Chinarevskoye Reserves
The Chinarevskoye field (Chinarevskoye) is the Group’s only producing field, governed by a PSA since 1997, with the licence valid until 2031. Since 2004, 105 wells and side-tracks have been drilled under the PSA.
The field features 17 reservoirs and 53 compartments spread over three areas, with commercial hydrocarbons identified in formations such as the Lower Permian, Bashkirian, Bobrikovski, Tournaisian, Frasnian, Mullinski, Ardatovski, and Biyski-Afoninski reservoirs. The licence is 100% owned by Zhaikmunai, the Group’s principal Kazakhstan operating company.
As of 31 December 2024, total 2P (Proven plus Probable) reserves are 18 mmboe, reflecting a net reduction of 2 mmboe due to increased water ingress. The 1P (Proven) reserves amount to 12.9 mmboe, a 3.4 mmboe decline year-on-year, primarily due to 2024 production and the reclassification of smaller reserves beyond the licence expiry.
The Proven and Probable reserves volume requires 13 CAPEX interventions, with an additional 10 OPEX well interventions for production maintenance (2023: 23.2 mmboe requiring14 CAPEX interventions).
Management’s estimates of reserves of 31 December 2024 and a comparison with the reserves of 31 December 2023 are summarized in Table 1. Please refer to page 147 for more details on estimation uncertainties.
The current Probable Undeveloped case assumes 10 rig-assisted interventions including five workover recompletions, side-tracking of three existing wells, and our new vertical well in the Bashkirian reservoir. After drilling 2 wells in 2023-2024 the company plans to continue its drilling activities and drill two more sidetracks in 2025.
In 2025, Nostrum plans to continue this workover and well intervention programme by targeting a limited number of reserves development wells along with production maintenance, and continue the drilling programme. This programme, together with the 45 existing producers, cover the estimated 2P reserves as at 31 December 2024. It should also be noted that there has been some decrease in volumes in undeveloped reservoirs associated with shifting of the drilling campaign.
Possible reserves of 5.1 mmboe as at 31 December 2024 (2023: 8.2 mmboe) are attributed to lower declines than the Proven and Probable cases in existing producers and 9 well interventions (4 WO, 2 sidetracks, 3 new wells).
Table 2 shows the breakdown of each reserves category by products.
Reserves by reservoir
The breakdown by reservoir is given in Table 3.
Biyski-Afoninski North-East
2P reserves are estimated at 4.91 mmboe, down 2.24 mmboe compared to 2023- year end (7.15 mmboe) which includes 1.14 mmboe of production in 2024 and a 1.1 mmboe negative revision due to further progressing of water encroachment.
Gas lift was introduced into the 2 last wells, predominantly through low cost rigless interventions and using the expanded Gas lift system commissioned in July 2023.
Probable and Possible Developed volumes are attributed to existing producing wells, with lower declines interpreted respectively. Infill well Ch-20 is planned to be temporary transferred to Fillippovski for the period 2028-2030. The idle Well Ch-222 is planned to be put back in operations in 2025 after recompletion to GL and water shut-off.
Tournaisian North-East, West and South
The Tournaisian North-East has a total 2P of 6.76 mmboe at 2024-year end, representing a 1.75 mmboe decline year-on year, including 1.1 mmboe production and a 0.65 mmboe negative revision to reflect recent well performance.
Proven Undeveloped volumes are associated with the planned sidetrack of well (Ch-725) which replaces the formerly planned Ch-201_2 and perforation of Tournaisian in well No.301, currently producing Mullinski, to be done in Q2 2025. Whilst Probable Undeveloped Reserves are associated with a sidetrack of well Ch- 225_2, recompletion of Ch-220 (from waterised Biyski) and continuing development of the Waterflood with one WO conversion and a sidetrack injection well (Ch-52_2). Production maintenance workovers are planned in the reservoir in the years up to and including 2027.
Tournaisian West 2P is 0.56 mmboe despite 0.15 mmboe production. The increase of reserves associated with Ch-33 and Ch-204 was achieved by successful stimulation of T2 layer in Ch-33. New P3 drilling target (+0.29 mmboe) was identified NE of Ch-204 and this attic oil meant to be produced from a sidetrack well Ch-204_1 starting 2027. In the Tournaisian South, there are limited PDP volumes associated with the three remaining producers and Possible reserves associated with one new well planned for 2027.
Ardatovski North-East and South
Proven Producing volumes are associated with three current producers. One Probable Undeveloped side-track well is planned for the Ardatovski North-East reservoir in 2026. No further reserves development is planned for the Ardatovski South reservoir, beyond the current producer.
Frasnian North
2P reserves are estimated at 0.36 mmboe at year end 2024, despite 0.1 mmboe of production in 2024.
The development plan now foresees only one additional Possible Undeveloped side- track planned for 2025-2026.
Mullinski North-East, North and South
Proven Developed Producing reserves now associated with four wells, three in the North- East and one in the North respectively. Additional 4th well is the successfully drilled well No.301, which is producing from Mullinski NE since May 2024. Proven Undeveloped volumes are attributed to one new well in the North-East block and planned for drilling in 2025.
One Possible Undeveloped category well locations have been identified in the North-East block and is a side-track of an existing well, while one new Possible well is planned for drilling in the Mullinski South. These two wells are planned for 2026-2027.
