A physical model for two-phase flow in steam injection wells

Abstract

The injection of steam for the recovery of heavy oil is the predominant method of tertiary oil recovery. Annual production in the U.S.A. exceeds 480,000 barrels of oil per day (Leonard, 1986). As deeper resources are exploited, an accurate knowledge of the changes in steam temperature and quality with depth is required so that saturated steam is delivered to the oil reservoir at the proper rate, pressure and heat content. This knowledge is also needed to prevent thermal damage to wellbore equipment during the steam injection process. Upward two-phase vertical flow of steam and hot water occurs in geothermal wells. Geothermal projects in the U.S.A. use aquifers that produce hot water or a steam-water mixture. The two-phase mixture is separated at the surface, and the steam is used for power generation. Again, knowledge of steam pressure and quality variations are needed for proper sizing and design of equipment. Several methods (Farouq Ali, 1981; Fontanilla and Aziz, 1982) are available to calculate changes in temperature, pressure, and steam quality with depth during two-phase steam injection and production from vertical wells. In general, these methods use correlations of dimensionless variables and do not model the process directly. This work was undertaken to find physical models that permit the analytical prediction of the flow patterns, pressure changes, and heat losses in two-phase vaporliquid injection or production.