Experience to date and future opportunities for subsea processing in StatoilHydro

Abstract

Subsea processing involves one or more combinations of fluid conditioning and pressure boosting of wellstream fluids and water at the seabed. The main benefits of applying subsea processing include increased hydrocarbon recovery and accelerated production, together with reduced CAPEX and OPEX, and HSE benefits. This paper provides an overview of field operating experience for subsea boosting in the LuFeng field and the separation, produced water reinjection and fluid boosting applications at Troll Pilot and the Tordis fields, including the Tordis restart plans. The paper also describes design and installation of the Tyrihans raw seawater injection and summarises the gas compression technology qualification activities underway for the Gullfaks 2030, Åsgard Minimum Flow and Ormen Lange Pilot projects. An overview of Statoil's future subsea processing opportunities is then presented and discussed, including new opportunities being assessed at the Norne and Astero and fields. All aspects of subsea processing are reviewed, including boosting, raw seawater injection, separation, sand handling and produced water reinjection, and subsea gas compression technology. The important role of large scale testing and technology qualification, and close collaboration with key technology suppliers is described, together with a step-wise approach to deploying increasingly complex subsea processing systems in ever more challenging environments. Step out distance, water depth and harshness of the local environment for new fields are all increasing and new, more cost-effective technologies will be need to profitably develop future fields. It is concluded that subsea processing has already provided positive business upsides, despite certain technical challenges, and Statoil expects to continue a stepwise development and deployment of subsea processing technology in the near and longer term future. Introduction Subsea processing involves one or more combinations of fluid conditioning and pressure boosting of wellstream fluids and water (from a reservoir or from the water column) at the seabed. Conditioning can include water removal from hydrocarbons, separation of liquids from gas, separation of sand and other solids from fluids, fluid cooling (or heating) and chemical injection. There are currently four main types of subsea processing application:Single and multiphase hydrocarbon boostingGas compressionSeparation systems (gas / liquid and liquid / liquid with produced water reinjection)Raw seawater injection

Subsea Processing versus Host Selection: An Imperative Correlation

“…Operators have shared their experiences with subsea processing projects, see for example (Albuquerque, 2013b), (Davies, 2010), and (Rambaldi, 2010), and this is an invaluable source of technical and operational information. The other authoritative source of information on subsea processing projects is (Forster, 2014); this chart is updated annually and distributed a couple of months before the Offshore Technology Conference; the authors have not had the chance to see the 2015 issue while writing this paper.…”

Gas Flotation of Petroleum Produced Water: A Review on Status, Fundamental Aspects, and Perspectives

“…These conditions also imply some changes in the process units compared to topside (offshore) design. Subsea separators and hydrocyclones for PW treatment are currently in operation or test use, − while new separation concepts have been proposed. , When it comes to CFUs, however, their performance at high outer pressure is still a key gap for possible subsea use. Moreover, the marinization, gas and production chemical logistics, and reject handling are other important reasons why subsea CFUs are not yet qualified.…”

Subsea Processing: A Holistic Approach to Marginal Field Developments

“…After separating the fluid into its constituent phases, the Tordis separator recombines the oil and the gas for pumping by the multiphase pump 7,18 . This separator can be re-configured to combine the separated water and gas (instead of oil and gas) before disposal by a multiphase pump into the reservoir.…”