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Compatibility Analysis of Surfactants Acid Additives and their Effect on the Reaction Rate

Jamalpour, Abbas | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 54254 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Fatemi, Mobeen; Bazargan, Mohammad; Mohammadi, Saber
  7. Abstract:
  8. Well stimulation techniques are used to increase the productivity of oil and gas wells. One of the effective well stimulation methods, is matrix acidizing. During matrix acidizing, acidic solution is injected into the formation at pressure below the formation fracture pressure. Most of the time, acid needs to be reached to low permeability layers for more efficient damage removal. Divertors are used for diverting acid from high permeability to low permeability layers.Successful performance of a viscoelastic acid during an acid job, is highly dependent on the surfactant rheological properties. For a betaine viscoelastic surfactant, we have studied the effect of different parameters on the viscosity of the acidic solution. We found that temperature, pH, salt concentration, acid concentration, and shear rate, substantially change the viscosity of viscoelastic surfactants (VES). We have discussed that how micelle structure is altered with the change of these parameters. When VES acidic solution reacts with the formation rock (CaCO3), salt concentration (CaCl2) increases. Increase of CaCl2, initially increases the viscosity to a great extent and then slightly decreases as the reaction goes on. When looking at the pH, degree of protonation comes into effect. Initially, from live acidic VES solution to pH~1, the viscosity increases where salt concentration effect is dominant. Then, from pH~1 to pH~3 the viscosity start decreasing due to the change of micelle shapes until it sharply increases and reaches its maximum at pH~4. Increase of the shear rate is found to have a destructive effect on viscosity of VES solution. Viscosity of VES spent acid solution, is larger when initial concentration of HCl is decreased from 15 to 10% wt. HCl. In all these cases, temperature has a significant effect. We found that for a betaine VES, viscosity versus temperature curves exhibit two peaks. The position of these two peaks is mainly temperature dependent while their magnitudes are influenced by the other aforementioned parameters. We have discussed important implications of this behavior for an actual acidizing job design
  9. Keywords:
  10. Surfactants ; Matrix Acidizing ; Viscoelastic Surfactant (VES) ; Reservoirs Acidizing ; Carbonate Resrevoirs ; Amphoteric ; Viscoelastic Diverting Acid

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