To those interested,There are a number of useful websites with...

To those interested,
There are a number of useful websites with glossaries explaining the terms which are typically contained in a drilling report (see ASX releases) or similiar.

Go to www.spwla.org (Society of Professional Well Log Analysts-website). Go to "library & info" then "glossary".

In short "wireline logging" describes a downhole survey of subsurface properties. It involves lowering a tool or more commonly a combination of tools connected to the surface by a digital cable down the borehole. At the desired depth the tools are switched on and measurements are made while the tool is winched to the surface.

Each tool has sensors specifically designed to detect different formation properties eg. density, natural radiation, hole conditions, acoustic impedence etc.

Based on these readings the following properties can be determined - porosity, permeability, saturation, net:gross, fluid type/s in the pore space eg. oil, gas or water etc.

By recording these properties from numerous wells in an area, the dimensions and characteristics of the target reservoir can be determined. These values can then be used to compute reserves and determine the wether a field is commercial or not.

The interpretation and evaluation of logs is a specialised field of its own (seperate to geology) and is carried out by "petrophysicists" (who are usually engineers rather than geologists by education).

Hope this helps.