30/5-1

General

Well is located centrally in the northern Viking Graben of the North Sea. It was the most northerly well drilled in Norwegian waters of the North Sea when it was drilled. Primary objectives of 30/5-1 were Paleocene sands, thought to

be productive in the Frigg Field and the recently discovered Heimdal Field, and potential sand or carbonate reservoirs in

the Early Cretaceous. The Late Cretaceous Chalk found so prospective in the south was considered to be a secondary objective in view of the possible northward shaling out of that formation.

Operations and results

Wildcat well 30/5-1 was spudded with the semi-submersible installation Transworld 61on 17 May 1972 and drilled to TD at 4124 m in the Early Cretaceous Åsgard Formation. The well was drilled with seawater and Lignosulphonate with additions of a total of 329 bbls of diesel oil.

In the main Paleocene objective a few thin water-bearing sand-streaks were present, and in the secondary Upper Cretaceous objective, the Chalk Formation, as expected, had virtually shaled out. Between a depth of 3475 and 3604 m four streaks of limestone occur, ranging in thickness from 1 - 3 m. The mud became gas cut while drilling the interval. From petrophysical logs the limestone streaks appeared to be gas bearing with porosities from 9 to 20% and water saturations in the range 20 - 60%. They were the only intervals recognisable from logs containing hydrocarbons. The total thickness of these limestone stringers was insufficient to justify a test. No

One core was taken at TD from 4114.8 to 4123.9 m with a recovery of 5.6 m (62. 5%). No wire lin