Abstract
The prediction of logs and reservoir properties from seismic data plays a critical role in the characterization of oil and gas reservoirs. Even though the physical relationships between seismic attributes and reservoir parameters are not always clear, statistical relationships should be preferred than deterministic approaches. This technique performs a statistical relationship between well data (porosity) and seismic data (attributes) then a calibration process and a residual correction will be calculated and finally the interpretation for the reservoir properties over the field will be carried out and the map of the log or reservoir parameter of interest will be prepared over the whole field.
Mathematically, we refer to multivariate geostatistics, which is a broad term that encompasses all methods like cokriging that utilize more than one variable to predict other variables of interest.
A volume attribute is defined as the sum of an instantaneous attribute over an interval. The interval can be specified between two zones, or as a constant window around one horizon or zone. So after extracting a volumetric attribute, each value point of the resulted map is the representative for the whole interval between the top and base of the zone under study, i.e. the resulted attribute map is the representative of the whole interval in average.
Effective porosity over producible zones of interest was predicted with the aid of multivariate geostatistics method and following data:
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A 3D cube of acoustic impedance.
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Quadrature trace, cosine of instantaneous phase and inverse of travel time attributes.
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Calculated effective porosity for 5 wells in the field.
The objective of this study is to find a link between 3D seismic data, which covers the whole field, and effective porosity that is only determined at 5 wells.
