Speaker
Description
Matrix acidizing is a well stimulation technique, consisting of injecting a reactive fluid, usually an acid, into the porous medium to dissolve minerals and remove near-wellbore damage. In carbonate formations, this process leads to the development of highly conductive channels known as wormholes, which provide preferential flow paths and significantly increase formation permeability. The effectiveness of matrix acidizing treatments is commonly quantified using the Pore Volume to Breakthrough (PVBT), defined as the injected pore volume required for the acid to create a dominant conductive channel that spans the sample. Although PVBT is a key performance indicator, its experimental determination through laboratory coreflooding tests is time-consuming and costly. Consequently, numerical simulation has become an important and efficient alternative to investigate acid–rock interactions, dissolution patterns, and wormhole propagation. Among the governing parameters of the acidizing process, temperature plays a critical role because it directly controls the reaction kinetics between the acid and the carbonate rock. In this work, we numerically investigate the effect of temperature on PVBT and on the dynamics of wormhole formation in carbonate porous media. A multiscale modeling framework is adopted, in which the fluid flow is described by the Darcy–Brinkman–Stokes equations, while the acid–rock reaction is modeled through a kinetic law whose reaction rate constant is temperature dependent according to the Arrhenius equation. All simulations were implemented in the OpenFOAM environment. The numerical results successfully reproduce the classical V-shaped behavior of PVBT as a function of injection velocity for all investigated temperature conditions. Distinct dissolution regimes were clearly identified: face dissolution at low injection rates, dominant wormhole formation at the optimal condition, and ramified or branched wormhole patterns at high injection rates. Furthermore, the results demonstrate that increasing temperature leads to higher PVBT values and shifts the optimal injection velocity toward larger magnitudes. This behavior is associated with the enhancement of reaction rates at elevated temperatures, which intensifies near-inlet acid consumption and demands higher injection velocities to achieve efficient wormhole penetration. These findings indicate that, in high-temperature reservoir scenarios, the use of retarded acid systems becomes essential to control the reaction rate, promote deeper wormhole propagation, and maximize stimulation efficiency.
| Country | Brazil |
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