Services

This page describes how to use the survey planning applet and gives a brief introduction to some of the things you need to consider when designing a geophysical survey.

For a snapshot of the program in use click here

To start the survey planning applet click here.

Brief Notes on Geophysical Survey Design Defining Survey Area Defining Line Direction and Spacing Starting the Computation Results Trouble Shooting Further work Warranty

If you have any comments or suggestions for this section please mail them to bwiggins@fugro.com

• Safety should be the main concern - features such as topography, water depths, power lines etc. should be taken into consideration when selecting acquisition parameters.
• The prime line direction is commonly selected so that the lines run perpendicular to the expected strike of the geology in the survey area.
• For gravity and magnetic surveys the line spacing should be less than half the expected depth to the sources.
• The tie line spacing is typically 4-5 times larger than the prime line spacing.
• In airborne surveys the flight height is determined by safety factors and by the expected depth of geological targets.

Many shipborne potential field surveys will be done in conjunction with a seismic survey. In these cases the survey geometry is defined by the seismic program. However, the judicious addition of tie lines (during transit or weather down time) can greatly improve the overall robustness of the survey.

The only reference that I know of is:

Aeromagnetic survey design Reid, A. B. GEOPHYSICS , VOL. 45, NO. 5 (MAY 1980); P. 973-976

If the survey outline have been given to you as latitude and longitude coordinates you will need to convert them to x,y positions. If you have Fugro-LCT software installed on your system you can use PROJPT, or GRDPRO to perform the calculations.

Click here if you do not have access to projection software

The survey outline may have been specified using a local datum. This may not be critical for a quick marketing proposal but may be significant when actually performing the survey. Click here to read an Introduction to Geodetic Datums

It is best if you keep the survey coordinates digitally in either an ASCII file or in a word processor. As part of the Java Applet security measures there is no way for the program to read a file directly on your computer. Use your operating system's copy/paste function to put the projected survey coordinates into the text area of the survey planner.

Enter the prime line and tie line directions in the relevant boxes.. The prime and tie lines are commonly perpendicular to one another with the prime lines running parallel to the dip of the major geological structures in the survey area.

Enter prime and tie spacings. The distance units must be the same as were used to define the survey outline.

Press the "Compute" button and the program will compute the actual navigation tracks. You can check the status area in your web browser to see if the programming is operating correctly. Once the program has finished it will display a map of the survey area and report the length of the prime and tie lines. The lengths will be in the same units as the survey polygon coordinates.

The bottom text area displays the start and end cooordinates of each of the survey lines. Java Applets cannot write to your machine's disk so you will have to copy and paste the results into a word processor or ASCII file.

It would be nice to have a print button but due to the security restrictions of JDK1.0 that is not possible. You can use a print screen function, or on UNIX try the great xv program or failing that SunOS's snapshot. If you need larger scale maps you can use the results in your favorite mapping program.

[Q] My polygon does not look right.

[A] In Netscape (and maybe other browsers?) you can select Options/Show Java Console. Look in this dialog box to check that your survey outline points were read in correctly. The program expects blank sperated fields.

[Q] How do I exclude an island/platform from the middle of my marine survey?

[A} The program can handle key hole polygons - though at the moment the resulting survey lines will be split into two. For an example click here .

The program can handle key hole polygons - though at the moment the resulting survey lines may be split into two.

Program should report the area of the survey (for 3d seismic survey quotes).

The default format of the line lengths and the survey coordinates needs to be changed.

Could extend the program to handle point survey data (for land gravity quotes).

Please email bwiggins@fugro.com if you would like to suggest an enhancement.

FUGRO-LCT MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, REGARDING THE SURVEY PLANNING APPLET. FUGRO-LCT DOES NOT WARRANT, GUARANTEE, OR MAKE ANY REPRESENTATIONS REGARDING THE USE OR THE RESULTS OF THE USE OF THE SURVEY PLANNING APPLET IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY, CURRENTNESS OR OTHERWISE. YOU, THE END USER (OR YOUR EMPLOYER OR ANOTHER THIRD PARTY AUTHORIZED TO PERMIT YOUR USE OF THE SURVEY PLANNING APPLET) WILL ASSUME THE ENTIRE RISK FOR THE PERFORMANCE AND RESULTS OF THE SURVEY PLANNING APPLET.