INCREASING RELATIVE PERMEABILITY IN COAL - A NEW APPROACH

Coalbeds are self-sourcing reservoirs that contain biogenic and thermogenic gas. Coal resources in the United States are enormous and have the potential to produce vast quantities of coalbed methane (CBM). At this time CBM is underutilized due to current methods of extraction and the low permeability of coalbeds. Extraction of CBM is controlled not only by coal composition, but also, by the ability of the coal beds to desorb their methane (i.e., their permeability). Coal permeability depends on the internal system of macroscopic (cleat) and microscopic (matrix), fractures, which are dependent on coal composition, coal rank, and timing of formation.

The application of various oxidizing agents, primarily H2O2, to coal thin sections is being used in the investigation of chemical enhancement of macro and microscopic permeability features. Atomic Force Microscopy (AFM) is being used to gain a more precise scale of maceral hardness and to determine the effectiveness of chemical oxidants on permeability features to support enhancement of CBM recovery. AFM analysis determines surface topography of a sample before and after application of the oxidizing agent in order to better estimate the change in relative permeability. Increasing permeability of coalbeds will allow increased CBM production and more efficient use of the resource. Additionally, this study will develop a better understanding of some chemical and physical characteristics of coal.