UK North Sea-focused oil and gas company IOG said Tuesday that the drilling of the Blythe H2 offshore well would take longer than initially thought due to 'abnormally' pressured gas and oil influx encountered while drilling through the Hauptdolomit formation.
Having spudded on March 5, IOG estimated that the H2 well would take about three months to drill, complete, and hook-up, subject to the usual operational risks.
The H2 well is being drilled by the Shelf Perseverance jack-up drilling rig under IOG's contract with Shelf Drilling (UK) Ltd ("Shelf") signed in 2020. Petrofac is the Well Operator, as with all previous Saturn Banks development wells.
"The H2 well was successfully 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 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. However, this now looks 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," IOG said.
"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. Options to progress include isolation of the influx zone with cement and, if necessary, side tracking of the well," IOG said.
Rupert Newall, CEO of IOG, said: "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."