功率超声影响的煤中甲烷气促解规律实验研究

 功率超声激励促解煤层甲烷气是一种不受储层地质条件和气源特性限制，具有普遍应用价值的增采技术。通过CT观测实验，对超声波作用下煤样不同尺度裂隙发展规律进行深入分析，从微观上揭示功率超声促解机制。在对比促解实验测定结果的基础上，研究功率超声作用煤样解吸量变化规律。研究结果表明：CT观测实验很好地证明了超声的机械震碎作用；在功率超声激励作用下，煤样裂隙条数显著增多，贯通裂隙增多且单条裂纹最大宽度显著增大；超声波作用后煤中甲烷气的解吸量有显著提高，建立超声声强参数影响的煤中甲烷气解吸量随解吸时间变化的修正公式。由修正公式拟合结果可知：煤中甲烷气饱和吸附后的解吸量 和 均随孔隙压力的增加而增大，相同孔隙压力下的甲烷气饱和吸附解吸量 大于无超声作用时的解吸量 ，其原因在于在功率超声的声场强度影响下，煤质点的动能和位能增加，煤表面甚至基质内部吸附的甲烷更容易脱附变成游离态，从而达到煤层甲烷气促解作用。

EXPERIMENTAL STUDY OF PROMOTING METHANE DESORPTION LAW IN COAL CONSIDERING POWER ULTRASOUND EFFECT

Power ultrasonic incentive promoting desorption of methane in coal seam is a kind of general applicable value technology，which is out of limit controlled by reservoir geologic conditions and source gas characteristics. Through CT observation and promoting desorption experiment，the rule of coal samples different scales fracture development is analyzed considering ultrasonic effect，from microscopy to reveal the power ultrasonic promoting desorption mechanism. In contrast to the experimental determination of promoting desorption results，the rule of gas desorption quantity in coal sample changing with time by power ultrasonic action is studied. Research results show that：CT observation is the good proof that the ultrasonic mechanical shatter role. In the power ultrasonic incentive effect，the number of coal sample fracture significantly increased；transfixion crack increased and a single crack maximum width increased significantly；methane desorption quantity of coal has increased dramatically by ultrasonic incentive；the modifier formula of ultrasound promoting methane desorption quantity changing with time in the coal is established. The fitting correction formula show that：gas desorption quantity   and   increased with increasing pore pressure after saturated adsorption；the methane saturated adsorption desorption quantity is greater than the desorption quantity  without ultrasonic incentive in same pore pressure；the reason is that in the influence of power ultrasonic field strength，coal point of kinetic energy and potential energy increase，the coal surface even matrix internal adsorption of methane easier to stripping into determination of free，so as to achieve coal seam methane promoting desorption effect.