Subsea Processing Systems: Future Vision

Abstract

To surpass the main challenges established by deep water, high gas-oil flowratios, flow assurance and constant increases in produced water, Petrobras is developing, within PROCAP Technology Program - Future Vision, several projects in the subsea processing area, such as: Compact Oil-Water and Gas-Liquid Separation Systems, Multiphase Pump with High Differential Pressure and Gas Compression System. The main applications of these projects are in fields with high fraction of gas and water, in fields/discoveries located far away from Production Units and to increase the reservoir recovery factor. Furthermore, the application of these technologies may have great benefits, such as: production anticipation, reduction of process system footprint on the Production Unit, decrease in CAPEX/OPEX and especially an increase of the topside oil processing capacity. This paper aims to present an overview of those technologies being developed in PROCAP - Future Vision. Also, this article shows the main motivations of these developments, the main benefits of using each technology, the technological challenges and gaps, typical application scenarios and results of the evaluations performed so far. Major petroleum companies are searching for new technical solutions that fulfill their needs of reducing both CAPEX and OPEX while increasing oil and gas production. The development of new subsea processing technologies, as stated above, will enable, and in some cases reinforce, the use of these technologies for deepwater and/or subsea to shore scenarios. Introduction Subsea processing is a key enabler for challenging field developments, and their benefits increase with water depth, flowrates and step-out. Regarding subsea separation, these advantages are maximized when employing subsea compact separation technologies. Also, subsea processing brings HSE benefits related to reduction of waste disposal to sea, an environmental contribution of subsea oil-water separation systems, and the possibility of using smaller platforms - or none at all - due to the use of processing equipment on the seabed instead of topside, reducing operational risks. In terms of compact separation technology development, Petrobras has been conducting several R&D initiatives for the last ten years. Firstly, these R&D initiatives were developed for topside and onshore applications, but always keeping on mind the subsea employment. In order to evaluate these technologies several tests have been performed. More recently, the Marlim SSAO 3-Phase Subsea Separation System is a very significative example of compact subsea technology employment, for a single producer well application. Multiphase boosting is always considered as a good alternative to develop oilfields, mainly for remote areas. Petrobras invested a lot on the development of twin screw and helicoaxial concepts for multiphase pumps, targeting applications with required differential pressures up to 60 bar. Recently, analysis has indicated that High Differential Pressure Subsea Boosting (up to 150 bar) is economically and technically attractive to various Petrobras scenarios and, because of that, many R&D efforts are being done to develop such technology.

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