Mechanism of heat transfer for gas-liquid two-phase flow in deep drilling

Abstract

Drilling fluid cooling technology is one of the key techniques of drilling technology. In order to study the influence of mechanism of drilling fluid on temperature and pressure, especially on thermophysical parameters and rheological properties, as well as the heat transfer mechanism between bubbles and liquid flow inside and outside the liquid film by test, simulation and theoretical research. Firstly, the test on thermophysical parameters of 10 kinds of drilling fluids at 7 different temperatures and 3 different pressure were analyzed, which would provide the key parameters for the establishment of downhole gas-liquid two-phase model. Then, study on rheology of cement slurry under high temperature and high pressure, and its heat transfer equations were derived. The results showed that the specific heat of mud decreases with the increase of density, and the thermal conductivity increases with the increase of density, almost linearly. Besides, gas is the main factor affecting heat transfer inside the well.