Marlim 3 Phase Subsea Separation System - Challenges and Solutions for the Subsea Separation Station to Cope with Process Requirements

Abstract

Abstract This paper presents the experience brought from the oil-water subsea separatorproject developed for the Marlim field, known as SSAO Marlim. Here, it will beaddressed the inherent arising challenges from a project of a subsea separationequipment, from the subsea mechanical design perspective, with special focus tothe additional requirements to the normally presented in conventional subseaequipment for oil and gas production. It will be part of the discussion the architecture selected for the system andthe main challenges imposed by:–Separation process (gas-liquid, liquid-liquid and sand removal system);–Requirements for modularization, installation and retrieval of subseacomponents;–Installation concept. Introduction The oil-water subsea separator is installed in a water depth of approximately870m in the Marlim field, located in the Campos basin, Brazil. The subseaseparation station has an envelope of 29m length, 10.8m width, 8.4m height andan overall assembly weight in-air of 392ton, and it will receive productionfrom selected well, separate produced water from oil and sand and re-inject itinto Marlim production reservoir via a centrifugal pump. The water separationhappens into a Pipe SeparatorTM based on a gravitational concept, while waterpolishment to meet quality requirements, i.e. reduce oil content in water toacceptable levels for the re-injection into reservoir, is performed by cyclonicequipment. The equipment also has a sand management system which the main aimis to minimize the operational impact induced by solids production. Figure 1 illustrates the oil-water subsea separation system of Marlim.