National Assessment of Oil and Gas 2002 USGS Assessmenthe Denver Basin ProvSouth Dakota, and WyoIntroduction

The U.S. Geological Survey (USGS) recently assesse

undiscovered, technically recoverable oil and gas resourof the Denver Basin Province (fig. 1) that have the potento be added to reserves in the next 30 years. Both conventional and continuous resources were assessed. Continuous-type accumulations include coal-bed gas (CBlow-permeability gas, and fractured shales, which differ from conventional accumulations in that they are not sigcantly affected by hydrodynamics, there is no downdip gwater contact, and conventional methods of assessing sizand numbers of accumulations are not appropriate (modifrom Klett and others, 2000). 

Using analyses based on the study of total petroleum 

systems, the U.S. Geological Survey mean estimates of petroleum potential in the Denver Basin Province are 10million barrels of oil, 2,519 billion cubic feet of gas, and 51

81 

illi

b

l

f 

t

l 

li

id

(NGL)

M
Table 1. Denver 

[TPS, total petroleuaccumulations in th

the assumption of p

Fractured Niobrar

Transitional A

Dakota Group and 

50390401 

Subthrust Structur

Permian-Pennsylv

50390501 

Pierre Shale Sand

TOTAL CONVE

RESOURCE

Niobrara-Codell (

50390661 

Dakota Group Ba

50390662 

Niobrara Chalk AFractured Niobrar

area) AU 503

Fractured Pierre SDenver Formation Laramie FormatioTOTAL CONTI

RESOURCE

TOTAL RESOU

Coal-Bed Methane TPS 503901

1. Denver Formation Coals AU 50390181—Hypothetical continuous coal-bed gas from the 

Upper Cretaceous and Paleocene Denver Formation in the central Denver Basin Province.

2. Laramie Formation Coals AU 50390182—Hypothetical continuous coal-bed gas from the 

Upper Cretaceous Laramie Formation in the central Denver Basin Province.

Upper Cretaceous Fractured Niobrara TPS 503902

1. Fractured Niobrara Limestone Transitional AU 50390201—Conventional; located in the 

central Denver Basin Province and excludes areas of AUs 50390261 and 50390761.

2. Fractured Niobrara Limestone (Silo field area) AU 50390261—Continuous; mostly oil 

production from the Upper Cretaceous Niobrara Formation in the Silo field area (fig. 1).

Upper Cretaceous Pierre Shale (Florence Field) TPS 503903

1. Fractured Pierre Shale AU 50390361—Continuous; oil production from the Upper 

Cretaceous Pierre Shale in the Florence field area (fig. 1).

Lower Cretaceous TPS 503904

1. Dakota Group and D Sandstone AU 50390401—Conventional; Cretaceous Muddy (J) 

Sandstone reservoirs located across the central third of the province.

2. Subthrust Structural AU 50390402—This hypothetical conventional assessment unit of 

Cretaceous and Paleozoic formations is located under and along the eastern edge of the Rocky Mountains.

Permian-Pennsylvanian TPS 503905

1. Permian-Pennsylvanian Reservoirs AU 50390501—Conventional; structural traps in 

limestones and sandstones concentrated in the northwestern half of the province.

Cretaceous Composite TPS 503906

1. Pierre Shale Sandstones AU 50390601—Conventional reservoirs in the Upper Cretaceous 

Richard, Terry (Sussex), and Hygiene (Shannon) Sandstones, Spindle field area (fig. 1).

2. Niobrara-Codell (Wattenberg area) AU 50390661—Continuous; oil and gas production 

from Upper Cretaceous sandstone and limestone, Spindle field area (fig. 1).

3. Dakota Group Basin-Centered Gas AU 50390662—Continuous gas accumulation in the 

Wattenberg gas field (fig. 1). Production is primarily from the Lower Cretaceous Muddy (J) Sandstone.

Upper Cretaceous Niobrara Biogenic Gas TPS 503907

1. Niobrara Chalk AU 50390761—Continuous; biogenic gas from the Niobrara Formation is 

located in the eastern third of the province and extends eastward into Kansas and northward into South Dakota.

FS-002-03.indd 2-3 
Denver Basin Province Assessment Team

Debra Higley (higley@usgs.gov, 303-236-5791), R

Schmoker. Christopher J. Schenk, National Assessm

For Further Information

Supporting geologic studies of total petroleum syst

from the 1995 National Oil and Gas Assessment projec

ht

References CitedKlett, T.R., Schmoker, J.W., Charpentier, R.R., Ahlbrandt

Team, U.S. Geological Survey World Petroleum A

//greenwood.cr.usgs.gov/energy/WorldEnergy/D

Magoon, L.B., and Dow, W.G., 1994, The petroleum syst

American Association of Petroleum Geologists M

NRG Associates, Inc., 2000, Signifi cant oil and gas fi eld

Associates, Inc., P.O. Box 1655, Colorado Springs

PI/Dwights Well History Control System database, 1999PI/Dwights petroROM Production Data on CD-ROM, 19