The Company currently owns a 10% interest in a special purpose company, Horse Hill Developments Limited, which is the operator and 65% interest holder in two Petroleum Exploration and Development Licences (“PEDL”) PEDL 137 and 246 in the northern Weald Basin between Gatwick Airport and London. The PEDL137 licence covers 99.29 square kilometres (24,525 acres) to the north of Gatwick Airport in Surrey and contains the Horse Hill-1 (“HH-1”) discovery and several other exploration leads. PEDL246 covers an area of 43.58 square kilometres (10,769 acres) and lies immediately adjacent and to the east of PEDL137.
The HH-1 well is located approximately 7.5 kilometres southeast of the producing Brockham oil field and approximately 15 kilometres southwest of the Palmers Wood oil field. The pre-drill primary target reservoir horizons were the Portland Sandstone, which is productive in the Brockham oil field, and the Corallian Formation, which is the producing horizon in the Palmers Wood oil field. Secondary targets for the well included the Triassic, which is productive in the nearby Wessex Basin and has previously tested gas in the Weald Basin, and the Greater Oolite Formation.
The HH-1 well commenced drilling operations in September 2014 and reached total depth at 8,770 feet MD in November 2014. Evaluation of electric logs and other data collected from the well resulted in the announcement on 24 October 2014 of a conventional Upper Portlandian Sandstone oil discovery. Subsequent analysis of the Kimmeridge, Oxfordian and Liassic sections in the well indicated that there was also substantial in place oil in the naturally fractured Kimmeridge Limestones and associated mudstones.
Approval for the testing of all three oil bearing zones was granted in late 2015 and the tests commenced in early February 2016. Tests lead to naturally flowing oil rates of the Kimmeridge Limestones at 460 bopd from the Lower interval and 900 bopd from the upper interval. The Portland Sandstone was placed on pump to stimulate flow and achieved a maximum stable rate in excess of 300 bopd. These flow rates substantially exceeded the expectations for the well and rank alongside some of the highest rates ever achieved on test for any UK onshore well.
Following the testing of the Portland Sandstone, when higher productivity and a lower than expected water cut were both observed, further analysis on the electric logs has led to a 200% increase in the anticipated oil in place at this stratigraphic level. Previous estimates of oil in place within the Portland Sandstone were 7.7 mmbbls per square mile and were increased to 22.9 mmbbls.
Based on analysis of published reports from all significant UK onshore discovery wells, the 1,688 bbl per day flow rate is likely the highest aggregate stable rate from any onshore UK discovery well.
The relevant licences have been extended to permit further work and UKOG has indicated that it hopes to perform long term testing on all three zones as part of a wider appraisal program that includes 3D seismic and further drilling. Planning permission is presently being sought for the next phase of testing which will establish the parameters of any development scheme and the commerciality of production from the various oil bearing intervals.
All of the reviews and reports mentioned above state that the OIP volumes estimated should not be construed as recoverable resources or reserves.