Abstract
Scale occurrence in a giant oilfield located in deepwaters off the Brazilian coast required the implementation of strategies to remediate and prevent scale formation, which was a cause of significant production loss in the field. To prevent scale formation, inhibitor squeeze treatments have been utilized since 2006, when two squeeze treatments indicated an inhibitor lifetime lower than the predicted from laboratory tests. The inhibitor used is derived from the phosphonic acid, making it possible to analyze the inhibitor concentration in the produced water, and consequently, determine its lifetime. Despite the lower lifetime, the wells did not show any production loss, even when inhibitor concentrations were lower than the minimum inhibitor concentration (MIC), determined in laboratory tests. Throughout 2007, due to operational and contractual concerns, it was not possible to perform the squeeze treatments. Consequently, by the end of that year, production losses were verified. In 2008, the inhibition campaign was restarted, and based on the results of 2006 operations, the squeeze treatment volumes were recalculated, in order to obtain a higher inhibitor lifetime. As a result, it was possible to extend the treatment lifetime and maintain the production of the wells stabilized. Historic cases of three wells will be shown, emphasizing the extensive production loss verified when the treatment was not performed, the impact observed in the production when the treatment was delayed and the success obtained when the treatment schedule was accomplished. Beyond the scale occurrence in the production wells, there are also severe scale problems in the production facilities, which will be discussed in this paper. This work describes and details the scale monitoring, prevention and remediation strategies employed in this field, exposing the results obtained, as well as the learned lessons and opportunities to improve the scale management strategy.
