This thesis presents a comprehensive simulation study on the impact of natural
fractures on the performance of surfactant polymer flood in a field scale surfactantpolymer
flood. The simulation model utilized for the study is a dual porosity dual
permeability model representing 1/8 of a 20-acre 5-spot pattern. The model parameters
studied include wettability alteration, IFT changes and mobility reduction effect. The
results of this study clearly indicate the importance of reservoir description and fracture
modeling for a successful surfactant-polymer flood.
Naturally fractured carbonate reservoirs are usually characterized by mixed
wettablility and low matrix permeability which leads to low oil recovery and high
remaining oil saturation. Enhanced oil recovery methods such as surfactant-polymer
flood (SPF) enhance the recovery by increasing the spontaneous imbibitions either by
lowering the interfacial tension or altering the wettability. However, one of the main
reasons for failed surfactant-polymer floods is under-estimating the importance of the
reservoir especially the description of natural fractures and their effect on recovery.
Sensitivity runs were made to compare oil recovery capillary force, buoyancy force
and viscous force. The simulation study indicates that critical water saturation should be
reached before the start of surfactant-polymer flood to maximize oil recovery and utilize
the capillary force. Also, when a surfactant alters the rock wettability, an optimum IFT
should be identified for faster and higher imbibitions. The study shows that a contrast in
permeability between that of the fracture and that of the matrix will result in a slightly
lower oil recovery. Having the fracture perpendicular to the injector producer will result
in a higher areal sweep and lower residual oil.
A sensitivity study on the effect of the size of surfactant polymer slug was not
conclusive. Maximum adsorption capacity was reached which was one of the causes of
low imbibitions rate. Following the surfactant-polymer with water flood was able to
reverse the adsorption and restore some of the movable oil. The results show that if the
enhanced fluid that alter the wettability, imbibed in the matrix, injecting high IFT brine
will increase the rate of imbibition. The study calls for further investigation of this
phenomenon through research using a scaled laboratory model to verify the simulation
results.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2010-08-8394 |
| Date | 2010 August 1900 |
| Creators | Sayedakram, Nawaf Ibrahim A |
| Contributors | Mamora, Daulat D. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | thesis, text |
| Format | application/pdf |
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