Gabriel Alvarez. Long Period Multiples Short Period Multiples.

Presentación del tema: "Gabriel Alvarez. Long Period Multiples Short Period Multiples."— Transcripción de la presentación:

1 Gabriel Alvarez

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3 Long Period Multiples Short Period Multiples

4 CMP Offset Time Multiple Primaries Offset Time Multiple Primaries NMOed CMP

5 Lower stacking velocities compared with primaries Offset Time Multiple Primaries Parabolic residual moveout after NMO correction with primaries’ velocities Larger-curvature hyperbolas than primaries Characteristics of Multiples V1 V2 V1<V2 Offset Time Multiple Primaries

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7 Seismic Section Time (S)

8 Velocity Analysis. CDP 640 with multiples Time (ms)

9 Velocity Analysis. CDP 4300 with multiples Time (ms)

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11 Energy Source: Dynamite, 1 shothole 10’ Acquisition Parameters Line Length: 75 Km Fold: 30 Shot Interval: 66.66 m Group Interval: 33.33 m

12 Cable Layout TR. 1 TR. 60TR. 61TR. 120 S.P. 1966.47 m. 116.65 m.

13 FFID 625 Time (s) Frequency (Hz) Amplitude

14 FFID 2155 Frequency (Hz) Amplitude Time (s)

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16 Multiples Offset Time Primaries Offset Time Primaries and Multiples Offset Time

17 Moveout0 Radon Transform Offset Time Primaries y Multiples Time Moveout0 Parabolic Radon Transform Multiples Offset Time Primaries Offset Time Offset Time CMP

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19 Offset (m) Time (s) 1 2 3 4 5 -1000-200010002000 Parabolic Radon Transform Time (s) 1 2 3 4 5 Moveout (ms) -1003002001000 CMP

20 CDP Primaries Offset -200020000-10001000 Time (s) 1 2 3 4 5 -200020000-10001000 Offset Time (s) 1 2 3 4 5 CDP Multiples

21 Supergathers. Primaries and multiples 1 0 2 3 4 Time (s)

22 Supergathers. Primaries 1 0 2 3 4 Time (s)

23 Supergathers. Multiples Time (s) 1 0 2 3 4

24 CMP Stack. Multiples with Velocity of Multiples Time (s)

25 CMP Stack. Multiples Time (s)

26 Comparison of primaries and multiples PrimariesMultiples

27 Migrated Stack. Primaries and Multiples Migrated Stack. Primaries Migrated Stack. Primaries and Multiples Migrated Stack. Primaries y MultiplesMigrated Stack. Primaries Migrated Stack. Primaries and MultiplesSección migrada. Primarios y MúltiplesMigrated Stack. Primaries y MultiplesMigrated Stack. Primaries and Multiples Time (s) CDP

28 Velocity Analysis. CMP 640 Primaries and Multiples Time (ms)

29 Velocity Analysis. CMP 640. Primaries Time (ms)

30 Comparison of Velocity Analysis. CMP 640 With multiplesWithout multiples

31 Velocity Analysis. CMP 4300. Primaries and multiples Time (ms)

32 Velocity Analysis. CMP 4300. Primaries Time (ms)

33 Comparison of Velocity Analysis. CMP 4300 With multiples Without multiples

34 CMP 4004400140024003400 0 1.0 2.0 3.0 Time (s) 1600 6000 Velocity (m/s) Stacking Velocity Profile Primaries Stacking Velocity Profile Primaries and Multiples Stacking Velocity Profile Primaries Stacking Velocity Profile Primaries y Multiples Stacking Velocity Profile Primaries Stacking Velocity Profile Primaries and Multiples Stacking Velocity Profile Primaries Stacking Velocity Profile Primaries y Multiples Stacking Velocity Profile Primaries Stacking Velocity Profile Primaries and Multiples Stacking Velocity Profile Primaries Stacking Velocity Profile Primarios y Múltiples Stacking Velocity Profile Primaries

35 Stacking Velocity Profile. Multiples Velocity (m/s) CMP 4004400140024003400 0 1.0 2.0 3.0 Time (s) 1600 6000

36 Muiltiple attenuation can be as critical an issue with land data as it is with marine data. Conclusions Subsurface Seismic Interpretation is valid for primaries only. The presence of multiples makes stacking velocity more difficult and unreliable.

37 Questions ?

38 V1 V2 V1<V2 Reflectors Primaries Surface Offset Time ModelCMP Gather Primaries Multiples V1 V3 CMP V1

39 Sección migrada. Primarios y Múltiples Sección migrada. Primarios

40 Sección migrada. Primarios y Múltiples

41 Sección migrada. PrimariosSección migrada. Primarios y MúltiplesSección migrada. PrimariosSección migrada. Primarios y MúltiplesSección migrada. PrimariosSección migrada. Primarios y MúltiplesSección migrada. PrimariosSección migrada. Primarios y MúltiplesSección migrada. PrimariosSección migrada. Primarios y MúltiplesSección migrada. Primarios

42 Velocidades de apilado bajas en comparación con los primarios Características de los Múltiples Presentan curvatura (moveout) residual parabólica luego de la corrección de NMO con las velocidades de los primarios Sus hipérbolas tienen mayor curvatura que las de los primarios

43 CMP Stack. PrimariesCMP Stack. Primaries and Multiples CMP Stack. Primaries CMP Stack. Primaries and MultiplesCMP Stack. PrimariesCMP Stack. Primaries and multiples CMP Stack. Primaries CMP Stack. Primaries and multiplesCMP Stack. Primaries CMP Stack. Primaries and multiples CMP Stack. Primaries and Multiples Time (s)

44 Sección migrada. PrimariosSección migrada. Primarios y MúltiplesSección migrada. PrimariosSección migrada. Primarios y MúltiplesSección migrada. PrimariosSección migrada. Primarios y MúltiplesSección migrada. PrimariosSección migrada. Primarios y MúltiplesSección migrada. PrimariosSección migrada. Primarios y MúltiplesSección migrada. PrimariosSección migrada. Primarios y Múltiples

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46  Hampson-Russell (HR) Software Used  Promax  Seismic Unix (SU)