Melhoria, proteção e recuperação da reologia de fluidos hidroargilosos para uso na perfuração de poços de petróleo.

Abstract

The development of this work was motivated by the constant search to improve the Theological behavior of bentonite clays dispersions from Boa Vista, state of Paraiba (major deposit of clay in South America), and the challenge to salve the frequent problems related to contamination of drilling fluids during drilling well operations. The main objectives of this work are: identify the causes of the poor rheological behavior of bentonite clays from Boa Vista, PB using electrodialysis and to evaluate the action of cellulose based polymeric additives to protect and recover the rheological and the water loss properties of bentonite clays dispersions contaminated by calcium and magnesium chlorides. For this purpose, three samples of natural bentonite clays and four commercial samples Paraiba state were selected. The natural bentonite clays were transformed into sodium bentonite by addition of concentrated Na2C03 solution. The rheological properties and the water loss value of bentonite clays dispersions prepared with 4.86% w/w and after several treatment conditions (thermal treatment, dialysis, electrodialysis, degradation, protection and recovery treatments) were obtained according to Petrobras standards. The results show that: i) the electrodialysis can be a valuable tool to identify the factors that dictate the rheological behavior of bentonite clay dispersions, after the cations exchange process; ii) the rheological properties and the water loss value are strongly dependent on bentonite/polymer interaction, which depends on the viscosity degree and the polymer chain length and iii) the different behaviors of dispersions, after protecting and recovery treatments, are useful to optimize drilling fluids applications.