Evaluation of Fracture Toughness and Master Curve in Tensile Armours Using Subsize Specimens: Experiments and Methodological Developments

• Grant number: 24/11162-6
• Support Opportunities: Regular Research Grants
• Start date: November 01, 2024
• End date: October 31, 2027
• Field of knowledge: Engineering - Naval and Oceanic Engineering - Shipbuilding and Ocean Systems Technology
• Principal Investigator: Claudio Ruggieri
• Grantee: Claudio Ruggieri
• Host Institution: Escola Politécnica (EP). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated scholarship(s): 25/01361-4 - A Local Approach Based on the Weibull Sstress to Predict Geometry Effects in Tensile Wirs, BP.PD

Abstract

The rapid increase in oil and gas (O&G) exploration and production activities in the Brazilian pre-salt reserves, located in ultra-deep waters in the South and Southeast basins, has motivated Petrobras to develop new and more efficient technologies more applicable to the high depths, elevated temperatures and pressures (HTHP - high temperature high pressure), and the presence of highly aggressive compounds. In particular, Petrobras has been widely using flexible risers with non-adherent layers, both as production pipelines for oil or gas from the seabed to the surface (platforms or ships) and for gas injection into reservoirs. However, Petrobras has also xpressed growing concern about the structural integrity of the tensile armor of flexible risers due to the occurrence of SCC (Stress Corrosion Cracking) by CO2, following recent failures in some of its offshore production units, which negatively impact the integrity of its operations. Therefore, extending the service life and assessing the criticality of defects in flexible pipelines and risers are of great importance and relevance for the safe exploration and production of O&G in deep and ultra-deep waters, in connection with the elimination or mitigation of severe environmental damage. Thus, the proposed research project aims for additional and significant advances in the development of a methodology for the correct and accurate assessment of the fracture toughness of tensile wires used in flexible pipelines. Concurrently, and no less importantly, the project's activities will advance the development of toughness testing protocols, including the assessment of the reference temperature, T0, associated with the Master Curve methodology using non-standard and sub-sized specimens. The exploration and development of this research line address five central and interconnected subprojects: 1) Development of Sub-sized Specimens and Toughness Testing; 2) Development of the Master Curve for Sub-sized Specimens and Tensile Wires; 3) 3D Numerical Simulations of Sub-sized Specimens; 4) Application and Validation of a Local Model Based on Weibull Stress; and 5) Correlation between Charpy Energy and Toughness for Sub-sized Specimens. (AU)