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Previous issue date: 2009-04-02 === The Potiguar basin has large fields of viscous oil where the used method for recovering is based on vapor injection; this operation is carried out by injecting vapor in the oilwell
directly, without the protection of a revetment through thermal insulation, what causes its dilation and, consequently, cracks in the cement placed on the annular, and lost of hydraulic insulation; this crack is occasioned by the phenomenon of retrogression of the compressive resistance due to the conversion of the hydrated calcium silicate in
phases calcium-rich, caused by the high temperatures in the wells, subjected to thermal recuperation. This work has evaluated the application of composite pastes with addition
of residue of biomass of ground sugar-cane bagasse as anti-retrogression mineral admixture for cementation of oil-wells subjected to thermal recuperation. The addition of the mineral residue was carried out considering a relative amount of 10, 20, 30, 40 and 59% in relation to cement mass, trying to improve the microstructure of the paste, still being developed a reference paste only with cement and a paste with addition of 40% of silica flour - renowned material in the oil industry as anti-retrogression additive. Pozzolanic activity of the ash was evaluated through XRD, TG/DTG, as the resistance
to compression, and it was also determined the physical and mechanical behavior of the pastes when submitted to cure at low temperatures (22 and 38? C); besides it was evaluated the behavior of the pastes when submitted to two cycles of cure at high temperature (280?C) and pressure (7 MPa). It was verified that the ash of the sugar-cane biomass presents pozzolanic reaction and has great efficiency in decrease the
permeability of the paste by filler effect, as well as that addition of ash in a relative amount of 10, 20 e 30% increases cured compressive resistance at low temperatures. It
was also showed that the ash in a relative amount of 40% and 59% has very significant efficiency as anti-retrogression additive, since it prevents the decrease of compressive
resistance and forms hydrated calcium silicate type xenotlita and tobermorita which have more resistance and stability in high temperatures === A bacia Potiguar tem grandes campos de ?leo viscoso, onde o m?todo de recupera??o utilizado ? a inje??o de vapor; essa opera??o ? realizada injetando-se vapor diretamente
no po?o, sem a prote??o do revestimento atrav?s de isolamento t?rmico, o que provoca a dilata??o do mesmo, provocando assim falhas no cimento colocado no anular, e
conseq?entemente, perda do isolamento hidr?ulico, esta falha tem origem no fen?meno de retrogress?o da resist?ncia ? compress?o devido a convers?o do silicato de c?lcio
hidratado em fases ricas em c?lcio, provocada pelas elevadas temperaturas nos po?os, sujeitos ? recupera??o t?rmica. O presente trabalho avaliou a aplica??o de pastas comp?sitas com adi??o de res?duos de biomassa do baga?o da cana-de-a??car mo?das como aditivo mineral anti-retrogress?o para cimenta??o de po?os petrol?feros sujeitos a recupera??o t?rmica. A adi??o do res?duo mineral foi realizada teores de 10, 20, 30, 40 e 59% em rela??o a massa do cimento, visando melhorar a microestrutura da pasta, sendo ainda produzidas uma pasta de refer?ncia, apenas com cimento e uma pasta com adi??o de 40% de silica flour material consagrado na ind?stria de petr?leo como aditivo antiretrogress?o. Foram avaliados a atividade pozol?nica da cinza atrav?s de DRX, TG/DTG e resist?ncia ? compress?o, determinando-se tamb?m o comportamento f?sico e mec?nico das pastas submetidas a cura com baixas temperaturas (22 e 38?C), al?m da avalia??o do comportamento das pastas submetidas a dois ciclos de cura a alta temperatura (280?C) e press?o (7 MPa). Verificou-se que a cinza de biomassa da cana apresenta rea??o pozol?nica, tendo grande efici?ncia na diminui??o da permeabilidade da pasta por efeito filler, e que as adi??es de cinza em teores de 10, 20 e 30% aumentam a resist?ncia ? compress?o das pastas curadas a baixas temperaturas. Constatou-se ainda que a cinza em teores de 40% e 59% tem ?tima efici?ncia como aditivo antiretrogress?o, pois evitam a diminui??o da resist?ncia ? compress?o e formam silicato de c?lcio hidratado do tipo xenotlita e tobermorita que se apresentam mais resistentes e est?veis as altas temperaturas
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