http://lattes.cnpq.br/2103532733658840; NÓBREGA, Karine Castro.
Resumo:
The purpose of this work is to evaluate the influence of the physical and chemical
properties of carboxymethylcelluloses (CMC) on filtration properties of polymeric
drilling fluids. The study was accomplished in three stages. In the first stage, the CMC
samples were characterized by measurements of purity, pH, viscosity and degree of
substitution, using the classification of the rheological behavior regarding to the
uniformity of substitution and spectroscopy tests by the Fourier Transform Infrared
Region (FTIR), X-ray Diffraction (XRD) and Thermogravimetric Analysis (TGA). On the
second stage, the CMC samples were evaluated according to the standards PE-
2POC-00727-0 and API Specification 13A. Finally, in the third and last step, six CMC
samples were selected to be evaluated as a fluid loss additive in polymeric fluids.
According to the results obtained from the characterization, the CMC samples
presented different degrees of polymerization as a function of the increase of the
viscosity values from 30 to 142cP and degrees of substitution (0.71-0.87), besides
different uniformities (thixotropic and pseudoplastic behavior). According to the tests
in the standard PE-2POC-00727-0, from the twelve samples studied, only CMC7
sample was considered to be faulty. In this way, all the other samples could be used
in the aqueous fluid in order to control filtration losses considering this standard.
However, no CMC sample was approved in API Specification 13A, which prevents the
polymer samples studied from being used as low viscosity CMC in drilling fluids. The
samples 3, 4, 5, 9, 10 and 11 were not only able to give the polymeric fluids the
reduction of the filtrate volume, but it was also possible to obtain lower filtrate volumes
than that obtained from the filtration of the formulated fluid with commercial CMC. Thus,
in view of the results obtained it is concluded that the CMCs studied have potential to
be used as fluid loss additive in drilling fluids and the performance of this function can
be optimized by selecting samples with a lower viscosity, a higher degree of
substitution and more uniformly substituted, considering the use in an aqueous
medium with low ionic strength.