L12_Log-Upscaling (5 Days)

7/28/2019 L12_Log-Upscaling (5 Days)

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Cells along the well path

Values assigned to cells

Upscaled logs used to fill in

the 3D grid

Up-scaling well logs Principle



Upscale well logs

Resample logs into cells intersected by well trackDiscrete logs: Assign the most frequently occurring log values to each

cell

Continuous logs: Averaged log values per cell

Arithmetic, Harmonic, Geometric average

Biased to a discrete log

Treat logs as points or lines

Options to treat partially penetrated cells



1 - Select the log to upscale or the

Well Tops attribute

2 –

Select the wells to be upscaled

3 – Select the Scale up settings

NOTE: The upscaled logs will be part of the 3D property at the well

positions. That means, the property will always have the values of the

upscaled logs at the position of the wells!

Process



Log as bias Why bias to a discrete log?

Raw facies Raw por Upscaled facies Upscaled por

Sand



Settings Averaging methods

Arithmetic: Typically used for properties such as porosity, saturation and

net/gross because these are additive variables.

Harmonic: Gives the exact effective vertical permeability if the reservoir islayered with constant permeability in each layer.

Geometric: Normally a good estimate for permeability if the population has

no spatial correlation and is log normally distributed.

Minimum: Samples the min value of the well log for the cell.

Maximum: Samples the max value of the well log for the cell.

Most of (only for discrete logs): Will select the discrete value which ismost represented in the log for each particular cell (used for Facies,Lithology Code, Zone logs etc.).



Settings Weighting

Select weighted as averagemethod.

Go to the weighted tab and set the

weighting factor for each facies.



As points: All sample valueswithin 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 each point involved

ni: log value of the point

N: total number of points

Settings Treat log as lines vs. points



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

Option to set a minimum number of

data points in a cell for it to be

included.

Neighbour cells: cells in the same cell

layer are averaged.

Settings Method



Upscaling logs QC of upscaled logs

Display the log in

the well section

Display theproperty directly in

the well section



Create Synthetic logs

Display synthetic logs

together with raw logs

Upscaling logs QC of upscaled logs



Scale up well logs

Exercise

Documents

L12_Log-Upscaling (5 Days)