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TIKIM “Kirchhoff pre-stack time migration” Overview

TIKIM “Kirchhoff pre-stack time migration” Overview. (Jean-Claude LANCELOT). Meeting EGEODE Massy. TIKIM overview Limited to 2D Marine Processing. Part1: Introduction to time imaging (reminder). Part2: Migration method (Kirchhoff). Part3: Kirchhoff PreSTM in real life: TIKIM.

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TIKIM “Kirchhoff pre-stack time migration” Overview

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  1. TIKIM “Kirchhoff pre-stack time migration” Overview (Jean-Claude LANCELOT) Meeting EGEODE Massy Software Product Management Massy

  2. TIKIM overviewLimited to 2DMarine Processing Software Product Management Massy

  3. Part1: Introduction to time imaging (reminder) • Part2: Migration method (Kirchhoff) • Part3: Kirchhoff PreSTM in real life: TIKIM • Part4: Software / Hardware issues Software Product Management Massy

  4. TIKIM overview TIKIM part 1 “Introduction to Time Imaging” Reminder Software Product Management Massy

  5. Shortcomings of the “Transformation to Zero Offset” sequence The need for pre-stack migration • “Transformation to Zero Offset” sequence does not provide optimum focusing • diffractedevents are not preserved in the stacking process • crossing events may generate velocity conflicts • velocities are not picked at migrated position Migrating the data before stack is the best solution Software Product Management Massy

  6. Post stack imaging Post Stack Time Migration Software Product Management Massy

  7. Pre stack imaging Pre Stack Time Migration Software Product Management Massy

  8. model complexity image quality pre stack depth migration pre stack time migration post stack depth migration post stack time migration TZO velocity work load Software Product Management Massy

  9. TIKIM overview TIKIM part 2 “Migration Methods” Software Product Management Massy

  10. Kirchhoff migration Kirchhoff Migration principle: Constructive and destructive interferences will recreate the image Software Product Management Massy

  11. Superposition principle • Superimpose a wave front chart onto traces. • The net result is an accumulation of energy at the migrated position ….so • the final reflector image results from constructive interference Software Product Management Massy

  12. TIKIM overview TIKIM part 3 PSTM and TIKIM Software Product Management Massy

  13. Kirchhoff PreSTM in real life Warning:Things to have in mind about TIKIM: • The output of TIKIM is Migrated data! • The picking of velocities after TIKIM is on migrated data (migrated gathers), i.e. direct picking of Migration velocities (very interpretative picking, so need of Client input). • There is no “Stack” output in the TIKIM sequence, but only the Migration. A De-migration can be proposed to obtain an un-migrated stack. • Tikim: • needs only the output target definition • does not care about the input geometry • Tikim 2D: just based on Word 4 (CDP) and Word 20 (Offset) Software Product Management Massy

  14. Kirchhoff PreSTM in real life Schematic Comparison between DMO and TIKIM processing sequences: DMO sequence • Pre-processing. • DMO Velocity picking • DMO Stack • Migration velocities. • Migration. TIKIM sequence • Pre-processing. • TIKIM Velocity picking • TIKIM migration • (De-migration Stack) x x Software Product Management Massy

  15. Target definition - 2D * TIKIM == 02 TRAFILE=2003,NUMTRA1,IDTRA=me,REWRITE NPE64,MACHINE=PC,DISTRIB ,BIMG02 DCDP12.5 IMAGE=(FCDP151,LCDP600) OFFSETS=(D150,ID100,XRM5800,XRP50) N0, LMU2,MUTE2 APERCDP5000 DIPLIM=(T400D20,T800D40,T4000D40,T4500D0) NOALIAS=(FMAX75) LVI1 Only definition of the output target! Software Product Management Massy

  16. Offset class definition * TIKIM == 02 TRAFILE=2003,NUMTRA1,IDTRA=me,REWRITE NPE64,MACHINE=PC,DISTRIB ,BIMG02 DCDP12.5 IMAGE=(FCDP151,LCDP600) OFFSETS=(D150,ID100,XRM5800,XRP50) N0, LMU2,MUTE2 APERCDP5000, DIPLIM40 NOALIAS=(FMAX75) LVI1 Software Product Management Massy

  17. Kirchhoff PreSTM in real life • migration parameters Software Product Management Massy

  18. Dip related parameters geological dip in degrees * TIKIM == 02 TRAFILE=2003,NUMTRA1,IDTRA=me,REWRITE NPE64,MACHINE=PC,DISTRIB ,BIMG02 DCDP12.5 IMAGE=(FCDP151,LCDP600) OFFSETS=(D150,ID100,XRM5800,XRP50) N0, LMU2,MUTE2 APERCDP5000, DIPLIM40 NOALIAS=(FMAX75) LVI1 Software Product Management Massy

