Calculating formation porosity from a Microlaterolog

Note that the Microlaterolog is a salt mud tool, and differs from the Microlog interpretation scheme in that you must first solve for Sw, then back-calculate the porosities by assuming various models. (The microlog routine gives porosity directly.)

You have the option of using a measured Rmf...if you trust it. It is usually better to let the program estimate Rmf from Rm.

Be sure to indicate whether the deep resistivity reading, Rt, is from a Laterolog, since the program applies a correction to it. If Rt comes from an Induction tool, no correction is needed.

Microlaterologs can be used quantitatively with a bit of care. Try to calibrate them to better porosity-measuring tools, like neutron-density logs. When comparing microlaterologs look for similar-vintage tools, run by the same logging company, using the same pad spacings.


Do you want to save your calculations? The input box at the very bottom of the screen records all the inputs and outputs for each calculation run. To save this information, select all the text in the box and copy it, then open a spreadsheet and paste it in as comma-separated values. Each data type will land in its own column, and each calculation run, or depth, will occupy a row. Format the spreadsheet to separate rows into different geologic formations, and you're done. Isn't that easier than writing everything down?

Don't have a spreadsheet handy? If you are working on a phone or a tablet, you can still copy the text and paste it into a note or an email.

The Recording box will reset if you press the "Help" or "Reset" buttons, or if you navigate to a different page.