Seabox subsea water treatment module with blue sky background

Seabox Subsea Water Treatment Technology

Optimize oilfield recovery by disinfecting raw seawater and settling suspended solids at the seabed, tailoring water quality to your reservoir needs.

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Description

Using the seabed for treatment of raw seawater, the Seabox™ module provides a flexible approach to getting more out of a reservoir. Seabox is a tool to improve sweep efficiency and for pretreatment for processing equipment to alter water chemistry in combination with either topside or subsea processing equipment.

With our water treatment technology able to be integrated to fit operators’ requirements, our solutions range from topside, subsea, or a combination of both. Our ability to tailor a water treatment solution to a field as an easy add-on any time in the field's life allows for flexible drainage strategies. Through the Seabox module and the different SWIT™ subsea water treatment applications, we can offer everything from purely disinfected, raw seawater as pretreatment to topside facilities to full-fledged subsea low-sulfate and low-salinity solutions for water injection.

The Seabox module enables an optimum water flooding regime and is based on the principles of electrolysis and gravitational separation.

The Seabox module uses electro-chlorination and hydroxyl radicals to eliminate bacteria, and a large chamber allows for 99% settlement of inorganic particles larger than 8.5 μm. We’ve moved water treatment to the seabed, where the 8 × 8 × 8-m Seabox module with a nominal capacity of 40,000 b/d treats surrounding seawater to superior quality for injection into oil reservoirs.

The Seabox module consist of three parts: tray, still room, and treatment unit—where all structures can be made of fiber-reinforced polymer. The tray is the base structure of the modules and has a chamber to collect settled out particles; the still room is a settlement tank that ensures an effective chlorine soak to disinfect water and to settle out suspended solids. Both the still room and the tray will stay on the seabed—either until end of field life or until moved to another injection wellsite.

All critical components with an operational lifetime such as the electrochemical processes as well as the module’s power and control system are placed in the treatment unit. Intervention intervals are expected to take place every 4 to 5 years, when the 9-ton treatment unit—the size of a 40-ft container—will be retrieved in its entirety.

The Seabox module is qualified for water depths down to 3000 m.

Features

  • Independent, standalone, and easy add-on solutions
  • Flexible timing of water treatment phasing
  • Superior water disinfection at the point of usage
  • Improved reservoir sweep efficiency
  • Zero hazardous discharge
Resources
  • Seabox Brochure
Rendering of the Seabox subsea water treatment module

Seabox and Ultrafiltration

The Seabox module can be combined with ultrafiltration at the seabed to enable removal of suspended solids with an absolute filtration down to 0.1 µm. The disinfection and sedimentation capabilities of the Seabox module allow for effective use of ultrafiltration while at the seabed. Treated seawater will be supplied to the respective ultrafiltration trains, where the ultrafiltration is based on a dead-end filtration principle. The filtrate quality will be independent of the feed water quality (suspended solids and turbidity loading). To maintain the flux through the filters for continuous production of the required quantity of filtered water, the filters are backwashed with filtered water. The filters are kept clean with backflushing only, and no chemicals are necessary due to the Seabox feed water's superior quality. The Seabox subsea water treatment module and ultrafiltration are controlled by Seabox’s Subsea Control Module (SCM), an all-electric solution, giving unique control of valve operations and filter performance.

The water from the Seabox module and ultrafiltration is well suited for matrix flooding, avoiding fracturing of the reservoir and preserving injectivity in tight formations.

Rendering of Seabox flow base, Ultrafiltration (UF) pump, and Nanofiltration

Seabox, Ultrafiltration, and Nanofiltration

The combination of the Seabox module, ultrafiltration, and nanofiltration can provide completely disinfected and particle-free water with low total sulfate content, typically to less than 40 mg/L. A subsea membrane feed pump is used to push water from the Seabox water treatment and ultrafiltration modules through the nanofiltration.

Combined with complete, maintenance-free operations on the seabed, our advanced technology is designed for more than 2 years of continuous operation with all membranes functioning at full capacity before any membrane replacement will be required.

Rendering of the Seabox flow base, Ultrafiltration (UF) pump, and Reverse Osmosis (RO) skid

Seabox, Ultrafiltration, and Reverse Osmosis

This combination of Seabox, ultrafiltration, and reverse osmosis (RO) technology is part of our SWIT technology applications, and together this configuration removes sulfate.

A subsea membrane feed pump is used to pump the water from the Seabox water treatment and ultrafiltration modules through to the reverse osmosis membranes. The required flow rate for the pump is 40,000 bpd with a differential pressure of 25 to 50 bar depending on the required final water quality.

The technology provides a completely disinfected and particle-free water with salinity levels according to a defined specification, typically a total dissolved solids (TDS) of 500 to 5,000 ppm and a total sulfate content of less than 2 mg/L. It enables us to tailor water quality for injection to exact specifications using different combinations of subsea water treatment equipment.

Combined with complete, maintenance-free operations on the seabed, our advanced technology is designed for more than 2 years of continuous operation with all membranes functioning at full capacity before any membrane replacement will be required.

Seabox water treatment module being deployed offshore
Aerial view of Seabox being deployed subsea by crane from offshore platform
Seabox flow base, Ultrafiltration (UF) pump, and Reverse Osmosis (RO) skid arriving offshore
Seabox water treatment module being lifted by crane from offshore platform for subsea deployment
Worker using the controls for the Seabox subsea water treatment module

Seabox Subsea Water Treatment System Installation

The development of Seabox started in 2003 with a series of joint industry projects (JIPs) backed by the Norwegian Research Council and major oil companies. Through these projects, the Seabox module and SWIT technology have been developed and are now ready for real applications.

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