Abstract: By analyzing the related domestic and overseas literatures and based on the theory of vertical multiphase flow and the law of energy conservation, this paper developed a model for calculating the distribution of temperature, pressure and steam quality in wellbore during production of extra-and super-heavy oils by steam injection process. The pressure drops of steam-fluid phases' vertical flow are calculated by this model with classical Orkiszewski method; the calculation of the temperature field is made by assuming one-dimensional steady-state heat conduction from the wellbore center to the cement sheath and two-dimensional unsteady-state heat conduction between the cement sheath and the strata, and the calculation of the steam quality is conducted by considering the change of steam enthalpy. The steam parameters are calculated using the four-rank Runge-Kutta method to make a program. The results given by this model are satisfactory when compared with measured data from the oil fields.

Key words: super heavy oil, extra heavy oil, steam injection, parameter, well bore