A model for lignin alteration - Part II: Numerical model of natural gas generation and application to the Piceance Basin, Western Colorado

The model presented here simulates a network of parallel and sequential reactions that describe the structural and chemical transformation of lignin-derived sedimentary organic matter (SOM) and the resulting generation of mobile species from shallow burial to approximately low-volatile bituminous rank. The model is calibrated to the Upper Cretaceous Williams Fork Formation coal of the Piceance Basin at the Multi-Well Experiment (MWX) Site, assuming this coal is largely derived from lignin. The model calculates the content of functional groups on the residual molecular species, C, H, and O elemental weight percents of the residual species, and moles of residual molecular species and mobile species (including components of natural gas) through time. The model is generally more sensitive to initial molecular structure of the lignin-derived molecule and the H2O content of the system than to initial temperature, as the former affect the fundamental reaction paths. The model is used to estimate that a total of 314 trillion cubic feet (tcf) of methane is generated by the Williams Fork coal over the basin history. ?? 2001 Elsevier Science Ltd. All rights reserved.