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Previous issue date: 2012-12-17 / Many challenges have been presented in petroleum industry. One of them is the
preventing of fluids influx during drilling and cementing. Gas migration can occur as
result of pressure imbalance inside the well when well pressure becomes lower than gas
zone pressure and in cementing operation this occurs during cement slurry transition
period (solid to fluid). In this work it was developed a methodology to evaluate gas
migration during drilling and cementing operations. It was considered gel strength
concept and through experimental tests determined gas migration initial time. A
mechanistic model was developed to obtain equation that evaluates bubble displacement
through the fluid while it gels. Being a time-dependant behavior, dynamic rheological
measurements were made to evaluate viscosity along the time. For drilling fluids
analyzed it was verified that it is desirable fast and non-progressive gelation in order to
reduce gas migration without affect operational window (difference between pore and
fracture pressure). For cement slurries analyzed, the most appropriate is that remains
fluid for more time below critical gel strength, maintaining hydrostatic pressure above
gas zone pressure, and after that gels quickly, reducing gas migration. The model
developed simulates previously operational conditions and allow changes in operational
and fluids design to obtain a safer condition for well construction / Muitos desafios t?m sido apresentados na constru??o de po?os, dentre eles o de evitar o
influxo de fluidos durante a perfura??o e cimenta??o. A migra??o de g?s ? resultante do
desequil?brio de press?es dentro do po?o, quando a press?o do po?o se torna menor que
a da zona contendo o g?s, e na cimenta??o isso ocorre durante o per?odo de transi??o da
pasta (de fluido para s?lido). Nesse trabalho foi desenvolvida uma metodologia para
avaliar a criticidade da migra??o de g?s durante a perfura??o e opera??es de cimenta??o
de po?os. Foi considerado o conceito de for?a gel e atrav?s de ensaios experimentais,
determinado o tempo inicial da migra??o de g?s. Foi desenvolvido um modelo
mecanicista para obter a equa??o que avalia o deslocamento da bolha atrav?s dos
fluidos enquanto eles gelificam. Por ser um comportamento dependente do tempo,
foram feitos ensaios reol?gicos din?micos de viscosidade em fun??o do tempo. Para os
fluidos de perfura??o analisados verificou-se que ? desej?vel que possuam uma
gelifica??o r?pida e n?o progressiva de forma a reduzir a migra??o de g?s sem
comprometer a janela operacional (diferen?a entre press?o de poros e fratura). Para as
pastas analisadas verificou-se que a mais adequada ? a que se mant?m fluida por mais
tempo abaixo do valor do gel cr?tico, mantendo a press?o hidrost?tica acima da press?o
da zona de g?s, e ao atingir esse valor, gelifique rapidamente, reduzindo a migra??o de
g?s. O modelo permite simular previamente as condi??es operacionais e propor
mudan?as no projeto da opera??o e dos fluidos de forma a obter a condi??o mais segura
para a constru??o do po?o
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/13022 |
| Date | 17 December 2012 |
| Creators | Pinto, Gustavo Henrique Vieira Pereira |
| Contributors | CPF:15724520800, http://lattes.cnpq.br/0022988322449627, Freitas, J?lio Cezar de Oliveira, CPF:00957245408, http://lattes.cnpq.br/2357217530716519, Martins, Andr? Leibsohn, CPF:80616121749, http://lattes.cnpq.br/7308057555474006, Silva, Em?lio C?sar Cavalcante Melo da, CPF:00775744433, http://lattes.cnpq.br/8643933669753466, Naccache, Monica Feijo, CPF:89027108749, http://lattes.cnpq.br/0010848295031388, Martinelli, Ant?nio Eduardo |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Ci?ncia e Engenharia do Petr?leo, UFRN, BR, Pesquisa e Desenvolvimento em Ci?ncia e Engenharia de Petr?leo |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/embargoedAccess |
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