The 30/6a-8 appraisal well wasspudded on 18th February 2010 and sidetrack 30/6a-8Z was kicked off onthe 26th April 2010. Both wells were drilled using the Galaxy II heavyduty jack-up drilling rig. A 30/6a-8 well was a verticalwell, drilled targeting a down flank location from the previousappraisal wells and close to the structural closure. The 30/6a-8Z wellwas a deviated well, targeting a mid flank location. All the principleobjectives of the well have been achieved.
Key well results:
30/6a-8
- 22.5 foot thick, good quality Andrew Sandstone reservoir
Equivalent to all other Stella wells and other wellsin the area
Porosity ave 22 %, Permeability ave30 mD, (up to 74 mD)
- Proved hydrocarbon column exceeds 820 ft (a ~500 ft increase)
- Stella structure is filled to spill and covers over 5,400 acres (22 km2)
- Recovered both moveable 39 degree API light oil and formation water samples
- The well flowed in excess of 5,000 barrels of liquid per day (oil plus water) consisting of 2,850 barrels of light oil per day and 2,150 barrels of water per day*
* flow was restricted due to equipment on board therig
30/6a-8Z
- 18 ft thick, good quality Andrew Sandstone reservoir
Equivalent to all other Stella wellsand other wells in the area
Porosity ave 22%
- Recovered hydrocarbon fluid samples and pressures
PreDrill Proven Hydrocarbons
Post Drill Proven Hydrocarbons
The Andrew Sand reservoir section was encountered at9,905 ft TVDSS in the 30/6a-8 well and the whole interval was coredsuccessfully before the well reached TD (total depth) in the underlyingEkofisk Formation on 25th March 2010. A comprehensive logging programwas carried out which indicated that the well had penetrated 22.5 ftgross of high quality, oil bearing Andrew Sand reservoir and 60 ft grosswater bearing porous chalk reservoir at the top of the Ekofisk. AverageNet reservoir Porosity in the Andrew Sandstone was 22 % (max 26 %) withan average permeability of 30 mD (max 74 mD). The presence of goodquality, productive reservoir down flank on Stella confirms thepre-drill reservoir distribution model and were within the rangeexpected pre-drill.
The 30/6a-8Z sidetrack, drilled up-dip from the30/6a-8 well to establish the nature of the fluids in the Stellastructure, encountered Andrew Sandstone reservoir at 9,627ft TVDSSbefore reaching TD in the Ekofisk on 30th April 2010. The samecomphrehensive logging program deployed in the 30/6a-8 well was alsocarried out in the 30/6a-8Z sidetrack. As planned, no coring or welltesting was carried out in the sidetrack. The data from the sidetrackindicated that the well had pentrated 18ft gross of Andrew Sand with anaverage Porosity in the Andrew Sandstone of 22% (max 27%).
The oil saturations observed in the reservoir in the30/6a-8 well predict a free water level (base of the hydrocarbon towater transition zone) at ~9,950 ft TVDSS which matches the geologicalspill point of the Stella structure to the East. Successful recovery ofhydrocarbons from this down flank location supports the conclusion thatStella is filled to spill with hydrocarbons. The presence ofhydrocarbons at this location also significantly deepens the previous"deepest proven hydrocarbons" (used to assign reserves) and consequentlyincreases the proven hydrocarbon column height by over 500 ft.
Stella Structure
As is common in gas / condensate fields, the hydrocarboncomposition in Stella may change with depth. The well was sidetrackedup-dip (30/6a-8Z) to ascertain the pressure and nature of thehydrocarbons at a mid-flank location. This information is important toallow development wells to target the most valuable fluids; it isessential to clearly understand the ratio of oil to gas / condensatebefore finalising the development scheme. The sidetrack also providedadditional information about the reservoir presence, thicknessand quality.
Stella Appraisal Well DST Flare 12th April 2010
The fact that the 30/6a-8 well penetrated the oil/watertransition zone was a real 'bonus'. We were able to get the water andoil samples for development assurance, by deliberately perforating bothwater and oil bearing zones in this well. On test the well flowed inexcess of 5,000 barrels of liquid per day (oil plus water) consisting of2,850 barrels of light oil (39 degrees) per day and 2,150 barrels ofwater per day. A prolonged and stabilized flow period was achieved andflow rates were significantly limited due to restrictions of theequipment on board the drilling rig.
Greater Stella Area Infrastructure