BASIN CLASSIFICATION

All giant fields occur in basins that have experienced several different structural and stratigraphic phases related to changing plate tectonic boundary conditions.

The basin style most responsible for one or more of the complex factors forming the giant, include, 1) formation of source rocks; 2) formation of reservoir rocks; 3) creation of structural and stratigraphic traps.

These events could have occurred in completely different settings. For example, the source may have formed during a rift phase, the reservoir may been deposited during a passive-margin phase, and the structural trap may have formed during the collision of a continent or island arc with the passive margin.

Therefore, identifying the basin-forming tectonic and stratigraphic phase responsible for source-rock deposition and/or structural trap.

Basin Classification

• A number of these classification schemes are published including those of Bally, Blois, Klemme and Kingston. Bally's work is based on the tectonic history of

basins. Blois and Klemme's work also used plate tectonic

historical terms, and added productivity data. Kingston's system added a systematic

nomenclature, designed to allow finer detail in describing the tectonic history of individual basins.

Basin Classification I

•Interior basins - large, ovate downwarps within stable cratonic shields (Michigan Basin) •Rift basins - narrow, fault-bounded valleys of various dimensions (East African Rift System) •Aulacogens - failed rift arm at triple-point junction (Reelfoot Rift) •Passive Continental Margin - Atlantic-type margins with sedimentary prism on shelf, slope, and rise

Basin Classification II

•Ocean basins - created by rifting, resulting in deep ocean floor •Subduction-related settings - seismically active continental margins with deep-sea trenches, active volcanic arc, and arc-trench separating (Aleutian Arc-Trench System)

•Strike-Slip basins - small pull-apart basins in response to lateral fault movement (Los Angeles Basin; transform marginal setting) •Collision-related basins - foreland basin development in response to thrust-loading of continent (Appalachian Basin)

Basin Classification

Basin Classification

Tectonic Settings of Giant Oil and Gas Fields

Using Klemme's classification scheme, the three most common basins containing giant oil fields are:

• collision zones (40%); • accreted margins (16%); • rifled margins (15%).

Using the Bally and Snelson classification, the three most common basins containing giant oil fields are:

• type-A fore-deeps (41%); • cratonic basins (23%); • Atlantic-type passive margins (15%).

PETROLEUM BASIN TYPE

TECTONIC EVOLUTION OF TYPICAL BASIN BY BASIN TYPE

GEOLOGIC AND PETROLEUM CHARACTERISTS OF BASIN TYPE

TYPE-1 INTERIOR SIMPLE

WORLD BASIN AREAS

BASIN TYPE IN RELATION TO PRODUCTIVITY

TYPE 2. COMPOSITE; 2a, complex

TYPE 3. RIFT

TYPE 4 DOWNWARP (OPEN OR CLOSED)

TYPE 5. PULL-APART

TYPE 6. SUBDUCTION TYPE (Back arc, Fore arc and no arc type)

Type7. Median

Type 8. Delta

BASIN CLASSIFICATION

All giant fields occur in basins that have experienced several different structural and stratigraphic phases related to changing plate tectonic boundary conditions. There are two approaches. One can assume, like Pettingill, that present-day basin style is representative of past basinal types, including those possibly responsible for formation of giant fields. [5]A second, more difficult, approach is to infer the basin style most responsible for one or more of the complex factors forming the giant, including: 1) formation of source rocks; 2) formation of reservoir rocks; and 3) creation of structural and stratigraphic traps. These events could have occurred in completely different settings. For example, the source may have formed during a rift phase, the reservoir may been deposited during a passive-margin phase, and the structural trap may have formed during the collision of a continent or island arc with the passive margin.For the classification shown on Fig. 2c and the subsequent maps, the authors have followed the second approach, with emphasis on identifying the basin-forming tectonic and stratigraphic phase responsible for source-rock deposition and/or structural trap. For elongate giant fields aligned with fold and thrust structures, an exception to this rule was made: Assume that these giants are predominately related to shortening at collisional margins (e.g., Arabian Peninsula).

Tectonic Settings of Giant Oil and Gas Fields

Giant fields account for about 55% of the world's petroleum reserves and cluster in 27 regions of the Earth's land surface. 877 giants.

Using Klemme's classification scheme, the three most common basins containing giant oil fields are:

• collision zones (40%); • accreted margins (16%); • rifled margins (15%).

Using the Bally and Snelson classification, the three most common basins containing giant oil fields are:

• type-A fore-deeps (41%); • cratonic basins (23%); • Atlantic-type passive margins (15%).

CONCLUSIONS

After reclassification of 592 giant oil fields into six basin and tectonic-setting categories, several conclusions were reached

1. Continental passive margins fronting major ocean basins account for 31% of giants.

2. Continental rifts and overlying steer's head sag basins form the basin type that contains 30% of the world's giant oil fields.

3. Terminal collision belts between two continents form a major basin type that contains 24% of the world's oil giants.

4. Arc-continent collision margins, strike-slip margins and subduction margins collectively form the setting for 15% of the world's giant fields.

Previous sorting of giant fields by basin type A) Histogram showing classification of 509 giant fields by Carmalt and St. Johns using Klemme's basin classification scheme. Klemme divides basins into eight main categories shown based on interpretation of their tectonic history

Sorting of giant fields by basin type. B) Histogram showing classification of 509 giants by Carmalt and St. Johns using Bally and Snelson's basin classification scheme. Bally and Snelson divide basins into nine categories, based largely on the degree that the basin is associated with a "mega-suture," or major convergent-plate boundary.

Fig. 2. Previous sorting of giant fields by basin type. C) Histogram showing classification of 592 giants by basin classification proposed by Paul et al, 2001. The authors classified the giants based on six commonly used basinal settings.

By Paul et al.,2001

Continental rifts and overlying steer's head sag basins.

Rifts and the overlying, generally marine, sag basin are key for localizing and forming source rocks in poorly-circulated marine straits and lakes during the early stages of continental rifting

• Late Jurassic-Early Cretaceous source rocks of Gulf of Mexico• Jurassic source rocks of West Africa.

Such rifts are either: aborted to form isolated intracontinental rifts surrounded by continental areas like the North Sea or West Siberian basin,

Or extended to form passive margins flanking major ocean basins such as the West African coast.

These rifts typically become deeply buried beneath a carbonate, evaporitic and/or clastic passive-margin section.

Extending into the Eurasian continental crust. The earliest rift phase occurred during the Carboniferous and Jurassic, with the rift-system trend closely controlled by pre-existing basement trends. An overlying steer's head sag basin was deposited over the Central Graben in Late Cretaceous time

The Central Graben hosts 30 giants localized along the complex normal and strike-slip faults running down the graben axis.

Source rocks were deposited in the initial rift during the Late Paleozoic and Kimmeridgian, with reservoirs at several levels.

