Generation and migration of petroleum from abnormally pressured fluid compartments
Much of the world's oil and gas has been generated from source rocks inside deep (> 3000 m) pressure compartments. The quantity and composition of the kerogen and the burial history of the rocks in the compartments determine the volumes of petroleum generated. But migration in an oil and gas phase is a pressure-driven process in which flow direction is controlled by the configuration and internal pressures of the fluid compartment. Many sedimentary basins have a layered arrangement of two or more superimposed hydrogeological systems. The shallow systems are usually basin wide in extent and exhibit normal hydrostatic pressures. the deeper systems where the oil is generated are not basin wide and are abnormally overpressured. They generally consist of a series of individual fluid compartments which are not in pressure communication with each other nor with the overlying hydrodynamic regime. Crude oil-source rock correlations have demonstrated that about half the world's petroleum has moved vertically from source to reservoir rock. About 75% of the petroleum reserves in the US Gulf Coast are in reservoirs within or just above the seal. In the Central graben of the North Sea, the Kimmeridgian source rock is in a pressure compartment under a seal that is horizontal for over 200 km. Oil and gas have broken through the seal and accumulated in Cretaceous reservoirs above. The concept of episodic dewatering of deep-basin pressure compartments needs to be considered in any basin modeling program where the bulk of the oil generation occurs in the compartmented overpressured section of the basin.
- Research Organization:
- Woods Hole Oceanographic Institute, MA (USA)
- OSTI ID:
- 5954405
- Report Number(s):
- CONF-890404-
- Journal Information:
- AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States), Journal Name: AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States) Vol. 73:3; ISSN AABUD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020200* -- Petroleum-- Reserves
Geology
& Exploration
ATLANTIC OCEAN
BITUMINOUS MATERIALS
CARBONACEOUS MATERIALS
CRETACEOUS PERIOD
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC MODELS
GEOLOGIC STRUCTURES
GULF COAST
KEROGEN
MATERIALS
MATURATION
MESOZOIC ERA
MINERAL RESOURCES
NORTH AMERICA
NORTH SEA
ORGANIC MATTER
PETROLEUM DEPOSITS
RESOURCES
SEAS
SEDIMENTARY BASINS
SOURCE ROCKS
SURFACE WATERS
USA