Fluids in the Cretaceous System of the San Juan basin, New Mexico, and Colorado

Conference · Sun Aug 01 00:00:00 EDT 1993 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:6689613

Whitehead, III, N H ^[1]

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1. New Mexico Bureau of Mines and Mineral Resources, Socorro, NM (United States)

Fluids in the Cretaceous System, which has produced over 17 tcf gas and has 26 tcf of proved reserves, are characterized by potentiometric maps and cumulative production maps of gas, oil-condensate, and water. Fruitland Formation coals contain artesian-induced overpressured reservoirs that are dewatered to allow desorption of coal-bed methane. Recharge is along the northern basin margin, with southward flow through extensively fractured coals, and discharge is upward into the lower reaches of the San Juan and Animas rivers. The hydraulic system for the Pictured Cliffs, Mesaverde, and Dakota reservoirs has (1) a hydrodynamic component with recharge on the outcrop, then gravity-driven flow around the perimeter of the basin and discharge upward to regional base level where the San Juan River exists the basin, and (2) a hydrostatic component in the central basin area that is gas saturated. The trapping mechanism probably is high water saturation in low-permeability rock, which forms an effective permeability barrier to the updip movement of gas. Pictured Cliffs reservoirs are hydraulically connected to the Fruitland aquifer, where they are directly overlain by coals, through probable out-of-zone fractures in low-permeability areas. Mesaverde reservoirs are the most hydrologically isolated and underpressured. Dakota reservoirs generally overlie water-bearing sands. On the south flank of the basin, thermal maturity trends strike northwest-southeast and dip southwestward, crossing stratigraphic boundaries. In the deeper Dakota reservoir, downdip limits of oil condensate, cumulative gas concentrations, and cumulative oil-condensate concentrations are offset southwest of the Mesaverde reservoirs.

• OSTI ID: 6689613
• Report Number(s): CONF-930947--
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Vol. 77:8; ISSN 0149-1423; ISSN AABUD2
• Country of Publication: United States
• Language: English

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ALKANES
COAL DEPOSITS
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DEVELOPED COUNTRIES
FLUIDS
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MAPS
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STRATIGRAPHY
SURVEYS
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WATER SATURATION