Equinor Energy AS has confirmed a 19-50 MMboe (3-8 million std cu m) discovery at the Grimsnes prospect in the North Sea and plans a rapid tieback to the Oseberg Sør platform. The Norwegian Offshore Directorate reported the find on 15 km southwest of Oseberg Sør and 145 km west of Bergen, in 96 m of water.

Well 30/8-7 S reached a vertical depth of 3,752 m subsea and terminated in the Drake formation of the Lower Jurassic. The semi-submersible rig Deepsea Bergen drilled the well, the fifth exploration well in production license PL 190. The takeaway: Equinor has a commercial-scale volume on its hands and intends to move fast.

What did the well actually find?

The primary target was Middle Jurassic reservoir rock in the Tarbert formation. Secondary targets were the Ness and Etive formations at the same geological level.

The results:

• A combined 54-m hydrocarbon column in the Tarbert formation — 39 m of gas over 15 m of oil.
• Total Tarbert thickness of 264 m, of which 111 m was sandstone with moderate to good reservoir properties.
• A 289-m sandstone layer in the Ness formation with quality ranging from poor to very good, aquiferous (water-bearing) with a few potential hydrocarbon-filled zones.
• Aquiferous sandstones totaling 10 m in the Etive formation, with moderate quality.

Equinor has collected data and taken samples. The well is now permanently plugged.

How would the development work?

Equinor plans to tie Grimsnes back to existing subsea infrastructure and produce the volumes through Oseberg Sør. The development concept is most likely two to three wells in a standard four-slot template (a seabed structure housing wellheads).

The partnership will mature the project rapidly toward an investment decision. Procurement of subsea production equipment is planned early next year. Because the equipment is standardized, Equinor said, it could be redeployed elsewhere if the partnership does not sanction the project or authorities do not approve it.

In plain words: Equinor is buying hardware before final approval, because the standard design caps the financial risk.

Why the hurry?

The development feeds Equinor's stated aim of holding production at 1.3 MMboe/d on the Norwegian continental shelf in 2035. The company expects about 70% of that volume to come from new wells and developments. Grimsnes is an appraisal-confirmed but unsanctioned piece of that plan until the partnership and regulators sign off.

What comes next for the rig?

Deepsea Bergen has released from the well and will proceed to the Visund Sør field to drill a development well.

Equinor operates PL 190 with 50% interest. Partners are Petoro AS at 40% and TotalEnergies EP Norge AS at 10%.

Watch item: subsea equipment procurement early next year, ahead of a partnership investment decision on the Grimsnes tieback.