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Experimental Study & Mathematical Modeling of Asphaltene Deposition in Porous Media

Bagheri, Mohammad Bagher | 2010

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 40609 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Kharrat, Riyaz; Ghotbi, Siroos
  7. Abstract:
  8. Asphaltene precipitation and deposition may cause severe problems during different stages of oil recovery. All proposed remediation techniques have proven costly and not highly effective, so prevention becomes the most beneficial way to counteract the problem. Revelation of the deposition mechanism and determination of the parameters are necessary in order to devise reliable prevention strategies.This work presents results of the effect of lean gas and CO2 injection process as well as natural depletion on dynamic asphaltene precipitation and deposition. In addition sets of experiments were performed in the same porous media using STO and solvent (with different volume ratios) to investigate the existed deposition mechanisms. Modeling the process of permeability changes as a result of asphaltene deposition is the next step. Also, Genetic algorithm technique was employed as the optimization tool to achieve the history matching and determination of model parameters. Another objective of this work was to generate a new scaling equation for predicting the asphaltene precipitation. Since the oil and asphaltene properties were not included in the previous developed equations, their universality is not trustable and it should be investigated more. As a result, analyzing the porosity reduction data and also asphaltene content data showed that the processes could be ranked in the order of severity from highest to lowest as: lean gas injection, CO2 Injection and natural depletion. Natural depletion experiments showed a considerable increase in asphaltene deposition and consequently permeability reduction in the core matrix by increasing of injection rate. Modeling and optimization of core experiment results show an accurate match with measured data. Optimization confirms that all major deposition processes (surface deposition, entrainment and pore throat plugging) are effective in permeability changes. Calculation of precipitated asphaltene saturation by the introduced equation help to get a sense about the volume fraction of porous media that has been evaded by the precipitated asphaltene particles. Meanwhile, by performing experimental tests on different crude oils and analyzing their properties a new scaling correlation was developed for the prediction of asphaltene precipitation of different crude oil samples which is the function of oil properties
  9. Keywords:
  10. Asphaltene ; Porous Media ; Sediments ; Optimization

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