Effects of igneous intrusions on coalbed methane potential, Gunnedah Basin, Australia

Changes in optical properties, chemistry, and micropore and mesopore characteristics of bituminous coal at the contact with dikes in the Illinois Basin

“…A study in the Gunnedah Basin, Australia, by Gurba and Weber (2001) contradicts these assumptions and presents a different situation where the gas content around sills is significantly higher than in unaffected coal, and the gas composition is not much different around the intrusion. The higher gas content is explained by a heat-induced increase in coal rank, as well as by the sill acting as an impermeable barrier and aiding in gas retention.…”

“…The zone of affected coal depends on the temperature of the intrusion and the size of the intruding body (Crelling and Dutcher, 1968;Bostick and Pawlewicz, 1984). Although the extent of the altered zone is usually close to the thickness of the intrusion (Gurba and Weber, 2001;Cooper et al, 2007), this may vary significantly depending on the type of intruding material and local emplacement conditions (Murchison, 2005), ranging from the fraction of the thickness of the intrusion (Mastalerz and Jones, 1988;Raymond and Murchison, 1988;Murchison and Raymond, 1989) to over several times the intrusion thickness (Jones and Creaney, 1977).…”

Coal metamorphism by igneous intrusion in the Raton Basin, CO and NM: Implications for generation of volatiles

“…Murchison and Raymond (1989) concluded that the regional reflectance pattern within the Midland Valley in Scotland was partially due to the pattern of igneous activity within the basin. Gurba and Weber (2001) determined that igneous sills in close proximity to coals are favorable for methane generation and production within the Gunnedah Basin, New South Wales, Australia. Both of these studies focused specifically on larger igneous sills, on the order of tens of meters thick.…”

On the fundamental difference between coal rank and coal type

“…between intrusions and coal seams (Gurba and Weber, 2001;Kisch and Taylor, 1966;Kwiecinska et al, 1992;Ward et al, 1989) to extensive areas of higher-rank coal within otherwise lower-rank coal deposits (Creaney, 1980;Daulay and Cook, 1988;Snyman and Barclay, 1989;Susilawati and Ward, 2006). Tectonically-driven geothermal fluids may also play an important role in coalification (Bayan and Hower, 2012;Gresley, 1896;Han et al, 1996;Hower and Gayer, 2002;Hower et al, 1993;Oliver, 1986Oliver, , 1992Ruppert et al, 2010;Uysal et al, 2000;Yang et al, 1996; among others).…”