Bashkirian North-East & West
PDP reserves remain for two wells produced via Electric Submersible Pumps (ESPs). One Probable Undeveloped new vertical well is proposed in the Bashkirian North-East from 2026.
Filippovski
Six low-cost workover recompletions (two Probable and four Possible) have been identified for the Filippovski reservoir. These are planned, subject to further technical and economic evaluation, to be carried out in 2025-2028.
Table 1 – Nostrum Reserves, mmboe
| 2024 | 2023 | Change | |
|---|---|---|---|
| Total PDP Total PUD/PDNP | 12.0 0.8 | 15.0 1.2 | -3.1 -0.4 |
| Total 1P Total Probable | 12.9 5.1 | 16.3 6.9 | -3.4 -1.8 |
| Total 2P Possible | 18.0 5.1 | 23.2 8.2 | -5.2 -3.1 |
| Total 3P | 23.1 | 31.4 | -8.3 |
Note: Barrel of oil equivalent (boe) totals are management estimates using a conversion factor of 5.327 mcf/boe.
Table 2 – Nostrum Reserves, by product and by reserves category
| Fluid | Unit | Proven Producing (PDP) | Proven Non-Producing & Undeveloped (PDNP & PUD) | Total Proven (1P) | Probable (2P) | Total Proven plus Probable | Possible (P3) | Total Proven, Probable and Possible |
|---|---|---|---|---|---|---|---|---|
| Oil/Condensate | barrels | 6,533,902 | 693,119 | 7,227,021 | 2,561,129 | 9,788,151 | 2,814,201 | 12,602,352 |
| Plant products (LPG) | barrels | 1,204,340 | 44,010 | 1,248,350 | 457,096 | 1,705,446 | 468,095 | 2,173,541 |
| Gas (after shrink) | mmcf | 22,882 | 473 | 23,355 | 11,200 | 34,555 | 9,600 | 44,155 |
| Gas (after shrink) | boe | 4,295,874 | 88,761 | 4,384,635 | 2,102,650 | 6,487,285 | 1,802,250 | 8,289,534 |
| Total | boe | 12,034,117 | 825,890 | 12,860,006 | 5,120,875 | 17,980,882 | 5,084,546 | 23,065,428 |
Table 3 – Comparison of reserves by reservoir 2024 versus 2023
| 31 December 2023 | 31 December 2022 | Change | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Reservoir | Proven, mmboe | Probable, mmboe | Possible, mmboe | 3P, mmboe | Proven, mmboe | Probable, mmboe | Possible, mmboe | 3P, mmboe | Proven, mmboe | Probable, mmboe | Possible, mmboe | 3P, mmboe |
| Biyski/Afoninski NE | 4.3 | 0.6 | 0.8 | 5.7 | 6.1 | 1.0 | 0.8 | 7.9 | -1.8 | -0.4 | 0.0 | -2.2 |
| Tournaisian NE | 4.9 | 1.9 | 0.6 | 7.4 | 6.1 | 2.4 | 1.3 | 9.8 | -1.2 | -0.6 | -0.7 | -2.5 |
| Frasnian N | 0.3 | 0.1 | 0.8 | 1.2 | 0.4 | 1.1 | 2.5 | 4.0 | -0.1 | -1.0 | -1.7 | -2.8 |
| Ardatovski NE | 0.8 | 1.6 | 0.1 | 2.5 | 1.5 | 1.6 | 0.1 | 3.2 | -0.7 | 0.0 | 0.0 | -0.7 |
| Filippovski | 0.3 | 0.4 | 0.7 | 1.4 | 0.2 | 0.2 | 0.8 | 1.2 | 0.1 | 0.1 | -0.1 | 0.2 |
| Tournaisian South | 0.3 | 0.1 | 0.7 | 1.1 | 0.3 | 0.1 | 0.7 | 1.2 | 0.0 | 0.0 | 0.0 | -0.1 |
| Mullinski NE | 0.7 | 0.1 | 0.3 | 1.2 | 0.6 | 0.0 | 1.1 | 1.8 | 0.1 | 0.1 | -0.8 | -0.6 |
| Bashkirian NE & W | 0.5 | 0.2 | 0.0 | 0.8 | 0.5 | 0.2 | 0.0 | 0.7 | 0.0 | 0.0 | 0.0 | 0.0 |
| Tournaisian West | 0.5 | 0.1 | 0.3 | 0.9 | 0.3 | 0.1 | 0.0 | 0.4 | 0.2 | 0.0 | 0.2 | 0.5 |
| Mullinski South | 0.0 | 0.0 | 0.6 | 0.6 | 0.0 | 0.0 | 0.7 | 0.7 | 0.0 | 0.0 | -0.1 | -0.1 |
| Bobrikovski South | 0.1 | 0.1 | 0.0 | 0.2 | 0.1 | 0.1 | 0.0 | 0.2 | 0.0 | 0.0 | 0.0 | 0.0 |
| Ardatovski S | 0.1 | 0.0 | 0.0 | 0.2 | 0.1 | 0.0 | 0.0 | 0.2 | 0.0 | 0.0 | 0.0 | 0.0 |
| Mullinski North | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Total | 12.9 | 5.1 | 5.1 | 23.1 | 16.3 | 6.9 | 8.2 | 31.4 | -3.4 | -1.8 | -3.1 | -8.3 |