Structures were mainly formed during Jurassic rifting, Tertiary magmatism and fault inversion related to the Alpine collision.

North Sea - a failed rift

North Sea: 317 Gullfaks, Norway, Oil/gas (N. North Sea) 318 - 9 Snorre, Norway, Oil/gas/cnd (N. North Sea) 320 Ekofisk, Norway, Oil/gas/cnd (S. North Sea) 321 Eldfisk, Norway, Oil/gas/cnd (S. North Sea) 322 Statfjord, Norway, Oil/gas/cnd (N. North Sea) 323 Valhall, Norway, Oil/gas/cnd (S. North Sea) 324 Frigg, Norway, Gas/cnd (N. North Sea) 325 - 6 Oseberg, Norway, Oil/gas/cnd (N. North Sea) 327 - 8 Sleipner West, Norway, Gas/cnd (N. North Sea) 329 Draugen, Norway, Oil/gas (Helgeland) 330 Heidrun, Norway, Oil/gas/cnd (More) 331 Troll West, Norway, Oil/gas/cnd (N. North Sea) 332 Midgard, Norway, Gas/cnd/oil (Helgeland) 333 Smoerbukk, Norway, Gas/cnd/oil (More) 334 Tyra, Denmark, Gas/cnd/oil (S. North Sea) 335 Forties, United Kingdom, Oil (N. North Sea) 336 Claymore, United Kingdom, Oil (N. North Sea) 337 Fulmar, United Kingdom, Oil/gas (S. North Sea) 338 - 44 Scott, United Kingdom, Oil/gas (N. North Sea) 345 Brent, United Kingdom, Oil/gas/cnd (N. North Sea) 346 Beryl, United Kingdom, Oil/gas (N. North Sea) 347 - 9 Cormorant, United Kingdom, Oil/gas (N. North Sea) 350 Piper, United Kingdom, Oil/gas (N. North Sea) 351 Magnus, United Kingdom, Oil/gas/cnd (N. North Sea) 352 - 3 Ninian, United Kingdom, Oil/gas/cnd (N. North Sea) 354 Morecambe South, United Kingdom, Gas/cnd (Irish) 355 - 6 Indefatigable, United Kingdom, Gas/cnd (S. North Sea) 357 Leman, United Kingdom, Gas/cnd (S. North Sea) 358 - 65 Groningen, Netherlands, Gas/cnd (NW German) 512 Salzwedel-Peckensen Germany, Gas (NW German)

26 giants subdivided into two regions: 1) to the west, the Illizi province of Algeria; and 2) to the east, the giants of Libya's Sirte rift. Tectonic history of North Africa is marked by convergence during the Paleozoic Hercynian orogeny, which left a major unconformity separating folded Cambro-Ordovician rocks from unfolded Permian-Triassic clastic sedimentary and volcanic rocks. During the Pangean breakup, rifts formed across northern Africa, including the Atlas rift system. Following rifting, the area subsided and received a thick section of evaporitic and clastic sediments. During the Late Cretaceous, convergence began between Africa and Eurasia resulted in the Alpine mountain chains in Northern Africa, including inversion of the Atlas rift to form the Atlas mountain belt. Giant fields in structural traps occur beneath the Hercynian unconformity Source: Ordovician and Silurian black shales. The Sirte basin is a rift basin with a complex extensional history that began in the late Cretaceous and extended into the Tertiary. 5 Source rocks are Late Cretaceous shales that thicken into the rift basins. Reservoirs comprise reef buildups on structural highs. Traps are combinations of structural and stratigraphic traps.

North Africa- continental rifts with overlying steer's head basins

Hassi Messaoud, Algeria, Oil/gas (Sahara basin) 2 Zarzaitine, Algeria, Oil/gas/cnd 3 Rhourde El Baguel, Algeria, Oil/gas (Sahara basin) 4 Tin Fouye-Tabankort, Algeria, Oil/gas/cnd (Illizi basin) 5 Taouratine, Algeria, Gas/cnd (Illizi basin) 6 Hassi R'Mel, Algeria, Gas/cnd/oil (Sahara basin) 7 In Amenas Nord, Algeria, Gas/cnd 8 Gassi Touil, Algeria, Gas/oil (Sahara basin) 9 Alrar, Algeria, Gas/cnd/oil 10 El Borma, Tunisia, Oil/gas/cnd 11 Bahi (032-A), Libya, Oil/gas 12 Amal(012-B/E/N/R), Libya, Oil/gas 13 Beda (047-B), Libya, Oil 14 Beda (047-B), Libya, Oil 15 Defa (059-B/071-Q), Libya, Oil/gas 16 Defa (059-B/071-Q), Libya, Oil/gas 17 Gialo (059-E), Libya, Oil/gas 18 Masrab (059-P), Libya, Oil 19 Sarir (065-C), Libya, Oil/gas 20 Augila-Nafoora (102-D/051-, Libya) Oil/gas 21 Sarir (065-L), Libya, Oil/gas 22 Intisar (103-A), Libya, Oil/gas 23 Dahra East-Hofra (032-F/Y), Libya, Oil/gas 24 Nasser (006-C/4I/4K), Libya, Oil/gas 25 Nasser (006-C/4I/4K), Libya, Oil/gas 26 Nasser (006-C/4I/4K), Libya, Oil/gas 27 Waha North (059-A), Libya, Oil/gas 28 Raguba (020-E), Libya, Oil/gas 29 Attahadi (006-FF), Libya, Oil/gas 30 Intisar (103-D), Libya, Oil/gas 31 Bu Attifel (100-A), Libya, Oil/gas/cnd 32 Messla (065-HH/080-DD), Libya, Oil/gas 33 Hateiba (006-S), Libya, Gas 34 Hateiba (006-S), Libya, Gas 35 Bouri (NC041-B), Libya, Oil/gas (Pelagian basin) 67 Waha South (059-A), Libya, Oil/gas

North Africa:

Caspian Sea controlled by a Jurassic rifting event at the northern Tethys margin. Source rocks deposited in this rift framework are Paleocene-Eocene. The area's 26 giant reservoirs are at various levels within the Cenozoic sectionStructural traps formed from the Cenozoic to present-day.

Continental passive margins fronting major ocean basins.

This category is reserved for giants which are clearly confined to non-rift controlled, passive-margin sections. It is difficult to rule out the importance of rifts and rift-localized steer's head basins in passive-margin tectonic settings, because the level of rifting can become so deeply buried in passive-margin settings that it is difficult to resolve seismically or reach by drilling.

Continental rifts and overlying steer's head sag basins.

Rifts and the overlying, generally marine, sag basin are key for localizing and forming source rocks in poorly-circulated marine straits and lakes during the early stages of continental rifting

• Late Jurassic-Early Cretaceous source rocks of Gulf of Mexico• Jurassic source rocks of West Africa.

