seismic processing flow

7/24/2019 Seismic Processing Flow

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DP START Houston2007

Schlumb

ergerPrivate

Processing Flow


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Schlumb

ergerPrivate

The objectives of data rocessing !a" be su!!ari#ed as $

To roduce seis!ic cross%section reresentative of geolog"

To enhance the signal and reject the noise

To !eet the e&loration objectives of the client

Data Processing 'verview


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Schlumb

ergerPrivate

The Se(uence of )ventsRaw shot records

(with some amplitude compensation applied)

Final migrated section

What do we start with in DataProcessing?

How do we get here?


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Schlumb

ergerPrivate

*efore an" rocessing can ta+e lace, we need to$

Internal project meeting Client meeting - determine objectives etc

Perform inventory check Produce testing plan Project set-up - resource allocationetc

Project Planning


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Schlumb

ergerPrivate

Data rocessing will usuall" co!!ence with the receit of thefollowing -or art thereof. $

New DataNew Data !ape containing recorded seismic data "trace se#uential or

multiple$ed% &bserver logs'reports (ield)eophysicist logs'reportsand listings Navigation'survey data (ield *+C+displays Contractual re#uirements

Data Processing % /n the beginning1


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Schlumb

ergerPrivate

,e-Processing,e-Processing

!ape containing recorded seismic data with geometry applied

"usually%+

Contractual re#uirements

Data Processing % /n the beginning1


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Schlumb

ergerPrivate

Data For!at3 defines$

How the data is arranged and

stored1

Refor!at

Processing Sequence

Reformat

This will usuall" follow an

/ndustr" standard convention1e1g1 S)4D, S)45for

!agnetic !edia


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Schlumb

ergerPrivate

Data Processing % raw shot data

Loss of amplitude with

time

Loss of frequencies with

time

Linear noise e.g. direct arrivals

Reflection - hyperbolic

Data corresponding to one shot (located somewhere on the earth) which was recorded into 9

(only data from !-9" shown on plot) different receivers (also located somewhere on earth#)

$ime %ero ref.

i.e. reference

is time when

shot fired


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SchlumbergerPrivate

Processing Sequence

Reformat

Geometry definition? ? ? ? ? ?

Where are the shotsand receivers located ?

Important values for data processing are

source receiver OFFSETS

4eo!etr" Definition


10/26


SchlumbergerPrivate

What if the surface

elevation changes ?

datum

Field Static 6orrections

Processing Sequence

Reformat

Geometry definition

Field Static corrections-land, shallow water, transition #one.

i.e. remove the difference

in travel time caused by

shots and receivers being at

different elevations


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SchlumbergerPrivate

Wheres all the source

energy gone ? Processing Sequence

Reformat

Geometry definition


!mplitude recovery

Geometric spreading" a#sorption etc

A!litude Recover"


12/26


SchlumbergerPrivate

How to remove noise? Processing Sequence

Reformat

Geometry definition


!mplitude recovery

$oise !ttenuation

oise Attenuation

Desi+e, 8%filtering, AAA 1


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SchlumbergerPrivate

How to improve the

vertical resolution? Processing Sequence

Reformat

Geometry definition


!mplitude recovery

$oise !ttenuation

%econvolution

Compensate for the filtering effects

of the earth etc

Deconvolution -n inverse of filtering process.


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SchlumbergerPrivate

How to order the data? Processing Sequence

Reformat

Geometry definition


!mplitude recovery

$oise !ttenuation

%econvolution

&'P gat(er

Some processes must be carried out in the

CMP domain

Multiple Coverage c!uisition techni!ues

69P 4ather


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SchlumbergerPrivate

:elocit" Anal"sis

Processing Sequence

Reformat

Geometry definition


!mplitude recovery

$oise !ttenuation

%econvolution

&'P gat(er

)elocity !nalysis

How to compute a

better velocity field?


16/26


SchlumbergerPrivate

How to remove false

reflections?

&'P gat(er

offsettime

De!ultile

Processing Sequence

Reformat

Geometry definition


!mplitude recovery

$oise !ttenuation

%econvolution

&'P gat(er

)elocity !nalysis

%emultiple *marine+


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SchlumbergerPrivate

How to correct for time

differences due to offsetwithin the CMP?

offset

time time differencedue to offset

&'P gat(er

9' 6orrection

Processing Sequence

Reformat

Geometry definition


!mplitude recovery

$oise !ttenuation

%econvolution

&'P gat(er

)elocity !nalysis

%emultiple *marine+

$'O correction


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SchlumbergerPrivate

"o the reflections all comefrom a single point?

midpoint

Processing Sequence

Reformat

Geometry definition

Field Static corrections

-land, shallow water, transition #one.

