ALMEIDA, L. R. B.; http://lattes.cnpq.br/9442377156145035; ALMEIDA , Leyllane Renalle Batista de.
Resumo:
The wide use of seismic prospecting method in the oil industry to generate images of
geological structures that are found in subsurface and to the monitoring of petroleum
reservoirs makes it essential to the knowledge of the petrophysical properties and the
factors that affect them. In this context, this research aims to carry out the petrophysical
and petrographical study of 30 samples of sedimentary rocks (sandstones and
limestones) from American formations, considered standards in the industry.
Petrophysical characterization tests were carried out by conventional laboratory
methods, empirical-through fluid-replacement models and simulations by computer
models, using the software Avizo Fire 8.1 and COMSOL Multiphysics 5.1, as well as
the compositional analysis from the x-ray diffractometry and thin sections description
in optical microscope. The petrophysical tests were performed under different
conditions of pressure and fluid saturation. The petrophysical properties were
influenced by several parameters, which differ according to the lithological rock type.
The saturation of rocks not reached 90%, being much lower for dolomitic matrix rocks
when saturated with oil, possibly due to their water wettability. Fluid saturation
influences definitely in elastic properties of rocks in both methods studied. When
saturated with oil most of the samples show higher compressional velocities as
compared to other conditions of saturation (dry or saturated with water). The models
of Gassmann and Brown & Korringa were more representative for the compressionais
waves, being efficient in some cases also for the shear ones. Biot model proved to be
more efficient for shear waves, especially in sandstones. The computational method
proved effective as the compressional velocity, at least for one of the receivers,
approaches or matches the value measured in the laboratory. The results obtained
show that the set of samples studied presents good potential for reservoir. The
mineralogical composition by DRX presented a good fit with the grain density
measured conventionally.