LABORATORY INVESTIGATION AND SIMULATION MODELING OF DIFFERENT I-WAG SCHEMES TOWARDS OPTIMUM DISPLACEMENT EFFICIENCY

Water alternating gas (WAG) injection is a well-known Enhance Oil Recovery
process to improve sweep and displacement efliciency by gas trapping and controlling
the mobility of gas. The main aim of the WAG injection is to maximize the three�phase flow region in the reservoir and minimize non-swept areas. The physics of the
displacement processes during WAG injection is, however, complex due to three�phase flow in porous media.
In this research, to better understand the active mechanisms of immiscible WAG
(I-WAG), a series of visual experiments have been conducted on a 20 sandpack by
using an X-Ray image technique with an industrial type of CT-Scan-high resolution�machine. The sand-pack is designed to simulate different schemes of 1-WAG with
considering the effects of viscous, gravity, and capillary forces in different injection
orientations (horizontal and tilted) at ambient and elevated pressure and temperature
conditions. The experiments are conducted in up dip and down dip orientations for
injection. 20 dynamic injection front profiles are captured that help to understand the
swept area, three phase flow region, and mechanisms of 1-WAG under the different
schemes were studied. Simulation studies are also conducted based on the physical
parameters of the sand-pack to simulate the experiments and to be able to run more
sensitivity analysis. The trained simulation parameters validated against the
experimental results guide the field simulation of the same process.
The efficiency of three different I-WAG injection schemes towards the
improvement of recovery factor are investigated by conducting numerical simulation
studies on one homogeneous model and one highly heterogeneous real field sector
models. The studied first scheme (Scheme I) is up dip gas injection and down dip
water injection and the second scheme (Scheme II) is the down dip gas injection and
up dip water injection.