Durability of Hardened Portland Cement Paste used for Oilwell Cementing

Abstract

Résumé -Durabilité d'une pâte de ciment durcie utilisée pour la cimentation des puits pétroliers -Les problèmes de durabilité des matériaux utilisés pour les sondages pétroliers sont une question essentielle pour l'industrie pétrolière. Nous avons mené des essais de vieillissement d'une pâte de ciment dans deux types de fluides en variant la procédure expérimentale. Nous montrons que les altérations observées sont très dépendantes de la façon dont les essais sont menés. Pour évaluer correctement la durabilité à long terme des matériaux cimentaires, il est notamment nécessaire de renouveler périodiquement le fluide dans lequel le matériau vieillit. En menant les essais ainsi, on montre que les propriétés macroscopiques d'une pâte de ciment durcie sont fortement dégradées. Abstract -Durability of Hardened Portland Cement Paste used for Oilwell CementingDurability of materials used for the completion of oilwell is of utmost importance for oil and gas industry. We carried out ageing tests on a hardened cement paste in two types

The Combined Effect of Temperature and Salinity on the Mechanical Behaviour of Well Cement

“…Table 1 shows the composition of sulphate resistance cement. Table 1 -Composition of sulphate resistance cement used in the study [8].…”

“…Zonal isolation in these wells is ensured by the steel casing and primary cementing. Hence, the primary cement should have a high strength and it has to be highly resistant to CO2, and chemical degradation under adverse pressure, temperature and salinity conditions [4,8]. The American Petroleum Institute (API) has recommended eight classes of well cement (Class A to F)based on their composition, acid resistance, bearable temperature etc.…”

“…Already, a few studies [7,8,9,12,16] focusing on the behaviour of well cement of oil wells under different temperature and salinity conditions have been done. Xingshan et al [16] have conducted a research using high sulphate resistance Class G cement slurry with a w/c ratio of 0.44 to study the effect of salt content on the properties of cement slurry and on the hydration process.…”

“…Lécolier et al [8] have investigated the physical and chemical effects of supercritical CO2 attack on well cement under different temperature (40ºC and 120ºC) and pressure (105 bar and 140 bar) conditions. When considering the effects of different temperature conditions on the cement degradation caused by supercritical CO2, it was found that the rate of hydration was higher at higher temperatures Thus, the higher amounts of Ca(OH)2 and C-S-H that are produced at temperatures higher than 40˚C may lead to the formation of higher amounts of smaller unhydrated grains.…”

Uso Da Microtomografia Computadorizada Para Avaliação De Danos Na Microestrutura De Pasta De Cimento Submetida a Carregamento Cíclico E a Temperaturas Elevadas

“…Um exemplo desses estudos foi a pesquisa feita por Lécolier et al (7), que analisaram a durabilidade de uma pasta de cimento utilizada em poços de petróleo. Como foi visto, a pasta de cimento destinada a esta estrutura sofre com alguns esforços que afetam sua durabilidade.…”