  19. Time variant dip limit * TIKIM == 02 TRAFILE=2003,NUMTRA1,IDTRA=me,REWRITE NPE64,MACHINE=PC,DISTRIB ,BIMG02 DCDP12.5, IMAGE=(FCDP151,LCDP600) OFFSETS=(D150,ID100,XRM5800,XRP50) N0 LMU2,MUTE2 APERCDP5000, DIPLIM=(T40D15,T300D45,T6000D20,T8000D30) NOALIAS=(FMAX75) LVI1 Software Product Management Massy

  20. dip limit 0° dip limit 20° dip limit 40° dip limit 60° dip limit 80° dip limit 90° Dip limit value 30° reference line Software Product Management Massy

  21. Aperture limitation half-width of the migration smile * TIKIM == 02 TRAFILE=2003,NUMTRA1,IDTRA=me,REWRITE NPE64,MACHINE=PC,DISTRIB ,BIMG02 DCDP12.5,IMAGE=(FCDP151,LCDP600) OFFSETS=(D150,ID100,XRM5800,XRP50) N0, LMU2,MUTE2 APERCDP5000 DIPLIM40 NOALIAS=(FMAX75) LVI1 Software Product Management Massy

  22. Aperture limitation 0 Dip 30° aperture 9km 6s APERCDP 12s Software Product Management Massy

  23. Dip 90° aperture 16km Aperturelimitation 0 6s APERCDP 12s Software Product Management Massy

  24. Kirchhoff PreSTM in real life • noise attenuation Software Product Management Massy

  25. Noise in TIKIM • input noise (addressed by the Pre-Processing) • coherent noise • random noise • irregular amplitudes • acquisition irregularities (addressed by the regularization) • offset/fold • migration noise (addressed by the Migration Parameters) • operator muting • aliasing Software Product Management Massy

  26. Missing or irregular data 60m 120m 240m 450m Regularized data 60m 120m 240m 450m Regularization: missing traces on event Software Product Management Massy

  27. Migration operator mute coding * TIKIM == 02 TRAFILE=2003,NUMTRA1,IDTRA=me,REWRITE NPE64,MACHINE=PC,DISTRIB ,BIMG02 DCDP12.5 IMAGE=(FCDP151,LCDP600) OFFSETS=(D150,ID100,XRM5800,XRP50) N0 MUTE1,LMU1, APERCDP5000, DIPLIM40 NOALIAS=(FMAX75) LVI1 LMU1 Software Product Management Massy

  28. Post-migration mute * TIKIM == 02 TRAFILE=2003,NUMTRA1,IDTRA=me,REWRITE NPE64,MACHINE=PC,DISTRIB ,BIMG02 DCDP12.5 IMAGE=(FCDP151,LCDP600) N0 LMU2,MUTE2 APERCDP5000, DIPLIM40 NOALIAS=(FMAX75) LVI1 REMUTE Based on Word6 input trace Software Product Management Massy

  29. TIKIM stack - REMUTE TIKIM stack stack Poststack mute Software Product Management Massy

  30. Aliasing • what is aliasing ? • dip aliasing • aliasing noise in Kirchhoff migration Software Product Management Massy

  31. Aliasing aliasing occurs when a signal is undersampled in time, or spatially Signal contain alteration 2ms sampling resampling 4ms filtered + resampling Software Product Management Massy

  32. Two dips low frequency signal high frequency signal Dip aliasing One dip a dipping event will be aliased because of spatial undersampling Software Product Management Massy

  33. 1 1 fmax= p < 2pd 2fd Dt 1 p = Dx f d Aliasing condition in 2D Software Product Management Massy

  34. After summation destructive interferences constructive interferences Aliasing noise in Kirchhoff migration migration contributions to a flat event Aliasing noise Software Product Management Massy

  35. Noalias coding * TIKIM == 02 TRAFILE=2003,NUMTRA1,IDTRA=me,REWRITE NPE64,MACHINE=PC,DISTRIB ,BIMG02 DCDP12.5 IMAGE=(FCDP151,LCDP600) OFFSETS=(D150,ID100,XRM5800,XRP50) N0 LMU2,MUTE2 APERCDP5000, DIPLIM=(T400D20,T800D40,T4000D40,T4500D0) NOALIAS=(FMAX75) LVI1 Software Product Management Massy

  36. Kirchhoff PreSTM in real life • 3 options of TIKIM (velocity definitions) Software Product Management Massy

  37. 3 options in TIKIM: kinematics: • straight ray (default) • anelliptic • raytracing (standard processing) Software Product Management Massy

