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Abstract The objective of this paper is to describe the adopted procedures and operations that were used to process commissioning and start-up the Marlim Subsea Oil and Water Separation and Water Re-injection System. This system is much more complex than the conventional subsea manifolds and, similarly to the previous phases of this project, the commissioning and start-up phases also faced many challenges that had to be overcome. Several subsea equipment are part of the system; among them we should mention an unconventional "harp" gas-liquid separator, an oil-water "pipeseparator", cyclonic desanders (both for multiphase inlet stream and for produced water stream), two stages of hydrocyclones to remove oil from produced water and a water injection pump. Besides these equipments, instruments and multi-functional control modules are also part of the system. The problems faced during commissioning and start-up activities and the adopted solutions to solve them are also discussed. This paper will cover the start-up activities describing the following sequence:re-start-up of the production well through the subsea system by-pass line to topside,alignment of well multiphase production stream through the subsea separation system to check separation performance and suitability of produced water quality for re-injection andfinally start up of re-injection of produced water into the injection well. The requirements for logistic support that are very much different from the ones required for topside installations are also discussed. New " paradigms" of operating facilities imposed by subsea environment constraints, are also suggested and discussed. Introduction The Marlim Subsea Oil and Water Separation and Water Re-injection System (SSAO) is an innovative pilot project installed as a Pilot System for the well MRL-141, connected to the host production unit (FPSO), P-37, in Marlim Field, Campos Basin. The objectives of the project are: platform debottlenecking of the water treating facilities; increasing production by reduction of back pressure on the wellhead. Besides these objectives, another important aim of the project is to prove the concept and qualify the adopted technologies for future other applications. As a pilot project, the SSAO was designed to work for a minimum of 5 years, without retrieving of any components, removing, treating and re-injecting free water from the production of MRL-141, as shown in Table 1.

Abstract This paper describes the control system design for the Marlim three phasesubsea separation system (SSAO) and how the standard subsea control system hasbeen adapted for the new requirements for automated control. This is the mostadvanced subsea process system to date with several " first ever" applicationsof separation equipment subsea: harp, pipeseparator, desanders andhydrocyclones. The SSAO has a total of 7 control loops and a number of complexautomatic sequences. Further, the paper addresses how dynamic simulation analysis has been used tovalidate the process control strategy and improve the operational proceduresdesigned during the basic engineering phase. Control and operation of the SSAO has proved to be very challenging for severalreasons:There are strong interactions between different process componentsThe system dynamics are stiff due to small liquid hold-ups and low GOR in thesystemThe pressure drops of inline cyclonic equipment need to be balanced to ensureoptimal performanceConstraints in valve opening/closing speed and the importance of limiting thenumber of valve movements put restrictions on controller performanceInstrumentation is limited compared to topside facilities The content described above contain several new aspects compared to atraditional subsea control system and this paper will describe systemconsiderations with regards to implemented process control and also theimportance of using dynamic simulations as a design tool. Introduction The Marlim three phase subsea separation system (SSAO) was designed to separatethe produced water from the multiphase well stream and re-inject this into theproduction reservoir. Water polishing is required due to the strict OiW contentrequirement of less than 100 ppm. By re-injecting the produced water subsea, the backpressure in the flowline is reduced and the production is increased. Inaddition less water handling capacity is required topside. The SSAO has been installed in the Marlim Field, Campos Basin, in a water depthof 876 meters, 341 meters from the production well and 2100 meters from theinjection well. Oil, gas, sand and some remaining water will be sent to theP-37, a Floating Production, Storage and Offloading unit (FPSO) with a turretsystem. The SSAO is connected to P-37 with a multiphase line of 2400 meters(riser and flowline). The control of the process system and chemical injectionmanagement system will be located topside on P-37, as well as the power supplyand VSD for the subsea pump. In Figure 1 it can be seen that the production first goes through a multiphasedesander, which removes most of the sand before the production flow enters thepipeseparator. This is important in order to reduce the amount of sand build upin the downstream equipment and reduced the required frequency of flushingoperations. In the harp, the free gas is removed before the liquid is sentthrough the Pipe Separator to the outlet vessel. The water level in the outletvessel is controlled varying the speed of the water injection pump (WIP). Theoil and gas are re-combined in the outlet vessel and then sent to themultiphase line connected to P-37. From the outlet vessel, the produced water goes through the water polishingequipment consisting of a desander and a two-stage hydrocyclone module, beforeboosting and re-injection. The requirement for solids and oil content injectedin the injection well is 10 ppm and 100 ppm respectively. For a projectoverview, please see OTC-23230.

