ProAZ

ProAZ maps fractures and predicts stress by observing azimuthal variations in the P-wave seismic data. Prestack azimuthally processed seismic data are analyzed in terms of time and amplitude azimuthal variations attributed to anisotropic effects.

ProAz Fence DetailPredicted fracture intensity and direction displayed in the visualization tool.

Anisotropy and Fracture Analysis

ProAZ provides a series of tools to enable interpreters to interactively explore for azimuthal variations in their datasets and generate azimuthal attributes to summarize the results.

Benefits of Using ProAZ include:

  • Single module to condition, analyze, and interpret the data
  • Easy QCs showing the distribution of azimuths and offsets at a particular location
  • Quick displays of azimuthally processed data and generation of common offset/common azimuth gathers
  • Interactive tools to explore for azimuthal amplitude variations
  • Multiple methods to generate azimuthal attributes
  • Ability to display azimuthal attributes as platelets in visualization software
Case Study Icon
P-wave AVAz Modeling:
A Haynesville Case study
 Download (PDF, 306 KB)

Azimuthal Gather  Conditioning

The conditioning of azimuthal data is as critical for accurate results as gather conditioning for standard AVO work. Starting from angle or offset gathers, the super gathering of azimuthal data can be done in two different ways:

  • Common-offset or Common-angle gathers with variable azimuth within each sector
  • Common-azimuth gathers with variable offset within each sector

ProAZ Analyze Detail Left: Prestack seismic data. Middle: Amplitude versus azimuth with angle information shown in color. Top right: Amplitude versus offset with azimuth information shown in color. Bottom right: Amplitude versus azimuth and offset with amplitude information shown in color.

Anisotropy Indicators - Azimuthal AVO Analysis

The azimuthal AVO analysis tool allows users to interactively analyze and observe amplitude data as a function of azimuth, offset, or both offset and azimuth on a single gather.

ProAZ Attribute Detail Left: Common-azimuth/common-offset gathers in the image two common azimuths with variable offsets at the well control are shown. Middle: Anisotropic gradient calculated from the gathers. Note the two anomalie highlighted at the well location. Right: Anisotropy gradient calculated on a data slice at the level of the shallower anisotropy anomaly highlighted. The blue line represents the 2D trace on the seismic gathers shown.

Anisotropy Indicators - Azimuthal AVO Attributes

When the azimuthal gathers are properly conditioned and the amplitudes are robust, ProAZ has the ability to create and extract several different azimuthal AVO attributes that can be used to detect and visualize anisotropy.

Two different approaches have been implemented:

  • Near-Offset R¨¹ger equation
  • Azimuthal Fourier Coefficients
ProAZ Viz Detail Left: Average value of the anisotropic gradient calculated over a 10 ms window centered on the base of the Haynesville shale formation (Louisiana). The anisotropic gradient provides fracture intensity information but not orientation. Right: The isotropy plane azimuth along with anisotropic gradient are shown as color-coded platelets providing both intensity and orientation information.

Interpretation and Visualization

Both approaches produce magnitude and azimuth attributes. The magnitude attributes contain information about fracture intensity while the azimuth attributes contain information about the fracture strike. The Bani and Фiso can be combined in the visualization tool (View3D) for a display of fracture intensity and primary direction of fracturing. These values can also be combined with attribute slices displayed in 3D to show regional trends between attributes and fracturing.


* With special thanks to the CSEG Recorder Magazine. Authors: Jon Fernando (CSEG RECORDER Chief Editor 2013), Lee Hunt, Jon Downton, Ron Larson (CSEG President 2013).This paper was recognized as CSEG Best RECORDER Paper in 2011.

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