UK Oil & Gas PLC announces that Horse Hill Developments ("HHDL"), a UKOG subsidiary company and the operator of the HH-1 Kimmeridge Limestone and conventional Portland Sandstone oil discovery, has informed the Company that, following the successful Portland Extended Well Test ("EWT") programme, it now considers the Portland oil field to be commercially viable.

HHDL now targets the start-up of long term Portland oil production during 2019, subject to the grant of necessary regulatory consents. The first future horizontal production well, HH-2, for which planning and Environment Agency consents are in place, is planned to be drilled in early 2019. HH-1 is located in licence PEDL137 in which UKOG holds a 46.735% beneficial interest. Key points and further details are summarised below:

Key Points:

• Following analysis of EWT results and economic modelling of HHDL's and Xodus Group's ("Xodus") forecast oil production profiles, HHDL now considers the Portland oil field to be commercially viable. Work is now underway towards a targeted long-term production start-up in 2019.
• HHDL currently envisages the Portland field development plan to consist of up to 3 production wells and up to 2 pressure support wells.
• A planning application for Portland and Kimmeridge field development is nearing completion and is targeted for submission to Surrey County Council ("SCC") before year-end.
• Xodus' calculated future Portland oil production profiles, based upon observed pressure and volumetric data from the EWT, show that oil recoveries of up to 45% of connected Oil in Place could be attained if a successful full voidage replacement pressure support scheme is incorporated into the field's development.
• The Portland field's first new horizontal production well, HH-2, which has SCC planning and Environment Agency consents, is planned to spud in early 2019 following completion of the Kimmeridge Limestone 4 EWT.
• As reported on 10 September, the HH-2 horizontal well has a targeted* sustainable daily Portland production rate of 720 to 1,080 bopd, 2 to 3 times the calculated* sustainable vertical well rate of 362 bopd derived from the EWT programme.
• Following submission of the planning application, Xodus' 2018 Portland Competent Persons Report will be updated to include recoverable reserves and net present values of cash flows associated with the envisaged Portland oil field development.

Note: * There can be no absolute guarantee that forecast, targeted or calculated rates of production will be achieved.

Stephen Sanderson, UKOG's Chief Executive, commented:
"HHDL's declaration of Portland commercial viability is a significant milestone for the Company. It transforms Horse Hill from solely exploration into a fully-fledged field development with a full-scale oil production start-up targeted in 2019. 

The better than expected EWT results have robustly demonstrated that the Portland has significant daily production potential in its own right, which could see the first planned horizontal producer attain sustained oil rates of 720-1,080 bopd. If realised, these rates could make the Horse Hill Portland oil field one of the UK onshore's top producers.

We also eagerly anticipate the possibility of combined long-term production from both the Portland and Kimmeridge, an exciting and potentially transformational prospect for Horse Hill and the Company."