填料对地热井固井材料导热性能的影响

Effect of thermally conductive filler on thermal conductivity of cementing materials in geothermal wells

在地热井固井水泥中加入导热填料能够明显改善水泥石导热性能,提升地热井取热效果。在总结导热路径理论和紧密堆积理论的基础上,通过试验研究不同填料种类、粒径及掺量对固井水泥导热性能的影响。试验结果表明:较其他种类填料,石墨对水泥石导热性能提升效果最好;石墨粒径越大对应水泥石导热系数越高。不同粒径的石墨混合,较单一粒径石墨对水泥石导热性能的提升效果更好,其最优混合配比为:石墨粒径为150μm与100μm,质量比为2︰1。随着石墨掺量增加,固井材料的导热系数逐渐增大,但流动度和48 h抗压强度逐渐降低。参照固井相关规范,提出固井材料中石墨掺量应控制在9%左右为宜。研究成果为地热井高导热固井材料的制备提供借鉴。

Adding heat-conducting filler to the cement of the geothermal well could significantly improve the thermal conductivity of the cement stone and enhance the heat extraction effect of the geothermal well.In this study,on the basis of summarizing the heat conduction path theory and concept of high packing density,the effects of different filler types,particle sizes and dosages on the thermal conductivity of cementing cement were investigated through experiments.The test results showed that graphite had the best effect on improving the thermal conductivity of cement stone compared to other types of filler;the larger the graphite particle size,the higher the thermal conductivity of cement stone.The mixing of graphite with different particle sizes had a better effect on improving the thermal conductivity of cement stone than graphite with a single particle size.The optimal mixing formula was:graphite particle size was 150μm and 100μm,and the mass ratio was 2︰1.With the increase of graphite content,the thermal conductivity of cementing materials increased,and the fluidity and compressive strength of 48 h gradually decreased.According to the relevant cementing specifications,the graphite content in the cementing materials should be controlled at about 9%.The research will provide references for the preparation of high thermal conductivity cementing materials for geothermal wells.