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

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Presentation on theme: "Fault-Fracture charachterization in OpendTect OpendTect Master Class June 15, 2014 Version 5.0."— Presentation transcript:

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

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

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 Introduction Automatic Fault Extraction −Algorithm −Interface −Examples New Fracture Attributes −Overview −Interface −Examples Outline

5 Finger Vein Pattern Technique Introduction Used typically for fingerprint data processing Biomedical technique extended to seismic

6 Finger Vein Pattern Technique Algorithm for automatically tracking faults 1.Input: A discontinuity volume with an enhanced fault pattern (e.g. Coherence or Similarity) 2.Curvature based score calculation for 2D profiles oriented along various azimuths (per Z-slice) 3.Extract connected components on each 2D profile (per Z-slice) 4.Apply thinning, merging algorithms on each connected component to form sticks 5.Sort and group sticks 6.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 Introduction Automatic Fault Extraction −Algorithm −Interface −Examples New Fracture Attributes −Overview −Interface −Examples Outline

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)

12 Fault Auto Extraction Interface: Parameter explanation Example Z-slice through a similarity volume. Note the faults lineaments with low similarity values (black). The “Minimum Fault Length per Z-slice” is the horizontal length of the fault on any Z-slice. 4 The “Minimum Number of Sticks” is the min number of Z-slices a fault must pass through, defines min vertical extent of fault 1

13 The “Search stepout between Z-slices” is the the horizontal displacement of the searching window over the inline/crossline direction when extracting the fault surfaces Zslice-by-Zslice 2 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. 3 Fault Auto Extraction Interface: Parameter explanation

14 1 Z-Slice 1 Z-Slice 5 1 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. Fault Auto Extraction Interface: Parameter explanation

15 1 2 2 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 Z-Slice 1 Z-Slice 5 Fault Auto Extraction Interface: Parameter explanation

16 1 2 Z-Slice 1 Z-Slice 5 3 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. 3 Fault Auto Extraction Interface: Parameter explanation

17 1 2 Z-Slice 1 Z-Slice 5 3 The “Minimum fault Length per Z-slice” is the minimum horizontal length of the fault on any Z- slice. 4 4 Fault Auto Extraction Interface: Parameter explanation

18 5

19 Either a “Fault Stick Set” or individual “Faults” can be outputted. 6 7 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. Fault Auto Extraction Interface: Parameter explanation

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

21 Fault tracker similarityFault scoreFault azimuth grey Binary faults 90%Binary faults 95% All faultsBiggest fault sticks Volume components Fault azimuth color Biggest fault sticksAll faultsVolume components Sponsored by:

22 Fault Auto Extraction Example: Gulf of Mexico Inline showing stacked seismic data after Fault Enhancement Filter application. A min similarity volume, computed from this fault enhanced seismic volume, is used as input for Auto Fault Extraction algorithm.

23 Fault Auto Extraction Example: Gulf of Mexico Inline showing stacked seismic data after Fault Enhancement Filter application with automatically extracted faults on top. Fault points

24 Fault Auto Extraction Example: Gulf of Mexico Z-slice at 400ms showing stacked seismic data after Fault Enhancement Filter application.

25 Fault Auto Extraction Example: Gulf of Mexico Z-slice at 400ms showing Min Similarity computed from fault enhanced seismic.

26 Fault Auto Extraction Example: Gulf of Mexico Z-slice at 400 ms showing Min Similarity computed from fault enhanced seismic with automatically extracted faults.

27 Introduction Automatic Fault Extraction −Algorithm −Interface −Examples New Fracture Attributes −Overview −Interface −Examples Outline

28 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 Density attribute 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 radius along Z-slices. New Fracture Attributes Overview

29 Introduction Automatic Fault Extraction −Algorithm −Interface −Examples New Fracture Attributes −Overview −Interface −Examples Outline

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

31 Introduction Automatic Fault Extraction −Algorithm −Interface −Examples New Fracture Attributes −Overview −Interface −Examples Outline

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

33 Colorbar unit = Meters Max curvature value of more than 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. New Fracture Attributes Example: Gulf of Mexico Z-slice at 400 ms Fracture Proximity Input: Maximum curvature Fracture threshold: 0.004

34 Max curvature value of more than 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. New Fracture Attributes Example: Gulf of Mexico Z-slice at 400 ms Fracture Density Input: Maximum curvature Fracture threshold: Radius: 400 m


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