October 2006
Columns
What's new in exploration
Microbial mystery. The non-biological origin of simple hydrocarbon gases is well accepted. Vast amounts of methane and ethane on Saturn’s moon, Titan, are believed to have formed in the upper atmosphere. But there is a connection to surface geology. Ponds and lakes (although not oceans) seem highly probable, as do subsurface reservoirs. Whether this has a corollary to Earth’s history is unknown.
Other theories hold that microbes could create hydrocarbons in commercial quantities as part of various processes that are mostly not understood. It is now believed that biogenic methane (as opposed to thermogenic), for example, could comprise as much as 20% of commercial natural gas reserves. It could be even more, with the discovery that some coalbed methane is not ancient, but instead, the result of more recent biological processes. The problem is that there are billions of microbes, and the food-metabolism-waste processes that are possible are vast.


