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DNO ASA announced the successful drilling and comprehensive formation evaluation of sidetrack appraisal well 35/10-14 A, drilled into the Heisenberg discovery structure in production license PL 827 SB in the northern North Sea. The sidetrack was kicked off from the primary exploration wellbore and drilled to a total measured depth of 3,745 meters by the semi-submersible rig Deepsea Yantai. The appraisal well encountered a 48-meter gross gas and oil column in high-quality sandstone reservoirs of the Hugin and Sleipner formations.
Formation pressure data and extensive fluid sampling confirmed that the hydrocarbon column in the sidetrack shares dynamic pressure communication with the main Heisenberg discovery well, while verifying that the oil-water contact extends deeper than previously modeled along the southern structural flank. Recovered fluid samples exhibited low gas-oil ratios and light API crude gravities with low sulfur content. Permeability measurements derived from wireline formation testers confirmed exceptional reservoir deliverability exceeding 800 millidarcies.
Following the appraisal results, the licensee group—comprising operator DNO with 40 percent alongside Equinor and Source Energy—upgraded the gross recoverable resource estimate for the integrated Heisenberg-Wolverine accumulation to between 110 and 150 million barrels of oil equivalent. The joint venture partners have formally initiated concept selection studies evaluating an electrified subsea tie-back directly to the Troll B or Troll C processing hubs, minimizing project development timelines and operational carbon intensity.
Corporate leadership stated that continuous exploration and appraisal success around the Heisenberg cluster highlights the significant remaining resource potential of mature infrastructure-adjacent provinces on the Norwegian Continental Shelf. Fast-tracking short-cycle subsea development schemes leverages existing offshore pipeline trunklines that deliver critical gas supplies directly to European industrial consumers. DNO confirmed that the rig will now be demobilized to undergo scheduled class inspections before commencing its 2027 drilling program.
DNO ASA emphasized that the successful Heisenberg appraisal operations demonstrate the value of infrastructure-led exploration and appraisal near the Gjoa production hub in the Norwegian North Sea. Reservoir pressure measurements and fluid sampling indicate excellent communication and permeability throughout the primary hydrocarbon-bearing interval. The joint venture partners will immediately incorporate the sidetrack results into ongoing development studies aimed at fast-tracking production through nearby existing subsea infrastructure and processing host facilities.