According to data from the pan-European Aggregated Gas Storage Inventory (AGSI) platform, published on the Energy Map portal, as of the end of gas day on 31 October, Ukraine’s underground gas storage facilities (UGS) held 11.31 bcm of gas. Including 4.64 bcm of long-term storage gas, total reserves amounted to 15.95 bcm.
This figure is almost 1.35 bcm (9.2%) higher than the baseline gas storage target for the start of the heating season set by the Ministry of Energy at 14.6 bcm.
Long-term storage gas consists of 942 mcm of gas that Ukrtransgaz (underground gas storage operator) transferred to its fixed assets in 2022-2025 and which serves as cushion gas, as well as 3.7 bcm of working gas stored in UGS to compensate for the shortage of cushion gas. These figures are based on Ukrtransgaz’s 2025 financial statements.
In October, 0.32 bcm of gas was injected into storages, down 64.9% compared to September 2026 and 22.8% compared to October 2025.
The average daily gas injection rate in October was 11.4 mcm. This was 59.8% below the 2026 injection season average of 28.3 mcm and 71.1% below the 2025 season average of 39.4 mcm.
The decline in gas injection volumes in October may have been influenced by the continuation and increase in re-exports of gas previously injected into Ukraine’s UGS under the customs warehouse regime. According to the Gas Transmission System Operator of Ukraine (GTSOU), commercial gas outflows from Ukraine’s GTS in October amounted to:
- To Hungary: 197.5 mcm (including 194.4 mcm under the customs warehouse regime), up 67.4% compared to September (118 mcm, including 116.1 mcm under the customs warehouse regime);
- To Poland: 94.9 mcm (including 80.8 mcm under the customs warehouse regime), 2.3 times higher than in September (40.8 mcm, the entire volume under the customs warehouse regime);
- To Slovakia: 112.8 mcm (the entire volume under the customs warehouse regime), whereas no re-exports to Slovakia took place in September.
The decrease in injection volumes is due to virtual natural gas substitution operations provided for by the GTS Code. Under this mechanism, instead of physically withdrawing from storage gas that is held under the customs warehouse regime and is subject to re-export, physical injection volumes are reduced by the amount of the counter-flow of re-exports. The corresponding volume of gas thus remains in storage but changes ownership.
The 2026 gas injection season ended on 28 October, having lasted 232 days, from 11 March through 28 October inclusive. By comparison, the 2025 season ran from 17 April to 3 November (201 days). For the purpose of determining the duration of the injection season, its start is defined as the first day of three consecutive days on each of which net gas injection (injection minus withdrawal) exceeds 1 mcm, provided that net injection remains positive for the following seven days. The same approach is used to determine the start of the withdrawal season.
In total, 6.56 bcm of gas was injected into Ukraine’s UGS during the 2026 season, 17.2% less than the 7.92 bcm injected during the 2025 season. The difference in injection volumes between 2025 and 2026 is attributable, among other factors, to the significant volumes of gas imports in 2025, which have been almost absent this year. This is clearly reflected in the data on physical gas flows into Ukraine’s GTS: from April to October 2025, these amounted to 4.26 bcm, compared to just 0.26 bcm over the same period in 2026.
At the same time, gas withdrawal from Ukraine’s UGS began. During the last three days of October, 1.9 mcm of gas was injected into UGS, while 14.3 mcm was withdrawn. One of the reasons for the start of gas withdrawals in October was the start of the heating season in some communities. Certain public institutions, hospitals and social facilities began receiving heat supply and consuming natural gas. This is also supported by temperature data: the average HDD** index in October was 200.0, compared to 80.3 in September. This indicates higher weather-driven heating demand in October and, consequently, increased demand for natural gas.
It is worth noting that on 7 October, for the first time since the beginning of the full-scale invasion, the government adopted a decision to partially lift the ban on exports of domestically produced natural gas. The resolution allows gas production companies, between 1 March and 30 November, to sell up to 15% of the gas delivered at entry points to Ukraine’s GTS in the previous month. However, the partial lifting of the export ban is unlikely to have had a significant impact on gas injection and withdrawal trends in October 2026. According to data from the Ukrainian Energy Exchange, published on the Energy Map portal, the earliest delivery date for exported Ukrainian-produced gas was 26 October 2026, while most of the auctions held specified November–December 2026 as the delivery period.
* To convert energy units (TWh, GWh) into volume units (bcm, mcm), a conversion factor of 10.595 kWh/m³ was used.
** Heating Degree Days (HDD) is an indicator used to assess weather-dependent heating demand. It is calculated as the sum of positive differences between the baseline comfort temperature (18°C) and the average daily outdoor air temperature. For the purposes of this article, Ukraine’s HDD values were determined based on average daily temperatures in four cities (Dnipro, Kharkiv, Kyiv and Lviv), with the national HDD figure calculated as the arithmetic mean of the HDD values for these cities.
For days on which the data provider did not supply gas injection data for the gas day, linear interpolation was used (the arithmetic mean of the gas injection figures for the days immediately preceding and following the date for which data was missing).