US 7,453,767 B1Granted

Method for deriving a 3D GRAZ seismic attribute file

OwnerMichael John Padgettinventor

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Abstract

A method of determining and analyzing spatial changes in the earth's subsurface. The method includes obtaining seismic attribute data as a 3D data volume and obtaining corresponding 3D dip and azimuth as a 3D volume and obtain corresponding 3D reliability volumes or 3D censor volumes which are representative of portions of the volume within in which a reliable dip and azimuth can be determined. The gradient of the seismic attribute data in the direction of structural dip is formed using either a dot product methodology or a derivative methodology after interpolation onto the direction of structural dip. At non-reliability locations or locations where no gradient could be meaningfully computed null values are stored. High gradient values in narrow time or depth ranges which are both statistically significant relative to a background level and contiguous designate regions likely to be proximal to a fluid contact or seismic flat spot.

Claims13

Dependent claims

A method of determining the existence of and location of hydrocarbon and water fluid contacts by analyzing spatial changes in a 3D seismic data set comprising the steps of:

a. obtaining seismic attribute data comprising attributes as a 3D data volume;
b. obtaining 3D dip and azimuth data as at least one set of 3D volume data and deriving corresponding 3D reliability volumes or deriving corresponding 3D censor volumes which are representative of portions of the at least one set of 3D volume data which 3D dip data and azimuth data can be reliably determined;
c. selecting a focused subvolume of interest within the at least one set of 3D volume data;
d. determining reliability locations within the focused subvolume of interest having a non-null 3D dip data and non-null 3D azimuth data within the 3D reliability volumes or 3D censor volumes across the focused subvolume of interest forming a sequence of reliability locations;
e. computing an average for a plurality of vector dips around each reliability location in the sequence of the reliability locations forming at least one structural dip vector for each reliability location;
f. obtaining a gradient of at least one of the attributes of the 3D data volume forming dot products using the gradient with at least one structural vector at each reliability location;
g. storing the dot products for each reliability location forming a 3D output subvolume;
and
h. repeating the method for the 3D output volume.

6 more elements

Dependencies are inferred from the claim text.