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

With most of the world’s largest and easiest-to-exploit deepwater oil reservoirs already under development or producing, the industry is now facing new deep offshore challenges: the production of smaller fields that often contain more difficult oils. The tie-back of new fields to existing facilities can be a viable method for developing such marginal offshore fields, which are often too small to be developed economically on their own. The use of subsea processing and innovative field architectures as development solutions is fast becoming a reality. Such challenges are already being addressed in the development of certain fields in the Gulf of Mexico (King, Perdido...), Brazil (Marlim, BC-10...) and the Gulf of Guinea (Pazflor). However, long subsea tie-backs come with inherent complications. The most demanding are the flow assurance issues arising from the different operating regimes, and these may be combined with more viscous fluids and/or reservoirs at low pressure or low temperature. This paper examines the advantages and limitations of various field architectures that may be considered for long satellite tie-back lengths in deep waters. The first part addresses production considerations such as turndown, preservation and restart management for each candidate architecture. The impact of tie-back length on operating modes is also evaluated. The second part examines the impact of these operating modes on the receiving facilities.