Quelque chose à améliorer ? Proposez une modification.
Summary
The U.S. Geological Survey assessed undiscovered oil and gas in sandstone reservoirs of the Upper Jurassic–Lower Cretaceous Cotton Valley Group, which curves underground from south Texas to the Florida Panhandle, in onshore lands and state waters of the U.S. Gulf Coast. Mean estimates:
| Resource | Mean |
|---|---|
| Conventional oil | 14 million barrels |
| Conventional gas | 430 billion cubic feet |
| Continuous (tight) gas | 34,028 billion cubic feet |
| Natural gas liquids | 391 million barrels |
The four Cotton Valley assessment units. USGS; base from the National Park Service.
The petroleum system
The assessment rests on a total petroleum system — source rocks, reservoirs, seals, traps and history:
- Reservoirs: river-delta and shallow-marine "blanket" sandstones with moderate to high porosity and permeability, and their "massive" deeper equivalents with lower porosity and permeability.
- Sources: likely the Upper Jurassic Smackover, Haynesville and Bossier formations.
- Seals: mudstone and thin limestone within the formation, and the regional Knowles Limestone.
- Traps: stratigraphic, structural or both — though low-permeability rock can hold petroleum without a well-defined trap.
Four assessment units
| Unit | Where | Notes |
|---|---|---|
| Updip Oil | between the updip edge of the group and a regional fault system | no production yet; oil expected in coastal and delta sandstones of the Schuler Formation |
| Peripheral Fault System Oil and Gas | wrapping the peripheral fault system, bounded by the edges of the East Texas Basin and the North Louisiana and Mississippi salt basins | mostly coastal and delta reservoirs |
| Downdip Oil and Gas | the salt basins and the areas between | river-delta and marine sandstones; accumulations tied to gentle salt structures along basin edges |
| Tight Sandstone Gas (continuous) | the tight "massive" Terryville Sandstone, from the southwest East Texas Basin across the Sabine uplift and northern Louisiana into southern Mississippi | where most of the undiscovered gas lies |
Two units overlap in east Texas and north Louisiana; production data from separate volumes of rock were assigned to each.
Results
Of the 14 million barrels of oil, the Updip unit holds 1, the Peripheral Fault System 2 and the Downdip 11. Total gas is 34,458 billion cubic feet — 430 conventional and 34,028 in the Tight Sandstone Gas unit.
Sources
Based on Jennifer D. Eoff and others, "Assessment of Undiscovered Oil and Gas Resources in Sandstone Reservoirs of the Cotton Valley Group, U.S. Gulf Coast," U.S. Geological Survey fact sheet; a work of the United States government in the public domain. The map is taken from the fact sheet's PDF.
Licence : CC0 1.0 (domaine public) · Adapté de pubs.usgs.gov
1
0
0
0
commentaires
