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Modelling the System Ionic Composition Effect on CO2 Generation during Carbonate Reservoirs Acidizing

Kardooni, Mohammad Mehdi | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53159 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Jamshidi, Saeed; Bazargan, Mohammad
  7. Abstract:
  8. Carbonate matrix acidizing using hydrochloric acid which causes CO2 generation is one of the most popular well stimulation techniques in recent decades. Lots of the wormhole propagation models developed for laboratory scale, assumes that the cores are fully saturated with aqueous solution and no CO2 gas is produced. Final purpose of this research is to develop a geochemical model describing equilibrium composition of a 3 phase system of acidic solution-gas-rock accurately in common pressure and temperature conditions of carbonate matrix acidizing to obtain main inputs of acid reactive flow in porous media from it. In this regard, concept of the “extent of the reaction” is defined and after decreasing the non-linearity of the governing equations of a geochemical system, a very quick and accurate algorithm to obtain equilibrium composition of the system during carbonate acidizing using HCl is presented and for the first time complicated jacobian matrix in Newton-Raphson method is calculated analytically which has affected the speed of solution of the problem and reduced its dependency to initial guess significantly. Also an appropriate framework is developed for generation of the initial guess for geochemical systems which was not found precisely in any of the literature reviewed in this research. Using the developed model, we will show for 2 common cases of carbonate acidizing i.e. 5% and 15% HCl, the assumption of complete dissolution of all generated CO2 in aqueous solution, which is the basis for lots of the developed wormhole propagation models in carbonate acidizing is violated. Large error of PHREEQC® software during regeneration of one of the accepted experimental results will be shown and the parameters of the developed model in this research will be optimized to reduce the error to about half of the PHREEQC® software (about 10%).
  9. Keywords:
  10. Matrix Acidizing ; Carbonate Resrevoirs ; Carbon Dioxide ; Geochemical Modeling ; Newton-Raphson Method ; Jacobi Matrice ; PHREEQC Software

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