ABSTRACT: Subsurface CO₂ disposal with enhanced gas recovery and biogeochemical carbon recycling

There is an enormous amount of methane in subsurface formations in the world. Most of the natural gas resources, however, is hardly economically recoverable as the methane is adsorbed in coal seams, trapped in hydrate clathrate or dissolved in saline groundwater. Shallow accumulation of methane is even a hidden threat of explosive global warming. Enhanced gas recovery by subsurface CO₂ injection (CO₂-EGR) is a practicable solution for the greenhouse gas control with efficient use of potential energy resources.

Extremely light isotopic compositions of carbon in methane suggest that methanogens formed many subsurface accumulations of methane-rich natural gas in the world. Chemolithotrophic methanogens, that belong to Archaea, form methane from CO₂ and gain energy without sunlight in anoxic circumstances. Methanogens are often blamed for greenhouse gas emission as they produce methane in bow els of cows and termites and in rice paddy. However, reapplication of CO₂-EGR for subsurface biogenic methane that is converted from disposed CO₂ makes the carbon recycling possible.

Subsurface ecosystem is somewhat similar to archaic ecosystem that is adapted to anoxic CO₂-rich atmosphere under high pressure and temperature. Bionic methanogenesis is active even in deep basaltic aquifers. Subsurface biogeochemical carbon recycling may realize greenhouse gas control with restoration of energy resources.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia