Experimental investigation of changes in methane adsorption of bitumen-free Woodford Shale with thermal maturation induced by hydrous pyrolysis

摘要

This study quantifies the effects of organic-matter (OM) thermal maturity on methane (CH4)-sorption, on the basis of five samples that were artificially matured through hydrous pyrolysis achieved by heating samples of immature Woodford Shale under five different time temperature conditions. CH4-sorption isotherms at 35 degrees C, 50 degrees C, and 65 degrees C, and pressures up to 14 MPa on dry, solvent-extracted samples of the artificially matured Woodford Shale were measured. The results showed that CH4-sorption capacity, normalized to TOC, varied with thermal maturity, following1 the trend: maximum oil (367 degrees C) > oil cracking (400 degrees C) > maximum bitumen/early oil (333 degrees C) > early bitumen (300 degrees C) > immature stage (130 degrees C). The Langmuir constants for the samples at maximum-oil and oil-cracking stages are larger than the values for the bitumen-forming stages.