Research presented in this thesis investigates the hydrocarbon molecular content, major and noble gas composition, the isotopic composition of noble gases and hydrocarbons, and select dissolved ions of gases and fluids from producing coalbed methane (CBM) wells. Samples were collected from the Illinois Basin in Sullivan County, Indiana. Samples analyzed in this study were compared with previously published data in the Illinois Basin to gain a greater understanding of fundamental fluid systematics and methane formation in coalbed reservoirs. Chapter 1: Conventional geochemical fingerprinting methods of hydrocarbon molecular and isotopic composition were used to determine the genetic source of natural gas in coalbed methane basins. Integration of isotopic and molecular hydrocarbon composition with noble gas geochemistry were used to determine the origin and migration of natural gas in the crust and relative role of coal seam waters and/or exogenous fluids in methane generation. Significant fluxes of exogenous thermogenic methane are observed in this coalbed methane reservoir. Chapter 2: Standard methods that assume steady state modelling and empirical methods for determining the residence time of natural gas and groundwater in coalbed methane fields using radiogenic ingrowth of 4He are compared. Previous age dating methods are corrected by taking into account significantly increased 4He diffusional rates specific to coal seams. By correcting for empirically determined rates of 4He accumulation, the geological time frame on which freshwater recharges into deeper sedimentary sequences, which may play a role in timing in which microbes are injected into coal beds and start to generate methanogenic natural gas, are more accurately constrained.