During a flow test of the Dvalin production wells, readings showed that the gas contained a level of mercury above the maximum permitted in the system.
The mercury content was also higher than encountered during the exploration phase 10 years ago.
Drilling of the production wells finished last summer. According to the company, the system start-up that followed was successful, the offshore infrastructure was functioning as expected, and first gas flowed in late 2020.
Wintershall Dea and its partners have initiated studies to identify a technical solution to enable full production, including use of established mercury removal solutions.
But until they have determined an appropriate remediation method, gas flow from the field will be curtailed.
The field comprises the separate Dvalin East and Dvalin West structures in a water depth of 400 m (1,312 ft). Development is via a subsea template with four gas producers tied back to the Equinor-operated Heidrun platform.
On arrival, Dvalin’s well stream will be processed in a new dedicated module and exported to Nyhamna, western Norway, via a new pipeline from Heidrun connecting to the Polarled pipeline.