【作者】 陈勇；

【导师】 刘荣华；

【作者基本信息】 湖南科技大学 ， 矿业工程， 2024， 博士

【摘要】 我国煤炭开采条件复杂,尤其是深部煤体“高应力、高瓦斯、低透气性”本真属性以及深部开采“强扰动、强时效”附加属性下,煤层开采致灾因素与伴生灾害更加难以精准预测和防控。基于煤体内含瓦斯且吸附性强的多孔介质属性,衍生了水对煤体瓦斯复杂作用机理,研究结论差异明显、甚至截然不同。水介质衍生“渗流驱替”促进瓦斯运移,衍生“渗透水锁”抑制瓦斯解吸,亦可衍生“渗流驱替”+“渗透水锁”协同效应。但无论是“渗流驱替”还是“渗透水锁”,均需一定的驱替、水锁程度来保证作用类型的表征。基于此,本文采用理论分析、实验测试、现场测试等技术手段,以水介质为载体,表面活性剂、微纳米气泡为工作介质,通过液载气获得液气耦合介质;并分别开展液气耦合介质共存特性与再生属性,液气耦合介质对煤体瓦斯渗流驱替尺寸效应与渗透水锁孔隙改性,以及基于液气耦合介质驱替与水锁后置效应等方面的研究,进而探讨液气耦合介质对煤体瓦斯渗流驱替与渗透水锁的强化机制与响应特性。主要结论如下:首先,表征了液气耦合介质共存特性与再生属性。通过液相界面接触量化、微纳米气泡与水液气互溶,表征了液气耦合介质后置共存共生与再生属性;基于环管流量与旋转粘度,确定液气耦合介质的减阻性能与界面接触特性,为煤体瓦斯渗流驱替与渗透水锁奠定基础。然后,量化了液气耦合介质对煤体瓦斯渗流驱替与渗透水锁改性特征。（1）表面活性剂、微纳米气泡以蒸馏水为载体实现液气耦合后,可对煤体瓦斯渗流驱替产生明显的促进作用,实现对煤体瓦斯渗流驱替的强化。（2）液气耦合介质对煤体瓦斯渗流驱替时,相对水介质渗流的入口压力降低、无烟煤与长焰煤之间的渗流驱替差异减小并趋于相近。（3）相同载荷条件下,液气耦合介质渗流驱替效应大于水介质,反应出液气耦合介质对煤体瓦斯渗流驱替更容易且强度更大。（4）液气耦合介质相对干燥、蒸馏水、蒸馏水+表面活性剂介质,煤体瓦斯解吸呈现明显衰减与分级特性。（5）不同粒径、不同变质程度、不同吸附平衡压力时,液气耦合介质煤样瓦斯解吸T₁指标处于最低水平。（6）随着作用时间的延长,液气耦合介质对煤体瓦斯解吸衰减更强烈,表现出渗透水锁强化效应。其次,探索了基于液气耦合介质界面冲刷与煤体孔隙改性的多源后置效应。（1）煤体表面SEM显示,液气耦合介质冲刷作用下煤体孔径变大,原有孔裂隙扩张,煤体表面孔隙、孔洞与干燥煤样表面形态形成鲜明对比。（2）液气耦合介质对煤体孔隙结构改性影响明显;低温CO₂吸附最大吸附量、微孔累计孔隙面积、微孔累计孔隙体积、最大孔隙体积、中间孔隙宽度,相对干燥煤样分别减少4.1474cm³/g、33.9549m²/g、0.0184cm³/g、0.007593cm³/g、0.0248nm。（3）低温N₂吸附形态、吸附量差异表明液气耦合介质在较强吸附性能的作用下渗透到煤体孔隙中;煤体介孔数量减少、吸附/解吸能力降低,液气耦合介质可改变煤体原有孔隙通道与类型。（4）液气耦合介质作用煤样单点表面积、BET表面积、Langmuir表面积相对干燥煤样分别减少为0.6090、0.6518、0.6387m²·g^-1;液气耦合介质作用煤样相对干燥煤样吸附/解吸累积孔隙表面积分别降低52.45%、49.10%,累积孔隙体积分别降低29.96%、28.35%。再次,解释了煤体瓦斯渗流驱替与渗透水锁强化作用机制。（1）液气耦合介质通过减阻性能优化,表面张力降低、边界滑移增强,以及活性作用下电荷改性和吸附强化,提供煤体瓦斯渗流驱替与渗透水锁协同作用动力。（2）基于孔隙渗流与边界滑移特征,将煤体内部孔隙结构类比圆管孔隙建立了减阻渗流模型,基于达西渗流解释了液气耦合介质对煤体瓦斯渗流驱替界面力学特性与宏观机制。（3）基于煤体对水与甲烷分子吸附时能量释放与吸附势阱,解释了液气耦合介质对煤体瓦斯渗透水锁作用机制,并通过瓦斯解吸T₁指标验证了渗透水锁效应。（4）煤体多孔介质本真属性下,液气耦合介质对煤体有润有渗、由润到渗、边界滑移的渗流驱替,以及电荷改性、表面吸附、孔隙改性的渗透水锁;通过性能优化与提质增效实现煤体瓦斯渗流驱替与渗透水锁协同作用强化表征。最后,提出了强化瓦斯涌出与弱化瓦斯解吸的协防协控技术。（1）基于液气耦合共存与再生、液气耦合渗流驱替与渗透水锁强化、压力作用下的稳定性,分析了液气耦合介质对煤体瓦斯渗流驱替与渗透水锁前置基础条件。（2）液气耦合介质注入煤体后瓦斯涌出依次出现快速增大、波动增长,再快速下降,验证了液气耦合介质对煤体瓦斯渗流驱替效应并促进瓦斯涌出。（3）液气耦合介质注入煤体后钻屑瓦斯解吸指标依次出现快速降低、快速增大、再降低,验证了液气耦合介质对煤体瓦斯渗透水锁效应并抑制瓦斯解吸。更多还原

【Abstract】 China’s coal mining conditions are complex,especially the deep coal"high stress,high gas,low permeability"of the true attributes and deep mining"strong disturbance,strong aging"additional attributes,coal mining disaster factors and associated disasters more difficult to accurately predict and control.Based on the porous media properties of coal containing gas and strong adsorption,the complex mechanism of water on coal gas is derived,and the research conclusions are different or even completely different.The"seepage displacement"derived from water medium promotes gas migration,the"seepage water lock"inhibits gas desorption and the synergistic effect of"seepage displacement"+"seepage water lock"can also be derived.However,whether it is"seepage displacement"or"seepage water lock"a certain degree of displacement and water lock is needed to ensure the characterization of the action type.Based on this,this paper adopts theoretical analysis,experimental testing,field testing and other technical means,using water medium as the carrier,surfactants,micro and nano bubbles as the working medium,and obtaining the liquid-gas coupling medium through liquid-carrier gas.The co-existence and regeneration properties of the liquid-gas coupling medium,the size effect of the liquid-gas coupling