0.6 0.074 0.141 0.3

0.80.167 0.004 0.033

During the simulation, the first table will be used for cells in layers 1 and 2, the second table for cells in layer 3 and 4, and the third table for cells in layers 5 and 6. Eclipse needs to be notified that we now have three saturation tables, by the flag NTSFUN in the TABDIMS keyword in the RUNSPEC section.

10. Simplified input and modification of Eclipse arrays

We have earlier defined the default Eclipse input format for an array (e.g. PORO) as a list comprised of one value per grid cell, with possible use of the n* - option.

Eclipse offers an alternative input format, that is more user-friendly, and often more efficient, by the keywords BOX, EQUALS, ADD, MULTIPLY, COPY, ...

In general these commands work by first defining a box where the associated input applies, and then defining the input. The BOX keyword is used to set such a box explicitly, but the box can also be defined as a part of the input.

NOTE: When a box has been defined, it remains valid until a new box is defined.

When Eclipse reads data it immediately performs an action on the data array it is processing. This action can be to overwrite an existing value, or do arithmetic to an existing value. With this knowledge we can build data arrays by repeated assigning and reassigning values, assuring that the end result is the final operations we performed.

Breakdown of the different edit-keywords,

BOX

A box is an index-cube, i.e. bounded by constant indices in all directions. A cell with index (ix, jy, kz) is in the box (ix1 – ix2; jy1 – jy2; kz1 – kz2) if ix1 ≤ ix ≤ ix2, jy1 ≤ jy ≤ jy2, kz1 ≤ kz ≤ kz2.

Defining the box above would be by the syntax,

BOX

ix1 ix2 jy1 jy2 kz1 kz2 /

When such a box has been defined, Eclipse takes array input exactly as usual, except only necessary and sufficient data to fill the box are expected. (The standard array input format is hence a special case where the box is the entire reservoir.)

Example

By the keyword

we specify that until the box is redefined, input data will be for cells (I, J, K), with I = 3, 4, 5, 6; J = 10, 11, 12; K = 5.

To set porosity φ = 0.26 in this box:

PORO 12*0.26 /

We have defined 12 entries, since the box is comprised of 4*3*1 = 12 cells.

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and in the REGIONS section:

Note that we don’t have to specify the number of cells in the box when we include the box definition in the EQUALS keyword.

ADD, MULTIPLY

The ADD and MULTIPLY keywords are very similar to EQUALS, but instead of specifying a value, we modify an existing value, that must have been defined earlier.

Example

In a grid with NX = NY = 9, NZ = 3, there is a region with bad properties in the middle. Region 2 is defined by IX = 4 – 6, JY = 4 – 6, KZ = 2. The rest is region 1.

In region 1, porosity is 0.3, horizontal permeability 2000 and vertical permeability 250. In region 2, porosity is 0.2, and permeabilities are ¼ of the values in region 1.

In this example we will first define data for the whole grid, then redefine in the central area. Note that there are many different ways to do this, and no “correct” or “best” solution. First defining one value for a large box (here the entire grid) and then redefining a sub-box is often efficient.

In the GRID section:

PORO

243*0.3 / (9*9*3 = 243)

PERMX 243*2000 /

PERMY 243*2000 /

MULTIPLY

--array value ix1 ix2 jy1 jy2 kz1 kz2

PERMX 0.25 / defaults to box defined above PERMY 0.25 /

PERMZ 0.25 /

/

In the REGIONS section

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COPY

This keyword is used to copy an entire array (or a box) to another array. Thereafter the modification keywords may be used if needed.

Syntax for each line of keyword:

SourceArray TargetArray (Box)

Each line is terminated by a slash, and an empty record (slash alone) terminates the keyword.

Example

We repeat the example above, this time using the COPY keyword:

First we define PORO and PERMX for the whole grid.

Then we modify the values for region 2

In the GRID section:

-- Real or dummy data for whole grid PORO

243*0.3 / (9*9*3 = 243)

PERMX 243*2000 /

--Modify to correct values in Region 2 ADD

--array value ix1 ix2 jy1 jy2 kz1 kz2

--PERMY and PERMZ are copies of PERMY in entire grid COPY

--From To BOX

-- Lastly, PERMZ is modified to be 12.5% of hor. permeability MULTIPLY

PERMZ 0.125 /

/

COPYBOX

While COPY is used to copy one array to another in the same cells, COPYBOX is used to make an exact copy of the same parameter in a box, in another, non-overlapping box. Obviously the two boxes must be of the same size in all three directions.

Example

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