Building PICScripts Click by Click

If you are not an experienced programmer, learning the PICScript programming language can be a little intimidating. However, function buttons, and automatic declarations will enable you to construct scripts even if you are a beginner.

The PICScript dialog provides buttons and lists so you can select items as building blocks for your script. For your convenience, you can move the Function tab to a floating button bar to make it easier to construct scripts.

The following takes you through the process to build scripts:

Laying out expressions

Before you construct your PICScript, it is a good idea to get a piece of paper and jot down your mathematical expression using descriptive words for each term. If you wanted to calculate an isopach from two depth grids, you might write:

deep grid - shallow grid

Now we will put the expression into the correct syntax. In a PICScript, the output (or result) is always on the left side of an equation. Since an isopach is in depth units, the output type will be depth. Each expression in a function block must end with a semicolon ( ; ). Also, aliases can't have spaces or mathematical symbols in them so you will want to remove the spaces or replace them with underscores. With all this in mind, the expression should read:

depth = deep - shallow;

Constructing a PICScript function

A PICScript can have more than one function and each function can be made up of multiple statements. Scripts can be quite sophisticated making use of logical operators, seismic functions, temporary variables and script flow statements. For demonstration purposes, this example is simple. But it should help you to understand how to construct a script using automatic declarations.

The PICScript dialog box

Go to the Tools menu and select PICScript. Use the tabbed options on the left hand side to construct a script in the text box on the right. You may place the contents of the function tab into a floating Function Button bar for easier access. View image

Select the Grid Math or Horizon Math radio button. The example we are describing will be a grid math script. Notice that a comment line is entered into the script text box. It will read //HorizonScriptMode or //GridScriptMode. Any line beginning with a "//" is ignored when the program runs, so these lines can be used to enter comments into the script. We will make declarations above this comment line and build a function below it. You will also notice that the framework for a function block is entered into the text box.
Click <Open Button Bar> to open the Functions tab in a convenient Function Button bar.

Output

Go to the Inputs/Outputs tab and select the Output Grid Attribute. View image

Click the text box after func{ and before the closing bracket ( } ). Your cursor will be blinking in this space. We are going to begin constructing the function expression as we make declarations. In the example, the output "depth" is on the left side of the equation. Follow these steps:

Double click on <output> depth. Notice that a declaration statement (output depth;) is entered in at the top of the text box and depth is entered inside the function brackets. depth will also appear in the list box as the Alias for <output> depth.
Click into the box provided for the Output Grid Name and enter a name for the result grid. For an example, Purple_Green_Iso. Keep the grid name to fewer than 20 characters, and use an underline to replace spaces.

First input grid

The cursor will be blinking next to the word depth inside the brackets for the function block. (If it is not, click into this space.) We will continue constructing the function and declare the first of our input surfaces. View image

Click the equals button ( = ) on the Function tab or Floating Function Button bar. The equals sign will be entered into the equation. This is the assignment portion of the statement. The results of the expression we create to the right of the equals sign will be assigned to the output alias "depth".
Double click on a depth grid in the listing. This should be the deeper of the two depth grids so that we get a positive isopach for our result grid.
A box will open asking you to enter an Alias for the input grid. In this example, when we wrote out our equation we chose deep as an alias to represent the deeper grid in our expression, so we will enter this name.

Notice that a declaration statement is entered at the top of the text box and deep is entered inside the function brackets. deep will also appear in the list box as the Alias for the grid.

Second input grid

To complete the function statement we need to enter the mathematical operator and the second grid followed by a semicolon.

Click the minus button ( - ). The minus sign will be entered into the equation.
Double click on a depth grid in the listing. This should be the shallower of the two depth grids.
A box will open asking you to provide an Alias for the input grid. In this example, when we wrote out our equation we chose shallow as an alias to represent the shallower grid in our expression, so we will enter this name.

Notice that a declaration statement is entered at the top of the text box and shallow is entered inside the function brackets. "shallow" will also appear in the list box as the Alias for the grid.

All statements must end with a semicolon. So click on the ;<NewLine> button to complete the statement. View image

Click File (upper left hand corner of the dialog box) and Save your script.

Run a Grid Script

Run scripts from the PICScript dialog.

Open PICScript . (Located on the Application toolbar under, | PICScript.)
Create a new Grid Math script or load an existing script.
Save the new script or update aliases for an existing script.
Go to the Geometry/Reference tab.
Specify a Reference Horizon. Use the drop-down list to select a horizon name. This will enable WinPICS to associate the grid with a horizon for tasks like displaying well tops on posted maps.
Specify the grid geometry for the output grid.

Ordinarily you will use the Available Geometries drop-down list to select the geometry of a grid or 3D in your project. The specifications for the grid you select will be displayed in the bottom portions of the tab. You may modify these settings before running the script. For example change the number of grid lines to create finer or coarser grid sampling.
To define a unique geometry, do not select an available geometry. Instead, supply the coordinate location for the origin of the grid (X-Origin, Y-Origin), an angle for the grid (Orientation), the number of grid lines (X-lines and In-lines) and the distance between grid lines (Spacing). Note that the WinPICS map is active while you are working with PICScript. This means that you can use your cursor to find coordinates. For more details and a geometry diagram, see grid geometry.

For grid scripts using input or output time grids, go to the Misc. tab and set time units. Options are microseconds, milliseconds or seconds.

Running the script

Click the <Execute> button. If there are no syntax errors in the script, a new grid will be created. If an error is encountered a message will pop up giving the number of the line in the script with the error. Correct the error. (Hint: The most common error is a missing semicolon ( ; ).) You will not need to setup parameters again, simply execute the script.

Viewing results and making modifications

Without closing PICScript , post your grid on the map. Look at the results and decide if you need to modify the script.

Make changes to the script or to parameters and execute the script again. If the output grid name remains the same, the results will automatically post to the map. Each time you run the script to last result grid will be overwritten.

Running the same script on another grid

Without exiting PICScript you can run the same script on a series of input grids. Simply update aliases, change geometry if needed, enter a new output name and execute.

Run a Horizon Script

Run scripts from the PICScript dialog.

Open PICScript. (Located on the Application toolbar under | PICScript.)
Create a new Horizon Math script or load an existing script.
Save the new script or update aliases for an existing script.
Go to the Lines/Areas tab.
Specify 2D Lines or 3D areas. Left click to highlight and select. Left click again to de-select. The script will run on all highlighted lines/areas.

PICScript will find and use the specified horizons for these files. The result horizon will be written for each line/area. If the results of the script are invalid for a given point, a No Pick will be entered for the output horizon.
If the script contains seismic functions, these lines/area will be used as source data.

Go to the Misc. tab and set time units. Options are microseconds, milliseconds or seconds. Milliseconds is the default.

Running the script

Click the<Execute> button. If there are no syntax errors in the script, a new horizon will be created. If an error is encountered a message will pop up giving the number of the line in the script with the error. Correct the error. (Hint: The most common error is a missing semicolon ( ; ).) You will not need to setup parameters again, simply execute the script.

Viewing results and making modifications

Use WinPICS ' map and seismic displays to check your script results. Without closing PICScript, right-click on the map and select New Horizon/Fault from the shortcut menu.

Select your output horizon from the list and post it on the map.

Look at the results and decide if you need to modify the script. Make changes to the script or to parameters and execute the script again. If the output horizon name remains the same, the results will automatically update the map and seismic displays. Each time you run the script using the same output horizon name, the last result horizon will be overwritten.

If you use a new output horizon name, a new horizon will be created. Right click on the map to open the shortcut menu, and select New Horizon/Fault to post the new output horizon.

What do you want to do?