基于相变蓄热原理的深井钻井液降温实验研究

Experimental Study of Drilling Fluid Cooling in Deep Wells Based on Phase Change Heat Storage

针对深部油气钻探开发中钻井液、井下仪器抗高温稳定性较差的问题,首次将相变材料应用于钻井液中,开展了基于相变蓄热原理的深井钻井液降温实验研究。在评价相变材料热物性的基础上,分析了相变材料的蓄热控温特性;对比评价了相变材料对钻井液流变滤失性能的影响;采用自制的钻井液循环模拟实验装置,测试了钻井液降温性能实验曲线。结果表明,1#—3#相变材料的相变温度为120~145℃,相变潜热为90.3~280.6 J/g;2#相变材料的相变潜热最大,相变蓄热特性最优,其与钻井液的配伍性能良好,加量达12%时钻井液的黏度、切力和滤失量基本不变,钻井液循环温度约可降低20℃,且具有良好的重复利用价值。研究结果表明,利用相变材料的“相变蓄热原理”可以降低钻井液的循环温度,为深井高温钻井液降温提供了新的技术思路。

Focusing on such problems as poor high-temperature stability of drilling fluids and downhole instruments in the development of deep gas and oil,phase change materials were introduced into drilling fluids for the first time to model the cooling of drilling fluids in deep wells based on phase change heat storage principle.First,the heat storage characteristics of the phase change materials were investigated on the basis of evaluating the thermophysical properties of the phase change materials.Then,the influence of phase change materials on the rheological and filtration properties of drilling fluids was comparatively evaluated.Finally,the experimental curves for the cooling performance of drilling fluids were measured using a self-made experimental device of drilling fluid circulating simulation.The results showed that the phase change temperature and the latent heat of phase change for the phase change materials 1#–3#were approximately 120–145°C and 90.3–280.6 J/g,respectively;and the phase change material 2#displayed the highest latent heat and the best heat storage performance of the phase change,exhibiting a compatibility with drilling fluid.Specifically,the viscosity,shear force,and filtration of the drilling fluids were basically unchanged when the concentration of the phase change material 2#increased to 12%,and the circulating temperature of the drilling fluids could be reduced by about 20℃,correspondingly.In addition,the phase change material 2#exhibited excellent reuse properties.In conclusion,the circulating temperature of the drilling fluids could be reduced by referring to the principle of phase change heat storage of phase change materials,which could provide a new technical thinking to apply to cooling technologies for high-temperature drilling fluids in deep wells.