It appears that an elephant has been slumbering off the southern Irish coast, but may be about to be awakened thanks to the persistence of Providence Resources.
Last month, the company said analysis of drilling, well-test and seismic data points to a field with in-place oil reserves of 1-1.6billion barrels.
This is a massive upgrade of prior estimates as P50 resources increase 180% to 1.043billion barrels from 373million barrels and P10 resources increase 80% to 1.612billion barrels from 893million.
This puts Barryroe on a par with the Buzzard field off the north-east of Scotland and Rockhopper’s Sea Lion discovery offshore the Falkland Islands.
Providence broke through earlier this year with a significant well-test . . . the first oil find offshore Ireland to flow at apparently commercial rates.
The latest resource estimate comprises two separate reservoir intervals – the Middle Wealden and the Basal Wealden. The upgrade is derived entirely from the assessment of the latter.
The Middle Wealden reservoir is still estimated to contain 287million barrels of oil (P50), with the possible upside estimate being 706million barrels (P10).
The Basal Wealden reservoir is now believed to contain 756million barrels of oil (P50), with an upside estimate of 906million barrels (P10).
The reservoir has been encountered in the range 1,950-2,225m (6,400-7,300ft) without evidence yet of the oil-water contact. According to Providence, there is unlikely to be any primary gas cap present in the Basal Wealden.
No formal conclusion has been drawn as to potential recovery rates but the oil is said to be “very mobile”.
The most recent well was situated about 274m (900ft) down-dip from the structural crest and still encountered oil to the base of the primary Basal Wealden Sand.
The Barryroe field is also believed to contain other oil reservoirs, and indeed an already discovered gas reservoir, in addition to the two reservoirs that make up the formal oil in place resource.
Further detail just released by Providence indicates that the Lower Wealden reservoirs comprise 300m (1,000ft) of inter-bedded hydrocarbon bearing sands and shales, and the Purbeckian lacustrine shales that underlay the Basal Wealden (and have not been tested).
The company has indicated that the Lower Wealden offers potential to provide further oil resources for the Barryroe field. These reservoirs have in the past been found to be thin, however Providence says they thicken to the west.
Moreover, the company believes that, following recent analysis, an unsuccessful Esso (Exxon) operated well test in 1976 may have been a failure because of mechanics rather than geology.
Further appraisal drilling is planned, with another six wells scheduled over the next eighteen months.
Providence is the operator of Barryroe with an 80% interest while Lansdowne Oil & Gas holds the remaining 20%.