OMV Norge announced the discovery of hydrocarbons in an HPHT exploration well drilled in Oswig prospect located in North Sea. With successful preliminary results, further sidetrack is now planned followed by DST in upper Tarbert formation.
OMV initiated the drilling of this well in start of August 2022 with 46 planned drilling days using jack-up rig "Maersk Intrepid". The objective was to investigate the Tarbert and Ness formations (Oswig prospect).
The surface location of the well is 60 ° 31´ 40.49” N and 2 ° 34´ 48.52” E having water depth of 148 meters in North Sea. In the map below, Location of this well is shown with each nearby dot representing wellbores in its vicinity, while red rectangular dots shows the live position of rigs. It was planned to be a vertical well, drilled in 4 sections up to depth of 5100 meters. Sea water was used to drill first sections while oil based mud was deployed for remaining three sections.
Geological Formations
Expected geological formations and groups encountered during drilling are listed below according to their TVDs from Rotary Kelly Bushing (RKB).
Pressure Gradients
Expected pore pressures and fracture pressure curves are depicted below in blue curves along with maximum mud gradients used in each section.
Well Sections
An overview of hole sections are described shortly here.
26” Section with 9-7/8" Pilot Hole
9-7/8” pilot hole was planned to be drilled from seabed at 148 meters up to 1000 meters from RKB using 1.03 sg sea water as mud. Then it was planned to drill 26" hole with sea water. After successful drilling of section, sea water was to be displaced with 1.3 sg WBM mud. Then 22” x 20” casing was planned to run, cementing it to top of seabed.
17-1/2” Section
17-1/2” section was planned to be drilled from 1,000 meters up to 2,495 meters through Hodaland Group and top part of Rogaland group using maximum 1.45 sg oil base mud. Followed by 13-5/8" casing string running and cementing with top of the cement almost 350 meters above the its shoe i.e. 2100 meters.
12-1/4” Section
12-1/4” section was planned to the Base of Rogaland group with section TD in Svarte formation, using oil base mud up to 1.65 sg. 9-7/8” casing was planned to set with shoe at around 4,308 meters.
8-1/2” Section
8-1/2” section was planned to drill through Brent Group having formations of Tarbert and Ness, using 1.9 sg oil base mud. There was no liner planned for this section and open hole tests were planned to be performed.
Note: All the information in the above article is Publicly available.
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