15 June 2026

Quantum Helium Limited

("Quantum" or the "Company")

Successful Sagebrush-1 Extended Production Test Confirms Helium-Bearing Gas, Reservoir Connectivity and Commercial Oil Production

New oil play identified alongside one of the largest independently certified helium resource positions on the London market

Quantum Helium Limited (AIM: QHE) is pleased to provide an update on the Extended Production Test ("EPT") at the Sagebrush-1 well in Colorado, where the Company holds a 90% working interest, which remains ongoing. The EPT has been successful in confirming helium-bearing gas, reservoir connectivity and commercial oil production from the Leadville Formation, while generating significant new data to support future development and resource evaluation.

Highlights

·      Helium concentrations of 2.5% confirmed by laboratory analysis of recovered gas samples - consistent with historical testing and significantly above typical industry concentrations of approximately 0.3% to 1.0%

·      Acid fracture stimulation successfully established connectivity with natural fracture systems, with pressure build-up reaching approximately 90% of virgin reservoir pressure as measured by downhole gauges

·      High injectivity confirms the presence of a significant natural fracture system, providing important information for appraisal and development planning

·      Commercial oil production identified from the Leadville Formation (between 7,250 and 7,360 feet depth) - an unexpected outcome that opens a new hydrocarbon play in the Sagebrush area, with potential rates of up to 40 barrels per day gross to working interest indicated by initial testing results and reservoir analysis over a more than two week period.

·      More than 80 barrels of oil recovered during testing operations to date

·      EPT production, pressure and fluid data to be provided to Sproule ERCE for review, including assessment of the newly identified oil potential

·      Next phase underway - additional perforations and completion modifications to increase reservoir exposure and accelerate further required cleanup, with existing production equipment on site to support longer-term operations. The Company  expects to inform flow rate potential from the Leadville following ongoing clean up operations to remove injected fluid

Operational Update

The EPT at Sagebrush-1 has generated a substantial body of production, pressure and reservoir data from the Leadville Formation. Helium-bearing gas continues to be recovered throughout testing operations, with laboratory analyses indicating helium concentrations of approximately 2.5%, consistent with historical testing and significantly above typical commercial helium concentrations. Other major gas components, including carbon dioxide, nitrogen and methane, are consistent with the original 1993 drill stem test, providing further confidence in the quality of the recovered gas stream.

The Company has successfully completed an acid fracture stimulation programme. Analysis of downhole pressure and production data indicates the treatment established connectivity with the natural fracture system and confirmed strong virgin reservoir pressure characteristics, with pressure build-up reaching approximately 90% of virgin reservoir pressure within four days following stimulation, as measured by downhole pressure gauges.

Strong gas flows have been consistently observed following swabbing operations. Early recovery of stimulation fluids, spent acid and formation liquids is progressing as expected, with continued cleanup expected to enhance gas deliverability and support improved production performance. Present operations are focused on recovering injected fluids, including spent acid, solvents, additives and load water introduced during stimulation operations.

The presence of stimulation fluids and load water within the fracture network currently impacts the Company's ability to accurately assess achievable sustained gas flow rates. Ongoing fluid recovery operations are therefore focused on restoring the reservoir to production conditions and enabling a more representative evaluation of long-term gas deliverability. While cleanup operations are expected to continue for a period of time, gas flow rates are expected to become progressively more representative as fluid recovery advances, enabling the Company to better assess the long-term productive capacity of the reservoir.

Testing has also demonstrated high injectivity within the formation, indicating the presence of a significant natural fracture system. Management believes this information will be important in guiding appraisal, development planning and field optimisation activities.

A significant and value-enhancing outcome of the Extended Production Test has been the identification of commercial oil production from the Leadville Formation - a result that was not anticipated prior to testing and that has established a new hydrocarbon play in the Sagebrush area, where commercial oil production from the Leadville Formation has not previously been demonstrated.

More than 80 barrels of oil have been recovered during testing operations to date.

Based on production data and analysis by the Company's technical team, the well may support oil production rates of up to 40 barrels per day gross to the Company's working interest and before royalties following completion of the optimisation programme currently underway, representing a significant addition to the overall value proposition of the Sagebrush Project and broader prospect inventory.

The Company believes the identification of oil at Sagebrush may have implications beyond the Sagebrush Project itself and could influence appraisal and development strategies across its wider Colorado portfolio, including the Coyote Wash prospects.

With the Extended Production Test now approaching completion, the Company is transitioning towards detailed analysis of the production, pressure and reservoir data collected during the programme. This analysis will assist in determining the optimal development strategy for both helium and oil at Sagebrush and will also provide valuable information for the evaluation of the Company's wider Colorado portfolio.

