A Novel Optimization of SAGD to Enhance Oil Recovery - The Effects of Pressure Difference

Abstract

Summary Steam-Assisted Gravity Drainage (SAGD) provides many advantages compared to alternate thermal recovery methods for bitumen recovery. Nowadays, most of researchers believe that the gravity mechanism is the main drive in SAGD recovery, ignoring the injector-producer pressure difference, which makes the field prediction deviate from reality. To tackle this problem, this paper makes further investigation on the injector-producer pressure difference. A series of 2D numerical simulations are conducted on the basis of Mackay River reservoir in Canada to investigate on influence of injector-producer pressure difference. Meanwhile, a new mathematical model considering injector-producer pressure difference is established. The results indicate that when the injector-producer pressure difference exists, SAGD usually has better recovery. Pressure difference can effectively improve SAGD operating performance to achieve a high economic efficiency. More pressure difference doesn’t necessarily lead to better recovery, for when the pressure difference increases to some certain degrees, it will cause steam breakthrough. Pressure difference usually plays an important role at the beginning of SAGD recovery, therefore it is better for us to increase pressure difference at the steam rising stage and decrease pressure difference at the steam chamber expansion to avoid steam breakthrough, and finally to achieve a high economic efficiency.