School of Safety Engineering, China University of Mining and Technology

为了最大程度上避免瓦斯钻孔成孔过程中卡钻现象,选取钠基膨润土为基料,研制了一种钠基膨润土基微泡钻孔液。通过实验研究不同种类及剂量的发泡剂和稳泡剂对微泡沫钻孔液的影响,测试钻孔液稳定性、流动性,评价钻孔液体系的流变性、抗高温、抗煤粉和抗酸碱性能;同时,利用数值模拟研究了钻孔液体系携煤粉的能力。实验结果表明,钠基膨润土基微泡钻孔液具有良好的发泡性能,在80℃以内能够保持稳定,对质量分数在10%以内的煤粉具有较好的抗侵蚀能力;通过岩屑沉降速度表征,该钻孔液的携岩能力强于普通清水。数值模拟研究表明,当钻孔液中煤粉浓度为4%体积分数时,在模拟打钻20s后,钻孔平均煤粉体积分数为4.5%,钻孔底部堆积的煤粉体积分数为15%左右,钻孔出口煤粉浓度大于入口煤粉浓度。同时,在相同条件下,提高流速和转速可以增强携煤粉能力,降低环空中煤粉浓度。

In order to minimize the occurrence of jamming during gas hole drilling and formation, a microfoam drilling fluid is developed with sodium-based bentonite as base material. Various foaming agent and foam stabilizer are tested in-lab for the influence in microfoam drilling fluid, including drilling fluid stability and mobility, and they are also evaluated for rheological property, high temperature resistance, coal powder resistance and acid and alkali resistance of drilling fluid system. Use numerical simulation to study drilling fluid carriage with coal powder. The experimental results show that sodium based and bentonite based microfoam drilling fluid has good foaming performance. It remains stable below ℃, and has good erosion resistance to coal dust with mass fraction less than 10%. The rock debris settling rate characterizes that the drilling fluid has better rock-carrying ability than ordinary water. Numerical simulation study indicates that when the coal dust concentration in drilling fluid reaches 4% volume fraction, after seconds stimulated drilling, average drill hole coal powder volume fraction will reach 4. 5%. Coal dust volume fraction at hole bottom is around 15%. The exit of opening has denser coal dust concentration than the entrance. Under the same condition, improvement of flow rate and revolving speed can carry more coal dust and reduce the concentration in air.

盛树平,程健维,罗望.膨润土基微泡瓦斯钻孔液制备及数值模拟研究[J].煤炭工程,2024,56(12):125-132.