U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2005–3027

April 2005

National Assessment of Oil and Gas Fact Sheet

Assessment of Undiscovered Oil and Gas Resources

of the Raton Basin–Sierra Grande Uplift Province

of New Mexico and Colorado, 2004

Printed on recycled paper

U sing geology-based 

assessment methods,

the U.S. Geological Survey

estimated a mean of 

2.35 trillion cubic feet of 

undiscovered natural gas 

and a mean of 28.1 million 

barrels of undiscovered 

natural gas liquids in the 

Raton Basin–Sierra Grande 

Uplift Province. This is a 

gas-prone province with 

very limited oil production or 

resources; for this reason, 

oil resources were not 

assessed.

Introduction

The U.S. Geological Survey 

(USGS) recently completed an 

assessment of the undiscovered 

oil and gas potential of the Raton 

Basin–Sierra Grande Uplift Province 

of northeastern New Mexico and 

southeastern Colorado (fig. 1). The 

assessment included the Raton Basin, 

the Las Vegas subbasin, and the 

Sierra Grande uplift. The assessment 

is based on the geologic elements 

of each Total Petroleum System 

(TPS) defined within the province, 

including hydrocarbon source rocks 

(source-rock maturation, hydrocarbon generation and migration), 

reservoir rocks (depositional setting 

and petrophysical properties), and 

hydrocarbon traps (trap formation 

Jurassic–Lower Cretaceous Reservoirs AU

Upper Cretaceous–Tertiary Sandstones AU

Raton Coalbed Gas AU

Vermejo Coalbed Gas AU

Fractured Reservoirs AU

Colfax Union

Las Animas

San Miguel

Pueblo

Taos

Mora Harding

Otero Bent

Huerfano

Fremont

Custer

Crowley Kiowa

Baca

Saguache

Alamosa

Dallam Hartley

Oldham

Cimarron

Conejos Rio Arriba

Taos

Raton

Pueblo

Cuchara

Cimarron

Costilla

La Junta

Florence

Las Vegas

0 50 Miles

WET MOUNTAINS

COLORADO

NEW MEXICO

SANGRE DE CRISTO MOUNTAINS

TEXAS OKLAHOMA

SIERRA GRANDE UPLIFT

RATON BASIN

LAS VEGAS SUBBASIN

0 50 Miles

Figure 1. 

105 o

37o

38o

36o

104 o 103 o

Figure 1. Raton Basin–Sierra Grande Uplift Province (orange line) of northeastern New 

Mexico and southeastern Colorado. The Upper Cretaceous–Tertiary Coalbed Gas Total 

Petroleum System (TPS) contains the Upper Cretaceous–Tertiary Sandstones, Raton 

Coalbed Gas, and Vermejo Coalbed Gas AUs (blue line). The Jurassic-Cretaceous Composite TPS contains the Fractured Reservoirs AU (pink line) and the Jurassic–Lower Cretaceous Reservoirs AU (green line). Red and gray squares within the AU boundaries are, 

respectively, cells that produce hydrocarbon gas and those that do not produce hydrocarbons. Two green cells near the northwest boundary of the AUs are oil productive. Cell sizes 

are about 1 mile square. Gas-productive cells contain at least one well that is gas productive and may also include nonproductive wells. Red and gray cells outside AU boundaries 

are not productive of hydrocarbons; they are instead dry or productive of carbon dioxide, 

nitrogen, and helium.
and timing). Using this geologic framework, the USGS 

defined (1) the Upper Cretaceous–Tertiary Coalbed Gas 

TPS containing one conventional oil and gas assessment 

unit (AU) (Upper Cretaceous–Tertiary Sandstones AU) 

and two continuous oil and gas assessment units (Raton 

Coalbed Gas AU and Vermejo Coalbed Gas AU), and 

(2) the Jurassic-Cretaceous Composite TPS containing 

two conventional oil and gas assessment units (Fractured 

Reservoirs AU and Jurassic-Cretaceous Reservoirs AU). 

Undiscovered oil, gas, and natural gas liquids resources 

were quantitatively estimated within the five AUs 

(table 1).

