35/9-13

General

Well 35/9-13 was drilled to test the Tethys prospect on the Måløy slope in the northern North Sea. The primary objective was to test the hydrocarbon potential in Intra-Heather sandstone of Oxfordian age. Dependent on the results of the well, optional production testing was planned to test reservoir productivity, in addition to an optional side-track to further evaluate the prospect.

Operations and results

A 9 7/8" pilot hole was drilled 30 m off location from the 35/9-13 well. No shallow gas or water flow was observed.

Wildcat well 35/9-13 was spudded with the semi-submersible installation Songa Enabler on 25 December. At 2555 m in the Tryggvason Formation the bit drilled into a fault zone and total losses occurred. Losses were cured with fibrous materials and reduction of mud weight. Drilling of the 12 ¼ hole commenced to 3223 m in the Early Jurassic Rødby Formation. While running in hole with the 8 1/2" BHA the operation was stopped at 1770 m due to observation of a

water flow around the well head. The water flow was identified flowing outside the 20” casing because of bad cement bond. The water most likely came from ca 661 m in the top of a Paleogene sand. It was decided to P&A the well for safety reasons. The well was drilled with seawater and hi-vis pills down to 948 m, with KCl/GEM/polymer mud from 948 m to 1822 m, and with Innovert oil-based mud from 1822 m to TD.

The well did not fulfil its objectives.

The only log on wire line was a CBL log to evaluate the cement behind the casing and source of the shallow water flow. No reliable formation temperature co