Enhance Flow Assurance in Large Diameter Gas Flexible Pipes

Abstract

Abstract Large gas field developments are an important trend of the oil and gas industry and is likely to be reinforced in the next decades. For these developments, flexible pipes with larger Inner Diameter (ID) and high flow rates are more and more required. This paper presents solutions developed to improve flow assurance in gas flexible pipes by assessing and removing flow induced pulsations (FLIP) risk occurrence and optimizing the maximum allowable flow rate. This trend leads the industry to have a kind interest in FLIP free flowlines and risers as well as in flexible pipes with improved flow rates capacities for equivalent diameters. Beginning of the 2000’s smooth bore gas export flexible riser was a pioneered FLIP free solution which is now a well-known, field proven and recognized technology. In addition, the market and industry trend have led to develop a full panel of solutions to answer new market requirements: FLIP and pressure losses methodologies, appropriate selection of conventional carcass and smooth bore flexible pipes (smooth carcass & plastic smooth bore). This paper describes the different solutions to enhance the flow assurance of flexible pipes for gas applications (less pressure losses & FLIP proof) with different flexible pipes solutions. Then a focus is done on the development of a cost-effective solution applicable to all types of pipes: the smooth carcass. This new carcass is an incremental improvement of existing technology. The industrialization, prototype manufacturing, qualification program and technical performances obtained so far including FLIP aspect, pressure loss and global mechanical behavior are detailed. Results have demonstrated that the smooth carcass allows reducing the pressure losses compared to flexible pipe with standard carcasses and thus to optimize the fluids flow rates or to reduce the flexible pipe internal diameters. Complete API 17J qualification compliance is planned for end 2018 for both static and dynamic applications. Specific dedicated competencies and technologies were developed to answer market requirements of the new gas field developments. Furthermore, the development of smooth carcass will tackle the singing phenomenon on gas flexible lines, and provide an optimized solution for flow assurance improvement to oil and gas operators.