LEAL, C. A.; LEAL, CALINE ALVES; http://lattes.cnpq.br/8919502201386990; LEAL, Caline Alves.
Resumen:
This work intends to understand the mechanisms of swelling and disintegration of
shales from the Northeastern Region of Brazil. Nine samples of shales and a sample
of sodium bentonite clay were analyzed. The study was carried out in three distinct
stages: in the first one, the samples were characterized by the cation exchange
capacity (CEC), specific surface (SS), particle size analysis, x-ray fluorescence
(XRF), differential thermal analysis (DTA), thermogravimetric analysis (TGA); X-ray
diffraction (XDR) and Fourier transform infrared spectroscopy (FTIR); in the 2nd
stage, the samples were evaluated according to their swelling capacity by means of
the ASTM swelling test, Foster swelling and determination of free water by the
capillary suction time test (CST). Finally, in the third step, the disintegration of the
samples was assessed in pressurized (100psi) and non-pressurized aqueous media.
According to the results, the shale samples studied presented moderate to high
reactivity and low or zero swelling. Furthermore, formations that do not present
reactive clay minerals can be considered unstable and the higher reactivity of
formations to aqueous fluids does not necessarily imply higher levels of
disintegration. It is also concluded that the presence of calcium oxide has a direct
influence on the disintegration of the shales, thus showing that different mechanisms
not associated to the swelling of the clay minerals may assume greater or less
importance in the instability of the formation.