  38. Ray kinematics x v1 v2 v3 v4 vrms ray tracing straight ray Anelliptic (shifted hyperbolae) t Software Product Management Massy

  39. New ray tracing : anisotropic & Turning-waves Kinematics >90° RAYTRACE (Turning Waves > 90°) Anelliptic Operator Straight Ray Operator High order NMO terms 50° 40° 4th order NMO 2nd order NMO Software Product Management Massy

  40. kinematics coding Straight Rays (up to 40 degrees) * TIKIM == 02 TRAFILE=2003,NUMTRA1,IDTRA=me,REWRITE NPE64,MACHINE=PC,DISTRIB ,BIMG02 DCDP12.5 IMAGE=(FCDP151,LCDP600) OFFSETS=(D150,ID100,XRM5800,XRP50) N0 LMU2,MUTE2 APERCDP5000, DIPLIM40 NOALIAS=(FMAX75) LVI1 Software Product Management Massy

  41. kinematics coding Anelliptic (up to 50 degrees) * TIKIM == 02 TRAFILE=2003,NUMTRA1,IDTRA=me,REWRITE NPE64,MACHINE=PC,DISTRIB ,BIMG02 DCDP12.5 IMAGE=(FCDP151,LCDP600) OFFSETS=(D150,ID100,XRM5800,XRP50) N0 LMU2,MUTE2 APERCDP5000, DIPLIM50 NOALIAS=(FMAX75) LVI1,LSH1 Time shift library Software Product Management Massy

  42. kinematics coding Ray Tracing (more than 50 degrees) (standard processing) * TIKIM == 02 TRAFILE=2003,NUMTRA1,IDTRA=me,REWRITE NPE64,MACHINE=PC,DISTRIB ,BIMG02 DCDP12.5 IMAGE=(FCDP151,LCDP600) OFFSETS=(D150,ID100,XRM5800,XRP50) N0 LMU2,MUTE2 APERCDP5000, DIPLIM=(T0,D150,T3500,D120,T6000,D40), NOALIAS=(FMAX75) LVI1,LSH1,RAYTRACE, TREND=local:/trendfile.cst Smoothed trend Software Product Management Massy

  43. Velocities in TIKIM • velocity analysis • coding • methodology Software Product Management Massy

  44. Constant velocity scan complex 2D geology with no velocity a priori * TIKIM == 02 TRAFILE=2003,NUMTRA1,IDTRA=me,REWRITE NPE64,MACHINE=PC,DISTRIB ,BIMG02 DCDP12.5 IMAGE=(FCDP151,LCDP600) OFFSETS=(D150,ID100,XRM5800,XRP50) N0 LMU2,MUTE2 APERCDP5000 DIPLIM=(T400D20,T800D40,T4000D40,T4500D0) NOALIAS=(FMAX75) ATTRIBUT=VELOCITY, CSTSCAN=(3000,3400,…,4600,5000) Software Product Management Massy

  45. 3000 m/s 3400 m/s 3800 m/s 4200 m/s 4600 m/s 5000 m/s Constant velocity scan Software Product Management Massy

  46. Percentage velocity scan * TIKIM == 02 TRAFILE=2003,NUMTRA1,IDTRA=me,REWRITE NPE64,MACHINE=PC,DISTRIB ,BIMG02 DCDP12.5 IMAGE=(FCDP151,LCDP600,ICDP2) OFFSETS=(D150,ID100,XRM5800,XRP50) N0 LMU2,MUTE2 APERCDP5000, DIPLIM40 NOALIAS=(FMAX75) LVI1 ATTRIBUT=VELOCITY, PERSCAN=(91,94,97,100,103,106,109,112) Software Product Management Massy

  47. 99% 101% 95% 97% Percentage velocity scan on stack Software Product Management Massy

  48. Velocity percentage scan on gathers 99% 99.5% 100% 100.5% 101% Software Product Management Massy

  49. Velocity picking - a word of advice • Picking tool: ChronoVista • Start from a smooth model • easier to pick the trends • Kirchhoff migrations like it smooth Software Product Management Massy

  50. TIKIM ISOTROPIC Simplified 2D Velocity Model Building Flow Pre-conditioned dataset Demultiple velocitiesLVI1 Straight-Ray Kirchhoff migration Perturbation Velocity Scan on Migrated Gathers (Reference= smooth demultiple velocities LVI1) TIKIM iteration1 Pick Velocity Trend (LVI2) on perturbed Stacks in ChronoVista Velocity Picking Back off LVI1 on gathers Pick Final Migration Velocities (LVI3) with GEOVEL in ChronoVista (Reference= LVI2) Full 2D Kirchhoff migration with LVI3 TIKIM iteration2 Migrated Gathers or STACK Software Product Management Massy

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