Day 4 M14 Log Upscaling 2008
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Transcript of Day 4 M14 Log Upscaling 2008
5/12/2018 Day 4 M14 Log Upscaling 2008 - slidepdf.com
http://slidepdf.com/reader/full/day-4-m14-log-upscaling-2008 1/14
WellCorrelation
Petrel Workflow Tools
5 Day Introduction CourseFault
Modeling
Well DesignVolume
CalculationPlotting
Pillar Gridding
Depth ConversionEdit of Input
I n t r o t o P e t r e l
E d i t I n p u t D a t a
I m p o r t d a t a
W o r k f l o w E d i t o r
Seismic
Introdution to Property
Modeling; Log Upscaling
5/12/2018 Day 4 M14 Log Upscaling 2008 - slidepdf.com
http://slidepdf.com/reader/full/day-4-m14-log-upscaling-2008 2/14
Upscaling of Well LogsObjectives
Gain Understanding of Concept and Process
Understand and Use Discrete Logs
± Averaging
Understand and Use Continuous logs
± Averaging ± Biasing to a discrete log
± Different averaging methods
Look at Different Scale-Up Settings
± Treat log as lines or points
± Method of which penetrated cells to useQC of Upscaled Logs
± Using well section window
5/12/2018 Day 4 M14 Log Upscaling 2008 - slidepdf.com
http://slidepdf.com/reader/full/day-4-m14-log-upscaling-2008 3/14
Overview
Cells exist along the well path.
Values assigned to cells based on
well log values along the well path.
Upscaled logs used to fill in the 3D
grid.
Upscaling assigns values to the cells in
the 3D grid that are penetrated by the
well logs. It averages the values so that
one cell gets one value only. These cells
are later used in Property modeling.
5/12/2018 Day 4 M14 Log Upscaling 2008 - slidepdf.com
http://slidepdf.com/reader/full/day-4-m14-log-upscaling-2008 4/14
Process
Select the Scale up well logs process under the
Property Modeling folder in the Process Diagram.
NOTE: The upscaled logs will be part of the 3D
property at the well positions. Property Modeling
processes will NOT overwrite upscaled cell values!
1. Cr eate new pr oper ty and Select input
from: W ell logs.
2. Select log: from drop-down menu
(captured from Global well logs folder)
3. Select the best Scale up settings
5/12/2018 Day 4 M14 Log Upscaling 2008 - slidepdf.com
http://slidepdf.com/reader/full/day-4-m14-log-upscaling-2008 5/14
Discrete Logs ² Averaging
Discrete logs, such as facies, have only
integer values (0,1,2 etc.).
1. The Averaging method is normally
Most of (will use the value which is most
represented in the cell).
2. In some situations it may be necessary
to use the weighting option. Click the Use
weighting and fill in Weighted tab.
5/12/2018 Day 4 M14 Log Upscaling 2008 - slidepdf.com
http://slidepdf.com/reader/full/day-4-m14-log-upscaling-2008 6/14
Continuous Logs ² Averaging
Continuous logs, such as porosity, have real
number values (decimals).
3) You can specify that there
should be a Min. number of points passing through a
cell for it to be populated
with a value.
1. Select the Average method. It is
normally Arithmetic for porosity (averages
all the values in the cell equally).
2) It is usually necessary to bias to facies.
Use the biasing option, to bias against a
discrete upscaled log (see next slide).
5/12/2018 Day 4 M14 Log Upscaling 2008 - slidepdf.com
http://slidepdf.com/reader/full/day-4-m14-log-upscaling-2008 7/14
Biasing to a Discrete Log
Raw facies Raw porosityUpscaled facies Upscaled porosity
Sand
5/12/2018 Day 4 M14 Log Upscaling 2008 - slidepdf.com
http://slidepdf.com/reader/full/day-4-m14-log-upscaling-2008 8/14
Settings ² Treat Log
As points: All sample values within each cell are used for averaging.
As lines: Data between points will be interpreted (points outside the
cell may affect the result).
vi: weighted value of eachpoint involved
ni: log value of the point
5/12/2018 Day 4 M14 Log Upscaling 2008 - slidepdf.com
http://slidepdf.com/reader/full/day-4-m14-log-upscaling-2008 9/14
Settings ² Method
Simple: All cells penetrated by the well
trajectory are included
Through cell: The well trajectory must
penetrate two opposite cell walls (top and
base - opposite sidewalls) to be included
Neighbor cells: Cells in the same cell
layer are averaged.
Option to set aminimum number
of data points in a
cell for it to be
included.
5/12/2018 Day 4 M14 Log Upscaling 2008 - slidepdf.com
http://slidepdf.com/reader/full/day-4-m14-log-upscaling-2008 10/14
QC of Upscaled Logs
Once upscaling is done it is a good habit to QC
the upscaled cells with the original log:
Press the Show results in Well Section or set up
a Well Section display on your own (discussed
below).
View the logs and Upscaled cells of interest; check
for inconsistencies. Review Upscaling if necessary.
If setting up a well Section; select raw logs from
Global well logs and upscaled properties from
Properties folder. Add a new track if desired.
5/12/2018 Day 4 M14 Log Upscaling 2008 - slidepdf.com
http://slidepdf.com/reader/full/day-4-m14-log-upscaling-2008 11/14
More Upscaling in Petrel
Property Modeling course (3 days)
Data analysis and basics of geostatistics
Data preparation, including well
correlation
Facies Modeling; sequential indicator
simulation, facies transition simulation,
object facies modeling (adaptive channel),
interactive facies modeling
Petrophysical modeling; data analysis,
porosity modeling, permeability modeling Modeling based on seismic attributes
5/12/2018 Day 4 M14 Log Upscaling 2008 - slidepdf.com
http://slidepdf.com/reader/full/day-4-m14-log-upscaling-2008 12/14
EXERCISE
Scale Up Well LogsQC Upscaled Properties
5/12/2018 Day 4 M14 Log Upscaling 2008 - slidepdf.com
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Upscaling of Well LogsAveraging Methods for Continuous Logs
Arithmetic mean - Typically used for properties such as porosity, saturation and
net/gross because these are additive variables.
Harmonic mean - Gives the effective vertical permeability if the reservoir is layered
with constant permeability in each layer. It works well with log normal distributions. It is
used for permeability because it is sensitive to lower values.
Geometric mean - Normally a good estimate for permeability if it has no spatialcorrelation and is log normally distributed. It is sensitive to lower values.
RMS (Root Mean Squared) - Will provide a strong bias towards high values.
Minimum/ Maximum - Samples the min/max value of the well log for the cell.
Mid Point Pick ² Will pick the log value where the well is halfway through the
cell. Essentially a random choice and is therefore more likely to give a property with the
same distribution of values as the original well log data.
Random Pick ² Picks a log point at random from anywhere within the cell. This random option avoids
the smoothing tendency of other methods and is therefore more likely to give a property with the same
distribution of values as the original well log data.
Generally:
RMS > Arithmetic
Arithmetic > Geometric
Geometric > Harmonic
5/12/2018 Day 4 M14 Log Upscaling 2008 - slidepdf.com
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Upscaling of Well LogsQC of Upscaled Logs
Create Synthetic logs; these will resemble the
properties (Upscaled logs) but are stored as
physical logs under Global Well Logs
1. Go to the Make logs tab of settings for Wells.
2. Select the property to make log from.
3. Press Make logs button; the log is stored in
the Global Well Logs folder and can be toggled
on from there.