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Do any of you have first hand experience using geo-microbial prospecting?

Thanks,

Jane

Yes, sort-of. I was a researcher for 13 years during which time Airtrace was developed, a geochemical method for oil & gas exploration which was used in air and ground surveys. A patent is available somewhere online explaining it. Air, snow, bark and leaves can all be sampled and analysed for hydrocarbon indicators. I also know where the teams members are who ran the systems.

A little known fact is that the method (Iontrace) was subsequently sold to Smiths Aerospace and ended up as a little blue box at every airport security line. Ever get swabbed by wand with a cotton pad - that was the original Oil exploration system.

Used it very effectively with my last company, we were able to show the presence of hydrocarbons, demonstrate that there was an active migration path, show that there were multiple sources, tie down several leads and show the effect of faults on the migration path.

Great value for money!

-James

Near surface geochemical exploration is a well established technolgy, both onshore and offshore, as you can see by some of the other comments mentioned.

The Microbial technique you mention is one of many indirect hydrocarbon indicators. There are several methods out there, including the latest being DNA analysis. Most common are methods that are simple bug counts after culturing a soil sample in a hydrocarbon based medium. Others methods look at the consumption of hydrocarbon gases in a culture cell.

Looking at trace metals and other alterations in the surface, most the result of either changing red-ox conditions or migrating fluids, are other indirect indicators.

The more direct indicators include sampling of soils or soil vapors for light and heavy hydrocarbons that have seeped from the reservoir. Macro-seeps can be searched for using sensitive field instrumentation, and micro-seeps with sampling and more sensitive lab instrumentation. Its simiply the modern version looking for oil and gas seeps with what is now very sensitive instrumentation, instead of the Jed Clampett method. Gases are analyzed by gas chromotorgraphy using a variety of extraction methods and oils are detected using solvent extraction followed by analysis on fluorescence spectrometers and/or high-resolution gas chromotography. Some of these methods can distinguish oil/gas composition types. You want to look for seepages patterns, paying close attention to your geology and structure, as well as concentration and compositional anomalies. Statistical modeling of some geochemical data can "fingerprint" some of these patterns over existing fields to be used as exploration models.

The types of methods you would want to use depend on many variables not least the environment you are sampling in, and your overall objectives.

PJBass has given a pretty extensive answer above, but I wanted to add that I agree with him that near surface techniques have been around for a while, but would add they have mades significant strides in he last 5 years. I know one technique, Amplified Geochemical Imaging, has a supposedly 90% accurate in predicting some level of charge in a reservoir and 95% accurate in predicting dry holes. To my knowledge it cannot tell you at what depth the possible accumulations may reside.