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Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain
Carbonate Enhanced Seismic Mapping Using Post-Stack Band-Pass Frequency Seismic Volume Filtering of Two Offshore Fields in Abu Dhabi, United Arab Emirates
(1) ZADCO, Zakum Development Company, Abu Dhabi, United Arab Emirates.
(2) ExxonMobil Upstream Research Company, Houston, TX.
During recent carbonate seismic interpretation projects of two offshore fields in Abu Dhabi, UAE, several carbonate/anhydrite intervals were mapped using Band-Pass frequency filtered 3D seismic volumes. Two types of band pass filtered seismic volumes were used to enhance Eocene/Palaeocene and Cretaceous carbonate reservoir intervals, where either Low-Pass or High-Pass frequency filters were designed specifically for the specific geologic purpose and target interval.
The first offshore field high resolution 3D seismic volume covers a salt-diaper pierced shallow carbonate and anhydrite layers with complex salt-tectonic fault and karsts geometries. Interpretations for several carbonate / anhydrite intervals, and faults are needed to be accurately mapped for highly deviated well-bores targeting karsted and faulted Rus (Eocene Anhydrite) and Umer Radhuma (Palaeocene Carbonate) geologic intervals. Significant seismic reflection events and fault displacement image improvements of shallow seismic high to low impedance reflectors were accomplished by using a Low-Pass frequency filter with a 6 - 35Hz frequency range. Continuity of seismic events and fault offsets were enhanced significantly and confirmed by well-ties and subsequent time/depth conversion model. The second offshore field 3D seismic volume covers a giant offshore Oil field where the main seismic mapping targets were Kharaib (Cretaceous Carbonate) reservoir faulted intervals. Similar to the first field positive results, significant seismic continuity and fault displacement image improvements were accomplished by using a High-Pass frequency filter with a 60- 100Hz frequency range.
The key objective of this paper is to show the significance of certain seismic frequency ranges which enhance specific geologic features at both early and late carbonate depositional systems, also to explain the workflow developed specifically to tackle seismic frequency ranges for well drilling operations and reservoir characterization purposes in carbonate depositional settings.