深部煤层气开发具有见气快、单井产量高、资源分布连续稳定等优势，成为天然气增储上产的重要方向，但其勘探开发技术仍面临诸多难题，深部煤层气地质储层特征与工程评价、气水赋存特征与开发机理、生产制度制定和提高采收率方法等方面的关键实验技术研究薄弱。

针对深部煤层和煤层气特点，提出了深部煤层在大尺寸煤样采集、高温高压高应力原位条件、亚纳米−纳米级微孔高精度表征与解吸、含气量准确测定4大方面的挑战，系统分析了深部煤多尺度孔裂隙表征、吸附性和含气性评价、煤岩力学特征及裂缝扩展规律、压后流体赋存−产出开发动态规律等实验技术进展与难点。

针对性提出深部煤层气开发及煤炭原位转化实验的7个发展方向：(1) 适用于特低孔、特低渗深部煤层小于2 nm微孔结构的清晰直接观测技术、“微孔大量发育−介孔少−宏孔多”的全孔径多尺度拼接技术及孔裂隙连通结构评价技术；(2) 考虑高温高压原位环境下深部煤层润湿性、压裂液侵入、高矿化度影响的原煤等温吸附测试技术；(3) 具有高保压率和高保温率、气量可位置追溯的密闭取心装置和原位保压取心技术；(4) 高温、高压等多场耦合作用下，基于“纳米科学”的深部煤层微孔气水赋存评价技术和“纳米−微米−毫米”多尺度解吸−扩散−渗流实验技术；(5) 适用于深部煤层高应力、低弹性模量、高泊松比特点的原位条件多功能力学实验设备研制及测试技术；(6) 适用于提高深部煤层气采收率的储层赋能(微波、激光、电热)、激励增渗改造(电磁脉冲、脉冲超声波、可控冲击波)、注CO₂驱替、超临界CO₂机械脉动联合等实验技术；(7) 适用于深部煤炭原位转化/利用的热解、煤炭地下气化、地热利用、CO₂地质封存等实验技术。分析认为，深部煤层气勘探开发的客观需求亟需建立相关实验技术的操作流程标准与规范，以期实现“绿色环保、增渗、促解吸、CO₂封存”多重功效，为深部煤层气和深部煤炭的高效开发利用提供重要支持，助力实现“双碳”目标。

Deep coalbed methane (CBM) production enjoys advantages including rapid gas shows, high single-well yield, and continuous resource distribution, which establish deep CBM as a significant target for reserve growth and production addition of natural gas. However, the exploration and production of deep CBM are still confronted with many technical challenges, and there is a lack of studies on key experimental technologies related to the geological characteristics and engineering assessment of deep CBM reservoirs, the occurrence characteristics and production mechanisms of gas and water, the formulation of production systems, and methods for enhanced CBM recovery.

Given the characteristics of deep coal seams and CBM, this study identifies four challenges in the exploration and exploitation of deep coal seams: the collection of large coal samples, the high-temperature, high-pressure, and high-stress in-situ conditions, high-precision characterization and desorption of sub-nano- to nano-scale micropores, and the accurate determination of gas content. Furthermore, this study systematically analyzes the advances and challenges in experimental technologies for deep coals, involving the characterization of multi-scale pores and fractures, the assessment of absorption and gas-content properties, the mechanic characteristics and fracture propagation patterns of coals, and the dynamic patterns of fluid occurrence and production post-fracturing.

This study posits seven development directions for deep CBM production and in-situ coal conversion experiments: (1) Clear, direct observation techniques for micropores (< 2 nm) in deep coal seams with ultra-low porosity and permeability, full-scale pore size splicing technology for multiscale pore structure characterized by abundant micropores, a few mesopores, and many macropores, and assessment techniques for pore-fracture connectivity. (2) Isothermal adsorption test technologies for raw coals considering the effects of deep coal seam wettability, fracturing fluid invasion, and high total dissolved solids (TDS) under high-temperature, high-pressure in-situ conditions; (3) Sealed coring devices and in-situ pressure-retaining coring technologies featuring high pressure retaining success rates, heat preservation rates, and traceable gas volume. (4) Nanoscience-based assessment technologies for gas and water occurrence in micropores in deep coal seams under high-temperature and high-pressure multi-field coupling, and experimental technologies for desorption, diffusion, and seepage across nano-micro-millimeter scales. (5) Techniques for developing and testing multifunctional mechanical experiment equipment applicable to in-situ conditions of deep coal seams featuring high stress, low modulus of elasticity, and high Poisson's ratio. (6) Experimental techniques for the purpose of enhancing CBM recovery of deep coal seams, including reservoir stimulation (microwaves, laser, and electric heating), stimulation for permeability enhancement (electromagnetic pulses, pulsed ultrasonic waves, and controlled shockwaves), displacement via CO₂ injection, and mechanical pulsation with supercritical CO₂. (7) Experimental techniques for in-situ coal conversion and utilization, including pyrolysis, underground coal gasification (UCG), geothermal utilization, and CO₂ geological storage. Analyses reveal that there is an urgent need to establish the standards and regulations for the operational procedures of these experimental technologies, as required by objective demand for the exploration and production of deep CBM. These experimental technologies aim is to achieve environment protection, permeability enhancement, desorption promotion, and CO₂ storage, thus providing vital support for the efficient production and utilization of deep CBM and coals and helping attain the goals of peak carbon dioxide emissions and carbon neutrality.