Abstract This paper presents the selected concept, the main challenges of the adoptedscenario and in consequence the requirements for a development of an extensiveTechnological Qualification Program performed on the components and on thewhole sub-sea water separation and re-injection pilot system for Marlim field -known as SSAO Marlim Project. Due to being a pioneer project, even consideringthe previous Troll and Tordis sub-sea separation and re-injection systems, itwas necessary to perform a very extensive and broad Technological QualificationProgram (TQP). Two main characteristics of the SSAO project are responsible forthe mentioned pioneer character of the project. Initially, in opposition to thementioned existing systems, separated water has to be re-injected in theproduction reservoir formation, due to non available disposal reservoir inproduction field area. Thus, required water quality, relating to oil andsediment content after separation, was very strict in order to avoid loss ofinjectivity. Furthermore, due to the deep water depth of the installation site(870 m) and due to the fact that the SSAO is a pilot for future deep waterinstallations, conventional gravity separators - as used in the mentionedprojects - would not be feasible and new technologies, not yet used elsewhere, have to be adopted.

A separação ciclônica vem se tornando nas últimas décadas um processo cada vez mais utilizado na separação gás-líquido, líquido-líquido e sólidolíquido, principalmente na indústria do petróleo. Com o crescente aumento das prospecções marítimas torna-se necessário reduzir o peso e a dimensão de equipamentos. Isto pode ser conseguido com a separação ciclônica, uma vez que pode-se criar um campo centrífugo diversas vezes superior ao campo gravitacional, tornando possível o desenvolvimento de equipamentos bastante compactos. A principal diferença entre os diversos ciclones é a sua geometria. A otimização dos mesmos para as variadas aplicações é, a cada ano, baseada menos em experimentos e mais em modelos matemáticos. No presente trabalho foi investigada a adequação dos modelos de turbulência de Tensões de Reynolds RSM (Reynolds Stress Model) e Grandes Escalas LES (Large Eddy Simulation) para a previsão do escoamento em um hidrociclone de alto teor de óleos através da comparação com dados experimentais e numéricos disponíveis na literatura. Após essa etapa foi investigada a influência de diversos parâmetros operacionais e geométricos como vazão, rugosidade e comprimento do hidrociclone no escoamento. Ambas as metodologias mostraram vantagens e deficiências, sendo que o modelo LES apresentou precisão superior com relação aos parâmetros turbulentos. Com relação à variação nos parâmetros do equipamento, a metodologia RSM foi capaz de prever corretamente, de acordo com evidências experimentais, a mesma tendência de redução de perda de carga com redução da vazão, aumento da rugosidade e comprimento. Cyclonic separation has became more and more important during the last decades as a unit process for gas-liquid, liquid-liquid and solid-liquid separation, mostly in the Petroleum industry. The off-shore exploration’s growth requires the development of smaller and lighter equipment. This can be achieved by cyclonic separation once centrifugal fields are several times stronger than gravity. This allows the construction of very compact systems. The major difference between the various cyclones is their geometry. Cyclone optimization for different uses is, every year, less based on experiments and more based on mathematical models. In the present work, the applicability of turbulent models, Reynolds Stress Model (RSM) and Large Eddy Simulation, was investigated to predict the flow inside a high oil content hydrocyclone, comparing the results with experimental and numerical data available in the literature. After this point, the influence on flow of operational and geometric parameters such as inlet flow, roughness and hydrocyclone length was evaluated. Both models have shown advantages and problems, being LES more accurate over turbulent parameters. Regarding the changing on hydrocyclone parameters, RSM model was able to foresee, on good agreement with experimental data, the expected results like reduction on pressure drop with: the inlet flow decreasing; increasing of roughness; and length.