Oil and Gas Operators are moving active production and injection equipment onto the seabed with the aim of reducing CAPEX and/or topside space requirements. Moreover, they want to minimize new production floating facilities (e.g. through tie-back to existing FPSO/Floaters). Given this scenario, the overall electric power needs may become an issue because of the extra power demand due to the increasing number of electric consumers placed subsea. These electric loads may include the subsea boosting (pumps or compressors) operations, pipeline heating or the typical subsea water, chemical injection and valves actuation (in the case of all electric control systems), just to mention some of potential subsea power consumers, and may exceed the existing FPSO/Floater power production capacity. A potential solution to overcome this issue consists of the deployment of wind generators combined with topside Island power generation. Offshore wind power is indeed more and more considered for shore power supply, but also by the Oil and Gas industry with the objective of reducing the carbon footprint of their facilities. High power marine wind generators are already consolidated technologies for near coast, and today they are evolving in the short-term to floating solutions for the open sea. Saipem has developed its own floating wind turbine solution, called Hexafloat, consisting in a pendular floating foundation made of tubular elements and connected through tendons to a counterweight. This solution is particularly cost-competitive for deepwater locations (thanks to the low mooring costs) even for harsh environmental conditions (thanks to an excellent stability), and will unlock the possibility to deploy large wind power generators far from the coastline in deep water. The system composed by the Hexafloat base and the wind generator may be equipped with onboard back-up generation utilities to provide continuous power supply for subsea, despite wind intermittency, and to provide support to certain subsea field development services, making the assembly a kind of supporting device for the subsea field or for the FPSO. This is the Windstream concept that is under internal development and that will be better described in the present paper through the explanation of the results achieved within a couple of case-studies analyzed.

The overall complexity of future subsea transportation systems is expected to increase due to new challenges posed by the novel field development schemes mainly dictated by the combination of tie-back distance and water depth with the target to make the field exploitation profitable, safe and reliable in the current Oil & Gas price scenario. It is becoming more frequent to face field development projects with long step-out distances associated with considerable water depth and/or low wellhead product temperature. During normal or transient conditions, these factors lead to flow assurance issues that can be avoided by deploying new cost effective technologies such as insulated and heated pipeline systems combined with subsea processing elements like Subsea Boosting. A dedicated team has performed different studies and internal development activities on this subject based on expected needs of Operators considering their real future subsea fields under investigation. New development schemes and operating philosophies have been identified together with the relevant technologies that, in some cases are under development, jointly with major suppliers. The most efficient production schemes have been selected and the conceptual design of its relevant technological building blocks has been performed. These building blocks have been further investigated in terms of market ownership & readiness with technology suppliers and O&G operators. The main enabling technologies involved for the oil fields are Subsea Active Heating/Insulation such as proprietary Electrically Trace-Heated Pipe In Pipe (ETH PIP), Subsea Boosting, Subsea Power Distribution and the All Electric Control System. ETH PiP, combined with Subsea Power Distribution (Subsea Switchgear, Subsea Transformers, Subsea VSD, etc.) and the All Electric Control System, can significantly support overall investment cost reduction and facilitate the tie-back development to an existing facility by ensuring the flexibility of operations and suitability with a wide range of project design basis. This paper outlines the selected development schemes for the long tieback oil fields and describes the main technological building blocks. It also outlines the actions initiated to provide a global solution for these types of fields and mainly to industrialize the second generation of the ETH PIP solution for longer tie-backs. It discusses the main components of the ETH PIP solution and the relevant Subsea Power Feeding System that provide and distribute power also to the other subsea utilities like boosting pumps and All Electric Control.

