Maximizing the use of existing topside facilities is an attractive approach to reduce project CAPEX and therefore unlock new reserves. However, as the tieback length to the host increases, technical and economic challenges arise. These include flow assurance, and costs of the umbilical and flowlines which inherently increase with length. These aspects, together with others independent from the length, such as power and space availability, have a significant impact and could result in making the project unfeasible or uneconomical. Technologies developed in recent years, or in their final stage of qualification, play a significant role, not only in solving the technical challenges, but also in finding cost-effective configurations, either by reducing and/or staggering capital and operational expenditures or by extending reserves recoverability or also by reducing significantly the risks associated with a development. In order to appreciate these advantages, different configurations have been outlined starting from those allowed by the conventional technologies and comparing them to the ones enabled by the new technologies. Actual advantages of each technological "bricks", considered alone or in synergies, depend on the specific projects and can be identified in a timely manner thanks to early engagement of Contractor in the architecture and associated pricing of subsea tiebacks. The paper will present a platform of technologies, their maturity status and how they can be integrated in novel architectures in an economic manner. Such technologies include: Boosting Distributed and local heating Subsea water treatment and injection Subsea separation Subsea chemical storage and injection All electric control system Local power generation

Offshore oil facilities are complex systems that involve elaborate physics combined with stochastic aspects related, for instance, to failure risk or price variation. Although there exist many dedicated software tools to simulate flows typically encountered in oil exploitations, there is still no tool that combines physical (mostly engineering fluid mechanics) and risk simulation. Such a tool could be useful to engineers or decision makers for specification, design and study of offshore oil facilities. We present a first step towards the creation of such a tool. Our current simulator is based on new Modelica components to simulate fluid flows and on stochastic simulation at a higher level, for modeling risk and costs. Modelica components implement physical models for single and two-phase flows in some typical devices of an offshore field. The risk simulation uses Markov chains and statistical indicators to assess performance and resilience of the system over several months or years of operation.

A new technology called Local Heating offers the possibility of significantly raising the temperature of the multiphase production fluid in order to improve flow assurance and consequently the economics of field developments. Heating the flowlines is a way to overcome the thermal constraints, mitigate hydrate & wax risks and provide operational flexibility. Indeed, in the case of long tiebacks, very deepwater applications or when the fluid temperature at the wellhead is too low, conventional flow assurance solutions might be very expensive or even not applicable. While other heating technologies such as DEH and Heat Tracing have been designed mainly to operate under transient operations (start-up, shutdown, preservation), this heating technology can be operated continuously during production and also during transient operations as long as there is fluid circulation in the flowline. The device is a very simple and robust system integrated into a compact subsea module, installed in parallel or in-line with the main flowline and which can be retrieved for maintenance or relocated. It is compatible with any type of field architecture and can be implemented either on greenfields or brownfields. In the case of greenfields, the use of Local Heating could also be a way to mitigate uncertainties on production fluid temperature or solve an unexpected poor thermal performance of the design. This solution is based on induction and is therefore able to provide very high-power levels (several MW) with a compact module. The temperature is continuously monitored throughout the heating module by means of fiber optic distributed sensors. The technology is fully compatible with preservation by flushing and allows pigging in the event of deposits. The main principles of the technology will be described in the paper, as well as a preliminary design performed for a specific case provided by an operator. The paper will also present the qualification work recently performed including heating performance lab tests using a small-scale submerged prototype operated under atmospheric conditions with multiphase fluid. The tests have confirmed the good electrical and thermal behaviour of the system. The paper finally describes the last qualification phase the objective of which is to install a subsea pilot to be connected to a subsea production system on a field located in Brazil. The intention is to perform this work in the frame of a Joint Industry Project.

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