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Experimental and Theoretical Study of Hydrodynamic Behavior and Mechanisms of Asphaltene Deposition

Jafari Behbahani, Taraneh | 2012

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 43896 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Ghotbi, Cyrus; Taghikhani, Vahid; Shahrabadi, Abbas
  7. Abstract:
  8. In this work, a new model based on the multilayer adsorption kinetic mechanism and four material balance equations for oil, asphaltene, gas and water phase has been developed to account asphaltene deposition in porous media under dynamic condition and the model was verified using experimental data obtained in this work and also with those reported in the literature. The results showed that the developed model can correlate more accurately the oil flooding experimental data in comparison to the previous models based on the mechanical plugging mechanism, in particular in carbonate core samples. Also, a series of experiments was carried to determine the permeability reduction of carbonate, sandstone and dolomite core samples due to asphaltene deposition using an Iranian bottom hole live oil sample which is close to reservoir conditions in order to study the effect of different parameters on asphaltene deposition mechanisms during dynamic condition in porous media. The performance of the effective parameters of porous media on asphaltene deposition such as mineral composition and morphology of surface were also studied using X-ray, elemental analysis and SEM micrographs. SEM micrographs of carbonate core sample showed the formation of large clusters of asphaltene with characteristic sizes that greatly exceed the monolayer deposition characteristic size. Also, a novel experimental method was designed and proposed to distinguish between the mechanical plugging and adsorption mechanisms of asphaltene using the cyclohexane or toluene reverse flooding and it has been found that 60-82 percent permeability reduction by asphaltene deposition was caused by mechanical plugging mechanism during a fast process, whereas 20 to 40 percent of formation damage is due to adsorption mechanism that takes place in a longer time. Also, a new scaling equation based on the PVT properties of bottom hole live oil including resin to asphaltene ratio, onset pressure, bubble point pressure, reservoir temperature, asphaltene content of bottom hole live oil and gas to oil ratio has been proposed to account asphaltene precipitation envelope under pressure depletion/ gas injection conditions and the model was verified using experimental data obtained in this work and also with those reported in the literature. The results showed that the proposed equation based on the PVT properties of bottom hole live oil can predict more accurately the asphaltene precipitation experimental data in comparison to the thermodynamic models based on complex properties of asphaltene as interaction coefficient and solubility parameter that their calculation is difficult
  9. Keywords:
  10. Porous Media ; Gas Injection ; Natural Depletion ; Asphaltene Deposition ; Kinetic Adsorption ; Mechanical Plugging

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