This document provides an overview of petroleum systems, including the key elements of source rock, migration pathways, reservoirs, seals, and traps. It discusses the organic material and rock types that form source rocks, including non-biogenic and biogenic origins. Biogenic source rocks include oil-prone and gas-prone kerogen types found in shales and coals. The document also covers generation of petroleum from organic matter, migration through the subsurface, accumulation in traps, and preservation. Various basins and their source rocks, fields, and representative petroleum system characteristics are briefly outlined.

1. Petroleum Systems
(Part One)
Source, Generation, and Migration
GEOL 4233 Class
August, 2011

2. Petroleum Systems
Source Rock
Migration Route
Reservoir Rock
Seal Rock
Trap
Elements
Generation
Migration
Accumulation
Preservation
Processes

3. Petroleum System Summary
• Source (Material and Rocks)
• Generation (Maturation)
• Migration
• Trap
• Reservoir

4. Source Material
Non-Biogenic Origins
Biogenic (Kerogen) – Host rock (Shales and Coals)
Kerogen Types
Type I – Algal (oil prone) sapropelic
Type II – Mixed
Type III – Woody (gas prone) humic

5. Siljan ‘Ring’
Inorganic Gas Prospect
Drilled to ~22,000’ in 1987
Found abiogenic methane,
but no poro-perm

7. Sedimentary Rocks – Where the Action Is

8. Source Material
Non-Biogenic Origins
Biogenic (Kerogen Types)
Type I – Algal (oil prone) sapropelic
Type II – Mixed
Type III – Woody (gas prone) humic
Host rock (Shales and Coals)

9. Types of Petroleum
Oil and gas are formed by the thermal cracking of
organic compounds buried in fine-grained rocks.
Algae = Hydrogen rich = Oil-prone
Wood = Hydrogen poor = Gas-prone

10. Kerogen Types
Type 1 Type 2 Type 3

11. From the Paleontological Research Institute <http://www.priweb.org/ed/pgws/history/pennsylvania/pennsylvania.html>

12. Ganges Deltaic
Sediments

13. Modern Mahakam Delta Plain
East Kalimantan, Indonesia
(A Rich Source of Kerogen)

14. Inferred Middle Booch Depositional Environments
Arkoma Basin in Oklahoma

15. Source Material
Non-Biogenic Origins
Biogenic (Kerogen Types)
Type I – Algal (oil prone) sapropelic
Type II – Mixed
Type III – Woody (gas prone) humic
Host Rock (Shales and Coals)

16. The Origin of Petroleum
Organic-rich
Source Rock
Thermally Matured
Organic Matter Oil

17. Source Rock for Petroleum
Organic-Rich Thin Laminae
3.39 378
Total
Organic
Carbon
LOMPOC Quarry Sample
Monterey Formation, CA
Hydrogen
Index
1 Inch

18. Woodford Shale (Oklahoma)

19. Channel-Fill Sandstone Resting on Marine Shale
Red Fork (Oklahoma)

20. Coals and Coaly Shales
San Juan Basin (New Mexico)

21. Source rock kerogen can
be correlated to oil/gas
found in carrier beds
and reservoirs

22. T.O.C.
Total Organic Carbon
Basinal Summary Chart

23. Petroleum System Summary
• Source (Material and Rocks)
• Generation (Maturation)
• Migration
• Trap
• Reservoir

24. The Petroleum Kitchen
Temperature-Pressure-Time
Geothermal Gradient: (thermogenic hydrocarbons)
Range: <1 to 11 degrees F per 100’
Typical Sedimentary Basins: 1.0-1.7 degrees F per 100’
Good average 1.2
Oil window of ~ 120-300F (50-150C), or about 5,000-20,000’
In practice, oil below 15,000’ rare
Gas – no practical limit to stable depth
Cracking of oil to gas controlled by source kerogen and temperature
Deep basins mostly gas
Practical limits related to maturity of source – not reservoir

26. Hydrocarbon Occurrence & Thermal Maturity

27. Oklahoma
Geologic Provinces

28. Map of Oklahoma Oil and Gas Fields; Distinguished By GOR and Coalbed Methane Production. From Boyd (2002)
(GOR Cutoffs: Oil <5,000; Oil and Gas 5,000-20,000; Gas > 20,000)

