Changes

  | part    = Predicting the occurrence of oil and gas traps

  | part    = Predicting the occurrence of oil and gas traps

  | chapter = Interpreting 3-D seismic data

  | chapter = Interpreting 3-D seismic data

  | frompg  = 13-1

  | frompg  = 13-22

  | topg    = 13-27

  | topg    = 13-22

  | author  = Geoffrey A. Dorn

  | author  = Geoffrey A. Dorn

  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch13/ch13.htm

  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch13/ch13.htm

==Rules of thumb==

==Rules of thumb==

Here are a few rules of thumb that the interpreter should apply when approaching the use of attributes in a 3-D seismic survey:

Here are a few rules of thumb that the interpreter should apply when approaching the use of [[Basics of seismic attributes|attributes]] in a [[3-D seismic data: the data cube|3-D seismic]] survey:

* Consider the geology.

* Consider the geology.

* Use different attributes.

* Use different attributes.

* Use normalized attributes

* Use normalized attributes

* [[AVO]]id using an interval attribute that involves the summation of a data measure that varies in a cyclic fashion over an interval

* Avoid using an interval attribute that involves the summation of a data measure that varies in a cyclic fashion over an interval

==Consider the geology==

==Consider the geology==

==Normalized attributes==

==Normalized attributes==

Be wary of using volume or interval attributes that are not normalized by the isochron of the interval over which they are calculated. This normalization can take the form of dividing the attribute by either the actual isochron or by the number of time samples in the interval. Although this normalization is not appropriate for some interval attributes (e.g., the maximum absolute amplitude in the interval), it is essential for any attribute that involves a summation over the interval. Without the normalization, the lateral attribute variation may simply be showing the variation in the isochron.

Be wary of using volume or interval attributes that are not normalized by the [[isochron]] of the interval over which they are calculated. This normalization can take the form of dividing the attribute by either the actual isochron or by the number of time samples in the interval. Although this normalization is not appropriate for some interval attributes (e.g., the maximum absolute amplitude in the interval), it is essential for any attribute that involves a summation over the interval. Without the normalization, the [[lateral]] attribute variation may simply be showing the variation in the isochron.

==Cyclic variation of an attribute==

==Cyclic variation of an attribute==

Avoid using an interval attribute that involves the summation of a data measure that varies in a cyclic fashion over an interval. For example, in several systems it is possible to calculate the sum of trace amplitude over a user-specified interval. Since the trace amplitude has both positive and negative values over most intervals (unless the interval is so small as to include only a half-cycle of the data), the positive and negative values tend to cancel each other out. A second example would be the sum of instantaneous phase over an interval in the volume

Avoid using an interval attribute that involves the summation of a data measure that varies in a cyclic fashion over an interval. For example, in several systems it is possible to calculate the sum of trace amplitude over a user-specified interval. Since the trace amplitude has both positive and negative values over most intervals (unless the interval is so small as to include only a half-cycle of the data), the positive and negative values tend to cancel each other out. A second example would be the sum of [[instantaneous phase]] over an interval in the volume

==Know the attribute==

==Know the attribute==

[[Category:Predicting the occurrence of oil and gas traps]]  

[[Category:Predicting the occurrence of oil and gas traps]]  

[[Category:Interpreting 3-D seismic data]]

[[Category:Interpreting 3-D seismic data]]