Such rifts are either: aborted to form isolated intracontinental rifts surrounded by continental areas like the North Sea or West Siberian basin,

Or extended to form passive margins flanking major ocean basins such as the West African coast.

These rifts typically become deeply buried beneath a carbonate, evaporitic and/or clastic passive-margin section.

North Slope of Alaska and McKenzie delta. Early Cretaceous rifting, which led to formation of oceanic crust in the Canada basin and formation of a rifted, passive margin along the North Slope. Early Cretaceous to recent sedimentation has been controlled by mainly clastic, passive-margin sedimentation, including deposition of the McKenzie delta with sources in the Brooks Range, located to the south. Sources, reservoirs and traps occur in the passive-margin section. 609 Prudhoe Bay, USA 612 Kuparuk, Alaska 614 Koakoak, Canada 615 Point Thompson, Alaska 618 Kopanoar, Canada 636 Parsons Lake, Mackenzie, Canada 654 Issungnak, Canada

Gulf of Mexico- a passive

margin fronting a major ocean basin, resulted from Middle Jurassic rifting between North America, Mexico, the Yucatan Peninsula and northern South America. Rifting resulted in passive margins flanking a small area of oceanic crust in the deep, central part of the basin.

Structures on passive margins include growth faults, salt-withdrawal basins and salt domes that were produced by remobilization of Jurassic salt from sediment loading. 42 giants fields Source rocks include Late Jurassic and Neogene marine shales.

Jurassic evaporites provide effective seals for deeper offshore hydrocarbons related to the earlier rift history.

These are now being tested by deepwater drilling.

593 Paredon, Mexico, Oil/gas (Salinas) 594 Jujo, Mexico, Oil/gas (Salinas) 595 Poza Rica, Mexico, Oil/gas (Tampico) 596 Samaria (Bermudez Complex), Mexico, Oil/gas (Salinas) 597 Agave, Mexico, Oil/gas/cond (Salinas) 598 Giraldas, Mexico, Oil/gas (Salinas) 599 Jose Colomo-Chilapilla, Mexico, Gas/cond/oil (Salinas) 600 Reynosa, Mexico, Gas/cond/oil (Gulf Coast 601 Chac, Mexico, Oil (Campeche) 602 Akal-Nohoch (Cantarell), Mexico, Oil/gas (Campeche) 610 Carthage, Texas 613 Monroe, Louisiana 616 Katy, Texas 620 Caillou Island, Louisiana 621 Old Ocean, Texas 622 Greta, Texas 623 Hawkins, Texas 625 Bayou Sale, Louisiana 626 Hastings, Texas 627 Conroe, Texas 628 Bay Marchand, Louisiana 630 Webster, Texas 631 Timbalier Bay, Louisiana 632 Bastian Bay, Louisiana 633 South Pass Block 24, Louisiana 635 Smackover, Arkansas 637 Reynosa, Mexico (Gulf Coast basin) 638 Bateman Lake, Louisiana 639 Van, Texas 640 West Ranch, Texas 641 Eugene Island, Louisiana 642 Thompson, Texas 643 La Gloria, Texas 644 Tiger Shoal, Louisiana 645 Grand Isle Block 43, Louisiana 646 West Delta Block 30, Louisiana 647 South Pass Block 27, Louisiana 648 Vermilion Block 39, Louisiana 649 Agua Dulce, Texas 650 Borregos, Texas 651 Pledger, Texas 652 Vermilion Block 14, Louisiana

Gulf of Mexico

Five giants occur in a limited part of the Campos basin that formed by early Cretaceous rifting from West Africa. Tectonic events included intense volcanic activity and rifting, with basins filled by alluvial, lacustrine and carbonate rocks. The end of the rifting phase was marked by formation of regional unconformity and initiation of passive-margin sedimentation.

Production comes from the overlying passive-margin section Sources - Barremian-Aptian lacustrine shales deposited in underlying rifts.

Reservoirs - Tertiary deepwater sandstones deposited in a passive margin setting.

588 Albacora, Brazil, Oil/gas (Campos) 589 Marlim, Brazil, Oil/gas (Campos) 603 Barracuda, Brazil, Oil/gas (Campos) 607 Marlim Sul, Brazil, Oil/gas (Campos) 608 Roncador, Brazil, Oil (Campos)

Brazil - passive margin fronting a major ocean basin

Continental collision margins

• These margins produce deep, short-lived basins in interior areas but broad, wedge-shaped foreland basins in more external parts of the deformed belt where most giants are found.

• There is a spatial correlation between location of foreland-basin oil fields and fold-thrust belt salients, or places where the fold-thrust belt protrudes or is convex to the foreland. Salient examples associated with oil fields include Alberta, Wyoming, Santa Cruz (Bolivia), Verkhoyansk (Siberia), northern Carpathians (Europe), Taiwan, Zagros and Apennines (Italy). In all cases, the greatest concentration of oil and gas fields is opposite the apex of the salient.

1) thicker, basinal-sedimentary rocks present at salients are more likely to yield greater volumes of source and reservoir rocks;

2) thicker basinal rocks also produce more fold culminations, which are likely to act as structural traps; and

3) slight along-strike extension at apex areas could result in increased fracturing that could provide the vertical permeability to permit migration of oil and gas in association with basinal brines.

Rocky Mountain foreland -stretching from Mexico through Canada and central Alaska, resulted from eastward thrusting of a westward-thickening wedge of mostly shallow-water, platform-deposited sedimentary rocks of Precambrian through Jurassic age. This occurred during Early Cretaceous through Eocene time. Major thrusts are oldest in the west and become progressively younger to the east.. Giants are largely concentrated in complex basins of the Utah-Wyoming area and in western Canada's asymmetrical foreland basin. The setting for these 18 giants is classified as a continental collision margin.

675 Elmworth, Canada, 680 Pembina, Canada 681 Blanco, New Mexico 684 Whitney Canyon, Wyoming 685 Basin, New Mexico 686 Kaybob South, Canada 687 Swan Hilis, Canada 689 Salt Creek, Wyoming 691 Anschutz Ranch East, Utah 692 Claresholm, Alberta, Canada 693 Rangely, Colorado 694 Redwater, Alberta, Canada 700 Judy Creek, Alberta, Canada 702 Elk Basin, Wyoming 703 Bonnie Glen, Alberta, Canada 713 Swan Hills South, Alberta, Canada 715 Leduc Woodbend, Alberta, Canada

