Geologic controls on occurrence and producibility of coal-bed methane resources in the Upper Cretaceous Fruitland Formation, San Juan Basin, Colorado and New Mexico

Conference · Tue May 01 04:00:00 EDT 1990 · AAPG Bulletin (American Association of Petroleum Geologists); (USA)

OSTI ID:6796056

Ambrose, W A; Ayers, Jr, W B ^[1]

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1. Univ. of Texas, Austin (USA)

A recent, marked increase has occurred in the number of coal-bed methane wells drilled in the Fruitland Formation; the authors estimate that more than 1,500 such wells will exist by January 1990, a substantially higher number than in 1985 when there were less than 100 wells. In a study funded by the Gas Research Institute, they used data from approximately 2,500 well logs to map depositional systems, and data from 1,730 well logs to evaluate the occurrence, resource, and producibility of coal-bed methane in the Fruitland Formation. Fruitland coal occurs in as many as 16 seams. The thickest and most continuous seams have a combined thickness greater than 50 ft and occur in belts 5 to 10 mi wide in Fruitland coastal-plain deposits that intertongue basinward (northeastward) with northwest-trending, retrogradational upper Pictured Cliffs barrier/strand-plain deposits. Northeast-trending belts of Fruitland coal seams formed in a flood plain setting. Coal seams in these dip-elongate belts, which are 2 to 8 mi wide, have a combined thickness of less than 50 ft. They conclude that the Fruitland Formation contains 44-49 tcf of methane in 245 billion short tons of coal between the depths of 400 and 4,000 ft. More than half of the Fruitland coal-bed methane occurs in the northwest quarter of the basin, in the northwest-trending belts where net-coal thickness exceeds 50 ft. In this area, in-place gas commonly exceeds 25 bcf/mi{sup 2} and locally exceeds 35 bcf/mi{sup 2}. Targets for fracture-enhanced permeability are areas where brittle Fruitland coal seams have been folded, such as the Hogback monocline, Ignacio anticline, and several minor tectonic folds that have less than 100 ft of structural relief. Additional targets for fracture enhanced permeability may exist, due to differential compaction, in areas where coal seams override and drape Pictured Cliffs shoreline sandstones or Fruitland channel-fill sandstones.

• OSTI ID: 6796056
• Report Number(s): CONF-900605--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (USA) Journal Volume: 74:5
• Country of Publication: United States
• Language: English

Related Subjects

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58 GEOSCIENCES
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ALKANES
COAL DEPOSITS
COLORADO
FEDERAL REGION VI
FEDERAL REGION VIII
GEOLOGIC DEPOSITS
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MINERAL RESOURCES
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ORGANIC COMPOUNDS
PERMEABILITY
RESERVOIR ROCK
RESOURCES
ROCKS
SANDSTONES
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
USA
WELLS