Chemical tracers have recently been used to identify oil and water production along different intervals in open hole slotted liner completion, compartmentalized with swellable packers. The reservoir is a fractured carbonate brown field containing several sub-areas producing asphaltene and clasts in which chemical inflow tracers have provided greater understanding of characterizing the reservoir and its' well performance in deviated wells. The permanent downhole tracer systems have been successfully applied in two onshore wells in Italy. The principle of this technology is to place a number of unique chemical tracer systems in different compartments along the length of the lower completion with only minor modifications for clean-up and production monitoring. The system releases tracer into the well stream when wetted by the target fluid, oil or water. When wetted by the opposite phase they will remain dormant, meaning no tracers will be released. The application of permanent oil and water tracer systems placed at pre-defined intervals along the production zones of the wells. Upon well start up, oil samples were taken at the surface and were analyzed to identify which zones were effectively contributing to oil and water production. Permanent water tracer systems were installed aiming at detecting the onset of early water breakthrough. After water break-through has occurred, a regular sampling program is performed and samples analyzed to identify the location of water production to understand the water profile evolution over time. Swellable packers have been used to segment the horizontal sections for the purpose of selective zonal stimulation and to optimize future water shut off intervention by treating the offending zones based on tracer detection. This paper will discuss an innovative wireless approach using chemical inflow tracers as the technology enabler with field proven case studies for clean-up verification, identifying where water and oil is flowing, assess stimulation job effectiveness and estimate relative flow contribution between intervals. Lessons learned for future installations will also be discussed. TX 75083-3836, U.S.A., fax +1-972-952-9435

Chemical injection in subsea fields is a consolidated practice to solve or prevent flow assurance issues that may occur linked to hydraulic, thermal and operability requirements, especially in transient conditions. The traditional approach adopted to supply chemicals to a subsea tieback is to position the chemical injection system, including pumps and storage, on the platform/FPSO, transporting the chemicals subsea through the umbilical or the chemical lines in case of high flow rates, and performing chemical distribution subsea up to the injection points. In the development of a long subsea tieback, costs for the umbilical system tend to increase based on its length and complexity. Moreover, pressure drops and control of chemical delivery pressures and flowrates through such a long umbilical can be extremely challenging, together with the risk of umbilical line blockages and their related issues. The design resolution to enlarge the diameter of the chemical conduits in umbilicals leads to an increase in unit weights and, combined with the umbilical length, additional costs and packing and installation challenges. These factors drive the need to review the conventional chemical injection system architecture and to make the development of a long tieback sustainable from the point of view of cost and technology. To overcome these major criticalities, the chemical injection system can be placed subsea, possibly close to the injection points. Recently, Saipem has mapped the typical chemical demand for a representative size oil fields, with the main aim of defining a subsea chemical injection system architecture and its related main components. The main result of this exercise is the definition of a configurable architecture for subsea chemical storage, injection and refilling facilities to be located close to the subsea users, based on operating consideration suitable for offshore and deepwater scenarios. A "building block" approach is followed together with a certain degree of equipment standardization, where possible, allowing for a flexible system that can be adapted and tailored to the specific field. Technology development status has been also considered and specific Saipem technologies, currently under qualification or being patented, have been considered and integrated in the concept.

The High-Performance DEH-PiP is a new technology for electrical heating of subsea tieback flowlines, able to be used for long distances thanks to an enhanced electrical efficiency. This paper describes the theoretical electrical model of this technology and its experimental validation. DEH-PiP is a well-known and field-proven technique for subsea flowline heating, but it exhibits a relatively poor electrical efficiency compared to emerging heat-traced PiPs. The approach presented in this paper to solve this drawback has been first to analyze the heat losses within the conventional DEH-PiP, then to design a new outer pipe to decrease dramatically its impedance. A strong effort was spent on the building of an accurate electrical model for the High-Performance DEH-PiP, and finally full-scale electrical tests on a representative prototype were carried out to validate the theoretical model. On the basis of the conventional DEH-PiP technology, specific design modifications were undertaken to enhance the electrical efficiency and thus the flowline step-out in the High-Performance DEH-PiP solution. A specific electrical model was developed and is detailed progressively in this paper from the basic electromagnetics considerations to the complete Finite Element Analysis including the magnetization curves of the pipe steel and the impact of magnetic hysteresis on the heating performances. Dedicated experimental works were conducted to validate the electrical model, on a specific prototype and the test bench associated. The electrical measurement curves are discussed, showing a good correlation between the theory and the experiments, and demonstrating the relevance of the electrical model. The impact of the improved electrical performance on the tieback heated flowline configuration is then discussed. This paper introduces the detailed experimental and modeling work performed to allow for the electrical engineering of a new DEH-PiP design, reaching significantly higher electrical efficiency, in the range of 90%-95%. This new solution allows reduced Greenhouse Gases Emissions by enhanced performance, lower voltage supply level enabling for longer flowlines, and lighter power chains.