After completing an engineering and design study for a seawater sulfate removal unit (SRU) system to help protect production wells for its Johan Castberg project in Norway, Statoil has awarded a consortium led by Suez and Halvorsen TEC the contract to supply the equipment and complete the project.

Suez will supply its seawater sulfate-reducing nanofiltration membranes and ZeeWeed 700B horizontal ultrafiltration system for the Johan Castberg (formerly Skrugard) project located about 100 km north of the Snøhvit field in the Barents Sea. The equipment is expected to be delivered in early 2020, while the first oil is expected to be produced in 2022.

“Working jointly with Halvorsen TEC last year on the FEED study enabled us to really showcase how well this technology would work for them and how we can engineer the design to meet their specific requirements,” explained Matt Boczkowski, director of marketing and growth initiative for Suez. “Sulfate removal is vital in the protection of production wells and for preventing barium and strontium scale. We are very happy to have our technology a part of the process.”

The SRU will allow Statoil to inject seawater at less than 20 parts per million of sulfate content and less than 20 parts per billion of oxygen. The SRU’s injection capacity will be 1188 cubic metres per hour.

The Suez-Halvorsen TEC SRU package will include:

  • Suez’s seawater sulfate reducing nanofiltration membranes, which eliminate nearly all sulfates from the injection seawater, remove divalent ions from the seawater to prevent barium and calcium scale formation while leaving monovalent ions like sodium and chloride to pass through the membranes.
  • Suez’s ZeeWeed 700B horizontal ultrafiltration system, which has been widely adopted in the desalination industry and provides superior fine solids removal.
  • Deoxygenation membrane technology from 3M.
  • Full single-lift SRU.

The SRU will be installed on a floating production, storage and offloading (FPSO) vessel. During production, seawater is injected into oil reservoirs to maintain or enhance oil production. However, because low-quality injection water can cause scale and corrosion that will plug and sour the field, operators first process the seawater.

A seawater sulfate removal unit.
A seawater sulfate removal unit.