Efeito de adições poliméricas na aderência de pastas de cimento a tubos metálicos após ciclagem térmica
Thermal recovery methods, especially steam injection, have been used to produce heavy oils. However, these methods imply that the metallic casing-cement sheath interface is submitted to thermal cycling. As a consequence, cracking may develop due to the thermal expansion mismatch of such materials, w...
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| フォーマット: | doctoralThesis |
| 言語: | por |
| 出版事項: |
Universidade Federal do Rio Grande do Norte
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| オンライン･アクセス: | https://repositorio.ufrn.br/jspui/handle/123456789/15579 |
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| 要約: | Thermal recovery methods, especially steam injection, have been used to produce
heavy oils. However, these methods imply that the metallic casing-cement sheath
interface is submitted to thermal cycling. As a consequence, cracking may develop
due to the thermal expansion mismatch of such materials, which allows the flow of oil
and gas through the cement sheath, with environmental and economical
consequences. It is therefore important to anticipate interfacial discontinuities that
may arise upon Thermal recovery. The present study reports a simple alternative
method to measure the shear strength of casing-sheath interfaces using pushthrough
geometry, applied to polymer-containing hardened cement slurries.
Polyurethane and recycled tire rubber were added to Portland-bases slurries to
improve the fracture energy of intrinsically brittle cement. Samples consisting of
metallic casing sections surrounded by hardened polymer-cement composites were
prepared and mechanically tested. The effect of thermal cycles was investigated to
simulate temperature conditions encountered in steam injection recovery. The results
showed that the addition of polyurethane significantly improved the shear strength of
the casing-sheath interface. The strength values obtained adding 10% BWOC of
polyurethane to a Portland-base slurry more than doubled with respect to that of
polyurethane-free slurries. Therefore, the use of polyurethane significantly
contributes to reduce the damage caused by thermal cycling to cement sheath,
improving the safety conditions of oil wells and the recovery of heavy oils |
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