Acidizing of a well requires careful optimization. However, the number of laboratory experiments on core dissolution is typically limited by the number of available cores. Thereby, for acidizing optimization reactive fluid flow simulation is frequently applied. Most of the available simulators use as an input a number of empirical coefficients and the choice of their values significantly affects the outcome of the simulation. Better understanding of acidizing process at pore scale can assist in selecting appropriate values for these coefficients.
Recently, we developed a pore-scale image based direct reactive flow modeling approach. This approach is based on a combination of the principles of chemical kinetics/thermodynamics and the density functional theory applied for hydrodynamics (DFH). DFH proved itself to be very effective for pore-scale modelling of multiphase flow regarding its ability to handle complex physical phenomena. Chemical reactions are introduced to hydrodynamic simulation within the framework of a partial local equilibrium assumption.
In the current study, it is demonstrated that developed approach adequately describes dissolution of dolomite rock by solution of hydrochloric acid. Simulations have been performed using 2D model of dolomite granule, 2D model of porous structure and 3D model of Silurian dolomite microstructure. Upon acid injection, the geometry of a rock is gradually changing along the path of acid penetration. The modeling results reveal the dependence of dolomite dissolution rate on the rate of fluid injection. Using the developed approach, it was also demonstrated that release of gaseous CO2 influences the rate of mineral dissolution. The correlations obtained from reactive fluid flow with exact geometry can be utilized for amendment of the reaction rate constants which are used for large scale simulations.
The suggested approach for reactive fluid flow simulation allows to test numerous “what if” scenarios and to evaluate the effect of different factors on mineral dissolution rate at pore scale. It paves the way for increasing the consistency between the models used for reactive flow modeling and pore scale heterogeneity of real rocks, which will lead to improvements in acidizing job design.
Anna graduated from Chemistry Department of the Lomonosov Moscow State University (Moscow, Russia) in 2010. In 2013 she got PhD degree in Chemistry from the same institution. Since 2007 to 2013 she worked as an engineer in Moscow State University and contributed into multiple research projects devoted to the investigation of catalytic reactions mechanisms and establishment of structure-property relationship using quantum chemical simulations.
In 2014 Anna joined Schlumberger Moscow Research as a Research Scientist. Her current research activity is focused on pore scale simulations of minerals dissolution.
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