In this month's AAPG BULLETIN...

February 2008

E&P NOTE

A megascale view of reservoir quality in producing sandstones from the offshore Gulf of Mexico

S. N. Ehrenberg, P. H. Nadeau, and Ø. Steen

GOM Reservoir Quality

A large data set of over 10,000 offshore GOM sandstone reservoirs is analyzed to highlight relationships between reservoir parameters (e.g., porosity, permeability, play type etc.). Results indicate that several trends exist that are useful for specifying realistic distributions of parameters for both exploration risk evaluation and reservoir modeling.

GEOHORIZONS

Disequilibrium compaction as the cause for Cretaceous-Paleogene overpressures in the Danish North Sea

Ole Valdemar Vejbaek

Danish North Sea Overpressure

Cretaceous–Paleogene over-pressure distribution in the Danish Central Graben coincides remarkably with the thickness of the overlying, rapidly deposited mid-Miocene to Holocene succession. Modeling results indicate overpressure development is consistent with disequlibrium compaction due to rapid sedimentation.

New insights into the volume and pressure changes during the thermal cracking of oil to gas in reservoirs: Implications for the in-situ accumulation of gas cracked from oils

Hui Tian, Xianming Xiao, Ronald W. T. Wilkins, and Yongchun Tang

Underestimated Gas Accumulation

Previous pressure-volume calculations assumed complete cracking of oil to gas by ~ 150°C, however, this likely underestimates the potential for gas accumulation in petroleum reservoirs. A new compositional kinetic model, applied to the Sichun and Eastern Tarim Basins, indicates the potential for much higher gas accumulation and recovery.

ARTICLES

Chalk porosity and sonic velocity versus burial depth: Influence of fluid pressure, hydrocarbons and mineralogy

Ida L. Fabricius, Lars Gommesen, Anette Krogsbøll, and Dan Olsen

Chalk Porosity and Velocity

Improving modeling of chalk velocity for inversion analysis requires understanding the influence of fluid pressure, hydrocarbons, and mineralogy. Porosity and sonic velocity in chalk from the over-pressured Danish central North Sea vary consistently with depth when fluid pressure and pore-volume compressibility are taken into account.

A three-dimensional insight into the Mackenzie Basin (Canada): Implications for the thermal history and hydrocarbon generation potential of Tertiary deltaic sequences

Karsten F. Kroeger, Robert Ondrak, Rolando di Primio, and Brian Horsfield

Mackenzie Basin 3-D Model

The poorly constrained thermal and maturation history of the Mackenzie Basin, Canada, is reconstructed with a 3-D model based on seismic and well data, resulting in an assessment of source-reservoir relationships that provides new perspectives on hydrocarbon systems.

Three-dimensional geologic imaging and tectonic control on stratigraphic architecture: Upper Cretaceous of the Tremp basin (south-central Pyrenees, Spain)

Benjamin Guillaume, Damien Dhont, and Stéphane Brusset

Aerial Photos Incorporated in 3-D Map

A 3-D geological picture of the Tremp Basin area (South-Pyrenean foreland, Spain) incorporates aerial photography and digital elevation modeling to facilitate visualization of the complete 3-D geometry, including variations in thickness of sedimentary bodies, and to elucidate tectonic controls on sedimentation.

About the BULLETIN

First published in 1917 as the Bulletin of the Southwestern Association of Petroleum Geologists--AAPG’s predecessor organization--in order to disseminate scientific material from annual meetings of the S.A.P.G., the AAPG Bulletin changed its name one year later when S.A.P.G. became AAPG.

The AAPG Bulletin has been delivering quality research to the scientific world ever since. The first issue contained papers written by the best-known geologists of the day, and included papers on such topics as South America, Europe, and general geologic problems of structure and sedimentation.

While the 21st-century AAPG Bulletin has undergone some changes since 1917, enlarging to 8 ½ x 11” size to incorporate more material and being published digitally as well as in print, it continues to adhere to the primary purpose of the organization, which is to advance the science of geology especially as it relates to petroleum, natural gas, other subsurface fluids, and mineral resources.

Delivered digitally or in print monthly to each AAPG Member as a part of membership dues, the AAPG Bulletin is one of the most respected, peer-reviewed technical journals in existence, with recent issues containing papers focused on such topics as the Middle East, channel detection, China, permeability, subseismic fault prediction, the U.S., and Africa.