seismic processing flow
TRANSCRIPT
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Processing Flow
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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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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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*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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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$ed% &bserver logs'reports (ield)eophysicist logs'reportsand listings Navigation'survey data (ield *+C+displays Contractual re#uirements
Data Processing % /n the beginning1
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,e-Processing,e-Processing
!ape containing recorded seismic data with geometry applied
"usually%+
Contractual re#uirements
Data Processing % /n the beginning1
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Data For!at3 defines$
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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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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Processing Sequence
Reformat
Geometry definition? ? ? ? ? ?
Where are the shotsand receivers located ?
Important values for data processing are
source receiver OFFSETS
4eo!etr" Definition
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7/24/2019 Seismic Processing Flow
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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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Wheres all the source
energy gone ? Processing Sequence
Reformat
Geometry definition
Field Static corrections-land, shallow water, transition #one.
!mplitude recovery
Geometric spreading" a#sorption etc
A!litude Recover"
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How to remove noise? Processing Sequence
Reformat
Geometry definition
Field Static corrections-land, shallow water, transition #one.
!mplitude recovery
$oise !ttenuation
oise Attenuation
Desi+e, 8%filtering, AAA 1
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How to improve the
vertical resolution? Processing Sequence
Reformat
Geometry definition
Field Static corrections-land, shallow water, transition #one.
!mplitude recovery
$oise !ttenuation
%econvolution
Compensate for the filtering effects
of the earth etc
Deconvolution -n inverse of filtering process.
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How to order the data? Processing Sequence
Reformat
Geometry definition
Field Static corrections-land, shallow water, transition #one.
!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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:elocit" Anal"sis
Processing Sequence
Reformat
Geometry definition
Field Static corrections-land, shallow water, transition #one.
!mplitude recovery
$oise !ttenuation
%econvolution
&'P gat(er
)elocity !nalysis
How to compute a
better velocity field?
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How to remove false
reflections?
&'P gat(er
offsettime
De!ultile
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+
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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
Field Static corrections-land, shallow water, transition #one.
!mplitude recovery
$oise !ttenuation
%econvolution
&'P gat(er
)elocity !nalysis
%emultiple *marine+
$'O correction
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"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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How to reduce the
number of traces?
69P Stac+
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
&'P stac,
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9igration
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
&'P stac,
'igration
"o the reflections all come
from vertically below?
midpoints
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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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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
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7/24/2019 Seismic Processing Flow
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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
Initial velocity field
Stac,ing
final products
Field data 7& 6 edit
P i S $%" l d&
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Processing Se!uence $%" land&9asic Processes9asic Processes
Field data in
Geometry
!mplitude recovery
$oise re0ection
%econvolution
&'P gat(er
'ute
$'O correction
1% %'O 6 Stac,
'igration
!mplitude scaling
Filtering
Final products
Residual statics
Field statics
loop
Initial velocity field
1% %'OFinal velocity field
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Su!!ar"
.irtually all processing projects will re#uire the following
ccurate locating of shots and receivers and their relationship!ime-correction to a known datum "land, shallow water, transition #one.mplitude recoveryNoise attenuation/ignal enhancementCmp gatheringDemultiple "marine%Normal move-out correction "including muting any noise introduced%
,esidual time-corrections "land data%Correction for smearing within a cmp - dip-moveout correction "for post stack
migration processing%Data reduction - stacking,epositioning ' imaging - 0igration
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/liocen
/leistocen
0iocene 0ediu
0iocen *uperior
retaceous-1ocene2ligocen-0iocen ,nferior
undament
retacic ,nferior%&
%-'
*-*%-(
3*$
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