26 giant fields in these basins, located in Texas and Oklahoma. This area experienced intraplate deformation and regional shortening during the Pennsylvanian-Permian collision between North America, northern South America and Africa. Deformation spread from east to southwest. Deformation in the Anadarko region reactivated an older rift feature at a high angle to the convergence direction and produced both thrust and strike-slip faulting. Deformation in the Permian basin produced a complex pattern of uplifts and basins that infilled with evaporites. Sources and reservoirs were mainly deepwater Paleozoic rocks deposited in basinal areas. 674 Hugoton, Kansas 676 Eunice, New Mexico 677 Yates, Texas 678 Wasson, Texas 679 Scurry, Texas 682 Slaughter, Texas 683 Sho-Vel-Tum, Oklahoma 688 South Sand Belt, Texas 690 Goldsmith, Texas 695 Oklahoma City, Oklahoma 696 McElroy, Texas 698 Mocane Laverne, Oklahoma 699 Golden Trend, Oklahoma 701 Spraberry Trend, Texas 704 Cowden South, Texas 705 Fullerton, Texas 706 Keystone, Texas 707 Cushing, Oklahoma 708 Seminole, Texas 709 Burbank, Oklahoma 710 Cowden North, Texas 711 Vacuum, New Mexico 712 Sand Hills, Texas 714 Blinebry-Drinkard, New Mexico 716 Puckett, Texas 717 Gomez, Texas

Permian and Anadarko basins-continental collisional margin

•Large areas of the foreland appear completely undisturbed by Zagros-related convergent deformation, as manifested in the variety of giant-field shapes.

•Elongate giants and foreland basin was classified as a continental collision margin, while those giants to the southwest were counted as continental rifts and overlying steer's head sag basins.

•The basal stratigraphic section underlying the present-day foreland basin was deposited along a Cambrian-Permian passive-margin setting along the southern Tethys margin.

•Deeply buried salt, possibly deposited in Cambrian rifts, was activated by small-displacement basement faults during Permian to Jurassic time giving rise to salt ridges and diapirs, forcing folds in the overlying sedimentary section, which include some of the largest giant fields, such as Ghawar, Saudi Arabia.

•These folds are at a high angle to later folds and thrusts related to the Zagros convergence.

• Source rocks include Cambrian-to-Permian units

• Main reservoir in the Permian.

•A second hydrocarbon-formation period occurred from the Triassic through Tertiary, with Middle Jurassic source rocks and Upper Jurassic reservoirs.

•Migration is primarily upward from underlying source rocks in giant fields that are removed from the Zagros deformation.

•7 Structural traps formed in the area adjacent to the Zagros foldbelt and relate to early collisional effects in Eocene and younger time.

Arabian Peninsula / Persian Gulf

151 giants parallel to folds and thrusts in the Zagros Mountain, concentrated in a large foreland basin formed during the Late Cenozoic collision of the Arabian Peninsula with Eurasia.

Downward flexure of the Arabian Peninsula beneath the Zagros Mountains of Iran / Iraq was caused by the northeastward consumption of the Tethys Ocean at the Zagros suture zone. Protracted convergent event has created the Persian Gulf and Mesopotanian lowlands as a sag in the foreland basin, as well as formation of the Zagros Mountains, with a culmination of fold-thrust deformation in Miocene and Pliocene time.

Arabian Peninsula / Persian Gulf.

Arc-continental collision margins

Foreland basins in these settings can sometimes be more narrow and contain thinner stratigraphic fill than in continent-continent collisional settings, because island arcs lack the size, crustal thickness and deformation effect of a colliding continent.

For example, many of the circum-Caribbean forelands are narrow for the above reasons and as a result of the oblique angle of collision between the Caribbean-arc and the continents of North and South American.

Subduction margins

These margins are the least productive for giant fields due to low porosity and clay-rich sediments common in arc environments. Subduction margins in tropical areas such as those in southeast Asia can contain carbonate traps

Experienced Late Jurassic to Early Cretaceous rifting from southern North America and the Yucatan block followed by prolonged Cretaceous subsidence in a passive-margin setting. The passive-margin phase was interrupted by the west-to-east collision of the Caribbean arc during Paleocene-to-recent time producing a thick foreland basin running the length of northern South America,

Contains nearly all of the region's 33 giant fields, including those in Maracaibo and Maturin basins.

Source rocks include Late Cretaceous black shales deposited during sea-level highstands.

Reservoirs include fractured carbonates and sandstones,

Ttraps are mainly faults and folds produced during collision.

Northern South America- arc / continental-collision margin

535 Cano Limon, Colombia, Oil (Llanos de Casanare) 536 La Cira, Colombia, Oil/gas (Middle Magdalena) 537 Cusiana, Colombia, Oil/gas/cond (west of Llanos) 538 Mene Grande, Venezuela, Oil/gas (Maracaibo) 539 - 46 Oficina, Venezuela, Oil/gas (Maturin) 547 - 50 Santa Barbara, Venezuela, Oil/gas (Maturin) 551 Mara, Venezuela, Oil/gas (Maracaibo) 552 Boscan, Venezuela, Oil (Maracaibo) 553 Guavinita, Venezuela, Oil/gas (Maturin) 554 Dacion, Venezuela, Oil/gas (Maturin) 555 Jobo, Venezuela, Oil/gas (Maturin) 556 Urdaneta Oeste, Venezuela, Oil/gas (Maracaibo) 557 La Paz, Venezuela, Oil/gas (Maracaibo) 558 Cerro Negro, Venezuela, Oil/gas (Maturin) 559 Furrial-Musipan, Venezuela, Oil/gas (Maturin) 560 Santa Rosa, Venezuela, Oil/gas/cond (Maturin) 561 Yucal-Placer, Venezuela, Gas (Maturin) 562 Quiriquire, Venezuela, Oil/gas/cond (Maturin) 563 Centro, Venezuela, Oil (Maracaibo) 564 Lama, Venezuela, Oil/gas (Maracaibo) 565 Lamar, Venezuela, Oil/gas (Maracaibo) 566 Lago, Venezuela, Oil/gas (Maracaibo) 567 Patao, Venezuela, Gas (near Paria) 568 Lagunillas (Bolivar Coasta), Venezuela, Oil/gas (Maracaibo) 569 Tia Juana (Bolivar Coastal), Venezuela, Oil/gas (Maracaibo) 570 Bachaquero (Bolivar Coastal), Venezuela, Oil/gas (Maracaibo) 571 Cabimas (Bolivar Coastal), Venezuela, Oil/gas (Maracaibo) 572 - 4 Soldado Main, Trinidad and Tobago, Oil/gas (Paria) 575 Sacha, Ecuador, Oil/gas (Putumayo) 576 Shushufindi-Aguarico, Ecuador, Oil/gas (Putumayo) 577 - 86 La Brea-Parinas, Peru, Oil/gas (Talara) 604 Cupiagua, Colombia, Oil/gas (west of Llanos) 605 - 06 Volcanera 1, Colombia, Gas/cond (west of Llanos)

Northern South America

                                                                               

                                                                                                                                                  

Sunda

The 26 giant fields in Sunda occur in three main areas These are: 1) central and northern Sumatra, 2) Brunei on the western margin of Borneo, 3) the Pattani trough, offshore Thailand.

