Purificação de argilas bentoníticas de novos depósitos do município de Pedra Lavrada- PB, para uso em fluidos de perfuração.

Abstract

The state of Paraíba has one of the largest deposits of bentonite in the country. Where the main reserves until recently, were concentrated in city of Boa Vista. Recently were discovered new bentonite deposits in the regions of Cubati and Pedra Lavrada - PB, thereby providing an expectation of ampliation of mineral insumes in the region. To potentiate the use of these clays as mineral component in drilling fluids, this work aims to study the purification of bentonite clays of the city of Pedra Lavrada, by hidrocycloning, for use in water-based drilling fluids. The natural clays (before purification) were subjected to the beneficiation process, then determined the physical-mineralogical properties and the rheological properties. Subsequently, the clays were purified by hydrocycloning, where the clays were to stand for varying periods of 7, 14, 21 and 28 days before the purification process, in order to evaluate the influence of the hydration of clays in this tipe of process. The purified samples were characterized and determined their rheological properties. The results showed that the clays are composed of smectite, kaolinite and quartz. And the rheological tests of natural clays were not satisfactory for use in water-based fluids. However, after purification, the clay fraction of the samples increased considerably and the sand was completely eliminated; the rheological properties of purified clays improved with respect to the natural clays, proving the effectiveness of the purification process by hydrocycloning. With regard to the days of resting, there was no influence on the rheological properties of the samples, however, the results of granulometry, in general, were better for the samples with 14 days of rest. The purified clays have shown promissing for use in water-base fluids.