Organofilização de argilas esmectíticas purificadas para uso em fluidos de perfuração e em diferentes bases orgânicas.

Abstract

The state of Paraiba is the largest producer of bentonite clays in the country. Currently, the noblest varieties of bentonite clays produced in Brazil, mainly in the city of Boa Vista, PB, are being depleted due to years of disordered exploration. On the other hand, it was recently discovered new bentonite deposits of smectite clays in the city of Cubati and Pedra Lavrada, PB, which may represent an interesting alternative for the provision and expansion of feedstock, aiming its use for various industrial purposes, mainly in drilling fluids. The bentonite clays have important functions in non-aqueous drilling fluids, however, impurities in the clay and the inappropriate choice of surfactant used in the process of organophilization can compromise the compatibility of the clay-environment system. In this paper, it was proposed the study of bentonitics clays purification in the regions of Boa Vista and Cubati, using a hydrocyclone, aiming the development of organoclays to be used in oil based drilling fluids and various organic bases. An industrial clay, Brasgel PA, was used and a variety of the noblest smectite clays, Chocolate, from Boa Vista, PB. In addition, it was used four kinds of clays from the city of Cubati, PB: Superior Grey, Lower Grey, Superior Green and Lower Green. Initially, a process of hydrocycloning beneficiation was done in order to eliminate the accessory minerals for subsequent organophilization with ionic surfactant Praepagen WB®. Subsequently, a study was conducted to verify the compatibility of organoclay by Foster swelling in various organic bases in order to verify their suitability for various uses. Also, from these results, it was chosen the best organic environment to study the rheological properties of oil based drilling fluids. The results showed that the purification process was effective in reducing impurities in the bentonite. The incorporation of the surfactant used in clays increased significantly the interlayer spacing. The purified and unpurified organoclays showed better Foster swelling values, primarily for the organic environment diesel oil and then for kerosene, which can be widely used in various sectors of the chemical industry. Regarding to the application in drilling fluids, diesel oil was used because it provides better compatibility with organoclay, and for this environment, it was verified that some samples showed the organoclay rheological properties suitable for oil based drilling fluids.