In Sumatra, inverted Late Neogene rift structures on continental collision are present in a backarc setting and were classified as a continental collision zone. The Borneo area was classified as an arc-continent collision zone, and the Pattani trough as a pull-apart basin on a strike-slip fault.

Strike-slip margins

Strike-slip margins form during the later stages of continental or arc collision as in Anatolia today, or during a ridge-subduction event along a subduction boundary, as in California.

Despite their generally small area extent relative to foreland and rift basins, strike-slip basins can contain extremely thick sedimentary sequences, including excellent source rocks formed during early basinal history. The inherent complexity of strike-slip boundaries with lateral offsets and structural overprinting probably makes it too difficult to achieve the ideal combination of source-reservoir and trap needed to make giant fields.

Forearc structure is less prominent in the now strike-slip disrupted areas of coastal and Southern California. Sources are Tertiary in age. Traps are mainly folds and faults related to Late Tertiary strike-slip faulting and shortening at the restraining bend of the fault in the Transverse Ranges. Southern California basins include complexly faulted, elongate basins like the Los Angeles; as well as more traditional pull-apart and fault-wedge, strike-slip basins. For these reasons, the tectonic setting of California's 17 giants is classified as strike-slip.

655 Wilmington, 656 Midway Sunset, 657 Kern River, 658 Elk Hills, 659 Ventura Avenue, 660 Huntington Beach, 661 Long Beach, 662 Kettleman Hills, 663 Coalinga, 664 Buena Vista, 665 Santa Fe Springs, 666 Belridge South, 668 Coalinga Nose, 669 Rio Vista, 670 San Ardo, 671 Brea, 673 Point Arguillo,

Southern California

20 giants occur along the rifted margin formed by the opening of the South Atlantic Ocean.

Rift history comprised a Neocomian-to-Aptian period of continental rifting, with lacustrine or brackish sediments infilling half-grabens. This was followed by an Albian-to-recent passive-margin phase, which was dominated by landward-derived, prograded clastic-carbonate platforms, locally deformed by underlying salt deposits.

The two stages are separated by formation of a large, Aptian salt deposit along most of the West African margin which forms an important seal for hydrocarbons derived from the pre-rift section, as well as having created structural traps in the overlying passive-margin section.

West Africa- a continental passive margin fronting a major ocean basin

Black Sea. 10 giant fields. A composite basin formed by rifting in the Aptian (western basin) and Paleocene-Eocene (eastern basin) along the northern edge of Tethys.

Source rocks range in age from Paleozoic through Cenozoic, with dominantly Eocene reservoirs.

Structures formed during the closure of Tethys and include the inverted Dneiper-Donetsk rift to the north of the Black Sea.

370 Starogroznyy, Russia, Oil/gas (Caucasus) 387 Ozeksuat, Russia, Oil (Caucasus) 392 Prilukskoye (Dnepr), Ukraine, Oil(Dneiper-Donetz) 423 Malgobek-Voznesensko-Ali-Y, Russia, Oil/gas (Caucasus) 453 Stavropol'-Pelagiada Sever, Russia, Gas (Caucasus) 481 Shebelinka, Ukraine, Gas/cnd (Dneiper-Donetz) 485 Yefremovskoye, Ukraine, Gas/cnd (Dneiper-Donetz) 499 Astrakhan', Russia, Gas/cnd (Caspian North) 527 Krestishchenskoye Zapadnoy, Ukraine, Gas/cnd (Dneiper-Donetz)

Ural Mountains. This region (Fig. 7.) formed the rifted eastern margin of Baltica during Ordovician-to-Permian time, with grabens forming major Paleozoic depocenters in the basin. A foreland basin was superimposed on this margin during collision of the Ural arc during the Late Permian to Early Jurassic. Structural trap formation occurred during this orogeny and created the area's 23 giants, which resulted in folds forming as far as 300 mi west of the Uralian deformation front. Source rocks are traceable Devonian shales deposited during the early graben phase prior to collision. 9

West Siberia Oil and Gas Bearing Basin: Giant and Unique Petroleum Systems

The West Siberian Province, subdivided into 10 oil and gas regions, is the largest oil- and gas-bearing province recognized on Russian territory. Four areas in the northern part of the province (Nadym – Pur, Pur – Taz, Yamal and Gydan) are predominantly gas bearing.

Other, such as Pre- Ural and Frolov in the west of the province, Sredny Priob and Kamys in the central part, and Vasyugan and Paidugin in the east, are oil-and gas-bearing and contain the bulk of oil reserves.

Giant oil field as Samotlor, Mamontovo, Fedorovo, Priob, Krasnoleninsk, Talin. Giant gas field as Urengoy, Yamburg, Medvezhie, Bovanenkovo, Kharasavey,Yubileynoe, Zapoliarnoe, which contain the main oil and gas reserves of West Siberia.

The confinement of the gas accumulations to coal bearing sediments

The principal source of the gas in the cenomanian sediments was organic matter of humic type, the carbonized remains of which saturate the entire rock sequence of the Pokur supergroup.

Lower cretaceous and upper jurassic are source rock for oil systems of the central and southern provinces.

West Siberian basin.

66 giants formed in a northward- plunging Jurassic-Quaternary sag basin overlying a Permo-Triassic rift system.

Such rifts are aborted to form isolated intracontinental rifts that are surrounded by continental areas.

Reservoirs lie in Cretaceous sag fill.

Source rocks include both Cretaceous and Upper Jurassic shales.

Siberia.

Seven giant fields have been discovered in Precambrian-Cambrian sedimentary rocks in this underexplored region of the Siberian platform,

Reservoirs and sources comprise late Precambian-Cambrian clastic rocks and carbonate rocks, with seals provided by Cambrian evaporites.

A rift setting for these fields was

inferred.

passive margin fronting a major ocean basin Rifted during the Middle Jurassic. Five giant fields are mainly found in the overlying Upper Jurassic-to-recent passive margin section, which drapes earlier rift structures.

Northwest Australia passive margin fronting a major ocean basin

Three giant fields in the Bass Strait area are underlain by the Gippsland rift basin, which is the most prolific oil and gas province in Australia. Geologic development of Gippsland basin is marked by a protracted and multistage Early to Late Cretaceous rift history, including separation of Australia and Antarctica and the opening of oceans east and west of Australia. Sources and reservoirs occur in the late to post-rift sequence. 6 Despite location of the giants above a failed east-west rift that extends westward from the Tasman Sea, this setting was classified as

Bass Strait, Australia / Tasmaniaa continental passive margin fronting a major ocean basin

10 giant fields in eastern China occur mainly in Bohai basin , one of a family of early Cenozoic extensional basins that lie along the eastern margin of Asia from Russia to Vietnam.

