الفهرس 
MethodologyOnly 14 pages are availabe for public view
 |  | from | 302 |  |  |
| | | from | 302 | | |
Abstract
The East Bahariya concession lies in the eastern Abu Gharadig Basin (northern part
of the Western Desert of Egypt). The present study is based on the analysis of 3D
seismic and borehole data. Detailed seismic interpretation of key tectonic events
was integrated with data of 76 wells to develop a 3D structural model of the
reservoir rocks of the area using the Schlumberger Petrel software. These 3D
interpretation techniques besides flattening of seismic sections provide accurate
details of the structural geometry and fault patterns in the area. They also reveal
structural deformation represented by large buried NE-trending inversion anticlines
that play an important role in the hydrocarbon potentialities of the area. This
tectonic inversion took place in post-Coniacian time and continued slightly during
the Tertiary, till the Oligocene. Three main episodes of deformation have been
detected in the area of study: (1) A Jurassic-Early Cretaceous extensional episode,
resulting in the formation of NE-trending extensional faults bounding asymmetric
half-grabens, (2) Santonian-Oligocene positive inversion of these extensional faults
and (3) Post-Early Miocene Extension. Structural traps have proven successful to
date in the area of study, particularly fault-dependent, footwall three-way dip
closures (fault-block traps) and hanging wall four-way dip closures (inversion
anticlines).
A set of tectonosequences related to the opening and the subsequent
convergence of the Neotethys was mapped. The inclusion of 3D seismic isochore
data facilitated mapping the thicknesses of the tectonosequences. Each identified
tectonosequence has its own unique drive mechanism and geometry. Recognition of
these elements allows illustration of the Neotethyan basin evolution of East Bahariya
concession through time as well as understanding the tectonic and stratigraphic
framework and effective prediction of the petroleum system.
A fault seal study was performed for selected oil fields in East Bahariya
concession. Together with petrophysical logs, the constructed 3D model of the fault
displacement was used to compute the variation of fault seal potential (shale gouge
ratio or fault-zone percent shale) on each fault surface and to predict cross-fault
juxtaposition relationships in 3D space, based on the geometries of strata that are
cut by faults. Compilation of many shale gouge ratio analyses with in situ pore
pressure data has allowed a better definition of the relationship between calculated
shale gouge ratio and maximum trapped hydrocarbon column height, i.e. the ‘fault
seal-failure envelope’. This example demonstrates that a 3D analysis leads to
significant improvements in the prediction of fault seal, the analysis of the
interaction of the sealing properties of multiple faults, and the interpretation of fault
seal within the context of sedimentary basin geometry.
Keywords: East Bahariya concession, Western Desert, 3D structural model, inversion
anticlines, post-Coniacian, tectonosequences, shale gouge ratio, fault
seal.