Corrosão dos aços SAE 1010, API K55 e API N80 na presença de CO2 em condições de armazenamento geológico de carbono

• Autor(a) principal: Barros, Adriana Lopes
• Data de Publicação: 2015
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da PUC_RS
• Texto Completo: http://tede2.pucrs.br/tede2/handle/tede/6995
• topic: AÇO - CORROSÃO; CARBONO - ARMAZENAMENTO; ENGENHARIA DE MATERIAIS; ENGENHARIAS

The technology for CO2 capture and storage (CCS) consists in the CO2 capture and separation, transport and injection into geological reservoirs and is an important technology to mitigate environmental impacts. Oil and gas reservoirs, saline aquifers and deep layers of coal are options with great potential for CO2 storage. However, for storage of large amounts of CO2, it should be in supercritical state. Failure by corrosion, mainly induced by CO2, is a concern of using this technology once it requires integrity of materials used in the wells for long periods of time. However, many of the steels used in casings have a low performance in CO2 rich environments. The corrosion rate depends on the structure and morphology of corrosion scales formed on the steel surface and the environmental conditions as chemical composition of the corrosive medium, temperature, pressure and exposure time. This work has as main objective to investigate the corrosion of SAE 1010, API K55 and N80 steels at high CO2 pressure in different corrosive media, simulating scenarios present in CO2 injection wells for purposes of geological storage of carbon. Corrosion was evaluated at a pressure of 15 MPa using different temperatures (50°C and 90°C) in CO2 saturated aqueous solutions containing NaCl or CaCl2 and wet supercritical CO2. The morphology and the chemical composition of the films of corrosion products depended on steel, temperature, corrosive environment and the type of salt present. The thickness of corrosion scales had no direct relationship with the corrosion rate. The API N80 steel exihibited the higher corrosion rate in aqueous solution containg NaCl, while the SAE 1010 steel presented higher corrosion rate in aqueous solution with CaCl2. Electrochemical measurements indicate that the corrosion rates of steels can decrease with time of exposure to the corrosive environment, once corrosion scales exhibited characteristics of protection hindering the diffusion of ionic species through the film. The analysis of the corrosion of carbon steel in different conditions of geological storage process is complex, once it was observed that the way each parameter affects corrosion depends on the steel, not only in terms of chemical composition but also the microstructure.