medium on gas seepage displacement and the modification of water lock pores of the coal body,and the post-effect of the liquid-gas coupling medium on gas seepage displacement and water lock of the coal body were studied respectively,and then the strengthening mechanism and response characteristics of the liquid-gas coupling medium on gas seepage displacement and water lock of the coal body were discussed.The main conclusions are as follows.Firstly,the coexistence and regeneration properties of the liquid-gas coupling medium were characterized.The post-position coexistence and regeneration properties of the liquid-gas coupling medium were characterized by the liquid phase interface contact quantization and the miscibility of micro-nano bubbles with water-liquid-gas.Based on the flow rate and rotational viscosity of the loop pipe,the drag reduction performance and interface contact characteristics of the liquid-gas coupling medium were determined,which laid a foundation for gas seepage displacement and seepage water lock in coal.Then,the modification characteristics of gas-liquid coupling medium on gas displacement and seepage water lock are quantified.（1）After the coupling of liquid and gas with distilled water as the carrier,surfactant and micro and nano bubbles can significantly promote the gas seepage displacement of coal,and realize the strengthening of gas seepage displacement of coal.（2）When the coupled liquid and gas medium percolates for gas displacement in coal body,the inlet pressure of percolation in water medium decreases,and the difference of percolation displacement between anthracite and long flame coal decreases and tends to be similar.（3）Under the same load condition,the seepage displacement effect of the liquid-gas coupled medium is greater than that of the water medium,which indicates that the liquid-gas coupled medium is easier and stronger for the seepage displacement of coal gas.（4）Compared with dry,distilled water,distilled water+surfactant medium,the gas desorption of coal body shows obvious attenuation and classification characteristics.（5）Under different particle size,metamorphism and adsorption equilibrium pressure,the coal-sample gas desorption T₁ index of the liquid gas coupling medium is at the lowest level.（6）With the extension of the action time,the gas desorption attenuation of the liquid gas coupling medium is more intense,showing the effect of infiltration water lock strengthening.Thirdly,the multi-source aftereffect based on the interface erosion of liquid-gas coupled media and the modification of coal pores is explored.（1）SEM of coal surface shows that the pore size of coal becomes larger under the scouring effect of liquid-gas coupled media,the cracks of the original pores expand,and the surface pores and holes of coal are in sharp contrast with the surface morphology of dry coal samples.（2）The effect of liquid-gas coupling medium on the modification of coal pore structure is obvious.The maximum adsorption capacity,cumulative pore area,cumulative pore volume,maximum pore volume and intermediate pore width of low temperature CO₂adsorption decreased by 4.1474cm³/g,33.9549m²/g,0.0184cm³/g,0.007593cm³/g and0.0248nm respectively,compared with dry coal samples.