7120/2-1

General

Wildcat well 7120/2-1 was drilled on the Loppa High in the Northern part of the block, a previous unexplored province. The primary objective of well 7120/2-1 was to test the reservoir and hydrocarbon bearing potential of Early-Middle Carboniferous rocks, truncated by a major unconformity predicted at Base Ladinian

The secondary objective was to test the reservoir (and thereby the seal) potential of Intra Middle Triassic sediments deposited above the Base Ladinian unconformity, and to also penetrate a sufficiently thick interval of the Lower Permo-Carboniferous wedge, which was prognosed to pinch out above the Early Middle Carboniferous section, in order to obtain adequate stratigraphic evaluation. It was considered a possibility that such an interval would be of reservoir quality, though probably being better developed to the east. The well was also expected to fulfil the license commitment by drilling into Devonian rocks, or to 4000 m, whichever came first.

Operations and results

The well was spudded with W.Wilhelmsen semi-submersible rig Treasure Scout on 5 May 1985 and drilled through ?Early Carboniferous sediments to TD at 3502 m in altered dolerites of indeterminate age. Due to a work conflict, while drilling a pilot hole prior to the 17 1/2" section, drilling was halted for 13 days. The drill string penetrated a pocket of shallow gas between 618 m and 622 m as predicted by shallow seismic reflectors. The well was drilled with seawater and hi-vis pills down to 1050 m and with KCl/polymer mud from 1050 m to TD.

A major unconformity (613 m) separates the Tertiary from the Triassic sediments with missing sediments in the age range Late Triassic to Early Paleocene. The Triassic sandstone prognosed to 1850 m was not found. A second stratigraphic break was observed at 1945 m, where Middle Triassic sediments were found resting unconformably on sediments of Early Permian age (the Base Ladinian Unconformity). A