doctoralThesis
Estudo da organofilização da argila paligorsquita para uso em fluido de perfuração não aquoso
Date
2022-01-12Registration in:
SILVA, Rhaul Phillypi da. Estudo da organofilização da argila paligorsquita para uso em fluido de perfuração não aquoso. 2022. 96f. Tese (Doutorado em Ciência e Engenharia de Petróleo) - Centro de Ciências Exatas e da Terra, Universidade Federal do Rio Grande do Norte, Natal, 2022.
Author
Silva, Rhaul Phillypi da
Institutions
Abstract
The petroleum industry accounts for a significant portion of the clay market share, where they
are used in drilling fluids as thixotropic agents. It is responsible for some important
physicochemical characteristics, which must be controlled so that the fluid can perform its
functions properly. Among the important functions of clays in drilling are cooling the bit,
waterproofing the geological formation and maintaining solid suspension. In water-sensitive
drilling operations, the use of oil-based fluid is often necessary, and in this case, clays lose
their thixotropic properties, since their natural state is hydrophilic, they cannot be used
without undergoing an organic treatment to make them hydrophobic. Different studies have
been carried out to obtain organophilic clays, by different methods, capable of meeting the
necessary requirements for their use. In this context, this research aimed to determine the
ideal content (maximum point of surfactant adsorption) of palygorskite (Plg) to obtain
organophilization using cationic surfactant cetyltrimethyl ammonium bromide (CTAB) at
different concentrations. The adsorption tests were carried out in a finite bath, varying the
content of Plg and CTAB in the solution. In these tests, parameters such as time, temperature,
pH and thermodynamic characteristics were observed. To analyze the results, mathematical
models for adsorption processes (Langmuir, Freundlich, Dubinin-Radushkevitch (D-R) and
Tempkin) were used. In addition, X-ray fluorescence (FRX), X-ray diffraction (DRX),
Thermogravimetric and differential analysis (TG and DTG), measurement of contact angle,
and rheological analysis were performed. The collected data showed that an increase in clay
content in the dispersion leads to a decrease in surfactant adsorption on clay. However, it was
possible to obtain the ideal clay content for the organophilization of Plg at different
concentrations of the CTAB surfactant. The data obtained in the experiments fit well with the
Freundlich model. The Dubinin-Radushkevitch and Tempkin isotherms confirmed the
chemical adsorption of CTAB on clay Plg. X-ray fluorescence identified the main
constituents of the Plg sample. X-ray diffraction showed that organophilization does not
change its crystal structure. The thermogravimetric and differential analysis allowed
observing the main events associated with thermal degradation of Plg. The contact angle test
showed that there was a change in wettability after the adsorption process, which is influenced
by pH, as was observed in the results of the rheological analysis, confirming its affinity for oil
phase due to the increase in rheological parameters.