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Shell has developed a novel mono-diameter well concept for oil and gas wells as opposed to the traditional telescopic well design. A Mono- diameter well contains multiple casing sections with the same internal diameter. This is achieved by expansion of the casing sections concerned using an expansion cone. Since the well is drilled in stages and casings are inserted to support the open hole, an overlap section between two consecutive (expandable) casings exists which has to be expanded. When the cone enters the overlap section, the expansion force increases dramatically due to the expansion of two casings, cured cement and formation layers. When the cone finalizes the expansion of the overlap section it pops out, the expansion force vanishes and the cone accelerates upwards and it generates an empty volume to be filled by the well fluid (mud). As a result of this, fluid starts to flow through the drill pipe, around the cone and the fluid volume below the cone starts to decompress. This induces a surge pressure wave traveling upwards and a swab pressure wave in the expanded casing traveling downwards. If the pressure difference between outside and inside of the expanded casing exceeds the collapse rating of the casing, the casing will collapse which leads to the loss of the concerned well section. Repair of such a failure costs time and money, therefore this swab pressure must be well predicted to enable the installation process to be designed such that this collapse can be avoided. A model of fully coupled fluid-structure interaction between cone and the well fluid is built for calculating the swab pressure propagating downward and surge pressure propagating upward resulted from transient process occurring after cone pops out. This model has shown an effective tool for predicting the swabbing pressure in field deployments performed lately in Gulf of Mexico and according to its output the suitable cone is selected in order to avoid the casing collapse.

International audience; Among Non-Destructive Evaluation, vibration-based methods present some peculiarities. Structural damages change the dynamic behavior of the system, and vibrations should be used to detect these changes and to evaluate damages placed not accessible locations. These methods respond to the current tendency which is to integrate into the structure identication and monitoring systems; to this aim transducers and sensors are embedded with the mechanical system and driven by suitably designed electronic controllers. The major limit of this and the other indirect identication techniques based on frequency response measurements turns out to be the small sensitivity to local variations of mechanical characteristics: it reflects on a uncertainty on the identied parameters, since it implies a small curvature of any reasonable identication functional build on these quantities. An enlightening example for the application of the proposed technique is given through a beam-like structure coupled to a network of piezoelectric patches.