Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-07-28T17:55:36Z No. of bitstreams: 1 2016 - Frederico Martins Costa.pdf: 7875693 bytes, checksum: 1f9e0aaff0875ac10e2311a35da16d31 (MD5) / Made available in DSpace on 2017-07-28T17:55:36Z (GMT). No. of bitstreams: 1 2016 - Frederico Martins Costa.pdf: 7875693 bytes, checksum: 1f9e0aaff0875ac10e2311a35da16d31 (MD5) Previous issue date: 2016-12-27 / CAPES / The process of well cementing is very complex, beyond the fact that cement paste presents high density, different rheology fluids are injected into the annulus, altering downhole pressure due to changes on hydrostatic pressure and frictional losses. Knowing the operational window and assuring downhole pressure inside this constraint is primordial for security and well life cycle purposes. Due to downhole variations caused by the disturbances, the superior (fracture) and inferior window limits can be exceeded. As a result, loss circulation problems (mud penetration into a fracture) or kick (reservoir fluid inflow into the annulus) can disturb the cementing process, leading to serious accidents, financial losses, environmental damage and human losses. In order to represent the most important phenomena of cementing process, an experimental unit was built using on line flow, density and pressure measurements. Downhole pressure control through pumping 8, 11 and 14 ppg (lb/gal) fluids was analyzed under loss circulation and kick phenomena. The tracking of the downhole pressure at the set point, by employing a feedback control loop (PI), was implemented through using the opening index of the choke valve as the manipulated variable. / O processo de cimenta??o de po?os ? bastante complexo, al?m da pasta de cimento apresentar elevada densidade e ocorrer o bombeio de fluidos de diferentes reologias, a press?o no fundo do po?o sofre grandes varia??es, devido ? mudan?a na press?o hidrost?tica do po?o e ?s perdas por atrito. Conhecer a janela operacional do po?o e manter a press?o anular de fundo dentro desta ? primordial para a seguran?a e a vida ?til do po?o. Devido ?s varia??es na press?o ocasionadas pelos dist?rbios, a press?o anular de fundo pode extrapolar o limite superior (press?o de fratura) e o inferior (press?o de poros), da janela operacional. Ao extrapolar tais limites, os fluidos da regi?o anular podem migrar para a fratura (perda de circula??o) ou os fluidos nativos do reservat?rio podem migrar para a regi?o anular (kick), essas situa??es s?o indesejadas durante a cimenta??o, podendo causar s?rios acidentes, perdas humanas, preju?zos financeiros e danos ambientais irrevers?veis. Para representar os fen?menos mais importantes do processo de cimenta??o, foi constru?da uma unidade experimental com instrumenta??o capaz de quantificar vaz?o, densidade e press?o em tempo real. Foram analisados o comportamento da press?o anular de fundo no bombeio de fluidos com diferentes densidades (8, 11 e 14 ppg), al?m dos fen?menos de perda de circula??o com kick de g?s, controlando a press?o em um valor desejado (set point), utilizando uma estrat?gia de controle por realimenta??o (controlador PI), atrav?s do ?ndice da abertura da v?lvula choke.