Paleocene to early Eocene rifting was diffuse, trans-tensional, and related to rollback of the subducted Pacific plate beneath the Asian continent, while Middle Eocene rifting appears to have been more organized in a large, right-stepping basin that formed as a very large pull-apart basin on right-lateral strike-slip faults. Narrower trans-tension zones are present north and south of the basin.

Reservoirs include carbonate karst units that are sourced by Paleogene shales.

China

264 - 6 Shuguang (Liaohe Complex), China, Oil (Bohai) 267 - 79 Shengtuo (Shengli Complex), China, Oil/gas (Bohai) 280 Huanxiling (Liaohe Complex), China, Oil (Bohai) 282 Saertu (Daqing Complex), China, Oil (Songliao) 284 Gudao (Shengli Complex), China, Oil/gas (Bohai) 285 - 88 Renqiu, China, Oil/gas (Bohai) 289 - 99 Gudong (Shengli Complex), China, Oil/gas (Bohai) 301 - 02 Shenyang (Liaohe Complex), China, Oil/gas (Bohai) 304 - 09 Dagang Complex, China, Oil/gas (Bohai) 316 Jingbian-Hengshan, China, Gas (Ordos)

MAIN FACTORS CONTROLLING SOURCE ROCK DEPOSITION AND EFFECTIVENESS

Geologic Age Paleolatitudes

Structural Forms Biologic Evolution

Maturation of Source Rocks

Explanation for lithofacies and structural forms maps,

Silurian petroleum source rock map

Silurian lithofacies and structural forms map.

Basin orProvince*

StructuralForm**

Source Rock

Dominant Kerogen Type***

Main Reservoirs Principal Maturation

Stage

Reference

Basins Having Silurian Source Rocks

ArabianIranian

Platform Gahkum and

Tabuk fms; graptolitic

shals

II Khuff Fm (Permian); carbonate and clastic

rocks

Late Permain-Triassic

Ala et al., 1980; al-Laboun, 1986

Erg Oriental, Erg Occidental

Platform Silurian graptolitic

shales

II Cambrian-Triassic sandstones

Cretaceous Tissot, 1984a; Balducchi and

Pommier, 1970; Magloire, 1970

Permian, Anadarko

Platform Silurian Marine shales

II Silurian carbonate rocks

Pennsylvanian-Early Permian

Jones and Smith, 1965

Michigan Circular sag

Niagara Fm, off-reef

carbonate Rocks

II Silurian carbonate rocks

Late Cretaceous-early

Tertiary(?)

Gardner and Bray, 1984

Upper Devonian-Tournaisian petroleum source rock map

Upper Devonian-Tournaisian lithofacies and structural forms map

Basin orProvince*

StructuralForm**

Source Rock

DominantKerogenType***

Main Reservoirs

PrincipalMaturation

Stage

Reference

Basins Having Upper Devonian-Tournaisian Source Rocks

Volga-Ural, Timan-Pechora, North Caspian

Plaform Domanik Fmand facies

equivalents;Marine

shales and carbonate

rocks

II Middle Devonian sandstones, Lower

Carboniferous sandstones, Upper Devonian-Middle

Carboniferous carbonate rocks

Late Permian-Triassic

Zhuze et al., 1975; Ashirov et al.,

1981; Ulmishek, 1982, 1988

Alberta Platform Duvernay, Ireton, and

Exshaw fms; marine shales

II Upper Devonian carbonate rocks

Middle Cretaceous-late Tertiary

Parsons, 1973; Porter et al., 1982

Anadarko, Permian

Platform Woodford Shale; marine

shales

II Silurian-Devonian carbonates

Pennsylvanian-Early

Permian

Landes, 1970; Hill, 1971; Campbell et

al., 1988; Jones and Smith, 1965

Appalachian Platform Chattanooga Shale; marine

shales

II Devonian sandstones Pennsylanian-Early Permian

Landes, 1970; Ray, 1971

Basin or Province*

Structural Form**

Source Rock

Dominant Kerogen Type***

Main ReservoirsPrincipal

Maturation Stage

Reference

Basins Having Upper Devonian-Tournaisian Source RocksVolga-Ural, Timan-Pechora, North Caspian

Plaform Domanik Fm and facies equivalents; marine shales and carbonate rocks

II Middle Devonian sandstones, Lower Carboniferous sandstones,

Upper Devonian-Middle Carboniferous carbonate rocks

Late Permian-Triassic

Zhuze et al., 1975; Ashirov

et al., 1981; Ulmishek, 1982, 1988

Alberta Platform Duvernay, Ireton, and Exshaw fms;

marine shales

II Upper Devonian carbonate rocks Middle Cretaceous

- late Tertiary

Parsons, 1973; Porter et al.,

1982

Anadarko, Permian

Platform Woodford Shale; marine shales

II Silurian-Devonian carbonates Pennsylvanian-Early Permian

Landes, 1970; Hill, 1971;

Campbell et al., 1988; Jones

and Smith, 1965

Appalachian Platform Chattanooga Shale; marine shales

II Devonian sandstones Pennsylanian-Early Permian

Landes, 1970; Ray, 1971

Williston, Michigan, Illinois

Circular sag

New Albany Shale, Antrim Shale, Bakken Fm

II Devonian-Pennsylvanian sandstones and carbonates

Late Cretaceous-early Tertiary(?)

North, 1985; Barrows and Cluff, 1984;

Meissner, 1984

Pripyat, Dnieper-Donets

Rift Upper Devonian-Tournaisian marine

shales and carbonate rocks

II Upper Devonian carbonate rocks (Pripyat), Carboniferous-Lower Permian clastic rocks (Dnieper-

Donets)

Pennsylvnian-Early Permian

Chaykovskaya and Volik,

1986; Il'inskaya and Kulayeva,

1979

Illizi Platform Upper and Middle Devonian marine

shales

II Devonian-Carboniferous sandstones Middle Cretaceous

Tissot, 1984a; Aliyev et al.,

1979

Pennsylvanian-Lower Permian petroleum source rock map

Pennsylvanian-Lower Permian lithofacies and structural forms map.

