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 distance tie-backs, 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 are only used under transient operations (start-up, shutdown, preservation), local heating is a different solution, mainly to be used continuously during production and also during transient operations as long as there is fluid circulation in the flowline. The local heating device is a very simple and robust system integrated into a compact subsea module, installed in parallel of the main flowline and which can be retrieved for maintenance or relocated. The technology 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 is a way to mitigate uncertainties on production fluid temperature or solve an unexpected poor thermal performance of the design. The main principles of the local heating technology, as well as a preliminary design performed for a specific case provided by an operator, will be described in the paper. 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 paper will also present the qualification work performed by Saipem to date including heating performance tests performed mid-2018 on 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 next qualification step entails new tests to be performed on a medium scale prototype using crude oil as process fluid. The main objective is to qualify the heating performance tests and the fabrication method of the local heating module under representative conditions: representative process fluid and representative module geometry. The intention is to perform these tests on an existing Brazilian onshore test site in the frame of a JIP.

Innovative flow assurance solutions are required to make new field developments both technically and economically feasible. Indeed in the case of long distance tie-backs, very deepwater applications or when the fluid temperature at the wellhead is too low, conventional flow assurance solutions might not be applicable. In this case, heating the flowlines is a way to overcome the thermal constraints, mitigate hydrate and wax risks and provide operational flexibility. Existing heating solutions are based on distributed heating technologies (DEH and Heat tracing) and are mainly considered for hydrate management under transient operations (start-up, shutdown, preservation). Local heating is a different solution, intending to be used continuously during production. Local heating allows for the integration of the system into a compact subsea station, installed in parallel of the main flowline, which can be retrieved for maintenance or relocated to another location. The technology can be implemented either on new fields or for the extension of existing lines. The purpose of this paper is to present an overview of the local heating technology under qualification by Saipem. The heat is provided using induction. This solution is thus able to provide a very high power density leading to a very compact solution. The internal diameter of the line in the heating station remains unchanged from the main production line, which makes the solution fully compatible with preservation by flushing and allows to pig the system in case of deposits. The temperature is monitored throughout the heating module by means of a network of optical fibers. The paper will introduce the main features of the technology, the main scenarios for which this solution is particularly suitable as well as the impact on the field operations. Information will be based on the results of flow assurance studies performed for various types of oils and field configurations. Some preliminary designs of the subsea station will be given, going up to 3MW of thermal power delivered to the fluid. Finally the paper will present the qualification testing recently conducted on a reduced scale prototype, with a description of the prototype and the main results obtained.

Brazilian Pre-salts fields lie in approximately 2200 m w.d. in a challenging environment and are often characterized by highly corrosive produced fluids that pushed to the extreme the application of the most advanced material technology and engineering. Nevertheless, Lula, Sapinhoá, Mero and Búzios are definitively world-class prospects with production rates that may exceed 30.000 barrels per day per well. The development scheme of the Pre-salt fields followed the experience and the track record of the large number of deepwater fields that were previously developed in Brazil, in the post-salt regions, and is based on satellite wells tied to the floating production platform by means of dedicated production and service risers (i.e. each well has dedicated production and service lines). This satellite configuration offers the advantage to be simple, straightforward and resilient to field layout changes even during the project execution phase. However, the continuous pressure to which the Oil & Gas industry is exposed in order to increase profitability, reduce cost and, more recently, green house gas emission is encouraging Operators to evaluate different field architectures that are more traditionally implemented in other deepwater provinces outside Brazil and that the recent technology and construction asset developments made suitable also for a potential application in the Pre-salt fields. Moreover, those field architectures that are normally based on commingling of wells production are also prone to provide a faster production ramp-up and a reduced time to break even. This paper presents a description of possible Daisy Chain and Manifold-Based subsea architectures that are suitable to be applied to Brazilian pre-salt fields. The pros and cons of these alternative subsea layouts are explored. Additionally, cost and schedule analyses are presented to show the benefits of such architecture regarding CAPEX and ramp-up compared to satellite architecture, considering the "Brazilian pre-salt" scenario. Finally, a generic proposal for subsea architecture is presented for pre-salt developments jointly with practical solutions for typical operation demands related to flow assurance issues like, for instance, wax and hydrate management.