Using a method based on geology, the U.S. Geological Survey estimates that the Bazhenov Formation of Russia's West Siberian Basin Province holds, on average, 12 billion barrels of oil and 75 trillion cubic feet of gas in continuous (unconventional) accumulations that could be recovered with current technology.
The Bazhenov Formation
The Upper Jurassic Bazhenov is a self-sourced, organic-rich mudstone — at least 2 percent total organic carbon by weight — with mostly Type II kerogen. It has been widely studied: its source-rock properties, tectonic and thermal history, and when it matured and generated oil and gas. Several fields in the south of the basin already produce continuous oil from fractured Bazhenov rock (Salym Field, for example). At the time of the study, no field produced shale gas from it.
For this assessment, a continuous source-and-reservoir rock needed:
- at least 2 percent total organic carbon by weight;
- thermal maturity in the oil or gas window;
- 15 metres or more of organic-rich shale;
- Type I or Type II organic matter.
The West Siberian Basin Province, with the Bazhenov Continuous Oil unit in the south and the Bazhenov Shale Gas unit in the north, around the Kara Sea inlets. USGS map, on a National Park Service base.
Two assessment units
- Bazhenov Continuous Oil — the south of the basin, where the Bazhenov is mature for oil.
- Bazhenov Shale Gas — the north, where it lies deeper and is presumed mature for gas. No shale gas has been produced there, but the rock is presumed similar to the south's.
Both units leave out discovered accumulations and places where conventional fields exist or might, on structural highs; undiscovered continuous oil and gas most likely lie between the highs.
Because detailed production data outside the United States are hard to obtain, recovery per well, drainage areas and success rates came from U.S. continuous-oil and shale-gas wells.
| Assessment unit | Mean potential area (acres) | Mean drainage per well (acres) | Mean recovery per well | Probability |
|---|---|---|---|---|
| Bazhenov Continuous Oil | 68,000,333 | 180 | 0.065 million barrels | 1.0 |
| Bazhenov Shale Gas | 32,250,333 | 120 | 0.522 billion cu ft | 1.0 |
Half of wells were expected to succeed in each (range 10 to 90 percent).
The results
| Assessment unit | Oil, mean (million barrels) | Gas, mean (billion cubic feet) | Natural gas liquids, mean (million barrels) |
|---|---|---|---|
| Bazhenov Continuous Oil | 12,219 (2,774 to 26,716) | 4,888 (1,106 to 10,721) | 69 (14 to 158) |
| Bazhenov Shale Gas | — | 70,268 (16,340 to 148,563) | 1,546 (340 to 3,444) |
| Total | 12,219 | 75,156 (17,446 to 159,284) | 1,615 (354 to 3,602) |
Ranges run from a 95 percent to a 5 percent chance.
Sources
- West Siberian Basin Province Assessment Team (Timothy R. Klett, Christopher J. Schenk, Michael E. Brownfield, Heidi M. Leathers-Miller, Tracey J. Mercier, Janet K. Pitman and Marilyn E. Tennyson), Assessment of Undiscovered Continuous Oil and Shale-Gas Resources in the Bazhenov Formation of the West Siberian Basin Province, Russia, 2016, USGS Fact Sheet 2016–3083, November 2016. https://doi.org/10.3133/fs20163083
- Results: USGS Energy Resources Program, http://energy.usgs.gov
Licence: CC0 1.0 (public domain) · Adapted from pubs.usgs.gov
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