Modification of constant volumetric displacement model for the steady-stage SAGD process

Abstract

This paper points out a deficiency of constant volumetric displacement (CVD) model used by Reis (JCPT 31, 1992), Zeinab Zargar and S. M. Farouq Ali (SPE J, 2016) and modifies the CVD model by considering the variation of the amount of oil in the area ahead the steam front to obtain a new oil production rate formula for steady-stage steam-assisted gravity drainage (SAGD) process. The new oil production rate formula is in a good agreement with experimental data as reported by Butler et al. (Can J Chem Eng 59:456–460, 1981) and indicates that the actual oil production rate in steady-stage SAGD process is not a constant no matter that the extent of the reservoir is infinite or finite, which is different from previous results. It is the sum of a constant oil rate and another oil rate which is a linear function of time. However, the value of the latter oil rate is so small compared with the constant oil rate that the experimental data of the whole oil production rate seems to be a constant. In addition, the distribution of the oil saturation in the area ahead the steam front is solved with detailed deduction in the solution process.