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7th Middle East Geosciences Conference and Exhibition
Manama, Bahrain
March 27-29, 2006
Attribute
Seismic
Volume Facies Classification for Predicting Fractures in Carbonate
Reservoirs
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.