Thesis (M.Eng.)--Chulalongkorn University, 2013

Gas and water flooding are known as improved oil recovery method. Implementation of these IOR for volatile oil reservoir is essential to oil recovery and project economic. Different IOR schemes provide different mechanisms of flooding and pressure maintenance for volatile oil reservoirs. Hence, understanding of volatile oil behavior and each IOR performance will lead to a proper scheme selection. Compositional simulation study is performed in order to find the optimum way to recover volatile oil. Simulation of natural depletion, waterflooding, gasflooding, and water alternating gas are investigated and compared in aspect of oil recovery performance and project economic. From simulation results, we found that gravity segregation of solution gas is the most influential drive mechanism to volatile oil recovery of natural depletion. Hence, enhancement of this drive mechanism is the key to production optimization and completion design. For water and gas flooding, starting maintaining the reservoir pressure above the bubble point pressure and before free exists in the reservoir will maximize the recovery. For waterflooding, if free gas exists, displacement efficiency is reduced due to gas blockage effect. For gasflooding, existing of free gas is lower capability in miscibility condition achievement because the intermediate components in oil phase already flash to gas phase and cannot be used to develop miscible flood front. And when compared all studied production schemes, waterflooding can recover oil less than gasflooding, but can yield similar net profit due to lower investment cost required. While water alternating gas yields the highest total oil recovery and net profit because it combines the advantages of both water and gas flooding.