Critical Flow of Wet Steam Through Chokes

Before steamflooding became an oil field practice, static chokes were used extensively and satisfactorily on gas wells to control the gas flow rate. The flow-rate equations and critical-pressure information were developed for gas, a single-phase fluid. Most steam used in steam EOR projects is a wet steam that is a two-phase liquid. The flow rate and pressure of the critical flow of wet steam are not fully understood. This paper investigates the critical-flow rate and critical-pressure ratio of the wet steam by use of analytical models and experimental data and establishes empirical correlations for the critical flow rate and critical pressure. Focusing on practical oil field applications, this study covers the critical flow of steam with steam pressures ranging from 50 to 2,000 psia (0.3 to 13.8 MPa) and steam quality ranging from 10 to 100%.