Otimização e modelagem de composições de argilas esmectitas do estado da Paraíba para uso em fluidos de perfuração de poços de petróleo.

Abstract

The State of Paraíba has large deposits of smectite clays and the main occurrences are found in the Municipality of Boa Vista, PB. Recently, new deposits were discovered in the municipalities of Cubatí, Pedra Lavrada and Sossego, being the most recent in the Municipality of Olivedos. Preliminary studies have shown that these clays have high levels of accessory minerals such as kaolinite, quartz and mica, compromising in many their industrial use. This work was developed with the objective of studying the optimization and modeling of compositions of the smectite clays of the Municipality of Olivedos for use in drilling fluids of oil wells. The clays were initially submitted to physical, chemicaland mineralogical characterization by means of the following techniques: granulometric analysis by laser diffraction, cation exchange capacity, specific area, chemical analysis by x - ray fluorescence, x - ray diffraction and thermal analysis. The compositions of the clays were formulated using the modeling methodology of experimental planning mixtures. From the statistical analyzes, experimental validation of mathematical models, response surfaces and graphic optimization, the properties of apparent viscosities (VA), plastic viscosity (VP) and filtrate volume (VF) of formulated dispersions were studied. The results showedthat the clays of the new deposits of the Municipality of Olivedos, PB, presented in their mineralogical composition the clayey mineral of the group of the smectite with high contents of minerals accessory kaolinite, free quartz and mica. Regarding the rheological and filtration properties, it is concluded that Olivedos clays presented the best results for use in oil well drilling fluids when the samples were added with Carboxymethylcellulose (CMC), then when mixed with the clays of Boa View. The results of the apparent and plastic viscosities of these samples added with MgO + CaCl 2 indicate an improvement of these parameters when compared to the results of the in natura clay, in relation to the volume of filtrate, however, no reduction of VF is observed.