Publications

The steamflood potential of light oil in the deltaic deposits of Central Sumatra was evaluated using a compositional steamflood simulator. Simulation results show that the channel sand, one of the two predominant sand body types in such deposits, is an attractive steamflood target because its fining-up bedding character places lower permeabilities at the top which retard steam gravity override and result in good vertical sweep. The bar sand, on the other hand, with its coarsening- up bedding character accentuates the steam gravity override, and hence is not attractive as a steamflood candidate.A geological investigation of the deltaic deposits identified two end-member sand body types, channel and bar sands, that dominate the deposits. Remaining sand bodies in these deposits have a more uniform reservoir character and fall between the two end-member types. Under primary depletion or peripheral waterflood, the deltaic deposits produce mainly from the high permeability zones.Reservoir models representing the two prevailing sand bodies were constructed and used for evaluating the steamflood potential of light oil in such deposits. Simulation shows that oil recovery by steamflooding in the channel sand can be more than twice as high as that by waterflooding, with the recovery depending on the state of depletion prior to steam injection. Hence, the channel sand appears better suited for steamflooding than for waterflooding. Steamflooding the bar sand, on the other hand, produces a small incremental recovery above that by waterflooding, which appears insufficient to justify the high cost of steam injection. Hence, the bar sand appears more attractive for waterflooding than for steamflooding.