الفهرس 
Overview of Study Area
Geological SettingsOnly 14 pages are availabe for public view
 |  | from | 190 |  |  |
| | | from | 190 | | |
Abstract
The present study was dedicating to carry out different volumetric seismic attributes and inversion schemes on the seismic surveying data at Southwest Abu Sennan (SWS) field, Northern Western Desert of Egypt.
Fault interpretation can be relatively easy and unambiguous if the seismic data is of good condition and the continuities/discontinuities are clear. Issues with regard to the fault correlation can normally be tied by interpreting on a denser grid or using additional faulting highlighting data like seismic interpretation advanced technique like seismic data attributes. However, in the case of noisy data and low resolution, the pick of a fault can be quite ambiguous and alternative interpretations be suggested.
Seismic attribute workflows applied in the present work were essential tools for the sake of improving the faulting patterns within the study area and obtained a new understanding of the subsurface geology. The edge detection method was useful for the detection of the existed faulting patterns as exhibited by our experience with model and real data. In order to be effective, it is highly recommended to apply the different fault detection methods be to reliable depth migrations and that de-convolution be used to prevent wavelet delay, also physical attributes, e.g., instantaneous phase attributes has proven results enhancing faults, reflectors continuity and discontinuities.
Structural interpretation is considered a conventional method for oil exploration and commonly used. The use of unconventional methods could lead to achieve significant results and reduce the drilling risk. The
subsurface image is completely objective, while merging the unconventional tool, e.g., seismic attributes and the conventional seismic interpretation workflow, to highlight the structural elements, which matched together.
The multi-dimensional seismic attributes computations, along with the use of time slices, are both independent of interpretation. This means that no prior interpretation is necessarily required and no interpretational bias to the seismic attributes results. Seismic attributes have been used to enhance the fault image and enhance the continuity of the reflectors.
The general structural fashion of SWS area is northeast doubly plunging asymmetrical anticline. The dominant faults have dissected the area into a number of separate reservoir blocks. These faults are trending in E-W, NW-SE and NE-SW directions.
The most obtained structural fault trends are N SE of alternating anticlinal and synclinal structures dissected by dip-slip faults. SWS field is structurally made up of anticlinal feature, which appears to be related to Syrian arc structure system as a series of NE S trending folds across the north Western Desert of Egypt. This system has been attributed to Cretaceous-Early Tertiary, N SE compressional forces.
Upon the horizon flattening, the encountered pre-Cretaceous faults within the vertically animated seismic data were better imaged and picked carefully.
Drilled Jurassic plays within SWS field were dry, failure mechanism may be due to structural leakage during the Jurassic time before the Late Cretaceous tectonic event, which brought the Jurassic rocks structurally-high as per the current-day situation. AR/ “G”, “C”, “D” Members, Khoman
151
and Apollonia Formations depth structure contour maps were generated to show the main fault sets, a dominant NW-SE set and a set trending NE-SW due to the Syrian arc structure system.
The present acoustic impedance inversion trials on the stacked–migrated seismic data at SWS field were proven a useful quantitative technique for the subsurface interpretation, where the Cretaceous hydrocarbon reservoirs geometry and lateral variations at SWS field were clearly imaged and reliably detected.
To invert such a high-resolution smoothed-earth impedance model, the initial model parameters have been consistently constrained by the available stratigraphic-control well data, real seismic reflections and a prior subsurface geo-information. The confidence of the inversion results was verified by cross-correlation of the resulting impedance log with the original impedance data at the rest the stratigraphic-control wells.
Post-stack seismic inversion workflow set out also to justify the process of seismic inversion by comparing it back to full-stack seismic data. A comparison of the absolute impedance inversion results shows that the used methods produced the best correlation with the synthetic generated after inversion. The inverted sections gave an improved subsurface image of seismic data and achieved the characterization of the reservoir in a relevant way.
The interpretation of the inverted sections shown that relatively low impedance values found indicating relatively low velocity and density values. The reservoir has low impedance values.
152
To sum up certain recommendations for the future upcoming work at SWS field, the following points should be taken into consideration:
It is highly recommended to propose a new seismic acquisition or to re-process the existed volume at SWS field to win a better resolution and obtain deep detailed structural elements and stratigraphic features.
It is better to apply the present (and different) seismic inversion schemes, using the whole available stratigraphic-control wells all around the study area, to obtain much better results.
A firm foundations in the form of a reliable wavelet, suitably and more wire-line logged wells and a sufficiently dense initial model is required to allow the maximum rewards from the method to be held and then the economic impact of the method could be assessed.
The results of the present work are suggested to be compared to other results using other methods to determine better inclusive conclusion.