Evaluation of Cyclic Steam Injectors in China

Abstract

Abstract For more than a decade, several fields in China have produced heavy oil from cyclic steam thermal operations. High temperature (650F) steam has been injected into the reservoirs. One field operates cyclic steam wells completed at 1600 meters in depth. This paper describes an innovative system to measure continuously, from surface to downhole, the pressure, temperature, and spinner responses in these steam injectors. Compelling data is presented to evaluate wellbore heat loss, steam injection profiles, and reservoir properties. A unique wellbore heat-loss model applies the measured temperature data to quantify downhole steam quality. Steam injection profiles have been obtained by analyzing spinner data against perforation intervals. During the steam soaking period, downhole pressure and temperature fall-off behaviors have been observed. The analysis of pressure fall-off curves yields wellbore skin and reservoir permeability. A new model to analyze temperature fall-off curves, by applying the Marx-Langenheim theory and a new set of type curves, yields heat transfer coefficients and steam swept zone size in the reservoir.