TY - JOUR
TI - A temperature-pressure coupling model for predicting gas temperature profile in gas drilling
AU - Liu Jinjiang
AU - Wu Wenlin
AU - Qian Peng
AU - Wang Shuo
JN - Thermal Science
PY - 2021
VL - 25
IS - 5
SP - 3493
EP - 3503
PT - Article
AB - In the gas drilling design, accurate prediction of wellbore temperature profile is very crucial. Different from liquid drilling fluid, physical and thermophysical parameters of gases are sensitive to the change of pressure and temperature, at the same time, the change of these parameters will react against the wellbore temperature and pressure. Based on the energy conservation principle, a temperature-pressure coupling calculation model was established to predict the gas temperature profile during gas drilling process. The model is solved by cycle coupling iteration method. The calculation shows that annular temperature rises sharply near the wellhead, drops sharply at bottom hole and is a little higher than the formation temperature in other places. Without considering the influence of friction heat, calculated temperature is lower than the actual temperature. Temperature trends are the same under different pump rates and larger pump rate leads to larger temperature range at the wellhead and at bottom hole. Compared with the pump rate, bit nozzle size has more influence on the temperature drop range. Temperature reduction increases from 31.3-57.2℃ while bit nozzle size decreases from 539-339 mm2.