抽采钻孔损伤机理分析及高效封孔材料研制

Analysis of damage mechanism of drainage borehole and development of efficient sealing material

为明晰钻孔破裂区漏气的本质原因,考虑煤岩的非均质性及瓦斯渗流作用,采用理论分析和数值计算方法,构建煤层钻孔围岩损伤数学模型,探讨煤层瓦斯抽采钻孔的损伤破裂机理.研究结果表明:提出的数学模型可较好地描述煤岩的损伤破裂;由于煤岩的非均质性,钻孔周边的损伤区域并非均匀分布,渗透率损伤区域呈现类似裂隙发育的形态;孔内支护压力可提高钻孔稳定性,减少钻孔围岩损伤区域,渗透率的损伤情况显著得到抑制.研制一种膨胀型高效封孔材料,与传统水泥材料相比该材料可产生显著的膨胀力.工业试验表明:采用该封孔材料可使得瓦斯抽采浓度提高约10%.研究结论显著改善了瓦斯抽采效果.

In order to clarify the essential causes of air-leakage in the rupture area of the in-seam borehole,theoretical analysis and numerical methods were adopted to construct a damage numerical model of in-seam borehole by considering heterogeneity of coal rock and gas seepage in coal.The research results show that:the present numerical model agrees well with the real damage of coal rock and can describe the damage and crack of coal;due to the heterogeneity of coal bulk,the damage zone around holes is distributed unevenly,and the permeability damage zone shape is similar with the one of fractures;the active support imposed on hole-wall can increase the stability of hole,and reducing the region of rock damage and permeability damage.Based on the conclusions,a novel efficient swelling material for borehole-sealing was developed.Compared with traditional cement materials,the novel material can provide a notable swelling force.Filed-scale test indicates the novel material can improve the coal seam gas drainage performance by about 10%higher.