Estudo, desenvolvimento e aplicação de modelagens para o cálculo do aumento de pressão anular (APB) em poços
Annular pressure build-up (APB) is a thermal phenomenon that happens when oil and gas wells face temperature variations along their life cycle, and is generally take in account in the safety factors applied for the well design. Casing design have to take into consideration high pressures, resulti...
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| Formato: | Dissertação |
| Idioma: | por |
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/26315 |
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| Resumo: | Annular pressure build-up (APB) is a thermal phenomenon that happens when oil and gas
wells face temperature variations along their life cycle, and is generally take in account
in the safety factors applied for the well design. Casing design have to take into
consideration high pressures, resulting from this effect to the annular, therefore mitigating
the risk of increasing internal pressure or collapsing the casing in weak points. Offshore
wells do not have the option of controlling their annular pressure, and remotely bleed off
annulus fluid in a controlled volume. Unmanned platforms and wells in remote locations
face similar problems. Besides that, HPHT (high-pressure and high temperature) wells
face high temperatures during long production times, which worsen the problem of
pressure build-up in annular, because the thermal expansion of liquids tends to increase
the temperature even more. From this context, this thesis presents the analysis of three
models for annular pressure build-up (APB), to verify if a more simplified model can
present an acceptable result. The first model, the simplest, considers that the thermal
expansion of the fluid is governed by the ratio between the isobaric thermal expansion
and the isothermal compressibility; the ballooning and reverse ballooning effect inside
tubulars, and the complete rigidity of casings where they are cemented. The second model
follows the same premises of the previous model; however, it also considers the
deformation of the casing by the Poisson coefficient, as they are assumed to have axially
fixed ends. The last model considers the well composed by a multiple sealed and
interactive annular spaces, where those spaces influence each other, interdependently. It
has a premise that the build-up in the annular pressure, caused by the fluid heating, and
the corresponding change in radial, tangential and axial tensions, acting on casing tubular,
reach the balance through the well. Results from the first two models shown that they
overestimate pressures, when the annulus tubulars are cemented. On the other hand, the
third model results show a good agreement with a commercial program, used as reference,
for any well configuration. |
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