The Black Sea · natural gas
Neptun Deep: in summer, the new gas needs pipes that carry no gas out of Romania today
From 2027, Neptun Deep, a gas field in Romania's sector of the Black Sea, is due to land about 8.0 billion cubic metres (bcm) a year at Tuzla, on the coast south of Constanța. That is 21.9 million cubic metres every day. In 2024, 8.6 bcm of Romanian gas entered the transmission system and 9.1 bcm left it for users at home. In winter the new gas has somewhere to go. In summer the country uses four times less gas than in January, the underground stores fill up, and the pipes out of the country are narrow. This page shows the measured balance of every day in 2024, then the same day in a model with Neptun Deep at plateau, assumptions in plain view.
Where Romania's gas goes on a chosen day
The Neptun Deep stream and the doors out of Romania, at one scale: thickness = million m³ a day
Million m³ a day. Converted from energy at 1 million m³ = 10.7 GWh, from the Depogaz table. On the map the stores sit at their AGSI+ coordinates; exit pipes are drawn at the border point, and the inland network and the Tuzla–Podișor pipe on schematic routes. In the model, a day's exports are shared between exits by capacity, and every store is equally full.
Any day of the year can be picked. The first setting shows that day in 2024 as Transgaz, Romania's gas transmission operator, reported it to ENTSOG, the European network of gas transmission operators: how much was produced, used in the country, put into or taken out of storage, and sent across the borders. The other two settings are a model, not a forecast: they add the Neptun Deep plateau, 21.9 million cubic metres a day, to the same 2024 day, fill storage first, then send the rest out through the existing pipes. Whatever has no room is shown as such.
The tightest modelled day is 15 June, on the 2024 pattern: output 45.0 million cubic metres, use 8.1 million. Through the exits that actually carried gas out of Romania in 2024, towards Hungary and Moldova, 23.5 million cubic metres have nowhere to go that day, more than Neptun Deep's whole output: some onshore gas would have no room either. Through every exit on paper, including towards Bulgaria, 1.6 million are left over. In the model the stores are already full from 28 March. It is a single day: on 15 June 2024 large industrial users took only 2.4 million cubic metres, against 4–7 million on the days around it, and 23 June was nearly as low. On the same day, as measured, the pipe to Hungary ran full at 7.4 million, while at Negru Vodă gas flowed into Romania.
The gas year: a tide between January and August
Onshore production runs almost flat all year, around 23.5 million cubic metres a day. Use makes the wave: 55.2 million on the day of highest use, 10 January 2024 and 8.1 million on a Saturday in June. Today the wave is smoothed by storage, which gave out an average of 16.5 million cubic metres a day from December to February and took in 9.4 million a day from May to August, plus winter imports. With Neptun Deep, daily output rises to about 45 million cubic metres, close to an ordinary January day's use. Winter stays tight only on the coldest days. The problem moves to summer.
| Month (2024) | Production | Use | Into storage | Out of storage |
|---|---|---|---|---|
| January | 23.9 | 47.5 | 0.1 | 19.9 |
| February | 24.1 | 36.7 | 0.3 | 9.1 |
| March | 24.2 | 33.1 | 0.9 | 6.0 |
| April | 24.2 | 16.4 | 8.8 | 0.9 |
| May | 23.4 | 13.0 | 9.4 | 0.1 |
| June | 22.7 | 11.8 | 10.2 | 0.1 |
| July | 22.9 | 13.3 | 8.1 | 0.0 |
| August | 23.3 | 11.9 | 10.0 | 0.2 |
| September | 22.1 | 12.7 | 8.1 | 0.2 |
| October | 23.8 | 20.7 | 2.8 | 1.5 |
| November | 23.5 | 38.4 | 0.1 | 18.0 |
| December | 23.9 | 42.3 | 0.0 | 20.1 |
How much gas can leave the country in a day
Romania has four interconnection points with firm exit capacity on paper; a fifth, Isaccea 1 towards Ukraine, had none in December 2024. Together they add up to 35.3 million cubic metres a day, or 12.9 bcm a year if they ran full all year. In 2024, though, gas flowed out almost only towards Hungary, 1.8 bcm, and towards Moldova, 0.4 bcm. The big pipe at Negru Vodă, on the Bulgarian border, which holds the largest exit capacity on paper, worked the other way all year: it brought 2.2 bcm into Romania from Bulgaria. The exits actually used in 2024, Hungary plus Moldova, can take at most 13.4 million cubic metres a day, or 4.9 bcm a year, below the model's annual surplus of 7.5 bcm.
| Exit point | Exit capacity | Actually flowed out in 2024 | Actually flowed in in 2024 |
|---|---|---|---|
| Csanádpalota to Hungary | 7.4 million m³ a day | 1.8 bcm a year | 0.0 bcm a year |
| Ungheni to Moldova | 6.1 million m³ a day | 0.4 bcm a year | 0.0 bcm a year |
| Giurgiu–Ruse to Bulgaria | 4.1 million m³ a day | 0.0 bcm a year | 0.0 bcm a year |
| Negru Vodă 1 to Bulgaria | 17.7 million m³ a day | 0.0 bcm a year | 2.2 bcm a year |
| Isaccea 1 to Ukraine | 0.0 million m³ a day | 0.0 bcm a year | 0.0 bcm a year |
Daily firm technical capacities, ENTSOG Transparency, December 2024. Isaccea 1, towards Ukraine, had no firm exit capacity in December 2024. Capacity on paper says what can pass through a pipe on a good day; what actually flows also depends on demand beyond the border and on booked capacity, which the model does not guess.
