Abstract: The temperature of coal core directly affects the gas loss during coring. In order to reduce the error of gas loss prediction, the evolution law of coal core temperature field during coring is studied by method combining experiment and numerical simulation. The field coring temperature measurement tests with coring depth of 40 and 60 m were carried out. The 3 stage thermodynamic model of coring drill bit-coring tube-coal body was established and compared with the test, which verified that the thermodynamic model was reliable. A thermodynamic model of coring drill bit-coring tube-coal body-coal core in the process of coal seam coring was established, and the evolution law of coal core temperature in the process of coal seam coring with different coring depths was numerically analyzed. The results showed that the core tube generated heat by rubbing with the coal wall during the coal coring advancement stage. In the drilling stage, the drill bit generated heat by cutting the coal seam and rub with the coal wall. During the withdrawal stage, the coring tube and the gas in the hole conducted heat exchange and heat dissipation. The temperature of the monitoring point of the coring tube measured at different coring depths was consistent with the temperature change law of the simulation results, with an error of ±10%, which fully showed that the thermodynamic model of coring was feasible. During the coring simulation, heat was conducted from the drill bit to the inside and bottom of the coal core at the same time. While the temperature increased with time along the axial and radial directions, the peak temperature decreased with time due to heat exchange with the gas in the borehole. When coring coal seams with different depths, the final temperature of the coal core center increased exponentially with the depth.

Key words: coal seam, coring, temperature measurement, coring depth, temperature field

摘要： 井下取芯时煤芯温度直接影响取芯过程中的瓦斯损失量。为了减小瓦斯损失量预测的误差，利用试验与数值模拟相结合的方法，研究了取芯过程煤芯温度场的演化规律。进行取芯深度为40和60 m的现场取芯测温试验，建立取芯钻头-取芯管-煤体的3阶段热力学模型并与试验对比，验证该热力学模型具有一定可靠性。建立煤层取芯过程中取芯钻头-取芯管-煤体-煤芯的热力学模型，数值分析不同取芯深度煤层取芯过程煤芯温度的演化规律。研究结果表明，煤层取芯推进阶段取芯管与煤壁摩擦生热；钻进阶段钻头切削煤层生热且与煤壁摩擦生热；退钻阶段取芯管与孔内气体发生热交换散热。不同取芯深度现场测试的取芯管监测点温度与模拟结果的温度变化规律一致，误差为±10%，表明取芯热力学模型可靠。模拟取芯时，热量从钻头处同时向煤芯内部及底部传导，温度沿轴向和径向随时间升高，由于与钻孔内气体换热，峰值温度随时间降低。不同取芯深度的煤层取芯，煤芯中心所达到的最终温度随深度呈指数上升。

关键词: 煤层, 取芯, 测温, 取芯深度, 温度场