Fault-Fracture charachterization in OpendTect

1. Fault-Fracture charachterization in OpendTect Version 5.0 OpendTect Master Class June 15, 2014

2. Outline • Introduction • Automatic Fault Extraction • Algorithm • Interface • Examples • New Fracture Attributes • Overview • Interface • Examples

3. Introduction • This presentation covers the concepts/workflows for • Automatic fault extraction in OpendTect • Two new fracture related attributes • System Requirements: • For visualization, a good system is required. • Multicore processor • RAM 8GB or higher, and a good graphics card (>1GB) • Licence Requirements • Automatic Fault Extraction Dip-Steering LICENSE • New Fracture Attributes Dip-Steering LICENSE

4. Outline • Introduction • Automatic Fault Extraction • Algorithm • Interface • Examples • New Fracture Attributes • Overview • Interface • Examples

5. Finger Vein Pattern TechniqueIntroduction • Used typically for fingerprint data processing • Biomedical technique extended to seismic

6. Finger Vein Pattern Technique Algorithm for automatically tracking faults • Input: A discontinuity volume with an enhanced fault pattern (e.g. Coherence or Similarity) • Curvature based score calculation for 2D profiles oriented along various azimuths (per Z-slice) • Extract connected components on each 2D profile (per Z-slice) • Apply thinning, merging algorithms on each connected component to form sticks • Sort and group sticks • Output a set of faults or a fault stick-set

7. Finger Vein Pattern Technique Algorithm for automatically tracking faults Z-slice through a discontinuity volume, e.g. Coherence Compute Curvature of the discontinuity attribute, along a 2-D profile (AA`) oriented along azimuth ‘j’ • Compute Score which includes both magnitude and width of fault anomaly • Assign Score to the 2-D profile AA`

8. Finger Vein Pattern Technique Algorithm for automatically tracking faults • Compute scores for all 2-D profiles along ‘4’ azimuths to get a “Capability slice” V(x, y) • Compute “Confidence slices” along different azimuths and choose the one with max value. • Move to next Z-slice

9. Outline • Introduction • Automatic Fault Extraction • Algorithm • Interface • Examples • New Fracture Attributes • Overview • Interface • Examples

10. Fault Extraction Start Position • Fault extraction produces two sets of outputs: • Volumes: fault scores, dip and azimuth • Faults: sticks or planes • Volumes launch: • Processing ->Create Seismic Output->Volume Builder • Faults launch: • Processing->Fault Extraction Volume Builder UI

11. Fault Auto Extraction Fault Planes User Interface The new Fault Auto Extraction tool is under the Processing menu • General threshold parameter (0) • Vertical parameters: Min sticks per fault (1) and Min vertical overlap rate (3) • Horizontal (per Z-slice) parameters: Min fault length (4), Search step-out (2) and optionally Merging faults (5) 0 1 2 3 4 7

12. Fault Auto Extraction Interface: Parameter explanation Z-Slice 1 1 1 Z-Slice 5 The “Minimum sticks per fault” is the min number of Z-slices a fault must pass through, i.e. it defines min vertical extent of fault.

13. Fault Auto Extraction Interface: Parameter explanation 2 Z-Slice 1 1 2 Z-Slice 5 The “Search stepout between Z-slices” is the horizontal displacement of the searching window over the inline/crossline direction when extracting the fault surfaces Zslice-by-Zslice

14. Fault Auto Extraction Interface: Parameter explanation Z-Slice 1 1 2 3 3 Z-Slice 5 The “Min vertical overlap rate” defines the minimum overlap between anomalies on adjacent Z-slices, in order for them to be considered part of one single fault.

15. Fault Auto Extraction Interface: Parameter explanation Z-Slice 1 4 1 2 3 4 Z-Slice 5 The “Minimum fault Length per Z-slice” is the minimum horizontal length of the fault on any Z-slice.

16. Fault Auto Extraction Interface: Parameter explanation 5

17. Fault Auto Extraction Interface: Parameter explanation Either a “Fault Stick Set” or individual “Faults” can be outputted. 6 1 2 3 The “Number of top faults” is the maximum number of tracked faults on any Z-slice. In case of noisy data, use of a small number here may be helpful. 7 4 5 6 7

18. Outline • Introduction • Automatic Fault Extraction • Algorithm • Interface • Examples • New Fracture Attributes • Overview • Interface • Examples

19. Fault tracker Biggest fault sticks Volume components All faults Biggest fault sticks Volume components All faults similarity Fault score Fault azimuth grey Binary faults 90% Binary faults 95% Fault azimuth color Sponsored by:

20. Outline • Introduction • Automatic Fault Extraction • Algorithm • Interface • Examples • New Fracture Attributes • Overview • Interface • Examples

21. New Fracture AttributesOverview Two new qualitative fracture characterization attributes, Fracture Proximity and Fracture Density, are going to be available in OpendTect v5.0 Fracture Proximity improves visualization of potential fracture anomalies. It computes the lateral distance (i.e. along Z-slice) from a trace location classified as a fracture. Whether a particular trace can be defined as being part of a fracture, is determined by a user-specified threshold, on various curvature/coherence related attributes such as Max Curvature. Fracture Densityattribute is useful in pin-pointing locations with maximum fracture activity, within a user-defined radius. This “radius” can for example be linked to fracking radius for drilling. It computes the ratio of “number of traces classified as being fractures” to the “total number of traces present”, in a circle of given radiusalong Z-slices.

22. Outline • Introduction • Automatic Fault Extraction • Algorithm • Interface • Examples • New Fracture Attributes • Overview • Interface • Examples

23. New Fracture AttributesInterface Input data should be a discontinuity attribute, e.g. Similarity & Curvature 1 1 Threshold value of input discontinuity attribute above which a fracture anomaly is expected 2 2 3 Choose to output either “Fracture Proximity” or “Fracture Density” 3 For “Fracture Density” a radius for scanning and computing the density of fracture anomalies, is also required. 4 4

24. Outline • Introduction • Automatic Fault Extraction • Algorithm • Interface • Examples • New Fracture Attributes • Overview • Interface • Examples

25. New dip-steered attributesExample: Gulf of Mexico Max curvature is a possible input for Fracture Proximity and Density attributes. Input: Maximum curvature Inl/Crl stepout: 2 Steering input : Detailed steering Z-slice at 400 ms

26. New Fracture AttributesExample: Gulf of Mexico Max curvature value of more than 0.004 denotes a possible fracture. The distance from all those traces where max curvature is higher than the threshold is computed by the Fracture Proximity attribute. Fracture Proximity Input: Maximum curvature Fracture threshold: 0.004 Z-slice at 400 ms Colorbar unit = Meters

27. New Fracture AttributesExample: Gulf of Mexico Max curvature value of more than 0.004 denotes a possible fracture. The ratio of all those traces where max curvature is higher than the threshold to the total number of traces, present in a circle of radius 400m, is computed by the Fracture Density attribute. Fracture Density Input: Maximum curvature Fracture threshold: 0.004 Radius: 400 m Z-slice at 400 ms