Estudo da dissolução de partículas de NaCl em fluido de perfuração base aquosa viscosificado com bentonita

Abstract

The drilling of oil wells in salt layers has been improved over the years and studies on the subject are carried out with the aim of perfecting the used techniques. The dissolution of the saline layers influenced as a physical-chemical well of the drilling fluids, with previously planned formulations required for each type of well. In this work, we intend to evaluate a dissolution of NaCl particles and an influence that this type of electrolyte causes on the chemical chemical properties of the fluids viscous with bentonite. For this purpose, characterization tests, rheology and sodium chloride dissolution experiments were carried out at different concentrations of bentonite and salt. The bentonite characterization tests were X-ray diffractometry, particle size analysis, scanning electron microscopy and pulse testicles. In the rheology study of the suspensions, tests were performed to evaluate the effect of time and the concentrations of salt and bentonite on the apparent viscosity of the suspension. For kinetic tests, an experimental unit that simulates a perfect mixing tank with volume of 1L is used. The measurement of the conductivity for the method used to evaluate how a NaCl dissolution occurs over time. The mathematical model was also used to estimate the mass transfer coefficient of the dissolution process. The results of dissolved salt concentration obtained experimentally were compared with those provided by the model. The deviations between an experimental concentration and a calculator by the model were less than 10%. The rheological test pointed out that as the bentonite increases without fluid, an apparent viscosity increases accordingly. It has also been found that an addition of salt to the drilling fluid and an apparent viscosity reduction. Reverse behavior for high salt concentrations, where an apparent viscosity rises. The behaviors are associated with a salt addition a compression and decompression of the diffuse double layer