# iMOD User Manual version 4.4 (html)

#### 8.10WELL-FUNCTIONS

##### 8.10.1DEVWELLTOIPF-Function

The function DEVWELLTOIPF converts Deviated Wells, described in CSV format, to an IPF file.

Example 1

FUNCTION=DEVWELLTOIPF
CSVFNAME=D:\AGS.CSV
IPFFNAME=D:\IPF.IPF

This example, converts the columns in the CSV file via the default columns setting to an IPF file, the outcome in 3D could look like the following image.

##### 8.10.2ASSIGNWELL-Function

The ASSIGNWELL function reads a geological model (TOP/BOT) in order to assign well screens to the right formation layer.

Example 1

FUNCTION=ASSIGNWELL
IPFFILE_IN=D:\DATA\WELL.IPF
IPFFILE_OUT=D:\DATA\WELL_ASSIGNED.IPF
NFORMATIONS=2
FORMATION1=1
FORMATION2=2
TOP_L1=D:\GEOHYDROLOGY\TOP1.IDF
BOT_L1=D:\GEOHYDROLOGY\BOT1.IDF
TOP_L2=D:\GEOHYDROLOGY\TOP2.IDF
BOT_L2=D:\GEOHYDROLOGY\BOT2.IDF

Above an example is given how to divide well filters in the file WELL.IPF over 2 model layers resulting in the file WELL_ASSIGNED.IPF.

##### 8.10.3MKWELLIPF-Function

The MKWELLIPF function computes the extraction strength for each well based on a weighed value according to their length and permeability of the penetrated model layer. At the end of the procedure iMOD echoes a summary of the total and average extraction per model layer.

The IPF file IMOD_MKIPF_WELLS_ALL.IPF contains all rows from the original IPF. This file is easier to analyse whether the well screen assigned have been computer properly. There is an attribute ERROR_CODE in the IPF that denotes the way the well has been assigned. The following codes are applicable; "@" means that the well is assigned to a nearby model layer; "#" means that the well could not be assigned; and "-" means that the well has been assigned appropriately. The IPF file IMOD_MKIPF_WELLS_UNASSIGNED.IPF contains all rows from the original IPF that could not be assigned to model layer.

Methodology

The following steps are carried out for each individual record in the IPF file (IPF{i}):

• 1. Compute the individual length of the well screen between the ITCOL and IBCOL into well screen segments, that penetrate any model layer. Well screen segments that are above the surface elevation (TOPIDF1) or below the lowest bottom elevation (BOTIDF{NLAY}) will be clipped off;

• 2. Compute the horizontal permeability (k-value) for all model layers that are penetrated by the remaining well screen segments. Assign a ratio to all well screen segments based on their individual length multiplied by the k-values of the corresponding model layer divided by their total summed value;

• 3. Correct any ratio for a mismatch between the centre of the penetrating model layer $z_{c}$ and the vertical midpoint of the well screen segment $f_{c}$, by:

\begin{align*} f=1.0-\frac {\left | z_{c}-f_c \right |}{0.5\Delta z}, \end{align*}

where $\Delta z$ is the thickness of the corresponding aquifer.

• 4. Remove ratio that are smaller than 5%.

• 5. If in aquitard, move it to the nearest aquifer above or below the aquitard, only whenever ICLAY=1;

• 6. If nothing in model, whenever system on top of model, put them in first model layer with thickness and permeability larger than MINKH.

Example 1

FUNCTION=MKWELLIPF
NLAY=3
TOPIDF1=D:\DATA\TOP1.IDF
TOPIDF2= D:\DATA\TOP2.IDF
TOPIDF3= D:\DATA\TOP3.IDF
BOTIDF1= D:\DATA\BOT1.IDF
BOTIDF2= D:\DATA\BOT2.IDF
BOTIDF3= D:\DATA\BOT3.IDF
KDIDF1= D:\DATA\KD1.IDF
KDIDF2= D:\DATA\KD2.IDF
KDIDF3= D:\DATA\KD3.IDF
CIDF1=D:\DATA\C1.IDF
CIDF2=D:\DATA\C2.IDF
NIPF=1
IPF1=D:\DATA\WELL.IPF

The example above, will classify each location in the IPF file D:\DATA\WELL.IPF according their length and associated transmissivity, within any penetrating modellayer.

Example 2

FUNCTION=MKWELLIPF
NLAY=3
TOPIDF1=D:\DATA\TOP1.IDF
TOPIDF2= D:\DATA\TOP2.IDF
TOPIDF3= D:\DATA\TOP3.IDF
BOTIDF1= D:\DATA\BOT1.IDF
BOTIDF2= D:\DATA\BOT2.IDF
BOTIDF3= D:\DATA\BOT3.IDF
KDIDF1= D:\DATA\KD1.IDF
KDIDF2= D:\DATA\KD2.IDF
KDIDF3= D:\DATA\KD3.IDF
CIDF1=D:\DATA\C1.IDF
CIDF2=D:\DATA\C2.IDF
IXCOL=1
IYCOL=2
ITCOL=3
IBCOL=4
IQCOL=8
NIPF=3
IPF1=D:\DATA\INDUSTRY.IPF
IPF2= D:\DATA\DRINKINGCOOPERATION.IPF
IPF3= D:\DATA\AGRICULTURE.IPF

The example above, will classify each location in three IPF files according their length and associated transmissivity, within any penetrating model layer. The content of the IPF files is different than the default IXCOL, IYCOL, ITCOL, IBCOL and IQCOL column identifications, and therefore added here.