Gravity assisted gas injection: assessment model and experimental study

Key words:  gravity assisted gas injection model  assessment model  laboratory experiment  influencing factors  improve displacement efficiency

Abstract:

In this study, laboratory experiments were conducted to investigate the displacement efficiency and mechanisms of GAGI, and the effects of dip angle, injection rate and oil viscosity on oil recovery were tested. The residual oil distribution after gas displacement and overall oil production were analyzed to reveal the EOR mechanisms of GAGI. A quantified GAGI assessment model (the N_GAGI number) was proposed, in which the geological and operational parameters were considered, such as dip angle, the density defference between the displacement and displaced fluids, oil layer permeability, crude oil viscosity and injection rate. The experimental results show that large dip angle, low injection rate and low oil viscosity can stabilize the gas/oil contact and improve oil recovery, and the residual oil saturation can be less than 10% after gas displacement. The experimental and field data indicate that gravity stablized gas injection can be realized when the N_GAGI number is greater than 1. The proposed N_GAGI model can be used as a creterion to assess the stablity and efficiency of GAGI for field project design and operation.