Palynofacies analysis and palaeoenvironmental reconstruction of the Upper Cretaceous sequence drilled by the Salam-60 well, Shushan Basin: Implications on the regional depositional environments and hydrocarbon exploration potential of north-western Egypt

AbstractHydrocarbon exploration in the Bernhardsthal and Bernhardsthal-Sued oil fields documents an up to 2000 m thick succession of middle and upper Badenian deposits in this part of the northern Vienna Basin (Austria). Based on palaeontological analyses of core-samples, well-log data and seismic surveys we propose an integrated stratigraphy and describe the depositional environments. As the middle/late Badenian boundary is correlated with the Langhian/Serravallian boundary, the cores capture the crucial phase of the Middle Miocene Climate Transition. The middle Badenian starts with a major transgression leading to outer neritic to upper bathyal conditions in the northern Vienna Basin, indicated byBathysiphon-assemblages and glass-sponges. A strong palaeo-relief and rapid synsedimentary subsidence accentuated sedimentation during this phase. The middle/late Badenian boundary coincides with a major drop of relative sea level by about 200 m, resulting in a rapid shift from deeper marine depositional environments to coastal and freshwater swamps. In coeval marine settings, a more than 100 m thick unit of anhydrite-bearing clay formed. This is the first evidence of evaporite precipitation during the Badenian Salinity Crisis in the Vienna Basin. Shallow lagoonal environments with diverse and fully marine mollusc and fish assemblages were established during the subsequent late Badenian re-flooding. In composition, the mollusc fauna differs considerably from older ones and is characterized by the sudden appearance of species with eastern Paratethyan affinities.

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Fades and depositional environments of the coal-bearing upper carbonaceous member of the Wepo Formation (Upper Cretaceous), northeastern Black Mesa, Arizona

Geological Society of America Special Papers - Stratigraphy, depositional environments; and sedimentary tectonics of the western margin, Cretaceous Western Interior Seaway ◽

10.1130/spe260-p167 ◽

1991 ◽

pp. 167-188

Author(s):

David A. Carr

Keyword(s):

Upper Cretaceous ◽

Depositional Environments ◽

Black Mesa

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THE VALUE OF INTEGRATING BOREHOLE RESISTIVITY IMAGES WITH GEOLOGICAL DATA: RELEVANCE TO HYDROCARBON EXPLORATION

The APPEA Journal ◽

10.1071/aj96019 ◽

1997 ◽

Vol 37 (1) ◽

pp. 301 ◽

Cited By ~ 1

Author(s):

B. E. J. Messent ◽

C.M. Yacopetti

Keyword(s):

Poor Quality ◽

Depositional Environments ◽

Hydrocarbon Exploration ◽

Qualitative Assessment ◽

Low Permeability ◽

Geological Data ◽

Close Proximity ◽

Potential Reservoir ◽

Low Permeability Reservoirs ◽

Selection Of

This paper outlines the contribution borehole resistivity images can make in a frontier exploration program when they are integrated with all available geological data. Specific examples are given from the Duntroon Basin.Dipmeter data and borehole resistivity images can be used to validate seismic structural interpretations. An example is given to show the comparison in interpretation of the different methods.Faults are identified on the borehole images and in addition, qualitative assessment of sealing potential can be made by determining the occurrence and extent of mineralisation. In Greenly-1 the hydrocarbon shows, which are interpreted as migrated hydrocarbons, are found In close proximity to faults identified on borehole images. It is postulated that the faults acted as a conduit for the migrating hydrocarbons. However, these fault planes are now mineralised and interpreted to be sealing. This interpretation is supported by the presence of isolated, over-pressured sandstones.Resistivity images readily identify the orientation of present day horizontal stresses with its implications for fault-trap integrity. However, this is not deemed to be an issue in the Duntroon Basin as there is evidence that at least some of the faults are sealing. Borehole images can also be used to assess caprock integrity by determining the presence or absence of fractures.Within potential reservoir units, borehole resistivity images assist in the interpretation of depositional environments, reservoir geometries and post-depositional changes which affect reservoir quality.Borehole resistivity images provide qualitative interpretations of permeability. It is therefore possible to use the images in the selection of pre-test seats and sampling points in poor quality boreholes or low permeability reservoirs.

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