AAPG Studies in Geology No. 50,
(Section Title: The Ferron Coalbed Methane Play) Chapter 20: Hydrodynamic and
Stratigraphic Controls for a Large Coalbed Methane Accumulation in Ferron Coals of
East-Central Utah, by Robert A. Lamarre, Pages 529 - 540
from:
AAPG Studies in Geology No. 50: Regional
to Wellbore Analog for Fluvial-Deltaic Reservoir Modeling: The Ferron Sandstone of Utah,
Edited by Thomas C. Chidsey, Jr., Roy D. Adams, and Thomas H. Morris
Copyright © 2004 by The American Association of Petroleum Geologists and the
Society of Exploration Geophysicists. All rights reserved.
The Ferron Coalbed Methane Play
Chapter 20:
Hydrodynamic and Stratigraphic Controls for a Large Coalbed Methane Accumulation in
Ferron Coals of East-Central Utah
Robert A. Lamarre1
1Lamarre Geological Enterprises, LLC, Denver, Colorado
ABSTRACT
Upper Cretaceous coals within the Ferron Sandstone Member of the Mancos
Shale contain large volumes of coalbed methane. Coals at the northern end of the 80-mi
(129 km)-long Ferron trend have produced 469 bcf of coalbed methane, as of the end of July
2003. At that time, 735 wells were producing 275 mmcfd. Analysis of cores from exploratory
wells indicate that the gas content of the coals decreases dramatically from north to
south, even though the rank and maturity of the coals decreases only slightly. The area
with lowest gas content correlates with the outcrop of the Ferron coals in the southern
portion of the trend. Hydrodynamic studies have shown that the Ferron coals are aquifers
that are recharged from the Wasatch Plateau to the west. Regional mapping indicates that
the productive fields are large stratigraphic traps in the central and northern part of
the trend where the coals pinch-out updip into tight marine shales to the east. Much of
the produced gas is secondary biogenic gas and migrated thermogenic gas that has moved
from the Wasatch Plateau and south margin of the Uinta Basin, respectively. In the
southern part of the trend, near the town of Emery, coals are present at the surface, but
most of the gas has been flushed out of the coals due to reduction of reservoir pressure
and active water flow from the west. Therefore, the entire Ferron trend probably contained
tremendous volumes of stratigraphically trapped coalbed methane before uplift and erosion
exposed the southern coals to the atmosphere.
