An improved SAGD analytical simulator: Circular steam chamber geometry

An elegant analytical model for the Steam Assisted Gravity Drainage (SAGD) process was firstly proposed by Butler and his colleagues for oil sands reservoirs in Canada. Some years later, Reis proposed two additional analytical linear and radial geometry models that were able to mimic the SAGD process satisfactorily. Since then, other mathematical models have been developed all with similar approaches considering that steam chamber has reached the caprock. This assumption causes the model to predict a constant oil production rate, which is not closely the case in reality.To overcome this shortcoming for practical history matching purposes, the current study modifies the Butler/Reis model to simulate the SAGD process from the beginning of the steam chamber growth. The study offers a circular geometry formulation using a discrete method of analysis, called the method of slices, to solve the analytical equations. The proposed geometry and formulation show better capability to reproduce the SAGD process analytically.

► We proposed an analytical model for SAGD, an improved version to Butler theory.
► The model considers relative oil saturation changes in advance of steam chamber.
► We have used a circular geometry for steam chamber.
► The model was verified using coupled numerical solutions.
► The model simulated nonlinearity in production.