Otimização de formulação de pastas de cimento contendo bentonita para aplicação em poços petrolíferos com baixo gradiente de fratura
The cementing is one of the most important operations executed between the stages of drilling a oil well. When the cementation isn’t well performed, there’s the risk of to occur failures and fractures, both in formation as in the cement itself. When the reservoirs have low depth, they tend to fra...
Na minha lista:
| Autor principal: | |
|---|---|
| Outros Autores: | |
| Formato: | Dissertação |
| Idioma: | por |
| Publicado em: |
Universidade Federal do Rio Grande do Norte
|
| Assuntos: | |
| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/19792 |
| Tags: |
Adicionar Tag
Sem tags, seja o primeiro a adicionar uma tag!
|
| Resumo: | The cementing is one of the most important operations executed between the stages of drilling
a oil well. When the cementation isn’t well performed, there’s the risk of to occur failures and
fractures, both in formation as in the cement itself. When the reservoirs have low depth, they
tend to fracture more easily, due to his low gradient of fracture, therefore, the density of the
cement slurry is of utmost importance to balance the pressures, avoiding fractures problems.
It’ll ensure the stability of the pressures acting between the oil well and the formation. Having
in mind that are necessary paste more lightweight to promote the insulation, without there
being this billing, is necessary to formulate cementing systems to reduce the hydrostatic
pressure of the cement column. Thereunto, are added to folders, materials with functions to
reduce the density. Therefore, this study had as objective formulations optimize of a cement
slurry of low density containing bentonite for application in shallow oil wells and with low
gradient of fracture, as well as to compare the efficiency of the bentonite extender additive
added to these pastes, by of variations of the density and concentrations and observing of
behavior of the rheological properties, stability and resistance to compression. The pastes
were formulated with the follows density values: 12,0 lb/gal; 12,5 lb/gal; 13,0 lb/gal to 13,5
lb/gal with different concentrations of bentonite (1,0; 2,0; 3,0 and 4,0 %) for each
composition. The results obtained through the rheological tests showed that the increase in the
bentonite concentration afforded the increase in particles dispersed in the middle, leading to
an increased of rheological parameters for all densities. In the stability tests the best results
were obtained at higher densities, becoming more stable with concentrations from 3 %,
showing no relegation. In the compressive strength tests, the paste with a density of 13,5
lb/gal with concentration of 4,0 % of bentonite got a higher mechanical strength, but very
viscous, which may hinder the pumping. Through the characterization of X-ray diffraction
(XRD) of pure bentonite was observed the presence of montmonrilonita and quartz phases
which are typical of clay. The XRD of the cement pastes of 13,5 lb/gal was observed that
there was the presence of etringite, portlandite, calcium silicate and quartz. It was also
observed that the images obtained by scanning electron microscopy (SEM) the paste of 13,5
lb/gal with 4 % bentonite showed notoriously the presence of ettringite needles, as well as the
steps of portlandite and calcium silicate cement hydration products. Finally, it can be
considered that the paste have worked best, are the pastes with a density of 13,5 lb/gal, with
concentrations of 2,0 % and 3,0 %, because they are more stable and mechanically strong,
compared with the other with lower densities. |
|---|