Ithaca's Wisdom Leads to Athena

Ithaca Energy's Athena field on the UK Continental Shelf is set for first production in 4Q 2011. The Athena field is in block 14/18b in the Outer Moray Firth area. The initial rate of production is expected to be about 22,000 bpd.

Ithaca Energy's Athena field

Athena was first drilled in 1991 and tested oil. The 14.18-7 well tested 847 bpd from the Lower Cretaceous Leek sands, which is the Athena reservoir interval. The 14/18-12 well, which was drilled in 1996, tested 1,302 bpd from the Upper Jurassic sands. No water was encountered. This well is not included in the Athena project.

Ithaca then drilled 14/18b in September 2006 after entering into a farm-out agreement with EWE Aktiengesellschaft, under which EWE earned a 20 percent interest in license 1293, which covers block 14/18b. Ithaca owned 70 percent of the block with EWE holding 20 percent and Zeus Petroleum (formerly Wimbledon) 10 percent interest.

Ithaca contracted the Bredford Dolphin semisubmersible to drill the well at a 60 degree angle to vertical through the prospective zones to 10,943 ft TD. The well was suspended for future production after testing 1,330 bpd from the Upper Leek sandstone.

Bredford Dolphin
Bredford Dolphin

In November 2006, Ithaca received an independent engineering evaluation of the Athena discovery. Sproule International Ltd. confirmed that Athena has about 27.99 MMbbl of gross recoverable probable undeveloped reserves (19.59 MMbbl net to Ithaca). Ithaca believed that Athena had significant upside development potential to be determined by additional drilling.

In August 2007, Ithaca contracted Senergy's Stena Spey semisubmersible to drill its next Athena well. The operator had previously expected to drill the well with the Byford Dolphin, but it was delayed. Ithaca started drilling the 14/18b-16 well in early September 2007. The well was drilled directionally into Lower Cretaceous Leek sandstones to 11,000 ft (9,640 ft TVD) and tested 28 degree API. The well encountered 355 ft of Upper Leek sandstone of which 92 ft was considered productive with an average porosity of 14.3 percent, compared to the No. 15 well that had 127 ft of pay. Ithaca suspended this well too for future development.

Senergy's Stena Spey
Stena Spey

In March 2008, Ithaca drilled a third appraisal well, 14/18-17, to 9,046 ft TVD to appraise the potential of an extension to the known accumulation. The Byford Dolphin drilled the well, which penetrated the Lower Cretaceous Leek sands at 8,842 ft. Although oil bearing, the reservoir was of poor quality; the well was suspended pending further evaluation.

Ithaca then announced in May 2008 that it had contracted Bluewater Energy to develop the Athena field using the Uisge Gorm FPSO. At the time the operator expected to bring the field online by the end of 2009 at a rate of 21,000 bpd.

Uisge Gorm FPSO
Uisge Gorm FPSO

The Stena Spey then drilled the Athena D development well in June 2008 in the center of the Athena accumulation (14/18b-18). Similar to the previous wells, this one was suspended for future use.

Development Plan

Back in February 2010, Ithaca purchased long lead equipment to initiate the development of the Athena field and finalized the Environmental Statement and FDP for submission in March 2010. Ithaca received development approval on Sept. 21, 2010.

Athena's field development plan called for four production wells and one water injection well. Transocean's Sedco 704 semisubmersible re-entered the 14/18b-15A, 14/18b-16 and 14/18b-18 wells, which were previously suspended. The rig also drilled the water injection well and one additional production well from January through June 2011. The wells were completed with downhole pumps to maximize field production rates, which were initially estimated to be 22,500 bpd. Production will be sent through a subsea manifold through a one mile, 8-in. diameter flowline to the BW Athena FPSO (formerly the Carmen FPSO). Produced gas will be used to generate power on the FPSO. Produced oil will be exported via shuttle tankers.

BW Athena FPSO
BW Athena FPSO

The FPSO underwent modification and recertification in Dubai Dry Docks. A vessel compartment was added to accommodate the Weatherford subsea control equipment, Baker Centrilift ESP Control equipment and the riser turret and buoy connection, which lengthened the vessel by 65 ft. The topsides process equipment was also refurbished. The FPSO is scheduled to leave Dubai in mid-November for a 20 day journey through the Suez Canal. It will arrive on location in December and start up procedures, including securing the STP Buoy, final hook up and commissioning of all surface and subsea systems will take 14 days to complete, Ithaca said in a release.

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In July 2011, the APL STP mooring system and suction piles were delivered. Ithaca awarded Bibby Offshore the contract to install the subsea equipment and the FPSO mooring system in December 2010. Under the contract terms, Bibby Offshore installed subsea manifolds, flowlines, power cables and umbilicals between the subsea wellheads and FPSO. Bibby also installed the 2 km seabed sections and the dynamic riser sections. The STP Buoy will be used to locate the FPSO at the Athena site. Bibby will install nine suction piles and associated anchor lines to complete the project.

Ithaca awarded Bibby an additional contract in January 2011 to tie back the four production and one water injection wells and to install the export system for the FPSO. The Bubby Topaz dive support vessel will take on all the construction-related work. Bibby will also need a high specification construction support vessel and a dedicated trenching vessel to complete the work.

Ithaca awarded other key contracts for Athena to Petrex for subsea engineering and project management; Xodus Group for the subsea design; Duco for the manufacturing of the umbilicals, power cables, and risers; BEL Valves for the manufacturing of the subsea valves; JPR Fabrication for the fabrication of the manifold and riser base; Wellstream for the manufacturing of flexible flowlines and risers; and Framo for the supply of the multiphase flowmeter.


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