Exploration significance of a possible subsurface meteorite impact feature in Garfield County, Montana
Geophysical information gathered near the western edge of the Williston basin by ARCO Exploration Co. indicates the presence of a structural anomaly resembling a meteorite impact feature. Seismic data indicates that Chimney Prospect has a central uplift with approximately 250 ft (76 m) of structural closure. It is surrounded by an identifiable rim syncline and a much less developed outer rim. Chimney Prospect encompasses approximately 2,000 acres (800 ha). The time of impact has been determined to be Jurassic, with deformation found in pre-impact sediments as old as the Mississippian Kibbey Formation. Chimney Prospect has been tested by the ARCO-1-1 BNRR/Coastal well. No significant hydrocarbons were encountered. Geologic evidence indicates that a small meteorite landed in a shallow Jurassic sea impacting soft, plastic sediments which dispelled much of the impact force. The underlying sediments at the time of impact were elastic enough to brecciate. Subsequent to impact, the open fractures were either healed or filled with calcite, thereby destroying the porosity and permeability in the potential reservoir prior to oil migration. The occurrence of astroblemes in the subsurface is rare. When detected, five main criteria must be met to enhance the possibilities of an economic reservoir: (1) a meteorite body of sufficient size and velocity to produce a brecciated reservoir, (2) preservation of open fractures and pore space through time, (3) effective seals for trapping hydrocarbons, (4) oil migration after impact and deposition of the seal, and (5) openminded management aggressive enough to drill such features.
- Research Organization:
- ARCO Exploration Co., Denver, CO
- OSTI ID:
- 6526486
- Report Number(s):
- CONF-8309274-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 67:8; Conference: AAPG Rocky Mountain Section meeting, Billings, MT, USA, 18 Sep 1983
- Country of Publication:
- United States
- Language:
- English
Similar Records
Ames Hole Oklahoma: Impact-formed petroleum reservoirs
The Ames astrobleme
Related Subjects
MONTANA
PETROLEUM DEPOSITS
EXPLORATION
GEOLOGIC STRUCTURES
METEORITES
RESERVOIR ROCK
RESOURCE POTENTIAL
SEISMIC SURVEYS
FEDERAL REGION VIII
GEOLOGIC DEPOSITS
GEOPHYSICAL SURVEYS
MINERAL RESOURCES
NORTH AMERICA
RESOURCES
SURVEYS
USA
020200* - Petroleum- Reserves
Geology
& Exploration