煤储层无水压裂技术现状及展望

中国煤层气产业已迈入全新发展阶段,水力压裂技术不断创新的同时,也面临着水资源消耗量巨大,煤储层伤害严重,裂缝扩展不充分等问题,寻求一种可替代的无水或少水压裂技术势在必行。文章研究总结出三种当前适用于煤储层的无水压裂技术(超临界二氧化碳压裂、液态氮气压裂、泡沫压裂),对其作用机理、理论创新以及国内现场应用的现状进行分析阐述。对各项压裂技术的优缺点特性开展了评价,结果表明无水压裂技术能减轻煤储层伤害,避免黏土膨胀和水锁效应,有效促进复杂缝网生成,缩短见气时间,实现产量显著提升,可很好应用于煤储层二次压裂改造,具备良好的环境效益和技术可行性;但同时也存在支撑剂携带困难,设备运维成本较高等问题。最后对煤储层无水压裂技术的发展提出展望,建议逐步开展煤储层无水压裂技术现场先导性试验,优化施工参数,研发地面—井下低温特殊工艺设备,推进开展低密度支撑剂和压裂液增稠剂的优选实验,巩固提升泡沫压裂液体系在高温高压环境下的稳定性能。

补连塔煤矿上覆采空区大面积火区综合治理技术研究

补连塔煤矿三盘区2-2煤层22305工作面回采放顶时,上覆1-2煤层12306采空区内浮煤发生自燃,导致了22305工作面CO超限,工作面停产。在进行火区状况分析后,采用多种方法进行火区治理,但由于采空区漏风严重、火区面积大、火区发展速度快,前期治理并未收到明显成效。后期针对火区特点,对22305工作面进行封闭并采取从地面向采空区灌注液态氮气和液态二氧化碳的措施进行治理,取得了良好效果,有效控制了22305工作面上覆采空区高温区域,使得22305工作面启封后安全回采。

手持式超导磁悬浮装置的制作与应用

人教版高中物理选修3-2"电能的输送"章节涉及"超导电缆输电"知识点,给学生理解知识带来了一定的困难。为了让学生真实地观察超导现象,避免简单的说教和"空对空"式的教学,可利用超导带材、液态氮气、铁板等实验材料制作手持式超导磁悬浮装置。它不仅能让学生直观地观察到超导磁悬浮现象,还能很好地诠释楞次定律。该自制装置具有现象生动明显、操作简单的特点,能有效提升学生的物理学科核心素养。

Experimental Study and Heat Transfer Analysis on the Boiling of Saturated Liquid Nitrogen under Transient Pulsed Laser Irradiation

The boiling behavior of the liquid nitrogen (LN2) under the transient high heat flux urgently needs to be researched systematically. In this paper, the high power short pulse duration laser was used to heat the saturated LN2 rapidly, and the high-speed photography aided by the spark light system was employed to take series of photos which displayed the process of LN2's boiling behavior under such conditions. Also, a special temperature measuring system was applied to record the temperature variation of the heating surface. The experiments indicated that an explosive boiling happened within LN2 by the laser heating, and a conventional boiling followed up after the newly-defined changeover time. By analyzing the temperature variation of the heating surface, it is found that the latent heat released by the crack of the bubbles in the bubble cluster induced by the explosive boiling is an important factor that greatly influences the boiling heat transfer mechanism.