Winters-2 and Stanley-5 Update

11 November 2021

Mosman Oil and Gas Limited

("Mosman" or the "Company")

Winters-2 and Stanley-5 Update

Mosman Oil and Gas Limited (AIM: MSMN) the oil exploration, development, and production company, announces an update on the Winters-2 and Stanley-5 wells in Polk County, East Texas.

The Winters-2 well was perforated from 6,788 to 6,808 feet. The well was swabbed on the morning of Friday 5 November and started to flow gas, oil and water. On Monday 8 November, the well was again swabbed and well testing on Tuesday 9 November from 11.00 to 16.00 flowed 48 to 96 thousand cubic feet of gas per day (Mcfgpd) of gas, minor amounts of oil and 240-480 barrels per day of water. The well is currently shut-in to measure pressure build up. This Wilcox zone will be flow tested again tomorrow. Note that nearby wells have seen oil production increase in the first days of flowing. If the oil rate does not increase, then the well may be re-completed in another zone. There are several other potential production zones identified on logs with potential pay having been identified in other Wilcox sands.

Stanley-5 is waiting on the delivery of required equipment, expected next week, before being put on production.

Further updates will be provided as appropriate.

Qualified Person's Statement

The information contained in this announcement has been reviewed and approved by Andy Carroll, Technical Director for Mosman, who has over 35 years of relevant experience in the oil industry. Mr. Carroll 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.

Enquiries:

Updates on the Company's activities are regularly posted on its website:

www.mosmanoilandgas.com