a three-dimensional microscope, and a simultaneous thermal analyzer, this study recorded the gas production regularities of tar-rich coals under different pyrolysis temperatures, determined the microscopic pore structures and pore size distributions of tar-rich coals after pyrolysis, and analyzed the fracture evolutionary patterns and surface fracture parameters, ultimately revealing the mechanisms behind the responses of coal structures and pyrolysis products to the pyrolysis temperature.

The results show that the total gas production and the maximum gas production rate of tar-rich coals through pyrolysis increased with temperature. When the temperature exceeded 300 ℃, the pyrolysis reactions became violent, accompanied by significantly increased gas production. The comparison of the pore and fracture structures under different pyrolysis temperatures revealed that the pore structure types changed with 300 ℃ as a threshold. Below 300 ℃, the pore types after pyrolysis were dominated by small bottlenecks and fractures/wedge-shaped pores, which were primarily mesopores. With an increase in the temperature, the predominant pore types transitioned to parallel slits, micropores increased, and mesopores and macropores further propagated and interconnected, forming microfractures. Compared to coal samples subjected to low temperatures, coal samples at high temperatures manifested elevated fracture aperture, fracture network density, and surface fracture ratio, as well as macroscopically damaged structures and reduced integrity. The evolution of pore-fracture structures during the pyrolysis of tar-rich coals was attributed to the combined effects of water evaporation, the desorption and precipitation of adsorbed gas, uneven thermal expansion, the pyrolysis of organic matter, and the escape of pyrolysis gas. The findings of this study serve as a useful reference for selecting parameters for in situ pyrolysis of tar-rich coals.