Sea Lion Reserves Evaluation

Rockhopper Exploration plc

02 April 2026

 

2 April 2026

Rockhopper Exploration plc

("Rockhopper" or the "Company")

Sea Lion Independent Recoverable Reserves and Resources Evaluation

Rockhopper Exploration plc (AIM: RKH), the oil and gas company with key interests in the North Falkland Basin, is pleased to announce the results from an updated independent technical report conducted by Netherland, Sewell & Associates, Inc. ("NSAI") on behalf of Rockhopper on the Company's Sea Lion field (the "Report"). The Report is effective as at 31 December 2025.

The Report shows that overall gross resource volumes are consistent with the Company's previous independent resource evaluation, also conducted by NSAI, dated June 2025 (the "June 2025 Report").

Importantly, the Report has reclassified volumes contained in the Sea Lion Field Northern Development Area ("NDA") Phases 1 and 2 from the Contingent Resources classification to the Reserves classification. This reclassification has been possible following the Company's Final Investment Decision ("FID") on the Sea Lion field, made in December 2025. Phase 2 of the Sea Lion development is expected to be financed from cashflow generated by Phase 1. Later phases of the Sea Lion development have remained within the Contingent Resources category.

Following completion of the placing, the Company had, as at 31 December 2025, a cash balance of approximately US$179 million (unaudited) which is anticipated to be sufficient to fund Rockhopper's proportion of the capex required for the Phase 1 development plan for the Sea Lion field.

Key Information (oil only)

Reserves

Summary of Gross and Working Interest Net Recoverable Reserves and Future Net Revenue attributable to Sea Lion Field NDA Phases 1 and 2

Rockhopper holds a 35 per cent working interest in the Sea Lion field.

	Oil (MBBL) Gross (100%)	Oil (MBBL) Working Interest (35%)	Future Net Revenue Working Interest (35%) (US$000) Undiscounted	Future Net Revenue Working Interest (35%) (US$000) NPV10
Proved Undeveloped (1P)	230,672.5	80,735.4	2,134,911.1	720,915.6
Probable	83,165.3	29,107.8	968,135.7	244,866.9
Proved + Probable (2P)	313,837.7	109,843.2	3,103,046.8	965,782.5
Possible	94,326.3	33,014.2	1,399,698.4	303,227.4
Proved + Probable + Possible (3P)	408,164.0	142,857.4	4,502,745.3	1,269,009.9

Note: Oil volumes are expressed in thousands of barrels (MBBL). Gross (100%) figures represent total field reserves; working interest figures represent Rockhopper's 35 per cent share. Future net revenue is after deductions for Rockhopper's share of state royalties, capital costs, abandonment costs, operating expenses and estimates of Falkland Islands corporate income taxes. NPV10 represents future net revenue discounted at an annual rate of 10 per cent. NPV10 should not be construed as the fair market value of the properties. All figures are based on the Base Price Case. See Economic Parameters below.

Contingent Resources

The contingent resources figures below are unrisked - they have not been adjusted for the probability of commercial development. These estimates should not be aggregated with reserves without extensive consideration of the differing degrees of technical and commercial risk.

Unrisked Gross (100%) Contingent Resources - Oil (MBBL)

	Low Estimate (1C) MBBL	Best Estimate (2C) MBBL	High Estimate (3C) MBBL
Development Pending	238,736.9	412,481.3	531,242.9
Development On Hold	78,971.1	181,078.2	299,712.5
Development Not Viable	5,713.6	9,602.7	14,529.9
Total	323,421.6	603,162.1	845,485.3

Unrisked Working Interest (35%) Contingent Resources - Oil (MBBL)

	Low Estimate (1C) MBBL	Best Estimate (2C) MBBL	High Estimate (3C) MBBL
Development Pending	83,557.9	144,368.4	185,935.0
Development On Hold	27,639.9	63,377.4	104,899.4
Development Not Viable	1,999.8	3,360.9	5,085.5
Total	113,197.6	211,106.7	295,919.9

Summary of Unrisked Working Interest (35%) Contingent Cash Flows after Falkland Islands Taxes

Economic analysis has been performed on the Development Pending contingent resources only.

	Total (US$000) Undiscounted	NPV10 (US$000)
Low Estimate (1C)	1,813,859.5	554,524.8
Best Estimate (2C)	4,286,664.2	1,202,666.3
High Estimate (3C)	6,244,948.0	1,610,092.7

Economic Parameters

The Report has been prepared using the following Base Price Case oil price parameters, based on Brent Crude prices adjusted for quality, transportation fees and market differentials:

Period Ending	Oil Price (US$/Barrel)
31 December 2026	62.99
31 December 2027	64.79
Thereafter	73.63

The development scenario underlying the NPV calculation for the contingent resources aligns with the previously disclosed multi-phase, two-FPSO scheme comprising the Northern Development Area ("NDA") Phases 1, 2 and 3 and the Central Development Area ("CDA") Phases 1 and 2.

