The calculation of wellbore temperature and pressure is an important part in deepwater subsea mud lift drilling (SMD) design. Considering the influence of temperature, pressure and mud property, this study established a model of flow and heat transfer in the borehole of SMD. The results show that affected by the low seawater temperature, the upper wellbore annulus temperature was lower than the mud entrance temperature; the temperature in the borehole of SMD was lower than that of regular deepwater drilling; the potential safety problems caused by gas hydrate formation need to be watched. The pressure gradients in the borehole were different between the sea section and underground section. The pump pressure above the ground was lower than the circulating pressure loss, and the pressure in the borehole of SMD was lower than that in regular drilling. Both mud density and viscosity had impact on the equivalent circulating density (ECD) and pump pressure and temperature in the borehole, while the former had relatively large impact on ECD, and the latter had relatively large impact on the pump pressure and temperature. When both were considered, the calculation error of pump pressure would be greatly reduced.

deepwater drilling  /  subsea mud lift drilling  /  temperature distribution  /  pressure distribution  /  mud property