Integrated Computer-Aided Design for Well Cementing: Analyzing Containment in Deepwater Wells

Resumo

Objective: This study investigates the impact of numerical simulations on cement integrity during the drilling of deepwater top holes through salt formations. The primary aim is to enhance well containment analysis by optimizing cement sheath quality.
Approach: We begin with a comprehensive literature review, examining industry practices for drilling and cementing in salt zones. By analyzing existing literature, we gain insights into best practices and challenges related to cementing in deepwater wells. Next, we leverage field data from hundreds of wells in the Santos basin pre-salt region. This data allows us to identify critical aspects affecting cement quality and determine the main variables necessary for consideration. The heart of our approach lies in real-scale numerical simulations using chemo-thermo-mechanical finite-element models. These simulations guide our design process, considering factors such as well geometry (inclination, tortuosity, and hole enlargement) and different cement slurry properties. Importantly, the simulations also account for severe thermal and mechanical stress during worst-case scenarios of discharge and shut in. By ensuring effective well-control containment, we assure that the casing cement will not fail in the event of a blowout.
Key Findings: For geometry requirements, meeting specific well geometry criteria is essential for achieving the desired cement sheath quality. As for cement slurry design, simulations indicate that salt-based cement slurry is favored due to its superior bond strength and field performance. We also evaluate the impact of cement expansion and shrinkage for different scenarios, showing the enhanced performance of expansive cement in long-term integrity.
Industry Impact: Integrating simulations into standard cementing practices offers significant advancements in maintaining deepwater well integrity. By optimizing cement sheath quality, we enhance well containment and contribute to safer drilling operations in challenging environments.