7228/7-1 A

General

Wellbore 7228/7-1 A is situated in the Nordkapp basin. The Nordkapp basin is the most pronounced structural element east of Loppa High, with a basinal-axis oriented NE-SW. From top Cretaceous and down to TD of the well the sediments are steeply dipping due to salt diapirism, with the salt diapir located SE of the surface location. Well 7228/7-1S unexpectedly drilled into a Permian block where the target reservoir was prognosed and so did not reach the main target for the planned well. Based on this result it was decided to drill sidetrack 7228/7-1 A. The main objectives of well 7228/7-1 A was to test the hydrocarbon potential of Upper and Middle Triassic sandstones of the Snadd Formation.

Operations and results

Well 7228/7-1 A was kicked off from well 7228/7-1 S T3 below the 13 3/8" casing shoe at 1341 m on 8 January 2001 and drilled with the semi-submersible installation "Transocean Arctic" to a total depth of 2881 m the in Early Triassic (Spathian) Klappmys Formation. The well was drilled with "Glydril" mud (KCl / Polymer / glycol) from kick-off to TD. As in 7228/7-1 S several good reservoir zones were penetrated in the Jurassic section, the Stø Formation, the Nordmela Formation and the Tubåen Formation. The Jurassic reservoirs were water wet as proved in 7228/7-1 S T3. Good reservoir zones were also penetrated in Snadd and Klappmys Formations in the Triassic section. The Lower Carnian sandstones in the Snadd Formation proved to be gas and oil bearing, whilst the Klappmys Formation was gas bearing. This was verified both by shows on cores, logs, samples and laboratory studies of the cores. Both hydrocarbon bearing reservoir zones were cored. Two of these were cut in the Snadd Formation, one in the Kobbe Formation, and one in the Klappmys Formation. Wire line MDT gas samples were taken at 2051.1 m and 2057.5 m, while a MDT oil sample was taken at 2091.1 m. The samples were considered of good quality. Well 7228/7-1 A proved an oil-d