Unconventional reservoir
An unconventional reservoir consists of an ultra tight source rock, trap and seal containing organic rich matter that has reached thermal maturity without migration.
Unconventional vs. Conventional
The difference between a conventional and unconventional reservoir is migration. The unconventional reservoir has hydrocarbons that were formed within the rock and never migrated. The conventional reservoir is a porous rock formation that contains hydrocarbons that have migrated from a source rock (unconventional reservoir).
Hydrocarbon Evaluation
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Unconventional reservoirs are evaluated based on their potential to be a successful hydrocarbon system. The following evaluations are completed to quantitatively determine this.
- Maturity- Have the kerogens spent enough time in the oil window to turn into hydrocarbons?
- Bulk Volume Hydrocarbon- Is the bulk volume of hydrocarbons within the source rock enough to make it economical (40-60% max expulsion)?
- Clay Content- If the clay content is too high, the rock will become ductile, which will make fracking the rock much more difficult.
- Kerogen Content- The type of kerogen found in a source rock is used to determine what type of [hydrocarbon] your reservoir can contain.
| Kerogen type | Predominant hydrocarbon potential | Amount of hydrogen | Typical depositional environment |
|---|---|---|---|
| I | Oil prone | Abundant | Lacustrine |
| II | Oil and gas prone | Moderate | Marine |
| III | Gas prone | Small | Terrestrial |
| IV | Neither (primarily composed of vitrinite) or inert material | None | Terrestrial(?) |
Geology
Unconventional reservoirs are formed in basins when a marine transgression occurs. During the transgression, low sediment input into the basin with a large organic content will result in a source rock that can then become an unconventional reservoir.
Major Unconventional Plays
Unconventional reservoirs have been found throughout the world. Below is a list of the top 10 countries by unproved technically recoverable shale oil resources.
1. U.S.
2. Russia
3. China
4. Argentina
5. Libya
6. United Arab Emirates
7. Chad
8. Australia
9. Venezuela
10. Mexico
References
- Treatise of Petroleum Geology/Handbook of Petroleum Geology: Exploring for Oil and Gas
Traps, Pages 6-1 - 6-41, Edited by Edward A. Beaumont and Norman H. Foster
See also
Important Papers
- Treatise of Petroleum Geology/Handbook of Petroleum Geology: Exploring for Oil and Gas
Traps, Pages 6-1 - 6-41, Edited by Edward A. Beaumont and Norman H. Foster
Kendall,Chiarenzelli, and Hassan, "Sources - World Petroleum"
External links
- Google:Conventional vs. Unconventional Reservoirs — Croft Production System Image of Conventional vs. Unconventional Reservoirs
- Van Eck Global Presentation September 2005 - Unconventional oil and gas- Van Eck Global Presentation
- [http://wiki.aapg.org/Kerogen AAPG Article Treatise of Petroleum Geology/Handbook of Petroleum Geology: Exploring for Oil and Gas
Traps, Pages 6-1 - 6-41, Edited by Edward A. Beaumont and Norman H. Foster] - Used for the Kerogen table
Top 10 Countries by Unproved Technically Recoverable Shale Oil Resources