29. Schematic Cross-section of the Anadarko Basin
Modified from Witt and others (1971).

30. Geologic Time Scale
Modified From Harland (1990) and Hansen (1991).
DIVISIONS OF GEOLOGIC TIME
Eon Era Period Epoch
Age (approx.)
in millions of
years
Cenozoic
Mesozoic
Paleozoic
Phanerozoic
Carboniferous
Pennsylvanian
Mississippian
Tertiary
Quaternary
Cretaceous
Jurassic
Triassic
Permian
Devonian
Silurian
Ordovician
Cambrian
Holocene
Pleistocene
Pliocene
Miocene
Oligocene
Eocene
Paleocene
Late
Early
Late
Middle
Early
Late
Middle
Early
Late
Early
Late
Middle
Early
Late
Early
Late
Middle
Early
Late
Early
Late
Middle
Early
Late
Middle
Early
0.010
1.6
5
23
35
57
65
97
146
157
178
208
235
241
245
256
290
303
311
323
345
363
377
386
409
424
439
464
476
510
517
536
570

31. Regional Stratigraphic Cross-Section
(Hung from Top of Booch)
Oklahoma Arkoma Basin (Booch)
(Present burial depth not necessarily maximum burial depth)

32. Arkoma Basin
Estimated Overburden Removal

33. Petroleum System Summary
• Source (Material and Rocks)
• Generation (Maturation)
• Migration (Expulsion)
• Trap
• Reservoir

35. Source Rock for Petroleum
Organic-Rich
Thin Laminae
LOMPOC Quarry Sample
Monterey Formation, CA
1 Inch

36. Migration Pathways
• Hydrocarbon Expulsion
• Vertical vs. Horizontal Migration
• Residual Saturations

38. GEOGRAPHIC EXTENT OF PETROLEUM SYSTEM
Present-Day
STRATIGRAPHIC
EXTENT OF
PETROLEUM SYSTEM
Petroleum accumulation
Top of oil window
Bottom of oil window
Trap Trap
Trap
Seal
Reservoir
Source
Underburden
Overburden
A A’
Magoon and Dow, 1994
Present-Day Petroleum System

39. Inferred Middle Booch Depositional Environments
Arkoma Basin in Oklahoma

40. Spill Point
Spill Point
Seal Rock
(Mudstone)
Reservoir Rock
(Sandstone)
Migration from
‘Kitchen’
1) Early Generation
2) Late Generation
Gas displaces all
oil
Gas beginning to
displace oil
Displaced oil
accumulates
Petroleum System

43. The Leaky Trap

44. Petroleum System Processes
24803
Petroleum System Elements
Petroleum System Elements
120° F
120° F
350° F
350° F
Generation
Generation
Migration
Migration
Seal Rock
Seal Rock
Reservoir
Rock
Reservoir
Rock
Oil
Oil
Water
Water
Gas
Cap
Gas
Cap
Entrapment
Entrapment
Accumulation
Source
Rock

45. Schematic Migrational Pathways
From Basin to Shelf

46. Asphalt Seep
Viola Limestone (Oklahoma)
The End of the Road

47. On to the Trap

48. One More Thing…….
Basin Assignments
• North American
• San Juan Michigan
• East Texas Appalachian
• Gulf Coast Big Horn
• Anadarko Salina
• Arkoma Pedregosa
• Powder River Denver
• Wind River Forest City
• Green River
• Williston
• Delaware
• Midland
• Black Warrior
• Fort Worth
• Others………..

49. Facts to Consider
Basin
Location, Size, Maximum Depth, Age (from basement to outcrop + max subsidence), Stratigraphy
Other items; eg - Structure (extensional, compressional)
Petroleum System
Source Rocks: Name(s), kerogen type(s), TOC, depth to top of oil window, kitchen location
Migration Pathways: Carrier bed(s), faults, distance (vertical and horizontal)
Traps: Structural, Stratigraphic, Combination (dominant type)
Reservoirs: Names, Rock types (both reservoir and seal)
Representative Fields (The biggest ones)
OOIP, OGIP, RF, Cum Prod
Other notable Facts – anything else you want to add (history, technology, companies, etc)
Powerpoint presentation: 10-12 slides (or more), approach as management presentation in which object is to highgrade
future exploration opportunities for your company. For any answers you cannot find, treat as source of increased risk of entry.

50. Map of Selected Sedimentary Basins
1-Williston Basin
2-Powder River Basin
3-Denver Basin
4-Salina Basin
5-Forest City Basin
6-Kennedy Basin
7-Big Horn Basin
8-Wind River Basin
9-Laramide Basin
10-Washakie-Red Desert B.
11-Green River Basin