Abstract: On the basis of the mathematical models of steam growth volume in—situ presented by P. J. Closmann and temperature distribution by Carslaw and Jaegar, this paper presents the methods for calculating the steam volume and the volume of pore volume in—situ at constant injection rate. lt suggests that existance of a gas state water may not be ignored during steamflooding, and a new equation for calculating cumulative injection/production ratio has been derived. Using actural data available, the values calculated is very close to field cases.

Key words: Thermal production for hcavy oil, Steamdrive, Steam volume, Cumulative injection/production ratio