At the exits, one important thing has changed since 2024. Since June 2025 Isaccea 1 has had firm exit capacity towards Ukraine, 11.5 million cubic metres a day, and between January 2025 and October 2026 it carried 0.3 bcm out, at most 4.1 million in a day, mostly in winter. Towards Bulgaria over the same period nothing left through Negru Vodă and almost nothing through Giurgiu, while 7.2 bcm came in at Negru Vodă. If the exit to Ukraine is added to those towards Hungary and Moldova, 24.9 million a day, the model still leaves 1.3 bcm a year with no room, on 197 days, and 12.0 million on 15 June.
The stores: 3.2 bcm behind a tap of 26.6 million a day
Romania's underground stores are emptied gas fields: Bilciurești, Sărmășel, Urziceni, Ghercești and Bălăceanca, run by Depogaz, a subsidiary of the state producer Romgaz, plus Târgu Mureș, run by Depomureș. On AGSI+, the European storage transparency platform, they declare a working volume of 33.9 TWh between them, about 3.2 bcm. On the map each store's area follows its capacity, and it fills with its stock as measured day by day. In 2024 the stock began at 83% on 1 January, fell to 50% on 28 March and rose to 103% on 21 October, a little above the declared volume. But gas cannot go in at any speed: the firm technical capacity reported to ENTSOG allows at most 26.6 million cubic metres a day of injection and 35.6 million of withdrawal, and in 2024 the busiest injection day reached 17.9 million. At the Neptun Deep plateau, the whole storage system equals 144 days of the field's output. Once full, it takes nothing more until winter. In the model, because a Neptun Deep winter barely touches the stores, they stay nearly full all year and lose their present job of moving summer gas into winter.
The model: a full year with Neptun Deep at plateau, on the 2024 pattern
This is arithmetic, not a forecast, and it predicts no prices. It takes each day of 2024 as measured and asks one question: if the Neptun Deep plateau had flowed on top of that day, where would the gas have fitted?
- Neptun Deep produces flat out, 21.9 million cubic metres a day, which is 8.0 bcm a year divided by 365 days. The field's owners, OMV Petrom (the Romanian arm of Austria's OMV) and Romgaz, put the plateau at about 8.0 bcm a year, reached towards the end of the third quarter of 2027.
- Onshore production and use stay as measured in 2024, day by day. New industrial or power-station demand, promised in various strategies, is left out on purpose, so that its absence is visible.
- Each day's surplus fills storage first, at up to 26.6 million cubic metres a day, up to 3.2 bcm. The rest leaves the country. A winter shortfall is covered from storage at up to 35.6 million a day. Storage starts the year at the level measured in 2024, 83% full. Capacity is the working volume declared on AGSI+.
- Leaving the country has two variants: only the pipes that carried gas out in 2024, towards Hungary and Moldova, 13.4 million a day; or every exit on paper, 35.3 million a day, including towards Bulgaria, where in 2024 gas flowed in.
- With the exits used in 2024, the model leaves 3.8 bcm with nowhere to go over a 2024-pattern year, on 220 days, and exports 3.2 bcm. With every exit on paper, small amounts are left over on 5 days in May and June and exports reach 7.0 bcm, provided someone beyond the border takes gas every single day.
What would change the answer: more summer demand at home, bigger stores, bigger exits westwards, or an offshore field that slows down on days without buyers. The model does not say which of these will happen. It says how much room is missing in today's pipes and stores.
Sources and limits
The daily flows and capacities for 2024 come from the ENTSOG Transparency Platform, where Transgaz reports daily physical flows for production, distribution, final consumers, storage and the interconnection points. The 2024 balance closes with a gap of 0.5% between gas in and gas out, within the range of the network's own use and rounding. ENTSOG's 2024 use figure, 97 TWh at the exits of the national transmission system, sits below Romgaz's estimate of about 106 TWh for total national consumption; this page uses the ENTSOG series throughout so that days stay comparable. The daily stock in each store and the declared working volume come from AGSI+, the storage platform run by Gas Infrastructure Europe. Daily injections and withdrawals on AGSI+ and those Transgaz reports to ENTSOG move almost identically (correlation 0.998). On the map, Neptun Deep is drawn at the published position of the licence area, in about 1,000 m of water, with the platform on the same bearing where the sea is about 100 m deep; the real pipe to Tuzla is about 160 km long. The Neptun Deep figures come from OMV Petrom and Romgaz statements: about 100 bcm recoverable and a plateau of about 8.0 bcm a year. For checking the gas installation and boiler in a Romanian flat there is a separate page, gas check and boiler check dates.