NATIONAL FUEL GAS CO

Seneca, which is part of the Company’s Integrated Upstream and Gathering segment, is engaged in the exploration for and the development of natural gas reserves in the Appalachian region of the United States. Seneca’s development activities in the Appalachian region are focused primarily in the Marcellus and Utica shales. Further discussion of exploration and production activities is included in Item 8, Note N — Supplementary Information for Exploration and Production Activities. Note N sets forth proved developed and undeveloped reserve information for Seneca. The September 30, 2025, 2024 and 2023 reserves shown in Note N are valued using an unweighted arithmetic average of first day of the month commodity price for each month within the twelve-month period prior to the end of the reporting period. The reserves were estimated by Seneca’s petroleum engineers and were audited by independent petroleum engineers from Netherland, Sewell & Associates, Inc. Note N discusses the qualifications of Seneca’s petroleum engineers, internal controls over the reserve estimation process and audit of the reserve estimates and changes in proved developed and undeveloped gas reserves year over year.

Seneca’s proved developed and undeveloped natural gas reserves increased from 4,752 Bcf at September 30, 2024 to 4,980 Bcf at September 30, 2025. This increase is attributed to extensions and discoveries of 632

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Bcf and revisions of previous estimates of 22 Bcf, partially offset by production of 426 Bcf. Upward revisions of 69 Bcf are mainly attributed to positive performance improvements and price revisions. The additions and upward revisions were partially offset by downward revisions of 47 Bcf from changes to development layout, the removal of one PUD location and operating expense-related revisions. The Company has no near term plans to develop the reserves at this PUD location.

Seneca’s proved developed and undeveloped natural gas reserves increased from 4,535 Bcf at September 30, 2023 to 4,752 Bcf at September 30, 2024. This increase is attributed to extensions and discoveries of 602 Bcf and revisions of previous estimates of 7 Bcf, partially offset by production of 392 Bcf. Upward revisions of 145 Bcf are mainly attributed to positive performance improvements, changes to the booked lateral length and optimized development layout. The additions and upward revisions were partially offset by downward revisions of 138 Bcf from the removal of nine PUD locations related to schedule changes and price-related revisions. The Company has no near term plans to develop the reserves at these PUD locations.

At September 30, 2025, Seneca had delivery commitments for natural gas production of 2,055 Bcf. The Company expects to meet those commitments through the future production of reserves that are currently classified as proved reserves and future extensions and discoveries.

The following is a summary of certain oil and gas information taken from Seneca’s records.

Production

(1)Average sales prices per Mcf of gas reflect sales of gas in the Marcellus and Utica Shale fields. The Marcellus Shale fields (which exceed 15% of total reserves at September 30, 2025, 2024 and 2023) contributed 574 MMcfe, 645 MMcfe and 521 MMcfe of daily production in 2025, 2024 and 2023, respectively. The average lifting costs (per Mcfe) were $0.72 in 2025, $0.72 in 2024 and $0.73 in 2023. The Utica Shale fields (which exceed 15% of total reserves at September 30, 2025, 2024 and 2023) contributed 591 MMcfe, 423 MMcfe and 495 MMcfe of daily production in 2025, 2024 and 2023, respectively. The average lifting costs (per Mcfe) were $0.61 in 2025, $0.64 in 2024 and $0.62 in 2023.

Productive Wells

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Developed and Undeveloped Acreage

(1)Of the 1,301,368 Total Developed and Undeveloped Net Acreage in the Appalachian region as of September 30, 2025, there are a total of 1,229,682 net acres in Pennsylvania. Of the 1,229,682 total net acres in Pennsylvania, shale development in the Marcellus, Utica or Geneseo shales has occurred on approximately 153,105 net acres, or 12% of Seneca’s total net acres in Pennsylvania. Developed Acreage in the table reflects previous development activities in the Upper Devonian formation, but does not include the potential for development beneath this formation in areas of previous development, which includes the Marcellus, Utica and Geneseo shales.

As of September 30, 2025, the aggregate amounts of gross undeveloped acreage expiring under lease in the next three years and thereafter are as follows: 18,458 acres in 2026 (16,150 net acres), 14,698 acres in 2027 (12,679 net acres), 7,248 acres in 2028 (6,558 net acres) and 177,270 acres thereafter (169,102 net acres). The remaining 470,917 gross acres (436,966 net acres) represent non-expiring oil and gas rights owned by the Company. Of the acreage that is currently scheduled to expire in 2026, 2027 and 2028, Seneca has 814.7 Bcf of associated proved undeveloped gas reserves. As a part of its management approved development plan, Seneca generally commences development of these reserves prior to the expiration of the leases and/or proactively extends/renews these leases.

Drilling Activity

(1)Fiscal 2025 and 2023 Appalachian region dry wells include 1.5 and 0.5 net wells, respectively, drilled prior to 2013 that were never completed under a joint venture in which Seneca was the nonoperator. Seneca became the operator of the properties in 2017 and plugged and abandoned the wells in 2025 and 2023 after Seneca determined it would not continue development activities.

Present Activities

(1)Includes wells awaiting completion.

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