Evaluating the coalbed methane potential of the Gething coals in NE British Columbia, Canada: An example from the Highhat area, Peace River coalfield

Does the Presence of Pseudovitrinite Indicate Gas-saturated Coals? Some Interesting Observations from the Gething Coals in Canada

“…However, this is unlikely because the lost gas ranged from 10-15.8% as a result of the wireline retrievable coring system used (Gentzis et al, 2006); thus, lost gas is close to the acceptable level of about 10%. A third possibility is that the pressure in each coal seam is not only different but also higher than that estimated by the injectivity test.…”

“…The CO 2 concentration in the desorbed gas from the Gething coals varied from 1.6 to 10%, with the average being 6% (Gentzis et al, 2006). As such, it would have been more ideal to use a mixed, but also expensive, gas isotherm because of the presence of CO 2 and traces of ethane in the desorbed gas.…”

“…The presence of partially mineralized fractures and cell lumens in inertinite macerals in the Gething coals is advantageous because they tend to keep the fractures partially open. The cleat aperture in the Gething coals, Highhat corehole, ranges from 0.005 to 0.2 mm (5 to 200 m), based on formation micro-imaging log (FMI), face cleat density is estimated to be 10-12 mm (2 cleats per 2.5 cm), and absolute permeability is about 0.5 mD (Gentzis et al, 2006). Based on the relationship between cleat density and maximum permeability of coals from the San Juan and Black Warrior basins developed by Laubach et al (1998), cleat aperture in the Gething coals should have been only 4 m. …”

“…The importance of volumetric strain on enhancing the permeability of such gassy coals in the Canadian foothills is also explored. The reader is referred to Gentzis et al (2006) for more details on the corehole location, coal sorption characteristics, general petrography, as well as field-derived coal permeability and short-term gas production rates of the Gething coals in the above corehole.…”

Organic Petrology: An Overview

“…Coalbed methane (CBM) has diverse origins, namely thermogenic and biogenic and isotopic analysis helps in its differentiation (Whiticar, 1996). On CBM there is a large amount of papers (e.g., Gentzis et al, 2006;Alsaab et al, 2008) Shale gas is an unconventional natural-gas reservoir, and refers to in situ hydrocarbon gas present in fine grained and organic rich sedimentary rocks. Gas produced from organic-rich shales is of both biogenic and thermogenic origin and is stored in situ, in shales as both adsorbed gas (on organic matter) and free gas (in fractures or pores).…”