Sea Lion Reserves Evaluation
Sea Lion reserves reclassified to higher category following Phase 1 FID; 2P reserves exceed 100 million barrels.
- 2P Reserves (Working Interest 35%) 109,843.2 MBBL
- 2P Reserves NPV10 (Working Interest 35%) US$965,782.5k
- Cash balance at 31 December 2025 US$179 million
- Working interest in Sea Lion field 35%
- 3P Reserves (Working Interest 35%) 142,857.4 MBBL
- Best Estimate Contingent Resources (Working Interest 35%) 211,106.7 MBBL
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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
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
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.
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. |
| 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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