The Polly discovery lies 2.5 km to the east of the Beatrice field and is an elongate structure which straddles blocks 11/30a and 12/26c. Development of Polly is now under serious consideration as either a subsea completion tied back to the Beatrice Bravo or Jacky platforms or a deviated well drilled directly from the Beatrice Bravo. Current work focuses on the optimal, simplest solution to move this potentially valuable addition to the Beatrice Complex towards development in 2010. The project is now ranking highly as one of the key enhancement opportunities that Ithaca is considering to boost the overall output from the Beatrice area.  The successful appraisal and development of Jacky and reinstatement of production from the Bravo platform has demonstrated the capacity of Ithaca to carry out similar projects.

 

Following successful workovers performed on Bravo wells at the end of 2009 and the forthcoming work on wells connected to the Alpha platform Ithaca is investigating options to further utilise a jack-up rig in the Beatrice area to potentially drill new wells and carry out further well interventions during 2010 and into 2011. This may provide the opportunity to complete the appraisal of Polly.  Engineering design scoping work on Polly is therefore being accelerated to optimise use of the rig.

Ithaca acquired the Polly prospect through the 23^rd UK Licensing Round and Beatrice acquisition. The prospect is a long, thin structure analogous to the adjacent Beatrice field. In 1986 the 12/21-4 well was drilled by Britoil at the north-east end of the structure and north of a major cross cutting fault.  The well encountered poorer reservoir quality Beatrice A sands and further work has shown this to be a valuable data point. 

The 11/30-A29 well drilled in 1989 from the Beatrice Alpha platform and tested the southwestern extremity of Polly.  The A29 well produced oil over an extended period from the Beatrice A, H, I and J sands and is currently shut in.

 

In February 2008 Ithaca and partners, North Sea Energy (UK) Ltd. drilled the 11/26c-5 well which tested the centre of the structure and proved moveable oil in place (sample recovered to surface by RFT). The well was not tested due to environmental considerations in the Inner Moray Firth but it remains suspended for re-entry and use in a potential development. The oil is of Beatrice type and is contained in the Beatrice reservoir sand equivalents in Polly.

 

 

The development of Polly is likely to be as a subsea tieback of two wells from a single surface location. A vertical appraisal well into the Northern extension of the field and a highly deviated development well towards the South would be completed for production. The likely host facility would be Jacky, although Beatrice Bravo may also be suitable.

 

Other options such as long step out wells from Bravo or Jacky are also being evaluated, with the additional drilling cost potentially being offset by the simpler and accelerated tie-in process.

 

Additional sub-surface studies are underway to evaluate production enhancement techniques that may increase the project value.

 

Planning for the appraisal well is underway with the aim of being ready to drill in 2010. Development work would then commence with an Environmental Assessment and Field Development Plan being submitted for approval by end 2010. Prompt FDP approval would allow host installation modification work, completion of the development well and subsequently first oil during the first half of 2011.

 

It is possible that injection support may be required. This would be provided by sidetracking and completing the discovery well with injection water being supplied from either Beatrice Bravo or Alpha.

 

The Polly structure is a direct analogue of the Beatrice field and comprises a westward tilted, narrow, elongate fault block (see figure below). Polly was discovered by well 12/26c-5, drilled by Ithaca Energy and North Sea Energy in February 2008. The well discovered approximately 14ft of permeable oil-bearing Beatrice A sand, with an average porosity of 14%. The oil bearing section of the A sand is overlain by approximately 12 ft of tight reservoir and underlain by an apparently water wet zone.

 

MDT data acquired during operations initially suggested that the lower part of the A sand was tight (due to low mobilities and unsuccessful attempts at retrieving a water sample). This conflicted with the initial view, prior to MDT measurements being taken, that an OWC had been encountered at approximately 7000ft MD. The log data suggests, both in 12/26c-5 and the offset wells 11/30a-A29 and 12/21-4, that reservoir quality in the A sand is poorer than that seen in the Jacky and Beatrice areas. Therefore, uncertainty exists as to whether 12/26c-5 had encountered an OWC, a tight reservoir zone or wellbore damage due to while mud invasion below the oil zone.

 

A study of the geology reveals that fluvial channel facies are interpreted to occur over the NE part of the Greater Beatrice area, particularly over the Jacky Field. These deposits are characterized by generally clean, coarse-grained and laminated sands, and preserve the best reservoir quality in the A sand over the entire Beatrice area, as seen from the core analysis data in 12/21-2. Fluvial channel deposits are also interpreted to occur in 12/21-4, at the NE end of the Polly structure, although this has been interpreted from the wireline log signature. In well 12/26c-5, the Polly exploration well, the fluvial channel deposits appear thinned and cemented, perhaps defining the edge of the incised valley fill.  Estuarine bar facies are observed in core from 11/30a-A29, and are interpreted to form the majority of the A sand section in the Polly exploration well, by calibration against wireline log data. These comprise of more poorly sorted, clay-rich and bioturbated sandstones, and have poorer reservoir quality than the fluvial facies. Estuarine bar facies are interpreted to occur in the south western part of the study area (in wells 11/30a-A29 and 12/26c-5), and are not seen in 12/21-4 and 12/21-2.  The conclusion of this study suggests that better reservoir quality Beatrice A sand could easily be present in the northern part of the Polly structure and represents considerable upside for any development.

 

Evaluation of the well results and 3D seismic mapping indicates some 18 mmbbls potentially in place in the Polly structure. An additional well in the northern section of the prospect is proposed after which the optimum development scheme will be finalised.