Source: Ithaca Energy
Ithaca Energy’s Stella field appraisal well (30/6a-8) has proved the presence of significant additional volumes of hydrocarbon and excellent quality reservoir. A successful Drill Stem Test has been performed providing critical information for development planning to now commence.
Well 30/6a-8 was drilled to appraise a large down flank extension of the Stella field, located in the Central North Sea, and well operations to date have satisfied all key objectives. The total measured hydrocarbon column height is now in excess of 820 feet, significantly increasing reserves beyond those previously independently assessed. The well confirmed hydrocarbons more than 500 feet lower than in any previous wells and this has demonstrated that connected hydrocarbons are present in the field down to the geological spill.
Wireline logs indicated the proximity of a hydrocarbon water contact, identification of which satisfies one of the objectives of the well. As part of the DST operation both the oil and the water bearing sections of the reservoir were deliberately perforated to extract essential samples required for development planning purposes.
On test the well flowed in excess of 5,000 barrels of liquid per day (oil plus water) consisting of 2,850 barrels of light oil (39 degrees API) per day and 2,150 barrels of water per day. A prolonged and stabilized flow period was achieved and flow rates were significantly limited due to restrictions of the equipment on board the drilling rig.
The well intersected a 22.5 foot section of Paleocene Andrew sandstone reservoir close to the mapped closure of the field, which is estimated to cover more than 22 square kilometers (approximately 5,400 acres). The excellent reservoir properties and thickness observed in this well are equivalent to wells at the crest of the Stella structure.
Appraisal wells drilled on the crest of the Stella structure produced up to 17 million standard cubic feet of gas per day and 3,000 barrels of condensate per day with no water. The light oil encountered at this new location, 500 feet deeper in the structure, is entirely consistent with predictions of gas, condensate and oil coexisting within the same reservoir.
The well will now be geologically sidetracked, as intended, to test the reservoir up-flank between this vertical bore and existing crestal wells to further investigate the quality of the reservoir and provide essential compositional information of the hydrocarbons at intermediate depths. The sidetrack will take approximately 15 days to penetrate the reservoir.
Following evaluation of the sidetrack information, the appraisal phase of the field will be complete and Ithaca will be ready to move to a full scale development of Stella and satellite discoveries using one of several development options for the Greater Stella Area. Stella first oil and gas production is anticipated in 2012.
Prior to testing, the well was drilled into the Ekofisk Chalk formation which underlies the main Stella accumulation. The penetration of the chalk reservoir was below the known oil water contact, but pressures taken confirm the lateral extent of reservoir formation. The Ekofisk Chalk formation will be penetrated again during the drilling of the sidetrack.
"This is a great moment for Ithaca,” said Nick Muir, CEO of Ithaca Energy. “The results of this appraisal well have proved very sizeable additions to the hydrocarbons originally encountered in the Stella discovery. The field is clearly even more significant than we thought, and the results of this well and the test have exceeded all our expectations. Stella can now go forward as a standalone but expandable development that will allow for the future tieback of other Ithaca operated discoveries in the Greater Stella Area, such as Harrier and Hurricane."