| The application of technologies such as coal seam water injection and hydraulic permeation enhancement will leave a large amount of water within the coal seam and enter the coal matrix through fractures and pores to achieve effective imbibition into the coal body.The imbibition of water by the coal body plays a key role in the water transport process,and the imbibition process is influenced by factors such as bedding structure(internal factors)and confining pressure and temperature(external factors),but the influence law of these factors is not clear,which restricts the application of measures such as coal seam water injection.In this paper,we use spontaneous imbibition experiments of coal body to study the influence law of internal and external factors on the dynamic process of water imbibition from coal body.1.Spontaneous imbibition tests were conducted using coal bodies containing 0°,30°,45°,60°,and 90° bedding.It was found that the bedding significantly affect the water transport behavior within the coal body,with water first reaching the top along the bedding and then imbibition into the surrounding matrix area,and the maximum total pore imbibition rate decreasing from 5.64 g/h to 0.03 g/h increasing with increasing angle to between,with increasing bedding angle prolonging the imbibition equilibrium time(up to 8 times).2.The spontaneous imbibition test of coal body under the circumferential pressure of 1MPa-9MPa was carried out,and the dynamic transport characteristics of water seepage in coal body under the circumferential pressure were analyzed.The maximum total pore imbibition rate decreased from 4.71g/h to 0.10g/h,and the water content of adsorption pore increased from 65.85% to 79.42%,while that of seepage pore decreased from 32.29% to 20.12%.The imbibition equilibrium time increased from 4h to 144 h,an increase of up to 35 times.3.Spontaneous imbibition tests were carried out at 25℃-65℃,and the influence law of temperature on the process of imbibition of moisture from coal body was analyzed.The increase of temperature firstly leads to the expansion of coal matrix and the reduction of pore size,and then further extends and extends the native micro-pores,so that the percolation rate rises first and then decreases,and the temperature is positively correlated with the volume of adsorption pores and negatively correlated with the seepage pores,which increases the percentage of water content of adsorption pores(71.06% to 81.14%)and decreases the seepage pores(28.54% to 19.28%).4.The fractal theory was applied to analyze the change rule of pore structure of coal body.The fractal dimension of adsorption pores increased from 1.08 to 1.13 due to the increase of bedding angle,and the fractal dimension within different pore scales was influenced by bedding,with obvious differences and high irregularity of internal pore structure.The increase of surrounding pressure increases the fractal dimension of seepage pores from 2.81 to 2.90,which changes the pore structure of seepage pores.The increase in temperature decreased the adsorption pore fractal dimension from 1.13 to 1.06,while the seepage pore fractal dimension increased from 2.83 to 2.90 due to the expansion of primary microcracks caused by the increase in intergranular stress.5.The spontaneous imbibition equilibrium time shows that the influence of the confining pressure on the imbibition moisture of the coal body is the most obvious,which increases the imbibition equilibrium time by a maximum of 35 times,followed by the bedding,which increases the seepage equilibrium time by a maximum of 8times;the influence of temperature is relatively minimal,and the maximum increase in equilibrium time is only 0.6 times in the test temperature range.Figure 51 Table 28 Reference 94... |
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