Senex Energy Ltd.’s Acrasia-6 well intersected 31 m (102 ft) of net oil pay and an additional 15 m (49 ft) of possible net oil pay, extending the productive life of the Acrasia oil field in the northeast of South Australia’s Cooper-Eromanga basin, the company said in a press release.

Acrasia-6 is a deviated appraisal well located approximately 300 m (984 ft) south of Acrasia-1, which has produced from the mid Tinchoo formation since 2002. The appraisal well was designed to assess the extent of the Acrasia Hutton sandstone oil accumulation; produce unswept oil in the Birkhead, Poolowanna, and Tinchoo sandstone reservoirs; and evaluate the potential of the Arrabury formation.

Acrasia-6 spudded on Nov. 14 and reached a total depth of 2,369 m (7,772 ft), according to the release. During drilling, good oil shows were evident throughout the sandstones of the Hutton, Birkhead, Poolowanna, and Tinchoo formations. Interpretation of wireline logs indicates approximately 31 m of net pay across these four target zones with an additional 15 m of probably pay calculated for the Birkhead and Tinchoo formations. Net pay in the Arrabury formation will not be known until the results of the core analysis are available to calibrate the wireline logs.

Results of the well confirm three key opportunities to increase production from Acrasia, including exploitation of partially swept oil accumulations in the Hutton, Birkhead, Poolowanna, and lower Tinchoo formations; production from a newly discovered oil accumulation in the upper Tinchoo sandstone; and further evaluation of the oil production potential of the Arrabury formation sandstones.

The Acrasia oil field is located 125 km (78 miles) northeast of Moomba, near the Queensland border, according to the press release. Acrasia-1 was the first well drilled by Stuart Petroleum Ltd., a South Autralian oil production company acquired by Senex in February 2011. The well was drilled in March 2003 and was brought online as an oil producer in July the same year after intersecting oil in the Birkhead, Hutton, Poolowanna, and Tinchoo reservoirs. Stuart subsequently drilled four successful development wells at the field, which have produced approximately 840,000 bbl of oil to date.

In 2013 structural remapping and oil-in-place calculations by Senex indicated significant potential for additional oil production from the field, according to the release. In August Senex drilled the Acrasia-7 development well to maximize the recovery of unswept oil from the mid Tinchoo formation and evaluate the potential of the Birkhead, Hutton, and Poolowanna formations. The well was cased and suspended as a future oil producer in September after intersecting interpreted net oil pay of 6.3 m (21 ft) in the Tinchoo and Poolowanna formations and is expected to commence production in December 2013.

During drilling of Acrasia-6, Senex cut core over an interval of 34 m (112 ft) from 2,262 m to 2,296 m (7,421 ft to 7,533 ft) through the interbedded sandstones and shales of the Arrabury formation, the company said. The coring program was designed to enhance understanding of the reservoir and calculate rock properties.

Analysis of the core indicates the presence of oil in the Arrabury formation at Acrasia-6. In 2002 the Acrasia-2 appraisal well produced at a rate of 430 b/d of oil from the Arrabury sandstone but was not able to be brought onto production, according to the release. Senex is now evaluating options to exploit this oil pool and assess the potential for similar Arrabury accumulations in the region.

Planning is now under way for an appraisal campaign at Acrasia to investigate the stratigraphic nature of the Birkhead accumulation and confirm the productive potential of oil in the Arrabury formation, according to the release. Initially, Senex will drill an additional well – Acrasia-8 – adjacent to Acrasia-6 to both accelerate production and access undrained reservoirs in the east of the field. An upgrade of existing facilities also is planned to enable rapid field development.