What's new in exploration

	Vol. 227 No. 10
PERRY A. FISCHER, EDITOR

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.

There’s been a hybrid theory around for many years that began in Russia, wherein oil was the result of abiogenic, mantle-derived methane, reacting with organics in source rock. From that point on, all of the evidence in Western oil-genesis theory is the same.

Microbial mysteries deepened recently as a result of the Ocean Drilling Program. Drill cores were taken off the Peruvian coast in 1,300-ft deep sediment, using the research drilling vessel JOIDES Resolution. In the core samples, a team of researchers found propane and ethane that they believe could not have come from ordinary thermogenic processes, given the geology of the area. Moreover, the isotopic carbon signatures are markedly different from thermogenic gases formed at high temperatures.

The case for the production of energy-laden gases appears in a paper in this week’s online edition of the Proceedings of the National Academy of Sciences of the U.S.A., written by Prof. Kai-Uwe Hinrichs (Research Center Ocean Margins, University of Bremen), co-author Prof. John Hayes (Woods Hole Oceanographic Institution) and colleagues.

The findings suggest that unknown microbes in the deep biosphere carry out previously unrecognized processes, “. . . which are highly relevant to both our understanding of global element cycles and the metabolic abilities of Earth’s microbial biosphere.”

Since sedimentary organics are a major food source used by the deep biosphere, the researchers hypothesize that during its decomposition by microbes, acetate--the ionic form of acetic acid--is formed. “We think that bacteria use hydrogen to convert acetate into ethane. Addition of inorganic carbon and hydrogen provides a route to propane,” said Hinrichs. Thus far, the scientists were able to demonstrate that under the conditions prevailing at depth, these processes could yield just enough energy for growth of bacterial communities.

Marine mammals: more protected than humans? The latest volley in what is now a battle of the absurd comes from the US National Marine Fisheries Service (NMFS). Despite the finding two years ago by MMS, that there was “no significant impact,” NMFS has proceeded to try to find something, anything, that would justify even further restrictions on seismic operations in US waters. Even though they failed at that a few months ago, NMFS issued its new Draft Recovery Plan for the Sperm Whale. Predictably, the industry advocates – IAGC, NOIA and API – voiced their objections in September. Two fundamental problems with the recovery plan can be found within the plan itself.

The plan finds that, “. . . the extent of depletion and degree of recovery of [sperm whale] populations are uncertain. Currently, the population structure of sperm whales has not been adequately defined.” How then, would NMFS know whether it’s having any effect with its plan, or whether its plan is even needed?

The second strange point is that there is no scientific evidence that oilfield seismic has harmed a single sperm whale. There’s a study that found sperm whales “. . . apparently moved away, possibly by 50+ km, when seismic surveys began (Mate, et al., 1994). Also, sperm whales in the southern Indian Ocean ceased calling during some, but not all, seismic pulses that were received from an airgun array >300 km away (Bowles, et al., 1994).”

Mate says that his study was not scientifically controlled, and the observation may have been a coincidence. The Bowles observation has not been repeated in any other study, including the ongoing Sperm Whale Seismic Study in the GOM. Most importantly, even if there were good data that a sperm whale was once harassed, there is absolutely no scientific evidence of physical harm to a single sperm whale, let alone detriment to whale populations, which is what the law says is important. But that seems irrelevant to NMFS. More information can be found at: www.iagc.org

Only 0.8 Mya? You may have heard the newest finding last month that the present period of global warming has the highest CO₂ levels in at least the past 800,000 years. Air trapped in the oldest ice cores shows that CO₂ levels change with the climate, but that present levels have increased about 35% in the last 200 years. In the previous 799,800 years, the CO₂ levels were in the range of 180 – 300 ppmv of air. Today, the level is at 380 ppmv. The problem will be to obtain other ice cores in Greenland and elsewhere that show the same record. That, and, of course, CO₂ levels for the last 300 million years.

Real 3D. Just in case you missed this several months ago (I know that I did), there’s been a breakthrough in the ability to solve the Helmholtz equation, a true 3D solution to wave propagation. Only recently have computers been powerful enough to solve this equation, and even then it is very computer-intensive, involving an enormous number of iterations, and so not usually employed. Attempts to make it faster created more problems than benefits, until now. Mathematical research at Delft University of Technology (Netherlands) by Yogi Ahmad Erlangga has resulted in a breakthrough. Erlangga received his doctorate last December for the work. He developed a method of calculation that enables computers to solve the Helmholtz equation a hundred times faster.

A purely mathematical solution, it has many applications, although the primary motivation for the work is seismic exploration. Funded by Shell and SenterNovem, the full paper can be found at: http://ta.twi.tudelft.nl/nw/users/vuik/numanal/erlangga.pdf