Frozen soil is a porous elastic-plastic-viscous material with temperature-sensitive properties. Borehole shrinkage occurs due to the plasticity and creep of frozen soil that ensues during drilling operations in cold regions. Based on the change of mechanical properties of frozen soil during the heat transfer process that occurs between the drilling fluid and the formation, a heat-fluid-solid coupling model is established in this paper to analyze borehole shrinkage behaviors in frozen soil. The results show that during drilling operations, the plastic and creep deformation of frozen soil will result in borehole shrinkage. When the borehole is drilled, a certain amount of plastic deformation will occur due to stress concentration. As drilling operations continue, both plastic and creep deformation gradually accumulate. The borehole shrinkage is dominated by the initial temperature of the formation, and the higher the formation temperature, the greater the shrinkage. At the same formation temperature, the initial borehole shrinkage decreases with increasing temperature of the drilling fluid, and the final shrinkage increases nonlinearly with increasing temperature. The drilling fluid temperature should be close to 0 °C when the formation temperature is high to reduce the drilling time. When the formation temperature is low, cold drilling fluid should be used to maintain borehole stability. This study provides a theoretical basis for the selection of drilling fluid temperatures during drilling operations in cold regions.

冻土是一种具有温度敏感性的多孔弹性塑料粘稠材料。钻孔收缩是由于在寒冷地区的钻井作业期间发生的冻结土壤的可塑性和蠕变而发生的。基于钻井液与地层之间传热过程中冻土的力学特性变化，建立了热-固-固耦合模型，分析了冻土中的井眼收缩行为。结果表明，在钻井作业中，冻土的塑性变形和蠕变变形将导致井眼收缩。钻孔时，由于应力集中，会发生一定程度的塑性变形。随着钻井作业的继续，塑性变形和蠕变变形都逐渐累积。井眼收缩主要受地层初始温度的影响，地层温度越高，收缩率越大。在相同的地层温度下，初始井眼收缩率随钻井液温度的升高而降低，而最终收缩率随温度升高而呈非线性增长。地层温度较高时，钻井液温度应接近0°C，以减少钻井时间。当地层温度低时，应使用冷钻井液以保持井眼稳定性。该研究为寒冷地区钻井作业中钻井液温度的选择提供了理论依据。在相同的地层温度下，初始井眼收缩率随钻井液温度的升高而降低，而最终收缩率随温度升高而呈非线性增长。地层温度较高时，钻井液温度应接近0°C，以减少钻井时间。当地层温度低时，应使用冷钻井液以保持井眼稳定性。该研究为寒冷地区钻井作业中钻井液温度的选择提供了理论依据。在相同的地层温度下，初始井眼收缩率随钻井液温度的升高而降低，而最终收缩率随温度升高而呈非线性增长。地层温度较高时，钻井液温度应接近0°C，以减少钻井时间。当地层温度低时，应使用冷钻井液以保持井眼稳定性。该研究为寒冷地区钻井作业中钻井液温度的选择提供了理论依据。地层温度较高时，钻井液温度应接近0°C，以减少钻井时间。当地层温度低时，应使用冷钻井液以保持井眼稳定性。该研究为寒冷地区钻井作业中钻井液温度的选择提供了理论依据。地层温度较高时，钻井液温度应接近0°C，以减少钻井时间。当地层温度低时，应使用冷钻井液以保持井眼稳定性。该研究为寒冷地区钻井作业中钻井液温度的选择提供了理论依据。