（3）The difference of adsorption form and amount of N₂ at low temperature indicates that the liquid-gas coupling medium permeates into the pores of coal under the action of strong adsorption performance.The number of mesoporous coal is reduced,the adsorption/desorption capacity is reduced,and the liquid-gas coupling medium can change the original pore channels and types of coal.（4）The single point surface area,BET surface area and Langmuir surface area of the coal sample under the action of liquid-gas coupling medium are reduced to 0.6090,0.6518 and 0.6387m²·g^-1compared with the dry coal sample respectively.The cumulative pore surface area and the cumulative pore volume of the coal sample were decreased by 52.45%and 49.10%respectively and the cumulative pore volume was decreased by 29.96%and 28.35%respectively.Fourthly,the mechanism of gas seepage displacement and water lock strengthening is explained.（1）The liquid-gas coupling medium provides the synergistic power of gas seepage displacement and seepage water lock through the optimization of drag reduction performance,the reduction of surface tension,the enhancement of boundary slip,and the charge modification and adsorption enhancement under the action of activity.（2）Based on the characteristics of pore seepage and boundary slip,a drag-reducing seepage model is established by comparing the pore structure of coal with that of circular pipe pores.Based on Darcy seepage,the mechanical characteristics and macroscopic mechanism of the interface of gas seepage displacement in coal are explained.（3）Based on the energy release and adsorption potential well during the adsorption of water and methane molecules by coal,the mechanism of water-locking effect of gas-liquid coupling medium on gas penetration in coal is explained and the water-locking effect is verified by gas desorption T₁ index.（4）Under the inherent properties of coal porous media,the liquid-gas coupling media can moisten and permeate coal,displace from moistening to permeating,slip at boundary and lock through charge modification,surface adsorption and pore modification.Through performance optimization,quality improvement and efficiency enhancement,the synergistic effect of gas seepage displacement and seepage water lock in coal is strengthened.Finally,the co-prevention and co-control technology of strengthening gas emission and weakening gas desorption is proposed.（1）Based on the coexistence and regeneration of liquid-gas coupling,the stability of liquid-gas coupling seepage displacement and seepage water lock strengthening and the stability under pressure,the basic conditions of liquid-gas coupling medium on gas seepage displacement and seepage water lock are analyzed.（2）After the liquid-gas coupling medium is injected into the coal body,the gas emission increases rapidly,increases in fluctuation,and then decreases rapidly,which verifies the effect of the liquid-gas coupling medium on the gas seepage and displacement of the coal body and promotes the gas emission.（3）The gas desorption index of drilling cuttings decreased rapidly,increased rapidly and then decreased after the liquid-gas coupling medium was injected into the coal body,which verified the water-locking effect of the liquid-gas coupling medium on the gas penetration of the coal body and inhibited the gas desorption.更多还原