Basin orProvince*

Structural Form**

Source Rock DominanKerogen

Type***

Main Reservoir

PrincipalMaturation

Stage

Reference

Basins Having Pennsylvanian-Lower Permian Source Rocks

Anadarko, Permian Foredeep(SE), rift

(NW)

Pennsylvanian-Guadalupian basinal facies, marine shales

II Pennsylvanian-Permian

sandstones and carbonate

rocks

LatePermian-Middle

Cretaceo

Adler, 1971; Hartman and Woodard, 1971; Jones

and Smith 1965; Campbell et al., 1988

Southern North Sea Foredeep Westphalian coal measure

III Rotliegende(Lower Permian)

sandstones

Triassic-Middle

Jurassic

Ziegler, 1980

North Caspian Circularsag

Carboniferolus-Lower Permian basinal facies,

marine shales and carbonate rocks

II Carboniferous-Lower Permian carbonate rocks

LatePermianTriassic

Fomkin, 1985; Krylov and Nekhrikova, 1987

Bighorn, Powder River, Wind River, Uinta, Piceance

Linearsag

Phosphatic shale members opf the

Phosphoria Fm; marine shales

II PennsylvanianPermian

sandstones

LaterCretaceou

EarlyTertiary

Claypool et al., 1978; Stauffer, 1971; Cannon,

1971; Peterson and Smith, 1986

Vilyuy Circularsag

Permian continental clastic rocks

III, coal Permian toCretaceoussandstones

JurassicEarly

Cretaceou

Cherskiy, 1986

Sichuan Platform Yangxin Fm; argillaceous limestones

II Permian-Lower Triassic

carbonate rocks

MiddleCretaceous

Huang, 1984; Wang et al., 1983; Li Xuehui and Li

Tiesheng, 1984

Cooper Rift Gidgealpa Group (Permian); coal measure

III, coal Permian sandstones

MiddleCretaceous

Kantsler et al., 1984

Upper Jurassic petroleum source rock map

Upper Jurassic lithofacies and structural forms map.

Basin orProvince*

StructuralForm**

Source Rock

DominantKerogen Type***

Main Reservoir

PrincipalMaturatIon

Stage

Reference

Basins Having Upper Jurassic Source RocksArabian-Iranian

Linear sag Hanifa, Diyal/Dukhan, and Sargelu fms; marine shales, marls, and

limestones

II Arab Zone (Upper Jurassic) and

Shuaiba (middle Cretaceous)

carbonate rocks

Late Cretaceous

and late Tertiary

Ayres et al., 1982; Klemme, 1984; Alsharhan, 1987; Alsharhan and Kendall,

1986; Murris, 1980; Koop and Stoneley, 1982

West Siberian

Circular sag Bazhenov Fm; marine siliceous shales and carbonate rocks

II Neocomian deltaic Sandstones

Late Cretaceous-

early Tertiary

Stasova, 1977; Ivantsova, 1969; Kulikov, 1979;

Kontorovich et al., 1975

North Sea, Greenland Sea

Linear sag Kimmeridgian Clay Fm and equivalents; marine siliceous shale

II Middle Jurassic sandstones, Upper Cretaceous-lower Tertiary chalk and

Sandstones

Early Tertiary Ziegler, 1980; Cooper and Barnard, 1984; Goff, 1984;

Baird, 1986

North Caucasus, Amu-arya

Linear sag Khodzhaipak Fm; Upper Jurassic rocks below salt layer; marine

shales and limestones

II Upper Jurassic limestones, Cretaceous

sandstones and Limestones

Late Tertiary Akramkhodzhayev andEgamberdyev, 1985;

Maksimov el al., 1986; Krylov, 1979; Semashev, 1983; Chakhmakhchev et al., 1987; Seregin et al.,

1982

Middle Cretaceous petroleum source rock map

Middle Cretaceous lithofacies and structural forms map.

Basin or Province*

Structural Form**

Source Rock

Dominant Kerogen Type***

Main Reservoirs

Principal MaturatIon

Stage

Reference

Basins Having Middle Cretaceous Source RocksArabian-Iranian Linear

SagKazhdumi Fm; marine shales

and Limestones

II Asmari limestone (Miocene)?; Burgan

delta (Early-middle Cretaceous)

Middle-late Tertiary

Hull and Warman, 1970; James and Wynd, 1965; Dunnington, 1958, 1967; Ala et al., 1980;

Murris, 1980; Koop and Stonely, 1982

Maracaibo Linear sag

La Luna Fm; Marine shales and

Limestones

II Eocene-Miocene Sandstones

Late Tertiary Zambrano et al., 1972; Blaser and White, 1984

East Venezuela, Middle Magdalena, Llanos Oriente

Linear Sag

Querecual and La Luna fms;

marine shales and Limestones

II Eocene-Miocene Sandstones

Late Tertiary Hedberg, 1950; Krause, 1988; McCollough and Padfield, 1985;

Zumberge, 1984

Alberta, Overthrust, GreenRiver

Foredeep Mannville Fm; marine shales and

Equivalents

III Cretaceous Sandstones

Late Tertiary Parsons, 1973; Moshier and Waples, 1985

Gulf Coast Circular Sag

Marine shales II Cretaceous carbonates and

Sandstones

Late Tertiary Rainwater, 1971; Holcomb, 1971

Basin or Province*

Structural Form**

Source Rock

Dominant Kerogen Type***

Main Reservoirs

Principal MaturatIon

Stage

Reference

Basins Having Middle Cretaceous Source RocksAmu-Darya, NorthCaucas,Crimea

LinearSag

Aptian-Albian marine Shales

II Cretaceous sandstones

Late Tertiary Arkhipov et al., 1979; Mirzoyev and Dzhaparidze, 1979,

Shestopal, 1979; Maksimov et al.,1987

South Atlantic Basins

Rift/linear Sag

Upper Neocomian-Aptian lacustrine and

marine shales; Turonian marine

shales

I, II Cretaceoussandstones and

carbonates; Tertiary

sandstones

Late Cretaceous-early Tertiary

Ponte et al., 1980; Clifford, 1986; Lehner and De Ruiter, 1977

West Siberia (northern)

Circular Sag

Pokur Fm (Albian-Cenomanian);

continental clastic Rocks

III, coal Albian-Cenomanian sandstones

Immature Newterov et al., 1978; Rice and Claypool, 1981; Kortsenshteyn,

1970; Grace and Hart, 1986

North Slope Foredeep HRZ shale, Hue Shale; marine shales

III Cretaceous Sandstones

Late Cretaceous-early Tertiary

Carman and Hardwick, 1983; Molenaar et al., 1987; Bird and

Magoon, 1987

Songliao Linear sag

Qingshankou and Nenjiang fms; deep

lacustrine shales

I Cretaceous Deltaic

sandstones

Late Cretaceous-early Tertiary

Yang et al., 1985; Zhou, 1985; Yang, 1985

Oligocene-Miocene petroleum source rock map

Oligocene-Miocene lithofacies and structural forms map

Basin or Province*

Structural Form**

SourceRock

Dominant KerogenType***

MainReservoirs

PrincipalMaturation

Stage

Reference

Basins Having Oligocene-Miocene Source Rocks

East Venezuela-Trinidad, Maracaibo

ForDeep

Oficina Fm and equivalents; deltaic and prodeltaic

shales

III (west), II (east)

