A new analytical model to simulate SAGD process considering geomechanics

Rock Engineering 2009 - Rock Engineering in Difficult Conditions
Rick J. Chalaturnyk,
Abstract SAGD (Steam Assisted Gravity Drainage) is an in-situ technique to extract oil in oil-sand reservoirs. In Canada, this method has been employed in the past 25 years for Alberta’s oil-sand reservoirs.

SAGD has been applied successfully in many projects and the technique has been quite understood. However because of the nature of oil-sand formations, geomechanics plays a very important role and it is often forgot to be considered. For modeling such a complex system two types of simulation are needed; the same as any other petroleum reservoir, 3-phase flow simulation is the first step. Besides, geomechanical modeling has to be applied. In between, permeability and porosity are the parameters that are modified during the process. Therefore, a coupled modeling is needed to catch the geomechanical behavior of the reservoir as well as oil production and flow characteristics.

This study proposes a simple analytical model to mimic SAGD process in both aspects; flow simulation and geomechanical behavior. The method has been constructed based on a linear geometry version of Butler’s theory that is able to predict oil production rate and shape of steam chamber. However, the method benefits from a classical geotechnical method of analysis called “limit equilibrium analysis” to change permeability and porosity interactively with flow simulator. This simple method shows how a mechanically failure zone moves in front of the steam chamber that affects the whole process. As a function, this model can be a good replacement of coupled numerical modeling.
Keywords: SAGD, Anaylitical Model, Oil-Sand, Alberta, Canada, Geomechanics, Coupled Modeling, Failure Surface
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