The gas leak was detected in the Statpipe receiving area at its major onshore gas process plant at Karsto late on January 7. A near-complete fracture occurred in an instrument fitting with an interior tube diameter of 9.1 mm. When the leak started, the pressure in the affected system was around 140 bar. The initial leak was estimated to be 1.3 kg/second. The gas leak lasted for 9.5 hours and the leaked volume is estimated at 22 metric tons.

The reason that the leak lasted so long was an absence of pressure relief opportunities from the control room for the processing segment where the leak occurred – due to a fatigue fracture in a free-standing instrument fitting pipe branch, arising from bend-stresses from high winds combined with lack of adequate pipe supports, plus the system's natural frequencies and vortex-induced vibration at normal wind speeds.

No-one was injured in the incident. However PSA Norway said that, had personnel had been in the proximity of the leak in the event of ignition, this could have caused serious personal injuries and potential fatalities. Its investigation of the incident has identified non-conformities linked to mechanical bracing of instruments and other points, and the operator –state-run Gassco, with Statoil as its technical services provider – has been asked to explain how these will be dealt with. 

Statoil reduces costs, DEA readies project

Separately on August 29, Statoil said that the breakeven price for phase 1 of its Johan Sverdrup oil development is now below $25/b, with its capital cost of the giant North Sea project now estimated at Nkr99bn ($11.9bn), which is Nkr24bn less than when the plan for development (PDO) was submitted. Phase 1 production capacity is now 440,000 b/d oil, whereas the PDO had estimated it between 315,000 and 380,000 b/d.

The estimate for the full-field investment has been improved from a range of Nkr170–220bn in 2015 to a 2016 value of Nkr140–170bn. Expected full production capacity is raised to 660,000 b/d, compared with the original PDO which estimated 550,000–650,000 b/d; however final concept selection for future phases has yet to be formally decided.

Meanwhile Russia-backed DEA said August 29 it is finalising its PDO for the Zidane gas development in the Norwegian Sea, ready for submission this autumn. It will be DEA's first as an operator in Norway. DEA Norge chief Hans-Hermann Andreae said: “With development starting this year, production start is planned for the year 2020.” The development concept consists of four producers utilising a 4-slot subsea template tied back to the Heidrun platform. Gas will be processed in a new gas module before it is transported via Polarled to Nyhamna Gas Terminal.

Zidane is named after the French-Algerian football player Zinedine Zidane, but it will be renamed after a Norwegian statesperson or iconic figure when developed.

Mark Smedley