Salinity issue forces temporary production cuts from North Sea Blythe, Elgood wells

Offshore staff

LONDON — IOG continues to encounter teething issues with its Saturn Banks gas project in the UK southern North Sea, which came onstream earlier this year.

Early last month, aqueous liquids from the Blythe and Elgood wells began arriving at the Saturn Banks Reception Facilities in Bacton, Norfolk. These liquids include water and mono-ethylene glycol (MEG), with the latter for use in a closed-loop system to inhibit free water and prevent hydrate formation in the pipeline.

It is injected at the Blythe and Elgood wells as an MEG/water mix, recovered at Bacton, then regenerated and sent back offshore for reinjection into the wells.

The volume of water and salinity levels have been higher than expected, with the salinity of the returned fluids currently above the maximum allowable for processing at Bacton. To prevent these high-salinity fluids contaminating other MEG users at the terminal, an alternating regime of batch slugcatcher liquid let down is in place.

These issues have forced IOG to cut back production to 30 MMcf/d to isolate the source of the produced water. Tests are in progress, which require switching off either Blythe or Elgood for periods of time.

For the time being, an alternative processing or replenish regime is needed, with a storage capacity of about 3,000 cu. m and a disposal route both established for the aqueous fluids. Now IOG is assessing processing options to confirm the most economical future operating regime.

At the Southwark Field, under development in license P1915, the company is aiming for first gas in the fourth quarter. The final closing spools for the pipeline and pipeline de-watering will both be completed during the final DSV campaign, which is due to start next month.

The jackup Noble Hans Deul resumed drilling the Southwark A1 (West) well in July. Progress to date has been hindered by drilling fluid losses, the extent of which has led to extended periods of nonproductive time.

Once the well is completed, both A1 and A2 will undergo hydraulic stimulation prior to coming onstream. In parallel, various Southwark platform modifications will take place, based on operating experience to date at the Blythe platform.