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Experimental Investigation of Oil Production by Low IFT Dynamic Imbibition

Harimi, Behrouz | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46158 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Masihi, Mohsen
  7. Abstract:
  8. Imbibition process is known to be an important recovery mechanism in naturally fractured reservoirs with water-wet matrix blocks that are imposed to water influx from an active aquifer or water flooding. Matrix blocks which are subjected to water flooding or water invasion from active aquifers do not become immersed in water at once, but they experience gradual rising of water in fracture. But most of imbibition studies are performed under conditions of totally immersed cores in static aqueous phase. Surfactants are known to reduce residual oil saturation by decreasing interfacial tension (IFT) between oil and water. On the other hand, considerable reduction of IFT due to surfactant solutions decreases capillary forces which are driving force of imbibition process. So surfactants may affect imbibition behavior intricately. Here, we employed oil/water and air/water systems, investigate the effect of injection rate, increasing aqueous phase, decreasing IFT and also the effect of injection rate under conditions of low IFT. Air/water imbibition results may be used to predict imbibition performance in naturally fractured gas reservoirs. These results can also be generalized to depict oil/water imbibition behavior. It can be concluded that a critical injection rate, proportional to the capacity of rock for imbibition. It is expected that increasing injection rate from zero to a critical injection rate enhances imbibition efficiency. But in higher injection rates, the imbibition rate increase is less than the corresponding injection rate increase. Generally, break through recovery and ultimate recovery decrease with increasing injection rate, but break through recovery is more sensitive to than ultimate recovery. 27 times increasing aqueous phase viscosity reduced break through recovery about 63% in both oil/water and air/water systems. Inverse bond number calculation shows that capillary forces are the main drive mechanism in performed experiments. So using surfactant solutions and consequent reduction in capillary force led to considerable decrease in break through recovery. However it is observed that ultimate recovery increases in low IFT system. Rate sensitivity in low IFT system reveals that the effect of injection rate on dynamic imbibition behavior is increased in comparison to high IFT system. It is observe d from results of air/water experiments that imbibition may be an efficient recovery mechanism in low permeability naturally fractured reservoirs
  9. Keywords:
  10. Wetting ; Surface Tension ; Surfactants ; Critical Rate ; Dynamic Imbibition Process ; Break Through Time

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