Geologic and hydrologic characterization of coalbed methane reservoirs, Fruitland Formation, San Juan basin, Colorado and New Mexico

Conference · Fri Mar 01 04:00:00 EST 1991 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:5875619

Ayers, Jr, W B; Ambrose, W A; Kaiser, W R; Laubach, S E; Scott, A R; Yeh, J S ^[1]; Tremain, C M ^[2]; Whitehead, III, N H ^[3]

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1. Univ. of Texas, Austin (United States)
2. Colorado Geological Survey, Denver (United States)
3. New Mexico Bureau of Mines and Mineral Resources, Socorro, NM (United States)

Geologic and hydrologic studies clarify coalbed methane reservoir characteristics of the Fruitland Formation. In geologic studies, data from geophysical logs were used to map coal (reservoir) occurrence and structural features; fractures in coal seams were described at outcrops and in cores. In hydrologic studies, Fruitland bottom-home pressures calculated from well head and pressure regime and to estimate vertical and lateral pressure gradients. Chemical facies of produced waters were defined by Piper and Stiff ionic-ratio diagrams. The thickest coal seams trend northwestward and occur in the north-central part of the basin; these seams are the most permeable units in the Fruitland Formation. In the southwest part of the basin, coal seams trend either northwestward or northeastward. Coal trends are predictable and are controlled by depositional setting. Fracture trends in coal seams in the southern two-thirds of the basin are north-northeast, whereas fracture trends in the northern third of the basin and underpressured in much of the rest of the basin. Overpressuring is attributed to artesian conditions. Large vertical and/or lateral pressure gradients indicate reservoir heterogeneity. Low-chloride, high-alkalinity waters coincide with overpressuring, and saline NaCl-type waters coincide with underpressuring. Geologic studies delineated coalbed methane reservoirs (coal seams), whereas hydrologic studies indicated reservoir conditions such as permeability and pressure regime. By integrating geologic and hydrologic findings, the authors divided the San Juan basin into regions having similar reservoir characteristics and defined areas with optimal conditions for coalbed methane production. The approaches used in this study are transferable to other coal basins.

• OSTI ID: 5875619
• Report Number(s): CONF-910403--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Journal Volume: 75:3
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
011000 -- Coal
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& Peat-- Reserves
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& Exploration
02 PETROLEUM
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58 GEOSCIENCES
580000 -- Geosciences
ALKANES
CHEMISTRY
COAL DEPOSITS
COAL SEAMS
COLORADO
DEVELOPED COUNTRIES
FEDERAL REGION VI
FEDERAL REGION VIII
FRACTURED RESERVOIRS
GAS ANALYSIS
GEOCHEMISTRY
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
GEOLOGIC STRUCTURES
GEOLOGY
GEOPRESSURED SYSTEMS
HYDROCARBONS
HYDROLOGY
METHANE
MINERAL RESOURCES
NATURAL GAS DEPOSITS
NEW MEXICO
NORTH AMERICA
ORGANIC COMPOUNDS
PRESSURE GRADIENTS
RESERVOIR PRESSURE
RESERVOIR ROCK
RESOURCES
SEDIMENTARY BASINS
USA
WATER CHEMISTRY
WELL PRESSURE