The development of Brazil’s Offshore fields has been performed using flexible pipes because this pipe technology offers significantly increased flexibility, enabling the movement of pipes between wells and reducing lead time to bring a well onstream as compared to rigid pipe solutions. In addition, the decision of where exactly to drill development wells can be delayed, thus making the drilling campaigns easier, cheaper and faster .
With the increased activity in Pre-Salt, some challenges to flexible pipes were uncovered and needed to be addressed, notably oil composition and corrosive agents, e.g. H2S, and, specifically for the case of this paper, CO2. At high pressures, such as found in pre-Salt fields, these contaminants create new Stress Corrosion Cracking (SCC) failure modes and several mitigation measures have been adopted to overcome them, focused either on the installed fleet or on the next generation of pipes to be delivered. SCC is a condition that induces failure in the pipes’ metallic layers, but it needs three elements to occur: water, tensile stress exceeding a critical level and a susceptible material. If one of these three elements is suppressed, the phenomena does not to happen.
This paper will cover and present a technology developed to detect the annulus water condition — dry or flooded — and thereby allow a correct integrity management strategy to be adopted. The technology is based on an embedded sensing system together with topside equipment to read the status. The use of such a system is important for the next generation of flexible pipes as it will allow better management of the fleet, with the required measurements performed from the production unit without the need of any support vessel and hence at a reduced cost.