Horizon Petroleum Provides an Operations Update for its Poland Operations and Confirms Wellbore Integrity at the Lachowice 7 well

CALGARY, AB, Aug. 12, 2026 /PRNewswire/ -- Horizon Petroleum Ltd. ("Horizon" or the "Company") (TSXV: HPL) (FRA: HPM) (Tradegate: HPM) is pleased to announce that further to its press release dated July 23, 2026, its wholly owned Polish subsidiary, Energia Karpaty Zachodnie sp. z o.o. ("EKZ"), confirms that the rig mobilization and installation is complete and the re-entry operations have commenced at the Lachowice 7 (L7) wellsite.

The L7 workover program is designed to confirm the long-term production flow potential of the naturally fractured carbonate reservoir at Lachowice. To date the Company has drilled out the cement and mechanical suspension plugs and run a milling assembly into the hole to a depth of 2,706m. Two casing pressure tests were conducted, and both confirmed the physical integrity of the wellbore. With this confirmation, the company can now move forward with the balance of the program.

The work program continues as follows:

• Removal of the existing downhole packer and completion equipment
• Re-perforate the naturally fractured, Upper Devonian aged carbonate reservoir section (with a gross interval of 65m) with new perforations
• Stimulate using a diverted acid stimulation and then production test the well to confirm sustainable production flow performance.
• Suspend the well for production upon completion of the Phase 1 development plan.

The workover program is on track, and the stimulation and production testing are expected to commence near the end of August and continue into early September 2026 as previously disclosed.

Roger McMechan, Chief Operations Officer of Horizon, commented: "Confirming the integrity of the well casing mitigates one of the key risks in re-entering the well. We look forward to executing and completing the workover and production testing safely and efficiently to confirm the long-term production capability of the Lachowice gas accumulation, which we believe has the potential to become a significant new domestic source of natural gas for Poland."

The Company will provide additional updates as operations progress.

About Horizon Petroleum Ltd.

Calgary-based Horizon is focused on the appraisal and development of natural gas reserves and clean energy sources to increase energy independence and security in Europe. The Management and Board of Horizon consist of oil & gas, business and finance professionals with significant international experience.

Website: www.horizon-petroleum.com

Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.

This press release contains "forward-looking statements" or "forward-looking information" (collectively referred to herein as "forward-looking statements") within the meaning of applicable securities legislation. Such forward-looking statements include, without limitation, forecasts, estimates, expectations and objectives for future operations that are subject to a number of assumptions, risks and uncertainties, many of which are beyond the control of Horizon. Forward-looking statements are statements that are not historical facts and are generally, but not always, identified by the words "expects", "plans", "anticipates", "believes", "intends", "estimates", "projects", "potential" and similar expressions, or that events or conditions "will", "would", "may", "could" or "should" occur or be achieved.

Forward-looking information is based on current expectations, estimates and projections that involve a number of risks, which could cause actual results to vary and in some instances to differ materially from those anticipated by Horizon and described in the forward-looking information contained in this press release.

Although Horizon believes that the material factors, expectations and assumptions expressed in such forward-looking statements are reasonable based on information available to it on the date such statements were made, no assurances can be given as to future results, levels of activity and achievements and such statements are not guarantees of future performance.

Oil and Gas Disclosure

Reserves are those quantities of petroleum anticipated to be commercially ‎recoverable by application of development projects to known accumulations ‎from the effective date under defined conditions. Reserves must be ‎discovered, recoverable, commercial, and remaining as of the effective date ‎based on the development projects applied. Reserves are further categorized ‎into Proven, Probable and Possible according to the level of certainty ‎associated with the estimates and may be sub-classified based upon ‎production status and project maturity. ‎

Reserves are classified according to the degree of certainty associated with ‎the estimates. Reserves are estimated remaining quantities of oil and natural ‎gas and related substances anticipated to be commercially recoverable from ‎known accumulations, from a given date forward, based on: ‎

• analysis of drilling, geological, geophysical, and engineering data; ‎
• the use of established technology; ‎
• and economic conditions, which are generally accepted as being ‎reasonable, and shall be disclosed. ‎

Proved Reserves (1P) are those reserves that can be estimated with a high degree ‎‎(>= 90%) of certainty to be recoverable. It is likely that the actual remaining ‎quantities recovered will exceed the estimated proved reserves. ‎

Probable Reserves (2P) are those additional reserves that are less certain to be ‎recovered than proved reserves. It is equally likely that the actual remaining ‎quantities recovered will be greater or less than the sum of the estimated ‎proved + probable reserves. ‎

Possible Reserves (3P) are those additional reserves that are less certain (<=10%) ‎to be recovered than probable reserves. It is unlikely that the actual remaining ‎quantities recovered will exceed the sum of the estimated proved + probable + ‎possible reserves. ‎

Resources are defined in the COGE Handbook Volume 1, section 5 as follows: ‎

Contingent Resources are those quantities of petroleum estimated, as of a ‎given date, to be potentially recoverable from known accumulations, but the ‎applied projects are not yet considered mature enough for commercial ‎development due to one or more contingencies. Contingent Resources may ‎include, for example, projects for which there are currently no viable markets, ‎or where commercial recovery is dependent on technology under ‎development, or where evaluation of the accumulation is insufficient to clearly ‎assess commerciality. ‎

Contingencies may include factors such as economic, legal, environmental, ‎political, and regulatory matters, or a lack of markets. It is also appropriate to ‎classify as contingent resources; the estimated discovered recoverable ‎quantities associated with a project in the early evaluation stage. Contingent ‎Resources are further classified in accordance with the level of certainty ‎associated with the estimates and may be sub classified based on project ‎maturity and/or characterized by their economic status. ‎

Not all technically feasible development plans will be commercial. The ‎commercial viability of a development project is dependent on the forecast of ‎fiscal conditions over the life of the project. For Contingent Resources, the ‎risk component relating to the likelihood that an accumulation will be ‎commercially developed is referred to as the "chance of development." For ‎contingent resources, the chance of commerciality is equal to the chance of ‎development. ‎

SELECTED ABBREVIATIONS

Unless otherwise indicated or the context otherwise requires, the following ‎abbreviations shall have the meaning set forth below:‎

               Crude Oil and Natural Gas Liquids                            Natural Gas

---

    Bbls/d                                       barrels of oil per day                 cf     
 
 cubic feet


    Bbls or
     Bbl                                         barrels of oil                         Mcf        thousand cubic feet


    Boe                                          barrel of oil equivalent               Mcf/d      thousand cubic feet per day


    Boe/d                                        barrel of oil equivalent               Mcfe       thousand cubic feet of gas
                                                  per day                                                  ‎
          equivalent


    Mbbls                                        thousand barrels                       Bcf        billion cubic feet


    MBoe                                         thousand barrels of oil
                                                  equivalent                            Bcfe       billion cubic feet equivalent


    NGL                                          natural gas liquids                    Bcm        billion cubic metres


    Bbl/MMcf                                     barrels of oil per million             MMbtu      million British thermal
                                                  cubic feet                                            ‎
          units


    ‎                                            dollars per thousand cubic
      $/Mcf                                       feet
             ‎                                                                          MMcf       million cubic feet


                                                                                        Mcm        million cubic metres


                                                                                        MMcf/d     million cubic feet per day

                                                                                        TCF        trillion cubic feet

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SOURCE Horizon Petroleum Ltd.