BaSO_4 Precipitation Impact on the Permeability of a Pressure Porous Medium/ BaSO 4 Impacto da Precipitação sobre a Permeabilidade de um Meio Poroso de Pressão

Currently, the petroleum sector is facing new challenges like ultra-profound waters and thick pre salt layers. One of the main concerns is the inorganic scale in production equipment. Scales can occur throughout the chain of petroleum production, from the reservoir until the surface facilities. Its occurrence in the near well region of the reservoir generates a greater impact on the fluids production, where the removal or inhibition of the salt became more complex. The most common scale in the near well region is barium sulfate BaSO 4 because its low solubility. This work proposes an experimental study that aims to monitor the effect of BaSO 4 precipitation on sandstone porous medium pressure drop using a core holder. Distinctly from others works in the area, this study used a simpler solution to observe the impact of precipitation reaction. The porous medium was saturated with a solution of barium chloride (BaCl 2 ) at 250ppm and afterwards was injected a solution of sodium sulfate (NaSO 4 ) at 2750 ppm. The injection rate was 5 x10 -8 m³/s for two hours under a pressure of 6.985MPa. During the precipitation reaction was observed an increase in the pressure of the system. This increase of pressure is a consequence of permeability reduction occasioned by the deposition of barium sulfate. The effect of precipitation can be observed more significantly at the first twenty minutes of reaction. At the end of experiment was observed a permeability reduction of more than 60% in the porous medium. The properties of the porous medium was measure, however this methodology could not estimate the rate of barium sulfate scale