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Modeling of gas generation from the Cameo coal zone in the Piceance Basin, Colorado

Zhang, Etuan and Hill, Ronald J. and Katz, Barry J, and Tang, Yongchun (2008) Modeling of gas generation from the Cameo coal zone in the Piceance Basin, Colorado. AAPG Bulletin, 92 (8). pp. 1077-1106. ISSN 0149-1423. doi:10.1306/04020806015.

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The gas generative potential of the Cretaceous Cameo coal in the Piceance Basin, northwestern Colorado, was evaluated quantitatively by sealed gold tube pyrolysis. The H/C and O/C elemental ratios show that pyrolyzed Cameo coal samples follow the Van Krevelen humic coal evolution pathway, reasonably simulating natural coal maturation. Kinetic parameters (activation energy and frequency factor) for gas generation and vitrinite reflectance (Ro) changes were calculated from pyrolysis data. Experimental Ro results from this study are not adequately predicted by published Ro kinetics and indicate the necessity of deriving basin-specific kinetic parameters when building predictive basin models. Using derived kinetics for Ro evolution and gas generation, basin modeling was completed for 57 wells across the Piceance Basin, which enabled the mapping of coal-rank and coalbed gas potential. Quantities of methane generated at approximately 1.2% Ro are about 300 standard cubic feet per ton (scf/ton) and more than 2500 scf/ton (in-situ dry-ash-free coal) at Ro values reaching 1.9%. Gases generated in both low- and high-maturity coals are less wet, whereas the wetter gas is expected where Ro is approximately 1.4–1.5%. As controlled by regional coal rank and net coal thickness, the largest in-place coalbed gas resources are located in the central part of the basin, where predicted volumes exceed 150 bcf/mi^2, excluding gases in tight sands.

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Additional Information:© 2008 American Association of Petroleum Geologists (AAPG). Manuscript received February 1, 2006; provisional acceptance May 1, 2006; revised manuscript received August 30, 2007; final acceptance April 2, 2008. We acknowledge the support of Chevron Corporation and Shell Exploration and Production Company, and express our appreciation for their approval to publish the results of our study. We also wish to thank Ron Johnson, Vito Nuccio, Adry Bissada, Jack C. Pashin, Jerry J. Sweeney, and Peter D. Warwick for constructive reviews that significantly improved the article.
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Chevron CorporationUNSPECIFIED
Shell Exploration and Production CompanyUNSPECIFIED
Issue or Number:8
Record Number:CaltechAUTHORS:ZHAaapg08
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11702
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Deposited On:20 Sep 2008 02:56
Last Modified:08 Nov 2021 22:01

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