Abstract: To address the problems of unclear coupling mechanism and imperfect optimization of production parameters in the process of steam injection in heavy-oil thermal recovery wells with multiphase flow, the influence of wellbore inclination was considered based on the theory of gas-liquid flow, a gas-liquid heat-fluid coupling model for whole interval of heavy-oil thermal recovery wells was established in combination of the distribution characteristics of fluid film in the wellbore, and the influence of different parameters on the thermal properties of wet steam in the wellbore was analyzed. The study indicated that, when the wellbore inclination angle was less than 45 °, the thermodynamic properties of wet steam were significantly affected by wellbore inclination; when the wellbore inclination angle was greater than 45 °, the influence on the thermodynamic properties of wet steam was gradually decreases; the pressure, temperature and dryness of the steam varied with the increase in well depth, especially in the horizontal interval. The optimization of injected steam volume and other parameters for three thermal recovery wells in Liaohe Oilfield resulted in a 15.3%, 16.6% and 14.7% reduction in injected steam volume under the expected well production conditions, greatly reducing the development cost of thermal recovery horizontal wells. The study is of great significance to guide the optimization of wellhead steam injection parameters and improve the thermal efficiency of steam injection.

Key words: thermal recovery well, heavy oil, coupling, wellbore, two-phase flow