Nutech Ltd. has upped estimates of total oil in place at the Horse Hill-1 (HH-1) well in the Weald basin of southern England to 158 million bbl/sq mile, excluding the previously reported Upper Portland Sandstone oil discovery.
US analogues have estimated recovery factors of 3-15%, which may be produced using conventional technology.
In a report to UK Oil & Gas Investments PLC (UKOG), which holds 20.36% interest in the 55-sq-miles Horse Hill licenses near Gatwick airport, Nutech says the oil lies within a 653-ft aggregate net pay section, primarily within three argillaceous limestones and interbedded mudstones of the Kimmeridge and the mudstones of the Oxford and Lias sections.
About 72% of the oil in place—114 million bbl—lies within the Upper Jurassic Kimmeridge interbedded limestone and mudstone sequence.
“Drilling the deepest well in the basin in 30 years, together with the ability to use concepts, techniques, and technology unavailable in the 1980s, has provided new cutting-edge data and interpretations to comprehensively change the understanding of the area’s potential oil resources,” noted Stephen Sanderson, UKOG chief executive officer.
HHI operator Horse Hill Developments Ltd. (HHDL) commenced drilling in September with a targeted vertical depth of 8,680 ft (OGJ Online, Sept. 3, 2014).
Sanderson describes Horse Hill as “a possible world-class potential resource in what is interpreted to be a new Upper Jurassic ‘hybrid play,’” with a rock sequence that’s “analogous to known oil productive hybrid reservoir sections of the Bakken of the US Williston basin, the Wolfcamp, Bone Springs, Clearfork, Spraberry, and Dean formations in the US Permian basin, and the Bazhenov formation of West Siberia.”
Sanderson said, “The company considers that the high pay thickness, combined with interpreted naturally fractured limestone reservoir with measurable matrix permeability, gives strong encouragement that these reservoirs can be successfully produced using conventional horizontal drilling and completion techniques.”
Further testing, drilling
The semi-regional resource potential of Weald’s eastern footprint is undergoing analysis as part of the contracted alliance between Nutech, UKOG, and Solo Oil PLC to establish estimates of total oil in place within the license area. UKOG says the results will be reported when completed.
Final assessments of the Upper Portland Sandstone and the Oxford and Lias sections are in progress, with further results expected shortly, UKOG says.
Appraisal drilling and well testing will be required to prove HH-1’s commerciality, UKOG says. HHDL and Nutech will flow test the Portland Sandstone and Kimmeridge Limestone sections to determine producibility and quantify an overall net discovered resource.
The HH-1 well is part of onshore exploration license PEDL 137 on the northern side of Weald.
HHDL is a special purpose company that owns 65% participating interest and operatorship of PEDL 137 and the adjacent license PEDL 246 in Weald. UKOG holds 30% direct interest in HHDL and 1.32% interest in HHDL via its 6% interest in Angus Energy Ltd.
In addition to UKOG, Solo, and Angus, stakes in HHDL are held by Alba Mineral Resources PLC, Regency Mines PLC, Stellar Resources PLC, and Doriemus PLC.