Viura Field Update

Prospex Energy plc / Index: AIM / Epic: PXEN / Sector: Oil and Gas

17 September 2025

Prospex Energy plc

("Prospex" or the "Company")

Viura Field Update

Prospex Energy plc (AIM: PXEN), the AIM quoted investing company focused on European gas and power projects, wishes to inform shareholders that it has been advised by the operator of the Viura field, HEYCO Energia Iberia S.L. ("HEI" or the "Operator"), that the resumption of production following the completion of the workover of the Viura‑1B well, in the Viura gas field in northern Spain, has been delayed owing to an unforeseen event during the well testing.

During the well tests performed last month with wireline downhole pressure monitoring, a failure in the pressure control equipment required the safe and controlled cutting of the associated cable while still inside the well. This has resulted in a wireline logging tool and its cable being left inside the tubing. The required equipment to retrieve the tool and the cable had to be mobilised from Aberdeen, UK, with gas production not being able to proceed safely until the cable either has been removed or its location is known to be secured below the safety valve in the well. Operations to remove the tool and the cable commenced on Tuesday 16 September 2025. At this time, the timing of the resumption of production is unknown.

Prospex owns 7.24% of the Viura field through its ownership of 7.5% of HEYCO Energy Iberia S.L. ("HEI" or the "Operator"). Prospex is accruing 14.47% of the production income from the Viura gas field until payback of its capital investment (expected to be ≈£8 million) plus the accrued 10% p.a. interest thereon.

Mark Routh, Prospex's CEO, commented:

"This is a very unfortunate setback in re-instating production from this prolific gas field. Safety of production operations is paramount and the Operator is working as quickly as it can to resume gas production from the field at stable and sustainable rates, but this has to be done safely. Until the logging equipment that remains in the hole can be removed or safely located and secured downhole, gas production can not resume. I look forward to updating shareholders when the Operator has brought the Viura gas field safely back into continuous production from the Viura-1B well."

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Background

The Viura-1B well is currently not in production and was shut in during April-2025 owing to the detection of a leak in the completion tubing which required a rig intervention to reinstate production. A rig was mobilised and the production tubing was replaced in July and operations are ongoing to re-instate continuous production.

Total natural gas produced from the Viura-1B well from start-up in December 2024 to the end of Q1-2025 was 30.2 MMscm = 1.1 Bcf (which is ≈ 4.4 MMscm = 154 MMscf net to Prospex).

The Viura acquisition significantly increased Prospex's estimated reserves by 6.5 Bcf (0.18 Bcm) net to Prospex. The Operator's best estimate of recoverable gross remaining reserves at the Viura field is 90 Bcf (2.5 Bcm) and is expected to increase upon further evaluation of the newly drilled horizons. This 90 Bcf most likely recoverable reserve number is not an independently derived 2P reserve number but is based upon the operator's most recent tests and studies with best estimates of gas in place and recovery factors. Once the newly reprocessed 3D seismic is reinterpreted it is the Operator's intention to update the reservoir model, gas in place and the reserves for the Viura field.

The information contained within this announcement is deemed by the Company to constitute inside information as stipulated under the Market Abuse Regulation (EU) No. 596/2014 as it forms part of United Kingdom domestic law by virtue of the European Union (Withdrawal) Act 2018, as amended by virtue of the Market Abuse (Amendment) (EU Exit) Regulations 2019.

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For further information visit www.prospex.energy or contact the following:

Notes

Prospex Energy PLC is an AIM quoted investment company focussed on high impact onshore and shallow offshore European opportunities with short timelines to production. The Company's strategy is to acquire undervalued projects with multiple, tangible value trigger points that can be realised within 12 months of acquisition and then applying low-cost re-evaluation techniques to identify and de-risk prospects. The Company will rapidly scale up gas production in the short term to generate internal revenues that can then be deployed to develop the asset base and increase production further.