In 2014 the U.S. Geological Survey estimated how much undiscovered, technically recoverable oil and gas might lie in the Silurian shales of Jordan — the organic-rich rocks that both generated the hydrocarbons and still hold them.
Shale oil is not oil shale
The assessment covered shale oil: mature oil already generated and still trapped in its source rock. It did not cover Jordan's oil shale, a rock whose organic matter (kerogen) is too immature to have made oil. Jordan's conventional oil and gas were assessed separately in 2012, as part of the Middle East.
What makes a candidate
To be assessed, a source rock must have:
- more than 2 weight percent total organic carbon;
- the right thermal maturity for oil or gas;
- more than 15 m of organic-rich shale;
- Type I or II organic matter;
- depths greater than 1,500 m.
Outside these limits, significant resources are unlikely without major technological advances or much higher prices.
The problem: uplift
Jordan's Silurian marine shales had already matured and generated oil and gas before the Hercynian orogeny, the mountain-building of the Devonian to Carboniferous. That event lifted and eroded the region by 2,500 m or more in places, so the key question was whether the oil and gas stayed in the rock. That retention risk shaped the whole assessment.
Three assessment units
The three areas of Jordan assessed. USGS, on a National Park Service base map.
| Assessment unit | Target | Geology |
|---|---|---|
| Sirhan Area | oil | 2,500 m or more of uplift and erosion left most of the shale shallower than 1,500 m, sharply reducing its potential |
| East Safawi Area, northeast | oil | uplift partly eroded the shales, so the risk that oil escaped is high |
| Risha Area | gas | perhaps 1,200 m of uplift, with less effect on retaining gas |
Inputs came from U.S. shale analogs:
| Input | Sirhan (oil) | East Safawi (oil) | Risha (gas) |
|---|---|---|---|
| Potential production area, acres (mean) | 106,333 | 315,333 | 460,333 |
| Average well drainage area, acres (mean) | 153 | 153 | 160 |
| Success ratio (mean) | 40% | 40% | 50% |
| Average recovery per well (mean) | 0.034 million barrels | 0.034 million barrels | 0.24 billion cubic feet |
The results
| Resource | Mean | Range (95% to 5% chance) |
|---|---|---|
| Shale oil | 11 million barrels | 0–45 |
| Shale gas | 320 billion cubic feet | 0–917 |
| Natural gas liquids | 25 million barrels | 0–79 |
- Oil: 8 million barrels in the Sirhan Area, 3 million in East Safawi.
- Gas: nearly all in the Risha Area — a mean of 312 billion cubic feet (0–885).
- The Risha and Sirhan units were given a 0.9 probability of holding any resource; East Safawi only 0.1.
The wide ranges, all starting at zero, reflect how uncertain it is whether Jordan's Silurian shales kept their oil and gas through the uplift.
Sources
Based on Schenk CJ, Pitman JK, Charpentier RR, et al., "Assessment of potential shale-oil and shale-gas resources in Silurian shales of Jordan, 2014," U.S. Geological Survey Fact Sheet 2014–3082, National and Global Petroleum Assessment Project; a work of the United States government in the public domain. The map and both tables were recovered from the fact sheet's PDF; the imported text lacked them.
Licence: CC0 1.0 (public domain) · Adapted from pubs.usgs.gov
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