Análise estrutural de poços submarinos: uma avaliação da influência do topo de cimento do revestimento de superfície

Abstract

This work presents a development to analyze wellhead movement in subsea wells for cases where surface casing may not be fully cemented. The structural casing is represented by a non-linear spring with hysteretic behavior, obtained by the Finite Element Method. In this context, the soil is represented by a set of t-z non-linear curves. For loading, unloading and reloading paths, new t-z curves was developed . The other casings are represented by linear springs. The structural model is analysed for each step of well construction and production/injection loads through the displacement compatibility and balance of forces on the wellhead. Beside that, the model proposed takes into account the correction of results due to surface casing buckling. An analysis of a representative case is done to present the methodology and verify the model. The results revealed that the uncemented extension of the surface casing shows great influence in the overall analysis, leading to high surface casing stress and significative wellhead movement. This influence is more pronounced in scenarios which the load capacity of structural casing is reached. The comparison between the model and Finite Element Analysis, using the software Abaqus®, showed good agreement.