Undrilled shallow giant trap in Denver basin, Colorado: mountain-front thrust
Along the southwestern margin of the Denver basin, Precambrian rocks have been upthrusted at least 15,000 ft (4600 m) in the Front Range and 8000 to 10,000 ft (2400 to 3000 m) or more in the Wet Mountains. Below the Precambrian, the precise configuration of the strata and the faults is unknown because there are no available seismic or drilling data, but reasonable interpretations can be made by analogy with other similar areas. Important reservoirs in the basin are the Permian Lyons Sandstone, the Lower Cretaceous J and D sandstones, and the Upper Cretaceous Codell Sandstone, Niobrara Formation, and Pierre Shale. Directly overlying the J are the major hydrocarbon-source rocks in the basin. Black shale is interstratified with the Lyons Sandstone in at least one drill hole in front of the upthrust. All source rocks probably reached maturity in late Cretaceous time and still are generating today. Below the Precambrian, simple upfolding permits an oil column as much as 5000 ft (1500 m) high, or more, the J, and as much as 4000 ft (1200 m) high, or more, in the Lyons, assuming a fault dip of 70/sup 0/ at depth; lower fault dips permit higher oil columns. Clayey fault gouge, breccia, and minute faulting, in a zone that is in many places hundreds of feet wide at the fault, should be a good hydrocarbon seal, like a cork in a tilted 5000-ft (1500 m) high bottle. If the strata roll over to the west to form a large anticline below the Precambrian, a different kind of trap of very large dimensions would be present. Any kind of trap can extend a combined north-south distance of nearly 65 mi (105 km). Even if roll over is absent and the fault dips steeply, drilling depths to most traps are likely to be only several thousand feet.
- Research Organization:
- McMahon-Bullington, Englewood, CO
- OSTI ID:
- 6373589
- Report Number(s):
- CONF-8304200-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 67:3; Conference: Annual AAPG/SEPM/EMD/DPA convention, Dallas, TX, USA, 17 Apr 1983
- Country of Publication:
- United States
- Language:
- English
Similar Records
Hydrocarbon potential of Bellingham basin, northwestern Washington and southern British Columbia
Potential of Denver basin for disposal of liquid wastes
Related Subjects
03 NATURAL GAS
COLORADO
SEDIMENTARY BASINS
PETROLEUM GEOLOGY
GEOLOGIC STRUCTURES
GEOLOGIC TRAPS
NATURAL GAS DEPOSITS
PETROLEUM DEPOSITS
SOURCE ROCKS
FEDERAL REGION VIII
GEOLOGIC DEPOSITS
GEOLOGY
MINERAL RESOURCES
NORTH AMERICA
RESOURCES
USA
020200* - Petroleum- Reserves
Geology
& Exploration
030200 - Natural Gas- Reserves
Geology
& Exploration