Abstract

Subsea processing and boosting can be key enablers or optimization alternatives for challenging field developments and their benefits increase with water depth, flowrates and step-out. Petrobras has invested a lot on the development of such technologies, supported, among other pillars, on an aggressive R&D policy through its technological programs like PROCAP, and several subsea processing and boosting systems have successfully operated in Petrobras fields. Considering that, these technologies are being considered for application in potential Petrobras' scenarios including mature and green fields.

This paper aims to give an overview of the systems developed and applied in Petrobras prospects during the last twenty years, such as the Vertical Annular Separation and Pumping System (VASPS), Boosting Systems with Electrical Submersible Pumps (Mudline ESP and MOBO), Subsea Multiphase Pumps, Subsea Raw Water Injection and Subsea Oil-Water Separation (SSAO). It also reports the new R&D initiatives related to subsea processing and boosting that are being developed within PROCAP - Future Vision technology program, showing the main motivations of these developments, the main benefits of using each technology, the technological challenges and typical application scenarios. Also, this paper illustrates the analysis and evaluations performed so far, for all of the new developments presented.

Introduction

Petrobras has developed and applied several technologies during the last 20 years, forming a very useful " toolbox" for subsea processing and boosting applications. After successful implementation of several technology-projects, on subsea boosting and processing, Petrobras and other operators have demonstrated that such technologies are definitely a very important field development tool, as predicted decades ago.

In the beginning of the exploitation of oil&gas offshore fields, the main concern is related to the initial investment to construct the production units, to drill the wells and to install all the equipment necessary for the production. During this phase, there is a lack of information regarding the field, mainly about the reservoir behavior. Normally, the reservoir behavior is calibrated during the productive life of the field. Due to this, the operators usually adopt a conventional solution, not considering the use of new technologies as the first alternative. These are considered most when they are vital for a specific field development.

For most fields in Campos Basin, Brazil, the main recovery mechanism for reservoirs, since the beginning of the production, is waterflooding. A typical curve of produced fluids starts with the predominance of oil, rising to the production plateau, until the water breakthrough occurs. At this point, the production presents increasing water content in the liquid stream. So, as it is necessary a massive water injection to keep the pressure of the reservoir, after a few years the watercut of the production increases a lot. Additionally to the two aspects described above, there is also a need to overcome the constraints of existing platforms.

These motivations led Petrobras to start in the early 90's the development of subsea processing and boosting solutions. Technological Programs were created to support these developments. Several processing and boosting projects were installed since year 2001, when the VASPS was deployed in the Marimba Field (Campos Basin, Brazil). These projects will be described in a brief way in this paper, focusing their main technological aspects.

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