Gabriel Alvarez

Long Period Multiples

Short Period Multiples

CMP Offset

Tim

eMultiple

Primaries

Offset

Tim

e

Multiple

Primaries

NMOed CMP

• Lower stacking velocities compared with primaries

Offset

Tim

e

Multiple

Primaries

• Parabolic residual moveout after NMO correction with

primaries’ velocities

• Larger-curvature hyperbolas than primaries

Characteristics of Multiples

V1

V2

V1<V2

Offset

Tim

e

Multiple

Primaries

Seismic Section

Tim

e (S

)

Velocity Analysis. CDP 640 with multiples

Tim

e (

ms

)

Velocity Analysis. CDP 4300 with multiples

Tim

e (

ms

)

•Energy Source : Dynamite, 1 shothole 10’

Acquisition Parameters

•Line Length : 75 Km

•Fold : 30

•Shot Interval : 66.66 m

•Group Interval : 33.33 m

Cable Layout

TR. 1 TR. 60 TR. 61 TR. 120S.P.1966.47 m. 1966.47 m.

116.65 m. 116.65 m.

FFID 625

Tim

e (s

)

Frequency (Hz)

Am

plitu

de

FFID 2155

Frequency (Hz)

Am

plitu

de

Tim

e (s

)

Multiples

Offset

Tim

e

Primaries

Offset

Tim

e

Primaries and Multiples

Offset

Tim

e

Tim

e

Moveout0

Radon Transform

Offset

Tim

e

Primaries y Multiples

Tim

e

Moveout0

Parabolic Radon Transform Multiples

Offset

Tim

e

Primaries

Offset

Tim

e

Offset

Tim

e

CMP

Offset (m)

Tim

e (s

)

1

2

3

4

5

-1000-2000 1000 2000

Parabolic Radon Transform

Tim

e (s

)

1

2

3

4

5

Moveout (ms)-100 3002001000

CMP

CDP PrimariesOffset

-2000 20000-1000 1000

Tim

e (s

)

1

2

3

4

5

-2000 20000-1000 1000Offset

Tim

e (s

)

1

2

3

4

5

CDP Multiples

Supergathers. Primaries and multiples

1

0

2

3

4

Tim

e (s

)

Supergathers. Primaries

1

0

2

3

4

Tim

e (s

)

Supergathers. MultiplesT

ime

(s)

1

0

2

3

4

CMP Stack. Multiples with Velocity of Multiples

Tim

e (s

)

CMP Stack. Multiples

Tim

e (s

)

Comparison of primaries and multiples

Primaries Multiples

Migrated Stack. Primaries and MultiplesMigrated Stack. PrimariesMigrated Stack. Primaries and MultiplesMigrated Stack. Primaries y MultiplesMigrated Stack. PrimariesMigrated Stack. PrimariesMigrated Stack. PrimariesMigrated Stack. PrimariesMigrated Stack. PrimariesMigrated Stack. Primaries and MultiplesSección migrada. Primarios y MúltiplesMigrated Stack. Primaries y MultiplesMigrated Stack. Primaries and MultiplesT

ime

(s)

CDP

Velocity Analysis. CMP 640 Primaries and Multiples

Tim

e (

ms

)

Velocity Analysis. CMP 640. PrimariesT

ime

(m

s)

Comparison of Velocity Analysis. CMP 640

With multiples Without multiples

Velocity Analysis. CMP 4300. Primaries and multiples

Tim

e (

ms

)

Velocity Analysis. CMP 4300. Primaries

Tim

e (

ms

)

Comparison of Velocity Analysis. CMP 4300With multiples Without multiples

CMP400 44001400 2400 3400

0

1.0

2.0

3.0

Tim

e (

s)

1600

6000

Ve

loc

ity

(m

/s)

Stacking Velocity Profile Primaries

Stacking Velocity Profile Primaries and MultiplesStacking Velocity Profile

PrimariesStacking Velocity Profile

Primaries y MultiplesStacking Velocity Profile

PrimariesStacking Velocity Profile Primaries and MultiplesStacking Velocity Profile

PrimariesStacking Velocity Profile

Primaries y MultiplesStacking Velocity Profile

PrimariesStacking Velocity Profile Primaries and MultiplesStacking Velocity Profile

PrimariesStacking Velocity Profile

Primarios y MúltiplesStacking Velocity Profile

Primaries

Stacking Velocity Profile. Multiples

Ve

loc

ity

(m

/s)

CMP400 44001400 2400 3400

0

1.0

2.0

3.0

Tim

e (

s)

1600

6000

• 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.

Questions ?

V1

V2

V1<V2

Reflectors

Primaries

Surface Offset

Tim

e

Model CMP Gather

Primaries

Multiples

Multiples

V1

V3

V3

CMP

V1

Sección migrada. Primarios y Múltiples

Sección migrada. Primarios

Sección migrada. PrimariosSección migrada. Primarios y Múltiples

Sección 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 MúltiplesSección migrada. Primarios

• 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

CMP Stack. PrimariesCMP Stack. Primaries and MultiplesCMP Stack. Primaries and MultiplesCMP Stack. PrimariesCMP Stack. PrimariesCMP Stack. PrimariesCMP Stack. Primaries and MultiplesCMP Stack. PrimariesCMP Stack. Primaries and multiplesCMP Stack. PrimariesCMP Stack. Primaries and multiplesCMP Stack. PrimariesCMP Stack. Primaries and multiplesCMP Stack. Primaries and MultiplesT

ime

(s)

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

Hampson-Russell (HR)

Software Used

Promax

Seismic Unix (SU)