Resource Summary

The USGS assessment of undiscovered conventional 

oil and gas and undiscovered continuous (unconventional) oil and gas within the province resulted in mean 

estimates of 2.35 trillion cubic feet of gas (TCFG) and 

28.1 million barrels of total natural gas liquids (table 1). 

Undiscovered continuous resources are estimated at 

1.59 TCFG from Raton and Vermejo Formation coals 

of the Upper Cretaceous–Tertiary Coalbed Gas TPS. 

The remainder of the undiscovered resources is probably 

structurally and (or) stratigraphically trapped conventional gas accumulations and possible unconventional gas 

within sandstones and shales ranging in age from Jurassic 

to Tertiary. 

For Further Information

Supporting geologic studies of TPS and AU results, 

and reports on the methodology used in the Raton Basin–

Sierra Grande Uplift Province assessment, are in progress. 

Assessment results are available at the USGS Central 

Energy Team Web site, accessed March 1, 2005.

http://energy.cr.usgs.gov/oilgas/noga/

Raton Basin–Sierra Grande Uplift Province 

Assessment Team:

Debra K. Higley (higley@usgs.gov), Troy A. Cook, 

Richard M. Pollastro, Ronald R. Charpentier, 

Timothy R. Klett, and Christopher J. Schenk.

R E S O U R C E S

Type

F95 F50 F5 Mean F95 F50 F5 Mean F95 F50 F5 Mean

Oil (MMBO) Gas (BCFG) NGL (MMBNGL) Total Petroleum Systems 

and Assessment Units (AU) 

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

17.52

0.00

14.64

0.00

184.48

0.00

316.65

0.00

584.10

216.64

900.75

1,117.39

0.00

54.00

0.00

78.04

0.00

605.39

0.00

572.83

0.00

939.31

737.43

1,512.14

2,249.57

0.00

113.12

0.00

199.31

0.00

1,073.12

0.00

1,036.25

0.00

1,510.54

1,385.55

2,546.79

3,932.34

0.00

58.53

0.00

88.76

0.00

615.09

0.00

611.26

0.00

979.32

762.39

1,590.58

2,352.97

0.00

0.54

0.00

6.86

0.00

0.00

0.00

0.00

0.00

0.00

7.40

0.00

7.40

0.00

3.00

0.00

23.29

0.00

0.00

0.00

0.00

0.00

0.00

26.29

0.00

26.29

0.00

0.00

0.00

8.35

0.00

46.45

0.00

0.00

0.00

0.00

54.81

0.00

54.81

0.00

0.00

0.00

3.54

0.00

24.58

0.00

0.00

0.00

0.00

28.12

0.00

28.12

Oil

Gas

Oil

Gas

Oil

Gas

Oil

CBG

Oil

CBG

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

Upper Cretaceous–Tertiary Coalbed Gas, Total Petroleum System 504101

Upper Cretaceous–Tertiary Sandstones 

AU 50410101

Jurassic-Cretaceous Composite, Total Petroleum System 504102

Fractured Reservoirs

AU 50410201

Jurassic–Lower Cretaceous Reservoirs 

AU 50410202

Upper Cretaceous–Tertiary Coalbed Gas, Total Petroleum System 504101

Raton Coalbed Gas,

AU 50410181

Vermejo Coalbed Gas, 

AU 50410182

TOTAL CONVENTIONAL RESOURCES

TOTAL CONTINUOUS RESOURCES

TOTAL RESOURCES

Conventional 

 Oil and Gas

Continuous Oil and Gas

Table 1. Raton Basin–Sierra Grande Uplift Province assessment results listed by name and code of Total Petroleum System (TPS) and 

Assessment Unit (AU).

[Resources are undiscovered oil, gas, and (or) natural gas liquids. MMBO, million barrels of oil; BCFG, billion cubic feet of gas; MMBNGL, million barrels 

of natural gas liquids. Type refers to mainly oil or gas accumulations in the assessment unit. CBG is coalbed gas. Fractiles are fully risked estimates. F95 

represents a 95-percent chance of at least the amount tabulated. Other fractiles are defined similarly. Fractiles are additive under the assumption of perfect 

positive correlation]