Avaliação da dissolução de partículas de halita em salmouras no escoamento ascendente em tubo

Abstract

With the confirmation of the existence of large oil reservoirs, found in the pre-salt region, researches are being developed with the purpose of overcoming certain challenges and technical limitations, especially when the salt layers are drilled. One of these challenges is to ensure good conditions for drilling operations. Proper drilling fluids control must be performed since salt cuttings can dissolve in the drilling fluid, thus modifying their physicochemical and rheological properties. Within this context, the objective of this work was the study of the dissolution of halite (NaCl) particles in brines in pipe flow. In order to carry out the study, it was necessary to design and built an experimental unit that operates under similar conditions to the drilling conditions of oil wells, which are similar Reynolds number, vertical upward flow of the fluid, movement of the solid particles together with the fluid. It was proposed a mathematical model based on an partial differential equations system that is based on the mass conservation for the solid and liquid phases. For the solution of the system two approaches were considered, the first considers the variation of the diameter of the NaCl particles along the flow and the second approach considers the particle diameter constant. The global mass transfer coefficient was estimated using the computational program MAXIMA, written in FORTRAN language, where the experimental concentration profiles were used as input data. The results obtained by the simulation were compared with the experimental results, where the mean relative deviation of the two approach was less than 5% and the estimated mass transfer coefficients are in the same order of magnitude as those found in the literature.