超细石墨复合改性水泥石的导热性能

Thermal conductivity of cement stone modified with superfine graphite

为提高地热的开采效率,在地热井采热段应使用具有高导热性能的固井材料。以超细石墨为提高导热性能的掺合料,选用十二烷基苯磺酸钠作为分散剂提高超细石墨在水泥浆中的分散稳定性;优选出适合的超细石墨分散液后,进一步制备超细石墨复合改性水泥石(简称为水泥石)作为固井材料;研究超细石墨掺量对水泥石的抗压强度和导热性能的影响;运用XRD、TG、MIP、SEM测试和表征水泥石的物相组成、孔隙率和结构致密性,研究不同掺量的超细石墨对水泥石导热性能的影响;探讨不同石墨掺量和孔隙率条件下的水泥石导热机制。结果表明:随着超细石墨掺量的增大,水泥石的导热系数先增大后减小,当超细石墨质量分数为12%时,水泥石导热系数达到最大值,为2.45 W/(m·K);超细石墨的导热性能、孔隙率与水化产物的含量均可影响水泥石导热性能;随着超细石墨掺量的增大,水泥石的抗压强度先增大后减小;综合考虑水泥石的导热性能与力学性能,超细石墨的优选质量分数应为10%~12%。

In order to improve the exploitation efficiency of geothermal energy,cementing materials with high thermal conductivity should be used in the heat recovery section of geothermal wells.Superfine graphite was used as an admixture to improve thermal conductivity,and sodium dodecyl benzene sulfonate was used as a dispersant to improve the dispersion stability of superfine graphite in cement slurry.After the suitable superfine graphite dispersion was selected,superfine graphite composite modified cement stones(referred to as cement stones)were further prepared as the cement materials.The effects of superfine graphite content on compressive strength and thermal conductivity of cement stones were studied.The phase composition,porosity and structural compactness of cement stones were tested and characterized by XRD,TG,MIP and SEM.The effects of different contents of superfine graphite on the thermal conductivity of cement stones were studied.The thermal conductivity mechanism of cement stones under different graphite contents and porosity were discussed also.The results show that with the increase of the content of superfine graphite,the thermal conductivity of cement stones first increases and then decreases.When the content of superfine graphite is 12%,the thermal conductivity of cement stone reaches the maximum value of 2.45 W/(m·K).The high thermal conductivity of superfine graphite,the porosity and the mass fraction of hydration products can affect the thermal conductivity of cement stone.With the increase of superfine graphite content,the compressive strength of cement stones first increases and then decreases.Considering the thermal conductivity and mechanical properties of cement stones,the optimal mass fractions of superfine graphite should be from 10%to 12%.