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Geology and oil and gas assessment of the Mancos-Menefee Composite Total Petroleum System: Chapter 4 in Total petroleum systems and geologic assessment of undiscovered oil and gas resources in the San Juan Basin Province, exclusive of Paleozoic rocks, New Mexico and Colorado

Data Series 69-F-4

This report is Chapter 4 in Total petroleum systems and geologic assessment of undiscovered oil and gas resources in the San Juan Basin Province, exclusive of Paleozoic rocks, New Mexico and Colorado (DS 69-F)
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Abstract

The Mancos-Menefee Composite Total Petroleum System (TPS) includes all genetically related hydrocarbons generated from organic-rich shales in the Cretaceous Mancos Shale and from carbonaceous shale, coal beds, and humate in the Cretaceous Menefee Formation of the Mesaverde Group. The system is called a composite total petroleum system because the exact source of the hydrocarbons in some of the reservoirs is not known. Reservoir rocks that contain hydrocarbons generated in Mancos and Menefee source beds are found in the Cretaceous Dakota Sandstone, at the base of the composite TPS, through the lower part of the Cliff House Sandstone of the Mesaverde Group, at the top. Source rocks in both the Mancos Shale and Menefee Formation entered the oil generation window in the late Eocene and continued to generate oil or gas into the late Miocene. Near the end of the Miocene in the San Juan Basin, subsidence ceased, hydrocarbon generation ceased, and the basin was uplifted and differentially eroded. Reservoirs are now underpressured. Eight assessment units were defined in the Mancos-Menefee Composite TPS. Of the eight assessment units, four were assessed as conventional oil or gas accumulations and four as continuous-type accumulations. The conventional assessment units are Dakota-Greenhorn Conventional Oil and Gas Assessment Unit (AU), Gallup Sandstone Conventional Oil and Gas AU, Mancos Sandstones Conventional Oil AU, and the Mesaverde Updip Conventional Oil AU. Continuous-type assessments are Dakota-Greenhorn Continuous Gas AU, Mancos Sandstones Continuous Gas AU, Mesaverde Central-Basin Continuous Gas AU, and Menefee Coalbed Gas AU. The Mesaverde Updip Conventional AU was not quantitatively assessed for undiscovered oil and gas resources, because the producing oil fields were smaller than the 0.5 million barrel cutoff, and the potential of finding fields above this cutoff was considered to be low. Total oil resources that have the potential for additions to reserves in the next 30 years are estimated at a mean of 16.78 million barrels. Most of this resource will come from reservoirs in the Mancos Sandstones Oil AU. Gas resources that have the potential for additions to reserves in the next 30 years are estimated at a mean of 11.11 trillion cubic feet of gas (TCFG). Of this amount, 11.03 TCFG will come from continuous gas accumulations; the remainder will be gas associated with oil in conventional accumulations.Total natural gas liquids (NGL) that have the potential for additions to reserves in the next 30 years are estimated at a mean of 99.86 million barrels. Of this amount, 96.95 million barrels will come from the continuous gas assessment units, and 78.3 percent of this potential resource will come from the Mancos Sandstones Continuous Gas AU.

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Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Geology and oil and gas assessment of the Mancos-Menefee Composite Total Petroleum System: Chapter 4 in Total petroleum systems and geologic assessment of undiscovered oil and gas resources in the San Juan Basin Province, exclusive of Paleozoic rocks, New Mexico and Colorado
Series title:
Data Series
Series number:
69-F-4
Year Published:
2013
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
Energy Resources Program
Description:
ix, 97 p.
Larger Work Type:
Report
Larger Work Subtype:
USGS Numbered Series
Larger Work Title:
Total petroleum systems and geologic assessment of undiscovered oil and gas resources in the San Juan Basin Province, exclusive of Paleozoic rocks, New Mexico and Colorado (DS 69-F)
Country:
United States
State:
Colorado;New Mexico