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7th Middle East Geosciences Conference and Exhibition
Manama, Bahrain
March 27-29, 2006
Exploration Technical Services Department, Saudi Aramco, P.O. Box
6684, Dhahran, 31311, Saudi Arabia, phone: 96638736396, fax: 96638730475, [email protected]
Understanding the fault and fracture distribution and orientation prior to drilling and completion of production and injection wells is critical for optimal oil production and maximizing recovery. In recent years multi-volume seismic attributes have been used more efficiently to help map these localized faults or fractured zones within reservoirs. In this study, covering a portion (about 750 Km2) of the Ghawar field in Saudi Arabia, unsupervised seismic facies volume classification was applied to multiple seismic attribute cubes to predict fracture zones in the Arab-D carbonate reservoir.
The pre-stack time
migrated 3D seismic dataset was processed to preserve relative amplitude information. Attribute
analysis of the input seismic volume showed several areas containing East-West oriented lineaments. Many of these
lineaments were not clearly observed either in
time
or horizon seismic amplitude
slices
. For lineament mapping, each
lineament must be recognizable in more than one seismic attribute volume. The mapped seismic lineaments were
interpreted to be small faults (or fractures) through which natural drainage may facilitate fluid migration through the
reservoir. The long extent of these lineaments (several kilometers in length) suggests they are probably faults. A binary
scheme (two seismic facies) of multi-volume seismic facies classification of fault-related seismic attributes was successful in
clustering areas of the field where optimum oil flow rate wells have been observed. This analysis of post-stack seismic
attributes helped improve the understanding of observed well performance by mapping the distribution of fracture systems
within the reservoir.