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8/6/2019 Intelligent Reservoir Characterization
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Well Log
Characterization
Lithological
Patterns
Seismic Syntax
Patterns
Seismic
Attributes
SeismicStratigraphy
Seismic
DepositionalPatterns
Depositional Sequences
Seismic SyntaxPatterns
Spectral Anal
Segmentation
Lithologies
Markov Chain
Sequence Stratigraphy Patterns
Seismic – Well Pattern Semantics
Geological Grammar for TranslationPattern Classification &
Characterization
3D Markov
Models
Geostats
Re
c
o
g
n
i
t
i
o
n
T
r
a
i
ni
n
gCalibration Prediction
Validation
High-level Methodology and Cycles
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Detailed Methodology
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Spectral Analysis for Determination of Sequence boundaries
T er t i ar yn o t d i f f er en t i a t e d
D e t a
i l e d
z on a t i on
W e l l d e v e l o p e d c y c l e s w i t h h i g h - r e s o l u t i o n
c o r r e l a t i o n p o t e n t i a l
A m a l g a m a t e d c y c l e s
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Segmentation
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Lithofacies From Logs
S t a n d a r d L o g A n a l y s i s –
A n a l o g
L i t h o l o g y C l a s s
e s
S p e c i a l I m a g e L o g s a n d D e r i v e d L i t h o I n d i c a t o r s
S t a n d a r d L o g S u i t e ( T o D o S
p e c t r a l + S e g m )
Lithfacies from Conventional Logs using Brigg’s Triangles. Calibrated
with Core and used. Requires Field level tuning
V e r y h i g h v e r t i c a l r e s o l u t i o n a n d c l a s s i f i c a t i o n a c h i e v e
d
S
e q u e n c e s t r a
t i g r a p h y c o n f i n e d M a r k o v i a n S t r i n g s ?
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Seismic Character and Scale-of-Support issue
Top of Reservoir
Changing Patterns of the tracespoint to lateral variations in thereservoir character.
Also, the vertical litho/fluid patternseen at the well is reflected by theseismic trace at the well-location.
And the seismic is responding inpatterns
Most analysis is limited to thereservoir zone, while the patterncalibration and classification
should consider entire loggedinterval
Scale-of-Support issue fromseismic will be addressed by thisapproach
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Classification & Categorization
• Such Patterns Exist in Real data
• The Various StructuredParameters Can be :
– On each Trace Separately
– Based on adjacent traces eitherside on 3D (1 look up= 4 traces)
– Based on Multiple adjacent
traces (2-5 lookup – How to do?)
While all of these refer to same reservoir – their characters are different
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Structural Elements from Seismic Traces of Reservoir
Does this litholog match here?
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Workflow steps with Well
Logs
There is no unique deterministic
solution to the depositional facies
implied in log data of a basin or field
• Data driven methods are essential to openthe possibilities (4th Paradigm)
• Log data structure is well established
• Conventional log analysis works on
acquisition, environmental and borehole
corrections
• Log analysis using standard empirical
equations and models (multi-mineral,
Thomas-Steiber etc.)
• These become INPUT to this WF
• A set of pathways will create multiple,
consistent and repeatable solutions and its
characters
Objective: consistentalgorithmic depofacies
1. Demarcate
Sequences
2. Segment logs in
Sequences
3. Petrofacies using
AI methods4. Determine
steady/unsteady
Markovian str.
5. Arrive at a
sedimentary unit
description &
character6. Determine
Depositional
Facies by
Classification
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Adjacent Trace Structures
1. Univariate occurs from using one Seismic Attribute and
Multivariate may originate from multiple attribute patterns2. Formal Method
a. Similarity index (For each trace) to be derived from earlier Structure
b. Classify the trace shapes
c. Distance of each trace from the FUZZY/ CLUSTER center of the group
d. Use to define the similarity/ dissimilarity between traces
e. Time Series Coherency
3. Syntactic method? Can a grammar defined?
4. Graphical method?
5. Geostatistical method?
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A Possible Workflow to Solution (Seismic Part)
• Use both reservoir and non-reservoir intervals to work with sparse wells
1. Select the AOI and the number of primary Seismic Attribute volumes
2. Obtain basis geological interpretation and model for convergence of result
3. From well’s facies logs – identify the pattern features in seismic
4. Select 3-4 units for analysis
1. Extract the (single) Seismic Trace Structure(STS) for each unit
2. Extract the seismic coherency structure(SCS) for trace-to-trace variability
3. Classify the (STS, SCS) into groups and map Check spatial meaning geologically
4. Converge for individual attribute volume and together providing the various spatial patterns andtheir spatial co-existence
5. Select STS, SCS and Converged Map for further integration with wells
1. Check for Anisotropy, Non-Stationarity of the patterns
6. Using well data – check the patterns implied at well location and match to Seismicsignature
1. Calibrate the Lithological signature and Fluid signature on seismic Patterns
7. Convert Seismic to Lithologies with allowable markovian variations8. Create Fine-scale geological models to map the lithological variations and understand
geological consistency
9. Forward model to create synthetic seismic to compare resulting patterns
10. Validate at blind wells if available – Recycle the workflow to improve