Aspects of Wellbore Heat Transfer During Two-Phase Flow

TLDR

Wellbore fluid temperature is governed by heat loss to the surrounding formation, which depends on depth and production/injection time. The study presents an approach and expression to estimate wellbore fluid temperature during steady‑state two‑phase flow in multiphase production. The method solves the thermal diffusivity equation, incorporates conductive and convective heat transport, and adapts the Hasan‑Kabir model for multiphase flow. Field examples and sensitivity studies show that convection is critical, temperature gradients are nonlinear, free gas reduces wellhead temperature via the Joule‑Thompson effect, and single‑phase expressions are unsuitable for multiphase flow.

Abstract

Summary Wellbore fluid temperature is governed by the rate of heat loss from the wellbore to the surrounding formation, which in turn is a function of depth and production/injection time. We present an approach to estimate wellbore fluid temperature during steady-state twophase flow. The method incorporates a new solution of the thermal diffusivity equation and the effect of both conductive and convective heat transport for the wellbore/formation system. For the multiphase flow in the wellbore, the Hasan-Kabir model has been adapted, although other mechanistic models may be used. A field example is used to illustrate the fluid temperature calculation procedure and shows the importance of accounting for convection in the tubing/casing annulus. A sensitivity study shows that significant differences exist between the predicted wellhead temperature and the formation surface temperature and that the fluid temperature gradient is nonlinear. This study further shows that increased free gas lowers the wellhead temperature as a result of the Joule-Thompson effect. In such cases, the expression for fluid temperature developed earlier for single-phase flow should not be applied when multiphase flow is encountered. An appropriate expression is presented in this work for wellbores producing multiphase fluids.