Water Alternating Gas (WAG) is one of the popular EOR techniques to displace oil after natural depletion. Essentially, WAG is a sequential injection of water and gas in specific ratio to sweep oil from the pores. It is a popular technique because of availability of water and gas as well as cheaper cost than chemical injection technique. More importantly, this project discovered that there is a relationship between well configuration design and efficiency of WAG in a 5 spot injection pattern. For example, the ideal WAG ratio of 1:1 that supposedly allows piston-like displacement is not always efficient for all well configurations. Only a horizontal injector and a vertical producer configuration gave the highest oil recovery while the other configurations did not. Ultimately, this project proposed approaches for both new field and mature field. For a new field, one might want to consider well configuration that gives the highest oil recovery to be drilled. On the other hand, for a mature field, the well configuration is already present. Therefore, it is proposed that a WAG scheme that yield the highest oil recovery for that well configuration design should be used
