LONDON — IOG continues to encounter issues with drilling in its Saturn Banks gas development in the UK southern North Sea.
Following drilling fluid losses in the 12-1/4-inch section in the Bunter sandstone formation, the Southwark A1 well advanced into the Bunter shale formation, where further fluid losses arose on drilling out of the 9-5/8-inch casing shoe.
The Southwark reservoir itself is well below this section, IOG stressed.
To date, the losses have not been sufficiently cured for drilling to safely continue, and the delays have reduced the time available until the hydraulic stimulation vessel is due to arrive. The company has therefore decided to securely suspend the A1 well and proceed with hydraulic stimulation and commissioning of A2 so Southwark can deliver first gas as planned in the current quarter, probably by mid-December.
In parallel, various options are under review to mitigate fluid losses and drill ahead at A1 in preparation for completing and producing the well after bringing A2 online.
The Seven Atlantic diving support vessel has been offshore connecting the outer section of the Saturn Banks Pipeline System from the 24-inch manifold to the Southwark platform, ahead of the introduction of gas. But a defective 6-inch offshore valve means the Saturn Banks Pipeline System will have to be depressurized to allow safe connection of the outer section to the manifold.
That will entail suspension of Saturn Banks production for about four weeks from late October, coinciding with the annual shutdown of the Bacton reception terminal.
IOG’s latest analysis of production and reservoir pressure data from the Blythe well following six months of first-half production suggests the well is located in a reservoir compartment materially baffled from the field’s central and northwest areas. It now anticipates ultimate recovery of 29 Bcf, compared to previous estimate ranges of 25.4 Bcf to 55.8 Bcf.
As for the Elgood well, the production rate recently fell below 10 MMcf/d and is set to decline further by year end. The decline has been faster than anticipated, with ultimate recovery from the field now assessed at 7.5 Bcf, of which about 4 Bcf has so far been produced.