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Sweetness is a seismic attribute that, especially when usedin conjunction with coherency, can be very useful for

channel detection.Although the attribute is not new, previous documentation ofits utility and derivation has been

mostly lacking. Sweetnessis derived by dividing reflection strength by the square rootof instantaneous frequency.

This mathematical definition capturesattribute relationships that seismic interpreters have beenusing qualitatively

for many years: isolated sand bodies inshale successions tend to generate stronger, broader reflectionsthan the

surrounding shale. Sweetness becomes less useful forchannel detection when acoustic impedance contrasts

betweensands and shales are low or when sands and shales are highlyinterbedded.

References:

Hart, B., 2008, Channel detection in 3-D seismic data using sweetness: AAPG Bulletin, v. 92, p. 733-742.

Pennington, W. D., 2002, Calibration of Seismic Attributes for Reservoir Characterization: Final Technical

Report, Michigan Technological University.

My experiences using sweetness attribute for channel detection

I am using Stratton data for channel detection using sweetness attribute. An apparent channel at approximately

842ms can be located in the shallow region of the Stratton Field. This channel is easily identified from amplitude

measurements on a time slice (Figure 1), but a phase change is introduced across this time slice by the gentle

dip of the beds.

Figure 1. Time

slice seismic amplitude 842 ms.

http://www.aananaya.com/wp-content/uploads/2011/06/Seis_Amp.jpg

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Figure 2. Time

slice sweetness attribute 842 ms.

http://www.aananaya.com/wp-content/uploads/2011/06/Seis_SW.jpg

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Sweetness

Sweetness (theory)is an empirical attribute designed to identify sweet spots, places that are oil andgas prone. The definition of sweetness is motivated by the observation that, in young clasticsedimentary basins, sweet spots imaged on seismic data tend to have strong amplitudes and low

frequencies. High sweetness values are those that most likely indicate oil and gas. The definition ofsweetness given here slightly modifies that given by Oliveros and Radovich (1997) to produce a morestable, smoothly-varying measure. Sweetness in Seismic Attribute Generation is the same attribute as"average sweetness" in the GeoProbe software.

The Samplesparameter (which specifies window length) affects only the computation of the averagefrequency, and rarely needs to be changed. Reducing it can enhance the character of the result, butalso makes it look noisier.

Sweetness tends to be driven more by amplitude than by frequency and often closely resemblesreflection strength. Sweetness anomalies of interest are therefore those that are more pronouncedthan the corresponding reflection strength anomalies. Hart (2008) argues that sweetness isparticularly useful for channel detection.

Note:The workflows are slightly different for2D linesand3D surveys.

http://esd.halliburton.com/support/LSM/DSD/DSD/5000/5000_8/Help/mergedProjects/attributes/sweetness_bg.htmhttp://esd.halliburton.com/support/LSM/DSD/DSD/5000/5000_8/Help/mergedProjects/attributes/sweetness_bg.htmhttp://esd.halliburton.com/support/LSM/DSD/DSD/5000/5000_8/Help/mergedProjects/attributes/sweetness_bg.htmhttp://esd.halliburton.com/support/LSM/DSD/DSD/5000/5000_8/Help/mergedProjects/attributes/sweetness.htm#2dhttp://esd.halliburton.com/support/LSM/DSD/DSD/5000/5000_8/Help/mergedProjects/attributes/sweetness.htm#2dhttp://esd.halliburton.com/support/LSM/DSD/DSD/5000/5000_8/Help/mergedProjects/attributes/sweetness.htm#2dhttp://esd.halliburton.com/support/LSM/DSD/DSD/5000/5000_8/Help/mergedProjects/attributes/sweetness.htm#3dhttp://esd.halliburton.com/support/LSM/DSD/DSD/5000/5000_8/Help/mergedProjects/attributes/sweetness.htm#3dhttp://esd.halliburton.com/support/LSM/DSD/DSD/5000/5000_8/Help/mergedProjects/attributes/sweetness.htm#3dhttp://esd.halliburton.com/support/LSM/DSD/DSD/5000/5000_8/Help/mergedProjects/attributes/sweetness.htm#3dhttp://esd.halliburton.com/support/LSM/DSD/DSD/5000/5000_8/Help/mergedProjects/attributes/sweetness.htm#2dhttp://esd.halliburton.com/support/LSM/DSD/DSD/5000/5000_8/Help/mergedProjects/attributes/sweetness_bg.htm

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FIGURE 1. Examples of original .bri shared memory volume (left) and resultant sweetness attributevolume (center) calculated using Seismic Attribute Generation. In this example, the attribute valuesrange from 0 (red) to 19.05 (blue), as shown in the default GeoProbe Sweet color map.

To create a 3D sweetness volume:

1. Select the Input and Output names in theInput/Output pane.

Note:If you limit the Zrange of the output in theArea of Interestpane, include the range inthe output file name. There is a 48-character limit to the file name.

2. Use the parameters in the Area of Interest pane to specify the limits of the output volume.3. Select the Attributesoption in the drop-down list on theOperations pane.4. Select the Miscellaneoussubtab on the Operations pane.5. Select Sweetnessin the miscellaneous attributes drop-down list.6. Specify the vertical dimension (Samples) of the output volume using the spinner controls.

The initial default value is 11 samples.

Note:The algorithm uses a Hamming window that requires odd-numbered values greaterthan 2 for Samples.7. If needed, adjust the output data range in theScaling pane.

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8. Click Applyto generate the sweetness volume.

Note: The generation of a sweetness attribute volume is relatively short compared to thegeneration of some other attribute volumes, especially relief attribute volumes.

Similarly,

To calculate a sweetness attribute display for 2D data:

1. Select the Input and Output names in theInput/Output pane.2. Use the parameters in theArea of Interest paneto specify the limits of the output in terms of

2D seismic lines.3. Select the Attributesoption in the drop-down list on theOperations pane.4. Select the Miscellaneoussubtab on the Operations pane.5. Select Sweetnessin the miscellaneous attributes drop-down list.6. Specify the vertical dimension (Samples) of the output lines using the spinner controls. The

initial default value is 11 samples.

Note:The algorithm uses a Hamming window that requires odd-numbered values greaterthan 2 for Samples.7. If needed, adjust the output data range in theScaling pane.8. Click Applyto generate the sweetness attribute display on 2D data.

Note: In general, the generation of 2D sweetness attribute data is relatively short compared tothe generation of structure-filter processed data or the generation of most structural attributedata.

9. Because a separate file is created for each 2D line when you generate sweetness attributedata, you can quickly create a lot of files.Click hereto learn how to delete unwanted seismicfiles using the Seismic Data Manager in the OpenWorks software.

References

Hart, B. S., 2008, Channel detection in 3-D seismic data using sweetness,AAPG Bulletin, 92, 733-742.

Oliveros, R. B., and B. J. Radovich, 1997, Image-processing display techniques applied to seismicinstantaneous attributes on the Gorgon gas field, North West Shelf, Australia: 67th SEG AnnualMeeting, Expanded Abstracts, 2064-2067.

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