Estudo da análise de tensões cisalhantes na interface aço-cimento devido a micro canalização produzida por gás.

Abstract

Cementing of oil wells is defined as the filling of the annular space between the casing pipe and the well wall. This operation is essential to prevent inflow of fluids from the formation to the well, to provide mechanical adhesion to the coating and to the formation and protection of the coating against corrosion. Gas migration from the reservoir through the cemented annulus is one of the problems that can occur, which may lead to the formation of micro channels that weaken the structure. Several studies have been conducted to solve the problem since the 60's, however, the problem involves several causes and is specific to each case. The present work aimed to analyze the influence of gas migration action on a cement paste. To this end, molds were created that simulate the annulment of an oil well. After that, the specimens (CP's) called reference 0 were cemented, ie without gas migration. Subsequently, other CP’s that were under the influence of gas migration were cemented. The shear strength test was performed with the CP’s at the ages of 7 and 14 days of cure at room temperature. The percentage reduction in shear strength due to gas migration to 14-day specimens was 20.0%. For specimens with 7 days, the percentage reduction was 26.7%. The free water content test was also performed to obtain more data about the cement paste produced. The free water content found was 0.15%. The cement paste produced was adequate in terms of free water content.