In high-temperature drilling environments, accurate management of wellbore hydraulics is made more difficult due to complex fluid viscosity-temperature profiles. Although most of the fluid samples reported in the literature have monotonically decreasing viscosity with temperature, several studies have found the relationship much more complicated. This study investigates thermal effects on annular pressure loss and cuttings transport for fluids with non-monotonic viscosity-temperature profiles while modeling the thixotropic behavior of the drilling fluid. To this end, three fluid samples have been studied that have distinctly different viscosity-temperature profiles: monotonically decreasing, parabolic and inverted parabola. The mathematical framework is based on the drift flux approach and is numerically solved using the computational fluid dynamics (CFD) methodology. The recently proposed rheological algorithm by the authors has been extended to model thixotropy. The results are presented for different inclinations and eccentricities. It is observed that for fluids with parabolic or inverted parabolic viscosity-temperature profiles, annular pressure loss is highly non-linear, and a single equivalent density value cannot be ascribed to the wellbore. The annular pressure loss near the inlet is significantly higher than that near the outlet. The fluid with a monotonic decrease in viscosity yields the lowest pressure loss but worst cuttings transport whereas, the fluid with a parabolic viscosity-temperature profile has best cuttings transport but causes extremely high-pressure loss.

在高温钻井环境中，由于复杂的流体粘度-温度曲线，井筒水力学的准确管理变得更加困难。尽管文献中报道的大多数流体样品的粘度随温度单调降低，但一些研究发现这种关系要复杂得多。本研究在模拟钻井液的触变行为的同时，研究了热对具有非单调粘度-温度分布的流体的环空压力损失和岩屑传输的影响。为此，研究了三种流体样品，它们具有明显不同的粘度-温度曲线：单调递减、抛物线和倒抛物线。数学框架基于漂移通量方法，并使用计算流体动力学 (CFD) 方法进行数值求解。作者最近提出的流变算法已扩展到模拟触变性。结果显示为不同的倾斜度和偏心率。观察到，对于具有抛物线或倒抛物线粘度-温度曲线的流体，环空压力损失是高度非线性的，并且不能将单个等效密度值归因于井眼。入口附近的环空压力损失明显高于出口附近的环空压力损失。粘度单调下降的流体产生最低的压力损失但最差的岩屑输送，而，