EVALUATION OF PERMEABILITY IN THE INTERFACE STEEL CASING - CEMENT SHEATH IN WELLS SUBJECTED TO VAPOR INJECTION
Cement, metallic casing, Latex SBR, experimental design, permeability.
For better efficiency and increase in the production factor of mature fields or heavy oil, recovery methods are used, being the thermal method with the highest success rate. Exposure of the metallic casing and the cement sheath to thermal cycling conditions can cause cracks to appear, allowing the passage of fluids through the cement sheath due to the difference in expansion coefficient between the two materials. This leads to serious socioeconomic and environmental risks, compromising the productive life of the well. Latex of the SBR type has been widely used in order to improve the mechanical properties of cementing materials for oil wells. However, few studies have presented new methodologies for evaluating the performance of these materials by physically simulating the condition of a well (cement / casing). Within this context, this work aimed to evaluate the permeability between a steel casing and a cement sheath with Latex SBR, simulating thermal cycling conditions in which oil wells are subjected during the recovery of heavy oils by thermal methods. From an experimental design for 2 independent variables, defined as SBR Latex concentration, varying between 0 L / m³ and 267.36 L / m³ (0 gpc and 2 gpc), and cement slurry density between 1.75 g / cm³ (14.6 lb / Gal) and 1.89 g / cm³ (15.8 lb / Gal), the permeability behavior was studied. The results showed that the variation in density was more significant in samples that were subjected to static well temperature conditions (68 ° C). It was also observed that the increase in the concentration of Latex SBR contributed to a better adherence of the cement matrix to the casing, favoring positively the results of the samples that were exposed to steam injection temperature (300 ° C). The experimental design helped to reduce the number of experiments or repetitions and improves the interpretation of the results obtained, consequently, to determine the best conditions for the formulation of slurrys applicable in cementing operations of oil wells subject to steam injection.