Influência do transporte advectivo no processo de dissolução de rochas carbonáticas em ácido clorídrico.

Abstract

Carbonate rock stimulation is a technique used in the petroleum industry to increase the productivity index of wells by increasing the permeability of a region close to the well. In acidification, an acid is injected into the reservoir rock. In carbonate rocks, the acid interacts with the rock to promote dissolution. The acid-rock occurrence is characterized by being essentially heterogeneous due to the different phases of the reactants. The quantification of occurrence taxa in heterogeneous systems is complex, as it involves a combination of several variables that are relevant to the manifestation of transport. The way in which acid interacts with the porous medium can be analyzed using various techniques and equipment that can help with understanding. The most common equipment is the Rotating Disk Apparatus (RDA), which consists of a reactor, which can operate different pressure and temperature ranges and different rotations. However, due to the difficulty of acquiring this type of equipment, several experiments have been reported using alternative methodologies. Thus, this work aims to study how measuring the reaction rate using different methodologies can influence the result. A comparative experimental study was conducted using three different methodologies, namely, static dissolution, dynamic dissolution, and rotating disk, to measure the impact of mineralogy, porosity, rotation speed, and pressure applied to the reaction system. The focus is to evaluate to what extent the results of the static and dynamic dissolution experiments diverge from the experiments conducted with the rotating disk, which is considered the standard for this type of analysis. In general, it was observed that increasing rotation promotes an increase in the reaction rate of 10.36% from static to dynamic at 100 RPM and 63.07% from static to dynamic at 500 RPM for Indiana limestone, a similar behavior was observed for other mineralogies. Additionally, from obtaining the diffusion coefficient in the process of dynamic dissolution and rotating disk of 3.75x10^-5 and 9.13x10^-5, respectively, for coquina samples, it was evidenced that the absence of pressure in the system hinders the mass transfer process due to the presence of CO2 (g), thus underestimating the diffusion in the carbonate – HCl system.