Seismic facies analysis

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Seismic facies are "mappable, three dimensional seismic units composed of groups of reflections whose parameters differ from those of adjacent facies units”.[1] Seismic facies analysis is the description and interpretation of seismic reflection parameters, such as configuration, continuity, amplitude, and frequency, within the stratigraphic framework of a depositional sequence. Its purpose is to determine all variations of seismic parameters within third-order sequences and their systems tracts in order to determine lateral lithofacies and fluid type changes.[2]

Control of thickness tuning and frequency tuning on seismic facies. Amplitude and its instantaneous attribute models are calculated with 90° Ricker wavelets of 20-, 35-, and 80-Hz peak frequencies (or 26-, 45.5-, and 104-Hz predominant frequencies, respectively). No noise is added to the convolution models.[3]

Reflection parameters

There are five useful reflection parameters:

  • Configuration (reflection geometry)
  • Continuity
  • Amplitude
  • Frequency
  • Interval velocity

Depositional environment, sediment source, and lithofacies can be interpreted by grouping these parameters into mappable, three-dimensional seismic facies.[4] The table below[1] summarizes the information obtained from each parameter.

Reflection parameter Geologic interpretation
Configuration
  • Bedding patterns
  • Depositional properties
  • Erosion and paleotopography
  • Fluid contacts
Continuity
  • Lateral continuity of strata
  • Depositional processes
Amplitude
  • Velocity-density contrasts of individual interfaces
  • Bed spacing
  • Bed thickness
Frequency
  • Bed thickness
  • Fluid content
Interval velocity
  • Lithofacies estimations
  • Porosity estimations
  • Fluid content

Seismic facies analysis procedure

The table below outlines a procedure to analyze seismic facies from a grid of sections (vertical) of 2-D or 3-D seismic data (modified from [1]).

Step Action
1 Divide each depositional sequence into seismic facies units on all seismic sections.
2 Describe the internal reflection configuration and terminations of each seismic facies unit, i.e., sigmoid, parallel, downlap.
3 Transfer seismic facies descriptions from seismic sections to a shot point map of each sequence.
4 Combine seismic facies distribution and thickness with the map distribution of any other diagnostic parameters, such as interval velocity or localized amplitude anomalies.
5 Integrate well and outcrop data with seismic facies distribution.
6 Interpret the seismic facies maps in terms of depositional settings such as marine or nonmarine, water depth, basin position, energy, transport direction, or any other depositional aspects.
7 Estimate lithology using depositional setting interpretation from step 6 and all available data.

See also

References

  1. ↑ 1.0 1.1 1.2 Mitchum, R., M., Vail, P., R., Sangree, J., B., 1977, Seismic stratigraphy and global changes in sea level, part 6: stratigraphic interpretations of seismic reflection patterns in depositional sequences, in Payton, C., E., ed., Seismic Stratigraphy and Applications to Hydrocarbon Exploration: AAPG Memoir 26, p. 117–133.
  2. ↑ Vail, P., R., 1987, Seismic stratigraphy interpretation procedure, in Bally, A., W., ed., Atlas of Seismic Stratigraphy: AAPG Studies in Geology No. 27, p. 2.
  3. ↑ Zeng, Hongliu, 2013, Frequency-dependent seismic-stratigraphic and facies interpretation: AAPG Bulletin, v. 97, no. 2, p. 201–221, DOI:10.1306/06011212029.
  4. ↑ Bally, A., W., ed., 1987, Atlas of Seismic Stratigraphy: AAPG Studies in Geology 27, vol. 1, 124 p.

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