!mplitude recovery

$oise !ttenuation

%econvolution

&'P gat(er

)elocity !nalysis

%emultiple *marine+

$'O &orrection

%'O &orrection

D9' 6orrection


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SchlumbergerPrivate

How to reduce the

number of traces?

69P Stac+

Processing Sequence

Reformat

Geometry definition


!mplitude recovery

$oise !ttenuation

%econvolution

&'P gat(er

)elocity !nalysis%emultiple *marine+

$'O &orrection

%'O &orrection

&'P stac,


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9igration

Processing Sequence

Reformat

Geometry definition


!mplitude recovery

$oise !ttenuation

%econvolution

&'P gat(er

)elocity !nalysis

%emultiple *marine+

$'O &orrection

%'O &orrection

&'P stac,

'igration

"o the reflections all come

from vertically below?

midpoints


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SchlumbergerPrivate

Pre Stac# migration $%" marine&

S-OT SORTE%

&'P SORTE%

OFFSET SORTE%

ST!&. SORTE%

Energy spreading corrections

Low-cut / velocity filtering

Wavelet compression / demultiple

Velocity Analysis

Near/far offset noise removal

Lowcut / highcut / signal enhance

Time variant amplitude balancing

osmetic plotting test!bias/gain

"ata re-ordering

"efine positions and relationships

#emoving multiples

$ossible additional velocity Analysis%umming traces within a cmp

#emove source wavelet from data

Field data in

'ute

&omp/ 'igr/ )els

'igration

Stac,

!mplitude scaling

Filtering

Final products

!mplitude recovery

$oise re0ection

%econvolution

&'P gat(er

Geometry

%emultiple

Signature %econ/


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Schlumbe

rgerPrivate

Processing Se!uence $'" marine ( Post

Stac# )ime Migration&

!mplitude recovery

$oise re0ection

%econvolution

$'O correction

&pply automatic field edits

' navigation data and select

binning strategy

123 data reduction

Temporal resample

Initial velocity field

%'O on velocity lines

$av/4seismic merge

5% %'O 6 Stac,

'igration

%emultiple

Time variant filtering

Time variant scaling

final products

7& s(ot data

!s early as possi#le

or *hallow water.

or Depth +ater we use ,' or nothing

Signature %econ/

Optional

Field data 7& 6 edit

Second velocity field

Optional

P i S $'" i


23/26

DP START Houston

2007

Schlumbe

rgerPrivate

Processing Se!uence $'" marine (

Pre Stac# )ime Migration&

8irchhoff 9igration

!mplitude recovery

$oise re0ection

%econvolution

&pply automatic field edits

' navigation data and select

binning strategy

123 data reduction

Temporal resample

Final 'ig velocity analysis

$av/4seismic merge

Final Stac,ing )el/ !nalysis

%emultiple

Time variant filtering

Time variant scaling

7& s(ot data

!s early as possi#le

Pre Stac, 'igration

or *hallow water.

or Depth +ater we use ,' or nothing

Signature %econ/

Optional

'igration )el 8ines


Stac,ing

final products

Field data 7& 6 edit

P i S $%" l d&


24/26

DP START Houston

2007

Schlumbe

rgerPrivate

Processing Se!uence $%" land&9asic Processes9asic Processes

Field data in

Geometry

!mplitude recovery

$oise re0ection

%econvolution

&'P gat(er

'ute

$'O correction

1% %'O 6 Stac,

'igration

!mplitude scaling

Filtering

Final products

Residual statics

Field statics

loop


1% %'OFinal velocity field


25/26

DP START Houston

2007

Schlumbe

rgerPrivate

Su!!ar"

.irtually all processing projects will re#uire the following

ccurate locating of shots and receivers and their relationship!ime-correction to a known datum "land, shallow water, transition #one.mplitude recoveryNoise attenuation/ignal enhancementCmp gatheringDemultiple "marine%Normal move-out correction "including muting any noise introduced%

,esidual time-corrections "land data%Correction for smearing within a cmp - dip-moveout correction "for post stack

migration processing%Data reduction - stacking,epositioning ' imaging - 0igration


26/26

DP START Houston

2007

Schlumbe

rgerPrivate

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undament

retacic ,nferior%&

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3*$

Depth onversionVelocity analysis of seismic and log data4 time-

depth conversion of seismic profile and

isochronous maps

)***

&)**

+**

,**

hm.

*)*,* &+&0&)*+ )tsec.

5666

*m

Top %a

Top 1)

Top 1&

Top 2&

Top 2)

)*

%onda 3* $

$ime7Depth chart

+ells pro8ected on seismic line

using depth to time conversion

seismic processing flow

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