UK-headquartered IOG plc has encountered a challenge that could extend its previous drilling duration timeline for the second Blythe production well, which is part of the Saturn Banks Project – Phase 1 in the UK Southern North Sea.
The Blythe H2 well was spudded on Sunday, 5 March 2023 with Shelf Drilling’s Shelf Perseverance (former Noble Hans Deul ) jack-up drilling rig, which is under contract with IOG, thanks to a deal signed in 2020 while the rig was still part of Noble’s fleet. Petrofac is the designated well operator. As explained at the time, IOG expected the H2 well to take approximately three months to drill, complete and hook-up, subject to the usual offshore operational risks to scheduling.
In an update on Tuesday, 18 April 2023, IOG outlined that the H2 well was drilled to the Basal Zechstein sequence, however, while drilling through the Hauptdolomit formation within the Zechstein, “an abnormally pressured gas and oil influx” was encountered, with associated drilling fluid losses. The company claims that the risk of such a well control challenge was identified during planning and is being safely managed by Petrofac and Shelf, in collaboration with the IOG team.
Rupert Newall , CEO of IOG, commented: “Encountering a gas and oil influx while drilling through the overburden above the reservoir is a known risk in the Southern North Sea. Associated drilling fluid losses present an additional challenge, however, this is being actively and safely managed by Petrofac, the well operator, and Shelf, the drilling contractor, working closely with the IOG team, to ensure that drilling ahead can be safely resumed.”
However, the firm highlights that this challenge is likely to impact the expected well duration, potentially by up to four weeks, while the associated cost impact will depend largely on the speed of resolution. According to IOG, the influx from the Hauptdolomit has been determined to contain non-commercial quantities of oil and gas and is not related to the target Rotliegendes gas reservoir which is over 500 ft deeper and isolated from the Hauptdolomit.
The well has been displaced to a mud weight above the formation pressure and the UK player underlines that options to progress include isolation of the influx zone with cement and, if necessary, side tracking of the well.
The IOG-operated Saturn Banks Project – Phase 1 – sanctioned in October 2019 – covers Blythe , Elgood , and Southwark fields in the UK Southern North Sea. The first two fields – Blythe and Elgood – were brought on stream in mid-March 2022. IOG holds a 50 per cent stake in this project and its partner, CalEnergy Resources, holds the remaining 50 per cent.