封堵高温裂隙的水泥基泡沫流体耐热性研究

Heat Resistance of Foam Cement Fluid for Sealing High Temperature Fracture

煤岩体受热破坏形成的高温煤岩裂隙是煤田火区演化和蔓延的主要成因。水泥基泡沫流体作为一种新型的高温煤裂隙防控材料,其泡沫流体的耐热特性是其重要的技术参数。基于自制泡沫流体隔热性能测试系统,测试了不同支架高度(2 cm、7 cm、12 cm、17 cm、22 cm)和不同喷注厚度(20 mm、40 mm、60 mm、80 mm)情况下水泥基泡沫流体的隔热特性,得出随着测试时间的增加,20~80 mm各个喷注厚度的新鲜泡沫流体冷面温度都增加,在测试时间为0~90 s以内,温升曲线斜率较大;隔热温度空间分布整体在一个曲面上,进而拟合得到了隔热温度、喷注厚度、热面温度三者之间的关系式。受热情况下泡孔液膜微观形态变化表征显示泡沫流体在200℃出现失稳定,并从表面张力、液膜基质粘度、自由水含量三个方面分析了受热对液膜排液速度的影响。

The fractures with high causes to the evolution and spread temperature formed by heat of the coal fire. The foam damage of coal and rock are the main cement fluid is a new type material for preventing and controUing the coal and rock fractures with high temperature. The heat resistant property of foam fluid is the important technical parameters. Based on homemade testing system for foam fluid heat insulation performance, the thermal insulation property of foam fluid with different bracket height （2 cm, 7 cm, 12 cm, 17 cm, 22 cm） and injection thickness （20 mm, 40 mm, 60 ram, 80 mm） were tested. It is concluded that with the increase of test time, the cold surface temperature of all the foam fluids increase from 20 mm to 80 mm, however, the slope of temperature rise curve is bigger within the test time of 0-90 s. The distribution of heat insulation temperature is in a curved surface as a whole. Then the relations of thermal insulation temperature, injection thickness and hot surface temperature were fitted. Under the condition of heating, the morphology change of bubble liquid film shows that the foam fluid is unstable at 200 ℃. The effects that heating on drainage rate of liquid film were studied from three aspects including surface tension, viscosity of liquid film substrate and free water content.