SIMULATION STUDY OF THE IMPACT OF MOBILITY RATIO ON MULTILAYERED RESERVOIR DURING WATERFLOODING PROCESS

Implementation of waterflooding technique in Waha reservoir requires the
injection of water into the oil zone for oil displacement, due to the primary recovery
mechanism used in the Waha reservoir. Previous study done concludes that there are two
factors that highly affected the waterflooding performances, which are the mobility ratio
and reservoir heterogeneity. Therefore, a numerical approach was used to study the
effect of mobility ratio and reservoir heterogeneity in the waterflooding project with
quarter of Five-Spot Injection Pattern. Eclipse simulator was used, in which the results
was estimated using the combination of Buckley-Leverett and Dykstra-Parson method.
Some theories involved were also discussed in this paper, such as Frontal Advance
Equation, Fractional Flow Equation and relevant researches done by others. Generally,
the mobility ratio more than 1 {M> 1) will achieve early breakthrough with less oil
recovery, while mobility ratio less than I (M<1) will achieve late breakthrough with
more oil recovery. Meanwhile, permeability is highly affecting waterflooding
performances in reservoir heterogeneity factor, compared to porosity and thickness.
High permeability formation enables the fluid to travel faster, and increase the mobility
ratio of the displacement, while low permeability formation enables the fluid to travel
slower, and decrease the mobility ratio of the displacement. The estimation based on
simulated results indicate that the mobility ratio equal to 0.8 (M=O.S) will optimize .the
waterflooding performances, given the permeability variation of 0.4