Bluewater, the FPSO operator, has served notice on the Aoka Mizu FPSO and the vessel is expected to leave its current location in mid-2026 ahead of a period of refurbishment work prior to deployment at Sea Lion.

Sam Moody, Chief Executive Officer of Rockhopper, commented:

"We are delighted to book in excess of 100 million barrels of 2P reserves following the sanction of Sea Lion Phase 1 - another milestone for Rockhopper. The new NSAI report independently confirms the significant value we are now on the path to unlocking. Navitas, our Operator, has recently reported good progress on the project and has reiterated its target for first oil in early 2028."

Additional Notes

NSAI has also provided estimates of gross and working interest (i) Contingent Gas Resources and (ii) Prospective Oil and Gas Resources. These have not been reproduced in this announcement as there is no plan in place for their development. The Report also includes economic analysis under Low and High Price Case sensitivities.

The information set out above does not constitute the Report, but is derived from the Report. A full copy of the Report will be available on Rockhopper's website later today: www.rockhopperexploration.co.uk

Resource Disclosure

The Report has been prepared in accordance with the definitions and guidelines set forth in the 2018 Petroleum Resources Management System ("PRMS") approved by the Society of Petroleum Engineers ("SPE"). The estimates of reserves and resources included in this announcement have not been adjusted for risk.

Lucy Williams (BSc Geology, MSc Petroleum Geology, Chartered Geologist), the Company's Geoscience Manager, has reviewed and approved the technical information contained within this announcement.

Enquiries:

Rockhopper Exploration plc

Sam Moody - Chief Executive Officer

Tel. [phone] (via Vigo Consulting)

Canaccord Genuity Limited (NOMAD and Joint Broker)

Henry Fitzgerald-O'Connor / James Asensio / Charlie Hammond

Tel. [phone]

Peel Hunt LLP (Joint Broker)

Richard Crichton / Georgia Langoulant

Tel. [phone]

Vigo Consulting

Patrick d'Ancona / Ben Simons / Fiona Hetherington

Tel. [phone]

Notes to Editors

Rockhopper Exploration plc is a UK-based oil and gas exploration and production company with key interests in the Falkland Islands. The Company holds a 35 per cent interest in licences in the North Falkland Basin, where it has sanctioned the development of the significant Sea Lion field, originally discovered by the Company in 2010.

Rockhopper's shares are quoted on the AIM market of the London Stock Exchange under the ticker RKH.

For more information, visit the Company's website at www.rockhopperexploration.co.uk.

Glossary

Term	Definition
1C	Low estimate scenario of contingent resources; there is at least a 90% probability that the quantities actually recovered will equal or exceed the 1C estimate.
2C	Best (most likely) estimate scenario of contingent resources; there is at least a 50% probability that the quantities actually recovered will equal or exceed the 2C estimate.
3C	High estimate scenario of contingent resources; there is at least a 10% probability that the quantities actually recovered will equal or exceed the 3C estimate.
1P / Proved	Proved Reserves - those quantities of petroleum that, by analysis of geoscience and engineering data, can be estimated with reasonable certainty to be commercially recoverable from known reservoirs under defined conditions.
2P	Proved + Probable Reserves. The sum of 1P and Probable Reserves.
3P	Proved + Probable + Possible Reserves. The sum of 2P and Possible Reserves.
CDA	Central Development Area of the Sea Lion field.
Contingent Resources	Those quantities of petroleum estimated, as of a given date, to be potentially recoverable from known accumulations by application of development project(s) not currently considered to be commercial owing to one or more contingencies.
FID	Final Investment Decision - the decision by the joint venture to commit to full-scale project execution, having secured all necessary approvals and funding.
FPSO	Floating Production Storage and Offloading vessel.
MBBL	Thousands of barrels of oil.
MMBBL	Millions of barrels of oil (= 1,000 MBBL).
NDA	Northern Development Area of the Sea Lion field.
NPV10	Net present value of future net revenues discounted at an annual rate of 10 per cent. NPV10 should not be construed as the fair market value of the properties.
NSAI	Netherland, Sewell & Associates, Inc., independent petroleum engineers.
PRMS	2018 Petroleum Resources Management System approved by the Society of Petroleum Engineers (SPE) - the industry standard framework for the classification and categorisation of petroleum reserves and resources.
Reserves	Those quantities of petroleum anticipated to be commercially recoverable by application of development projects to known accumulations from a given date forward under defined conditions. Reserves must be discovered, recoverable, commercial, and remaining as of the evaluation date.
SPE	Society of Petroleum Engineers.
bbl/d	Barrels of oil per day.

 

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