Petroleum Geology and Geophysics Images

Thermal anomaly induced by a salt tongue in the surrounding sediments. Red and blue indicate respectively hotter and colder than a temperature distribution when no salt is present. For more details see Mello et al. (1995).

Thermal anomaly induced by a salt diapir and associated effects on maturation. The green, red and yellow solid lines indicates the top of oil window, peak of oil generation, and bottom of oil windows, respectively. Black thin lines represents the heat flow streamlines deflected by the salt diapir. For more details see Mello et al. (1995) and Mello et al. (1994).

Porosity predicted for the Jurassic time (144 Ma) in the Gulf of Mexico basin. For more details see Mello and Karner (1994). This image will be featured in the next year "Beauty of Physics" calendar of the American Institute of Physics - AIP.

Predicted maturation for the structural top of the formation equivalent to Smackover.

Predicted maturation for the Gulf of Mexico basin at present day time. The red mesh represents the peak of oil generation.

Predicted evolution of overpressure for the base of Lower Cretaceous sediments. There were two major pulses of overpressure production: 1) Late Cretaceous, and 2) Quaternary.

3D visualization of the Gulf basin showing the spatial distribution of predicted vitrinite reflectance for a horizon equivalent to the base of the Upper Jurassic Smackover Formation for: a) a) end of mid-Neocomian (130 Ma); b) early Albian (115 Ma) ; c) end of Early Cretaceous (100 Ma); d) end of Late Cretaceous (68 Ma) ; e) end of Paleogene (24 Ma); f) and Present day. Onset of maturation within Smackover Formation and equivalents began in the early Neocomian in the western and central Gulf basin and along the West Florida Shelf area, and Louisiana and Mississipi salt basins. A maturation “front” propagates from offshore into shelfal and onshore regions as a function of time. For example, all the interior basins became mature for oil in the Early Cretaceous. It is because of this propagation that onshore sediments of the Smackover Formation became progressively incorporated into the oil window and continuous to the Present day. Similarly, a maturation front propagated from south to north across the Yucatan platform leaving the region in the oil window since the Early Cretaceous. Given that the Smackover equivalent in this area has the same quality as the northern Gulf basin, then it is an attractive oil-prone province. Smackover Formation is predicted to have exhausted its hydrocarbon potential in the depocenters of the interior salt basins during the Early Cretaceous.

3D visualization of the Gulf basin showing the spatial distribution of predicted vitrinite reflectance for a horizon equivalent to the base of the Eagle Ford Formation for: a) end of Late Cretaceous (68 Ma); and b) at Present day. Maturation onset of the Eagle Ford Formation and equivalents is predicted to occur during the Late Cretaceous offshore Mexico and along the Texas and Louisiana margins. A maturation front propagates from the western to the central Gulf basin. The restricted regions of the northern onshore Yucatan Plataform is predicted to enter the oil window in the Paleogene. Similarly, local regions in the southern Florida Platform also became mature during this time for oil.

3D visualization of the Gulf basin showing the spatial distribution of predicted vitrinite reflectance for a horizon equivalent to the base of the Wilcox Group for a) end of Paleogene (24 Ma); and b) at Present day. Maturation onset of the Wilcox Group and equivalents is predicted to occur just prior to the Miocene offshore Mexico and moving onshore in Rio Grande embayment and the Texas coastline. The western and northern Yucatan Platform and western Florida Escarpment are predicted to have entered the oil window recently. The central Gulf basin is predicted to be overmature for oil.

North-south and east-west sections across the Gulf basin showing the relationship between sediment overpressure and porosity for the Present day. The maximum overpressure in the western Gulf basin is associated with a normally compacted section. In contrast, the overpressure developed in the Neogene depocenter is associated with substantial undercompaction. Referring to the east-west section, the porosity for west Texas is significantly lower than the porosity at the same depth for offshore Louisiana.

Predicted temperature distribution across the Gulf basin for the Present day: 1) North-south and east-west sections showing the transient effect of sediment blanketing, and 2) temperatures at the base of the Upper Jurassic sediments. Rapid sedimentation has lead to the formation of an anomalously cold Neogene and Quaternary section west of the Florida Escarpment. There is no simple relationship between maximum sediment temperatures and basin depth because of the transient thermal behavior of recently deposited sediments.

Predicted maturation distribution across the Gulf basin for: 1) end of Neogene, and 2) the Present day. North-south and east-west sections show the geometry of the oil window (in red). Below is shown the spatial distribution of the peak of oil generation (1.0 %Ro) across the Gulf basin. When the sediments are in approximate thermal equilibrium, the maturation contours are relatively flat. Rapid sedimentation has created regions in thermal disequilibrium causing a depression of the oil window.