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Methane from the Move: Natural Greenhouse Gas Emissions over Geological Time

di Primio, Rolando 1; Horsfield, Brian 1; Kroeger, Karsten 2
1 GFZ-Potsdam, Potsdam, Germany.
2 GNS-Science, Lower Hutt, New Zealand.

In the assessment of past, present and future global climate the contribution of natural greenhouse gas emissions has been largely disregarded. A massive amount of organic carbon is known to be stored in sedimentary basins and its conversion into hydrocarbons and leakage into the hydro- and atmosphere is obvious from petroleum and marine geological studies. When taking into account the 21-fold stronger greenhouse gas properties of methane as compared to CO2 it becomes evident that natural methane emissions have an enormous capacity for driving global climate: only a tiny degree of leakage, particularly when focussed through the clathrate cycle, can result in high emissions. Paleoclimatologists find evidence for a close relationship between global warming and atmospheric methane increase during the past 65 Million years of earths history. In fact, methane may be the main factor driving global climate past so called tipping points leading to dramatic climate changes within 50 years. Understanding the workings of sedimentary basins in time and space is fundamental to gaining insights into Earths climate.

The aim of our efforts is to predict methane migration and emission from the subsurface and to identify potential climate feedback processes by integrated subsurface, ocean and atmosphere modeling involving the main experts world wide working now together within the MOM Research Group.

Timing of hydrocarbon generation from globally occurring prolific source rocks is regarded to be the key factor in quantifying gas release. In order to reach this goal the history of all petroliferous basins of the world needs to be reconstructed. In addition a better understanding of the fate of migrating methane in the subsurface as well as upon leakage to the hydrosphere and atmosphere needs to be reached. Here themes such as hydrate formation and decay, bacterial metabolisation rates of methane in different environments and the subsurface biogenic formation of methane need to be assessed in a quantitative manner. Our project Methane on the Move aims at integrating expertise on all the subjects listed in order to understand the interactions between sedimentary basin evolution in time and space and Earths climate. Initial studies performed in the Western Canada basin, the Mackenzie Basin of northern Canada, the Congo-Angola offshore basins as well the Orange Basin of South Africa indicate periods of strongly enhanced emission rates throughout the evolution of these basins.

 

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009