m5 log upscaling

7/25/2019 M5 Log Upscaling

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Module 5

Property Modeling


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Petrel Workflow Tools

3D Grid

Construction

Structural Gridding

Stratigraphic

Modeling

Pillar Gridding

Well Log

Upscale

Facies &

Petrophysical

Modeling

Make contacts &

Volume Calculation

IntrotoPetrel

Interface

Workflow

Editor

Property Modeling

Make HorizonsZones & Layering

3D Grid Construction: Structural Modeling

Studio

3D Grid

Construction

Structural

Framework

Fault Modeling

Introduction Surfaces and

Data edit


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Upscaling of Well Logs

Objectives

Gain an understanding of the concept and process

Understand and use discrete logs Averaging methods Facies weighting.

Understand and use continuous logs Averaging methods Biasing to a discrete log.

Look at different Scale-up settings

Treat log as lines or points Method of which penetrated cells to use.

QC of upscaled logs: Using well section window.


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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.

The Scale-up well logs process averages the values to the cells in the 3D grid

that are penetrated by the wells. Each cell gets one value per upscaled log.

These cells are later used as a starting point for Property modeling.

Note: An upscaled property will have a [U]following its name in the Propertyfolder in the Modelspane.


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Scale-Up Well Logs

Note: Upscaled logs will be part of the 3D property at the well

positions. The Property modeling processes will NOT overwrite

upscaled cell values!

1. Create a new property.

3. Choose a logfrom the drop-down list (captured

from Inputpane > Global well logsfolder)

4. Set the best scale-up Settings, depending on

the type of log (continuous or discrete).

2. Select Input from Well logs.

5. Click Applyor OK.

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Commonly used Averaging Methods

Averaging

method

Description

Most of Used together with discrete logs, it selects the discrete value that is most represented in

the log for each particular cell.

Arithmetic mean Typically used for additive properties, such as porosity, saturation, and net/gross.

Harmonic mean Gives the effective vertical permeability if the reservoir is layered with constant

permeability in each layer. It works well with lognormal distributions and is sensitive to

lower values.

Geometric mean Normally a good estimate for permeability if it has no spatial correlation and is lognormally

distributed. It is sensitive to lower values.


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Averaging Discrete Logs

Discrete logs, such as facies, have only

integer values (0,1,2, etc.).

2. The Average method is normally Most of, whichuses the value most represented in the cell.

3. In some situations, it may be necessary

to use the Weighting option. Click Use

weightingand fill in the Weighted tab.

1. Choose an input from a Facies well log to create a

new property.

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Averaging Continuous Logs

Continuous logs, such as porosity, have realnumber values (decimals).

4. Specify that there should be a Minimum number of

well log samples in a cell for it to be included in the

upscaling.

2. Set the Average method (here Arithmetic for porosity).

3. It is possible to bias to an already upscaled facies log.

1. Choose an input from a continuous Well log to create

a new property (here, porosity).

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Biasing to a Discrete Log

Raw porosityUpscaled facies Upscaled porosityRaw facies

Sand

Shale


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Settings: Treat Log as Lines or Points

Treat log Description

As points All sample values within each cell are used for averaging.

As Lines If the midpoint of a line between two sample points is inside a cell the point outside the cell

will be used in the calculation.


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Settings: Method of Which Penetrated Cells to Use

Method Description

Simple All cells penetrated by the well

trajectory are included.

Through cell The well trajectory must penetrate two

opposite cell walls.

Neighbor cell All penetrated cells are used but cellsin the same cell layer are averaged.


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Quality Checking Upscaled Logs

When upscaling is done, it is a good practice

to QC the upscaled cells with the original log

in a Well section window.

1. Click the Show result in well sectionbutton in

the Scale up well logs dialog.

2. Display the upscaled log in the same track.Right-click on the upscaled log (Modelspane>

Propertiesfolder) and click Add to template in

the existing raw log track.

Alternatively, set up a Well section display on

your own. Choose raw logs (Global well logs

folder > Inputpane), right-click, and select Add

to template in a new track.

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Averaged values for

each cell in the model

on top of the original

log


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EXERCISE


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Upscaling of Well Logs: QC of Upscaled Logs

Synthetic logs resemble the properties (Upscaled logs) but are stored as physicallogs under Global Well Logs.

1. Click the Make logstab of settings for Wells.

2. Choose the property from which the log will be made.

3. Click the Make logs button. The log is stored in the Global

Well Logs folder and can be toggled on from there.


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Averaging Methods for Discrete Logs

Averaging method Description

Most of Will select the discrete value which is most represented in the log for each particular cell

Median Will sort the input values and select the center value.

Minimun/Maximum Samples the min/max value of the well log for the cell.

Mid Point Pick Will pick the log value where the well is halfway through the cell.

Random Pick Picks a log point at random from anywhere within the cell.


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Averaging Methods for Continuous Logs

Averaging method Description

Arithmetic mean Typically used for additive properties such as porosity, saturation, and net/gross.

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 sensitive to

lower values.

Geometric mean Normally a good estimate for permeability if it has no spatial correlation and the is lognormally distributed. It is sensitive to lower values.

Median Sorts the input values and select the center value.

RMS (Root Mean

Squared)

Provides a strong bias towards high values.

Minimun/Maximum Samples the min/max value of the well log for the cell.

Mid Point Pick Picks the log value where the well is halfway through the cell.

Random Pick Picks a log point at random from anywhere within the cell.

m5 log upscaling

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