Next Phase of Operations

The Company is now implementing the next phase of the testing programme, which includes:

•   Removal of current isolation packer and retrievable bridge plug;

•   Commingling of multiple upper Leadville intervals;

•   Addition of approximately 25 feet of new deep penetrating perforations, increasing total perforated reservoir exposure to approximately 49 feet at a depth of between 7,215 and 7,240 feet.

•   Aggressive fluid recovery operations; and

•   Installation of rod pump and pumpjack equipment to facilitate longer-term fluid recovery and production operations.

•   As fluid recovery and reservoir cleanup continue, the Company expects to be in a progressively better position to assess sustained gas flow rates from the Leadville Formation. The resulting production data will form an important component of the Company's ongoing evaluation of the commercial development potential of the Sagebrush Project.

Management believes these modifications will provide significantly greater reservoir exposure and improve the Company's ability to evaluate the productive capacity of the Leadville Formation and further announcements will be made as appropriate. Data gathered from the EPT will be used to support engineering studies directed towards optimising further commercialisation of the Sagebrush Project.

Resource Base

Sagebrush hosts a Sproule ERCE independently verified 2U gross helium resource of 134 MMscf. Together with the 0.97 BCF 2U gross helium resource independently verified at Coyote Wash in December 2025, Quantum's total independently certified 2U gross helium resource base stands at 1.104 BCF across its Colorado portfolio, establishing the Company as one of the largest independently certified helium resource holders listed on the London Stock Exchange.

The objective of the EPT has been to optimise well performance and determine the most effective method of achieving sustained commercial production from an already independently verified helium accumulation. The principal focus now moves to engineering optimisation and reservoir cleanup.

Sproule ERCE Review

Quantum intends to provide the production, pressure and fluid data generated during the EPT to Sproule ERCE for review. At the time of the original Sagebrush resource evaluation, the Leadville Formation was assessed primarily as a helium and gas reservoir; the newly identified oil production was therefore not incorporated into that assessment. The Company believes this data may refine future resource assessments and provide an opportunity for Sproule ERCE to evaluate a broader hydrocarbon component of the Leadville Formation than previously considered.

Howard McLaughlin, Chief Executive Officer of Quantum Helium, commented: "We are nearing completion of a complex testing programme designed to evaluate reservoir potential and identify the most effective engineering solutions for field development. The preliminary results obtained to date have exceeded our expectations in several key areas and we look forward to conducting a detailed review of the data to help guide the future development strategy for both helium and oil across Sagebrush and the wider portfolio.

The Extended Production Test has confirmed helium concentrations consistent with historical testing, demonstrated reservoir connectivity, strong pressure characteristics and the effectiveness of our fracture stimulation programme. Pressure build-up following stimulation reached approximately 90% of virgin reservoir pressure, while recovered gas compositions match those recorded during the original 1993 drill stem test.

Sagebrush already hosts an independently verified helium resource, and Quantum holds more than 1.1 BCF of independently certified helium resources across its Colorado portfolio. This programme is about determining the optimal engineering solution for producing that helium, not proving its existence.

A significant and value-enhancing outcome from the programme has been the identification of commercial oil production from the Leadville Formation. More than 80 barrels of oil have already been recovered during testing and, importantly, commercial oil production from the Leadville has not previously been demonstrated in the Sagebrush area. With indicated production rates of up to 40 barrels per day gross, this represents a material addition to the overall value proposition of Sagebrush and may have broader implications across our Colorado portfolio."

Market Abuse Regulation (MAR) Disclosure

The information contained within this announcement is deemed to constitute inside information as stipulated under the Market Abuse Regulations (EU) No. 596/2014 ('MAR') which has been incorporated into UK law by the European Union (Withdrawal) Act 2018. Upon publication via Regulatory Information Service ('RIS'), this information is now in the public domain.

Qualified Person Statement

The information contained in this announcement has been reviewed and approved by Howard McLaughlin, Chief Executive Officer for Quantum Helium, who has more than 45 years of experience in the oil and gas industry and is a member of the American Association of Petroleum Geologists.

Enquiries:

Updates on the Company's activities are regularly posted on its website: www.quantum-helium.com

Notes to editors

Quantum (AIM: QHE) is a helium, hydrogen and hydrocarbon exploration, development, and production company with projects in the USA. Quantum's strategic objectives remain consistent: to identify opportunities which will provide operating cash flow and have development upside, in conjunction with progressing exploration. The Company has several projects in the US, in addition to royalty interests in Australia.