Miocene-Pliocene sandstones

Late Tertiary Michelson, 1976; Blaser and White, 1984

Niger delta Delta Akata and Agbada fms; deltaic shales

III, coal Upper Tertiary deltaic coal sandstones

Late Tertiary Ejedawe et al., 1984; Nwachukwu and Chukwura,

1986; Bustin, 1988

Mackenzie Delta

Delta Tertiary deltaic shales III Upper Tertiary deltaic

sandstones

Late Tertiary Snowdon, 1980; Snowdon and Powell, 1982

Mahakam Delta

Delta Miocene deltaic shales III, coal Upper Tertiary deltaic

sandstones

Late Tertiary Combaz and de Matherel, 1978

Gulf Coast and Mississippi delta

Half sag and delta

Tertiary marine and deltaic shales

III Tertiary Sandstones

Late Tertiary and

immature

Tipsword et al., 1971; Dow, 1978; Rice and Claypool, 1981

Indonesian Basins

Rift Pematang Brown Shale and Banuwati Shale,

lacustrine shales; Talang-Akar Fm, fluviodeltaic

shales

I ; III, coal Upper Tertiary Sandstones

Late Tertiary Kingston, 1979; Robinson, 1987; Gordon, 1985

Basin or Province*

Structural Form**

SourceRock

Dominant KerogenType***

MainReservoirs

PrincipalMaturation

Stage

Reference

Basins Having Oligocene-Miocene Source RocksNorth Kalimantan (Baram delta)

Delta Miocene deltaic shales

III Upper Tertiary sandstones

Late Tertiary ASCOPE, 1981

North China, Biyang, Nanxiang, Jianghan

Rift Lacustrine shales I Tertiary sandstones, Sinian carbonate

Rocks

Late Tertiary Lao and Gao, 1984; Li Desheng et al., 1984; Zha, 1984;

Huang et al., 1984; Tong, 1980; Li Chunju et al.,

1984

South Caspian Circular sag

Maykop Series and middle Miocene marine shales

II Pliocene sandstones Late Tertiary Ali-Zade et al., 1975; Korchagina and Zeynalova,

1986

North Caucasus

Foredeep Maykop Series and middle Miocene marine shales

II Upper Tertiary sandstones

Late Tertiary Burlakov et al., 1987; Shcherbakov et al., 1983;

Chepak et al., 1983

Suez Rift Rudies Fm; marine shales

II Cretaceous-Miocene

sandstones and carbonate rocks

Late Tertiary Kholief and Barakat, 1986

Carpathian (Ploiesti and western Ukraine)

Foredeep Menelitic Shale, marine

Shales

II Upper Tertiary Sandstones

Late Tertiary Paraschiv and Olteanu, 1970; Gavrish, 1985

Basin or Province

Structural Form

Source Rock

Dominant Kerogen Type

Main Reservoirs

Principal Maturation Stage

Reference

Basins having Oligocene-Miocene source rocks   East Venezuela-Trinidad, Maracaibo

Foredeep Oficina fm & equiv, deltaic & prodeltaic sh

III (west), II (east)

Miocene-Pliocene ss

Late Tert Michelson, 1976; Blaser & White, 1984

Niger delta Delta Akata & Agbada fm, deltaic sh

III, coal U Tert deltaic coal ss

Late Tert Aejedawe et al., 1984; Nwachukwu & Chukwura, 1986; Bustin, 1988

Mackenzie delta

Delta Tert deltaic sh III U Tert deltaic ss Late Tert Snowdon, 1980; Snowdon & Powell, 1982

Mahakam delta

Delta Miocene deltaic sh III, coal U Tert Deltaic ss Late Tert Combaz & de Matherel, 1978

Californian basins

rift Monterey fm, diatomaceous sh

II U Tert ss & sh Late Tert Graham & Williams, 1985; Crain et al., 1985

Gulf Coast & Mississippi delta

Half sag & delta

Tert marine & deltaic sh

III Tert ss Late Tert & immature

Tipsword et al., 1971; Dow, 1978; Rice & Claypool, 1981

Indonesian basins

Rift Pematang Brown sh & Banuwati sh, lacustrine sh; alang-Akar fm, fluviodeltaic sh

III, coal U Tert ss Late Tert Kingston, 1979; Robinson, 1987; Gordon, 1985

CONCLUSIONS

592 giant oil fields classified into six tectonic-setting categories

1 Continental rifts and overlying steer's head sag basins form the basin type that contains 30% of the world's giant oil fields.

2.Continental passive margins fronting major ocean basins account for 31% of giants.

3. Terminal collision belts between two continents form a major basin type that contains 24% of the world's oil giants.

4. Arc-continent collision margins, strike-slip margins and subduction margins collectively form the setting for 15% of the world's giant fields.

Stratigraphic distribution of effective source rocks given as a percentage of the world's original petroleum reserves generated by these rocks

                                                                         

Relative areal distribution of source rocks by paleolatitudinal zones. Source rock area of each principal stratigraphic interval is measured from maps and is normalized to 100%.

                                                                                                                               

                          

Relative areal extent vs. effectiveness of source rocks by paleolatitudinal zones. Both total area of source rocks of the six principal stratigraphic intervals and total petroleum reserves generated by these source rocks are normalized to 100%.

                                                                                                                                 

                   

Changes in typical conditions of source rock deposition through the Phanerozoic, and major events of biologic evolution that effected these changes

                                                                                                    

.

Effectiveness of source rocks deposited in various structural forms during each of the six principal time intervals, in percent of the total original petroleum reserves generated by source rocks of the six intervals

                                                                                                                                    

                

Cumulative chart of effective source rock deposition, source rock maturation, and petroleum trapped in the stratigraphic succession given as a percentage of world’s original petroleum reserves.

                                                                                                                               

                      

Maturation time of effective source rocks. Original petroleum reserves generated from source rocks of each of the six principal stratigraphic intervals are normalized to 100%.

Vertical migration of petroleum given as a percentage of the world’s original petroleum reserves

Oil vs. gas reserves generated by source rocks with kerogen types I and II, and kerogen type III and coal. The reserve amounts are expressed in percent of original petroleum reserves generated by source rocks of each stratigraphic interval.

Relative areal extent of petroleum source rocks given as a percentage of the total source rock area of the six principal stratigraphic intervals.

Generated vs. trapped petroleum reserves in the stratigraphic succession. The total world’s original reserves of petroleum are normalized to 100

                                                                                                                               

                        

Stratigraphic distribution of effective source rocks in basins with original reserves of less than 15 x 10{9} BOE given as a percentage of the world’s original petroleum reserves generated by these rocks.

Tectonics through time

In the mid 1960s J Tuzo Wilson formalised some key concepts in plate tectonics. Especially he showed that continents show a cyclic history of rifting - drifting and collision, followed by rifting again. He saw that the modern north Atlantic had been preceded by rifting which itself formed roughly along the site of an old mountain range ("mobile belt") that was it turn formed by the collision between two ancient continents (that we now call Laurentia and Avalonia). Use this diagram to find examples of the various parts of the Wilson Cycle in the modern world.