Experimental Investigation of Mechanism of Wettability Alteration Induced By Hot Water and Steam Injection

Salehi, Afshin | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47611 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Masihi, Mohsen
  7. Abstract:
  8. One of the most important production mechanisms of fractured reservoirs is wettability alteration. Since most fractured reservoirs are carbonate, and thus are often oil-wet; production of these reservoirs is facing their special challenges. Since most of our country reservoirs are fractured carbonate type, determination of the exact mechanisms of their production is necessary. Thermal EOR methods traditionally have been welcomed by big oil companies. Also, these methods of enhanced oil recovery techniques, have a much greater share in the production history of all EOR methods, rather than other EOR methods. Exponentially decreasing of oil viscosity on heating, is the main reason for using thermal methods. But since the majority of EOR projects on non-fractured sandstone reservoirs has been done, it is not simply possible to generalize the results of this projects for fractured carbonate reservoirs. For example, if we do thermal EOR operations on an oil-wet fractured reservoir, just only oil production will be acceptable; that somehow changes reservoir wettability to water-wet.This means that if rock wetting remains oil-wet, eventough oil viscosity shrinks thousands times; almost no oil will be produced. However, in the non-fractured oil-wet reservoirs, oil production is possible using forced imbibition. But in fractured reservoirs because of the very permeable gap, forced imbibition is almost impossible. If the hieght of matrix blocks in fractured reservoirs be short, gravity drainage also will have a very small share in production. Especially if reservoire oil is of heavy type, that will cause a sharp decline in Archimedean force. Therefore it is necessary that the matrix wettability change somehow towards favorable conditions. One of the known mechanisms of thermal EOR processes, is change in wettability. The objective of this study is to accurately investigate this mechanism in the process of injection of hot water and steam. After doing contact-angle and free imbibition experiments, that are representing wettability; existence of this mechanism was verified, and its value was calculated. Finally, using simulation and upscaling process, the first flow-based model, for wettability alteration induced by temperature increase, for two rocktypes of sandstone and limestone, was introduced
  9. Keywords:
  10. Steam Injection ; High Temperature ; Thermal Method ; Spontaneous Imbibition ; Enhanced Oil Recovery ; Wettability Alteration ; Fractured Reservoirs ; Hot Water Injection

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