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Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain
Multiple Incision Levels in Al Shaheen Field Offshore Qatar
(1) PED, Maersk Oil Qatar, Doha, Qatar.
(2) QP, Doha, Qatar.
Recent acquisition of a large high resolution 3D seismic data over Al Shaheen field offshore Qatar revealed the presence of several levels of channel incisions, which provide important information about the geological evolution of this part of the Arabian Plate. The acquisition parameters and subsequent processing flow were selected for best resolution of shallow targets at some 2000-4000ft. Data quality was hampered by the shallow water and present-day reefs, small-scale erosional features and interchanging lithology in the overburden. Ongoing efforts to improve data quality are designed to further eliminate multiples and to resolve imaging problems caused by the shallow erosional and deep collapse features and gas chimneys. Further data processing notwithstanding, the analysis of the data has already allowed us to recognise a number of significant stratigraphic features.
There are four levels of channels, starting as shallow as 100-160ms at Dammam level. Second, the Umm3 channelized drainage features with steep edges are recognised as one of the major causes of energy scattering which deteriorates imaging and overall data quality. These are short erosional channel-like features oriented radially around a topographic paleo-low. Third, top Halul channels which are also causing significant imaging problems due to a large velocity contrast between the infill and the surrounding sediments. These channels are long, relatively straight, and have dimensions that allow them to be easily recognised both on stratigraphic time slices as well as on seismic cross-sections. Fourth, incision at the top of the Shuaiba platform during sub-areal exposure, which has previously been established and described, has been confirmed for the whole block. Several levels and dimensions of channels are evident, with smaller channel systems towards the highest point of Shuaiba platform in the North and a larger meandering channel system in the South.
Each of these channel levels requires different tools and attributes for their delineation. The geological significance of these incised channel levels for the Arabian Plate geological evolution is discussed.