Wellbore temperature profiling for deepwater multi-gradient drilling
In order to study the distribution law of temperature in deep water CML dual-gradient drilling wellbore, the coupling relationship between wellbore temperature, pressure, drilling fluid density and rheological properties was comprehensively considered, and the transient heat transfer model of deep water CML dual-gradient drilling wellbore was established in combination with the characteristics of deep-water CML dual-gradient drilling process and the law of energy conservation. Based on an example well, the effects of cycle time and drilling fluid physical parameters on annulus temperature were analyzed and compared with conventional drilling. The results show that the annulus temperature in the lower part of the wellbore decreases and the annulus temperature in the upper part increases with the increase of the cycle time and the density, specific heat and consistency coefficient of the drilling fluid. With the increase of thermal conductivity of drilling fluid, the annulus temperature in the lower part of wellbore increases gradually, while the annulus temperature in the upper part decreases gradually. Compared with the wellbore temperature of conventional drilling, the overall wellbore temperature of CML drilling is about 3 °C lowers on average, and the temperature difference near the mud line can reach about 8 °C.