Abstract: Fault Mapping and Reservoir Characterization from Amplitude and Dip/Azimuth Extraction in Ship Shoal 274/293 Field
KULANDER, CHRIS
Texas A&M Geophysics, College
Station, TX
The Shell Offshore Inc. reservoirs located in Ship Shoal blocks 274 and 293 produce from fault-compartmentalized sand intervals. Faulting associated with salt tectonics controls hydrocarbon type and location.
The A-J reservoirs are a series of sand intervals each containing several
smaller sand layers. Sand groups D, F and G were mapped using the brightest
negative amplitude corresponding with the same sand interpreted on well
data. Amplitude extraction shows a series of lineaments separating bright
producing sands from dim water bearing sands and shale. Lineaments correspond
to NE-SW striking faults that appear to control compartmentalization of
the reservoir. Combining dip/azimuth plots of the producing intervals with
velocity data from sonic logs suggests that the throw of these faults is
40-60 ft. Electric log and dip variations observed in dipmeter data corroborate
this interpretation.
The abrupt change of amplitude across the smaller faults matches production variations in the field and suggests these faults seal and compartmentalize production. This interpretation is supported by production of oil updip from gas in areas where amplitudes indicate faulting. Parallelism of small-displacement faults and regional, large-displacement faults suggests genetic affinity.
AAPG Search and Discovery Article #90932©1998 GCAGS/GCS-SEPM Meeting, Corpus Christi, Texas