Drilling at The Bard, Vecta Project Completed

23 June 2025

Mosman Oil and Gas Limited

("Mosman" or the "Company")

Drilling at The Bard, Vecta Project Completed

Mosman Oil and Gas Limited (AIM:MSMN) the helium, hydrogen and hydrocarbon exploration, development and production company, announces that the Richardson well on "The Bard" lease area at the Vecta Project, Colorado, US, has completed drilling.

The well has been drilled to a total depth of 1007' feet. The Lyons Formation was encountered at a depth of circa 1000', 460' deeper than anticipated. The well flowed water from the Lyons Formation. Trace amounts of helium gas were noted during drilling.

The drilling crew are now preparing to move the rig to the "Garcia" lease to drill the third well, Green TH 345823C, in the five well Vecta drilling programme.

Location Map illustrating the five lease areas within the Vecta project. (Courtesy of Vecta Oil and Gas Ltd.)

Andy Carroll, Chief Executive Officer of Mosman, said: "The presence of helium, albeit it in trace amounts, supports the Vecta exploration model and does not impact the remaining three undrilled leases, each lease containing a standalone structure. The Company looks forward to progressing the next three wells in the current Vecta campaign starting with the next well on the Garcia lease."

Qualified Person Statement

The information contained in this announcement has been reviewed and approved by Andy Carroll, a Director and Chief Executive Officer for Mosman, who has over 35 years of relevant experience in the oil and gas industry and is a Member of the Society of Petroleum Engineers.

Market Abuse Regulation (MAR) Disclosure

The information contained within this announcement is deemed by the Company 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 the publication of this announcement via Regulatory Information Service ('RIS'), this information is now considered to be in the public domain.

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