Estudo Teórico e Experimental da Dissolução de Partículas de NaCl no Escoamento em Salmoura

Abstract

With the start of operation of reservoirs of pre-salt layer, technical problems have been encountered during drilling of geological formation, where cuttings salt are generated and invade the annular region of the well. During invasion, the particles generated are transported in suspension to the surface, tending naturally to dissolve into the drilling fluid. This dissolution leads to changes the physico-chemical and rheological properties of the fluid, impairing control of the entire operational process. Within this context an experimental unit was built which allows the dissolution of NaCl particles in suspension during flow in brine. Concentration were taken arranged along the structure, allowing the lifting of the experimental concentration profile at different operating conditions. For this study still was evaluated a mathematical model able to predict the dissolution of salt particles suspended during flow in brine. The proposed model consists in a system of three partial differential equations (PDE’s), considering the mass balance of salt in liquid phase, the mass balance of salt in solid phase and the overall energy balance for the mixture (solid / solution). The simulated data are compared with obtained experimentally data and it was observed that the model studied was shown satisfactory due to low deviations obtained, and lower than 10%.