A new SAGD comprehensive multi-stage model for oil production using a concave parabola geometry

Steam-assisted gravity drainage (SAGD) has become a widely used thermal method for developing heavy oil reservoirs. The accurate estimation of steam chamber expansion over the entire life of the SAGD process is very important to forecast its performance correctly. In this study, the concave parabola steam chamber geometry analytical model is expanded to include the rise and confinement stage of SAGD. Based on Darcy's law and material balance, analytical models in the rise and confinement stage of the steam chamber were established to estimate the oil production rate with time respectively. The energy balance is then used to estimate the SOR for different stages. The developed analytical models for different stages of SAGD are combined to obtain a comprehensive multi-stage model. The model is then validated against the experimental data obtained by Cheng and Butler and a numerical simulation with CMG-STARS. The comparison proves that the newly proposed model is more accurate than the previous model. After verifying the accuracy of the proposed model, some important production indicators of the SAGD process in different stages, such as oil production rate, cumulative production and effective height, and energy analysis during different stages of the SAGD process are discussed respectively. The influence of different parameters on the whole process of SAGD is discussed finally. The model proposed in this paper is significant for guiding the actual development of SAGD process in oil fields.

Automated summary

Steam-assisted gravity drainage (SAGD) is a widely used thermal method for developing heavy oil reservoirs. This study expands the analytical model for steam chamber geometry to include the rise and confinement stages of SAGD, establishing models to estimate oil production rate and SOR with time. The newly proposed model is validated against experimental data and numerical simulation, showing greater accuracy than previous models and providing significant guidance for the development of SAGD processes in oil fields.