The four continuous oil and gas assessment units in the Amu Darya Basin Province. Map: U.S. Geological Survey.
The U.S. Geological Survey (USGS) has estimated how much undiscovered, technically recoverable continuous (unconventional) oil and gas the Amu Darya Basin Province of Turkmenistan, Uzbekistan and Afghanistan may hold. It reassesses the province's tight gas, shale oil and shale gas using data that became available after the previous USGS assessment, completed in 2017.
The estimate
| Resource | Mean | F95 to F5 range |
|---|---|---|
| Oil | 519 million barrels (0.52 billion) | 128 to 1,062 million barrels |
| Gas | 82,934 billion cubic feet (82.9 trillion) | 18,321 to 183,175 billion cubic feet |
| Natural gas liquids | 660 million barrels (0.66 billion) | 142 to 1,475 million barrels |
F95 is a 95 percent chance of at least the amount given; F5 is defined the same way. The results are fully risked.
How the basin formed
- Triassic to Jurassic: the province began as an extensional backarc basin made up of horsts and grabens.
- Early to Middle Jurassic: the grabens filled with nonmarine synrift deposits, mostly sandstones, mudstones, widespread coal beds and carbonaceous shales.
- Late Jurassic: rifting slowed and thermal subsidence followed, laying down widespread carbonate platforms and, off the platforms, organic-rich marine shales. Jurassic burial matured the coal beds and carbonaceous shales enough to generate gas.
- Neogene: a foreland basin formed alongside the Köpetdag Fold Belt on the basin's southwestern margin. The added burial pushed coal beds and Jurassic organic-rich shales into the thermal gas window across much of the province. At the margins, such as the northern edge in Uzbekistan, Upper Jurassic shales reached only the oil window.
Two petroleum systems, four units
Mesozoic Composite system: gas from coal
Lower–Middle Jurassic coal beds crossed the threshold for gas generation over most of the province and are the basin's main gas source rocks. Their gas moved short distances into low-permeability ("tight") sandstone and carbonate, defined here as rock of 0.1 millidarcy or less.
- Lower–Middle Jurassic Tight Sandstone Gas unit. Gas trapped in fluvial, coastal plain, deltaic and nearshore marine sandstones, mainly in the east-central basin. The interval may be 1,600 meters thick and reaches depths of 7 kilometers. The coal beds may also have made oil that deeper burial turned to condensate.
- Lower–Upper Jurassic Tight Carbonate Gas unit. Gas trapped in fractured carbonate of platform margins, slopes and the basin floor. Natural and induced fractures may matter for getting it out.
No production tests or other evidence of movable gas exist here, so the assessment used U.S. tight sandstone and tight carbonate gas reservoirs as geologic and production analogs. Ultradeep, high-temperature, highly overpressured reservoirs, such as the Bereketli-Pirgui gas field, are left out.
Jurassic Shale system: oil and gas that stayed in the shale
This system covers the area where organic-rich Callovian to Oxfordian shales are mature for oil and gas. The shales are black, bituminous and up to 250 meters thick, with oil-prone type-II and -IIS kerogen and total organic carbon of up to 15 weight percent. They matured for oil in the Late Cretaceous and for gas in the Paleogene, and gas from them can carry up to 8 percent hydrogen sulfide.
- Jurassic Shale Oil unit. Oil left in the rock matrix after some of it migrated into conventional sandstone and carbonate reservoirs. It was drawn mainly from thermal maturity data in Uzbekistan showing the updip shales mature for oil rather than gas, though the boundary between oil and gas generation is uncertain.
- Jurassic Shale Gas unit. Gas from the shales, or from oil cracked to gas, left in the shale after part of it moved into conventional reservoirs.
Inputs and results by unit
Mean values; EUR is estimated ultimate recovery.
| Unit | Potential production area (acres) | Average drainage area (acres) | Average EUR | Undiscovered gas (billion cubic feet) | Gas liquids (million barrels) |
|---|---|---|---|---|---|
| Tight Sandstone Gas | 12,243,000 | 80 | 0.528 billion cubic feet | 41,023 | 328 |
| Tight Carbonate Gas | 3,423,333 | 140 | 1.534 billion cubic feet | 19,059 | 152 |
| Shale Oil | 1,270,333 | 100 | 0.081 million barrels of oil | 1,921 | 13 |
| Shale Gas | 7,986,000 | 100 | 0.528 billion cubic feet | 20,931 | 167 |
All the oil, a mean of 519 million barrels, comes from the Shale Oil unit. In every unit the success ratio ranges from 10 to 90 percent with a mean of 50, the whole area is untested, and the unit's probability is 1.0.
Results are also on the USGS Energy Resources Program website: https://www.usgs.gov/programs/energy-resources-program
Sources
- Schenk CJ, Mercier TJ, Le PA, Cicero AD, Gelman SE, Hearon JS, Johnson BG, Lagesse JH, Leathers-Miller HM. "Assessment of undiscovered continuous oil and gas resources in the Amu Darya Basin Province of Turkmenistan, Uzbekistan, and Afghanistan." U.S. Geological Survey Fact Sheet. https://pubs.usgs.gov/publication/fs20263013/full
- The fact sheet draws on Ulmishek (2004), Schenk and others (2017), Schenk (2026) for input data, and unpublished 2024 data from the Ministry of Mining Industry and Geology of the Republic of Uzbekistan.
Licence: CC0 1.0 (public domain) · Adapted from pubs.usgs.gov
1
0
0
0
Comments
