Parametric Study of the Influence of Casing Wear on Well Foundation Design

Resumo

During oil well drilling operations, the drill string may come into contact with the inner wall of the casing, generating lateral forces which, combined with the string’s rotation, lead to wear. Excessive casing wear reduces mechanical strength and may compromise the structural integrity of the well. The objective of this work is to conduct a parametric analysis of casing wear variations in order to assess their impact on the results of oil well foundation design. The proposed methodology assumes continuous casing wear along the length of the string, leading to a reduction in internal diameter. Mechanical resistance, load capacity, and safety factors are evaluated and compared for worn and unworn scenarios across various foundation types, including perforated and cemented, jetted, torpedo based, and driven casings. Different levels of casing wear were simulated, ranging from 0% to 30% of the original wall thickness, in order to evaluate the system’s behavior. A finite element software was employed to model the geometric changes and assess their effects on well integrity. The results of the parametric analysis indicate that casing wear has the greatest impact when it occurs in the surface casing, with a reduced influence observed in subsequent casing strings. These results highlight the need to account for casing wear already in the design phase, especially for wells with a higher likelihood of contact between the drill string and the casing, such as those with deviated or horizontal trajectories. The application of numerical models based on finite element analysis proved effective in predicting these variations and their impacts on the outcomes.