煤层注空气置换-驱替甲烷作用研究

Study on Displacement and Replacement of Methane in Coal Seam by Air Injection

为了研究注空气置换-驱替煤中甲烷过程中,置换作用和驱替作用主导地位的时效性变化规律,特开展低压注空气置驱煤中甲烷的模拟实验。实验结果表明:前8 min内,注入的空气全部滞留在煤体中,该阶段内注入的空气表现出的瞬时置换作用占据主导,瞬时驱替作用微弱。此后直至实验结束,瞬时置换作用一直保持减小的趋势,瞬时驱替作用一直保持增强的趋势,实验前期瞬时置换作用强于瞬时驱替作用,在112~122 min内,出现瞬时置换作用等于瞬时驱替作用的转折点,此后瞬时驱替作用反超瞬时置换作用。实验最后,瞬时置换作用逐渐趋近于0,瞬时驱替作用占据绝对主导。截止实验结束,注入空气表现出累计置换作比例为26%,累计驱替比例为74%,驱替作用表现出主导作用。

In order to study the timeliness change laws of the leading role of displacement and replacement in the process of injecting air to coal to displace and replace the methane in coal, we carried out the simulation experiment of injecting the air to displace and replace the methane in coal under the low injection press of air. The experimental results show that all the injected air has been trapped in the coal in the first 8 min after the start of the experiment, and the injected air in this stage show the displacement effect in the leading role, and the transient displacement is weak. Since then, the transient displacement has been decreasing, the instantaneous displacement effect has been increased all the time; but the instantaneous displacement remains strong in the instantaneous displacement at the early stage of the experiment, the turning point appeared in the 112 min to 122 min, the instantaneous displacement is equal to the instantaneous displacement, then instantaneous displacement effect is always stronger than instantaneous displacement. Finally, the instantaneous displacement tends to 0, and the instantaneous displacement effect is in the leading role. In the whole experiment, the cumulative effect of the injected air is 26%, and the cumulative effect of displacement is about 74%.