Coalbed Methane Exploration in an Extensional Terrain: Results from the Albuquerque Basin
Stark, T.J. 1, C.W. Cook1, R. Zelaya1, C.A. Presmyk2, J.E. Brown2, D.L. McFatridge2 (1) XTO Energy, Fort Worth, TX (2) Schlumberger, Fort Worth, TX
The Albuquerque Basin is a portion of the Rio Grande Rift, a Tertiary-aged structure extending from northern Mexico into Colorado. Initial structural development during the early Tertiary Laramide Orogeny resulted in localized uplifts bounded by high angle reverse faults. Subsequent extension overprinted a series of polarized rift grabens on the area, creating a complex system of extensional faults. While the depocenters were filled primarily with Tertiary-aged gravel, structural shoulders located upon rift flanks preserved Mesozoic and Paleozoic-aged sedimentary rocks.
Upper Cretaceous-aged coal-bearing strata of the Crevasse Canyon Formation (Mesaverde Group) are expressed as a series of regressive wave-dominated deltaic complexes prograding to the southeast. Continuous core evaluation was coupled with borehole imagery to define depositional environment and transport direction. The coal-bearing section reveals multiple paludal facies occurring within a lower deltaic sedimentologic setting. Primary environments include interdistributary bay fill, laterally accreting distributary channel, bi-modal tidal channel, crevasse splay and shoreface.
Specific coal members evaluated were the Upper and Lower Gibson coals. Coal rank was determined to be high volatile C bituminous. Very low desorbed gas volumes were encountered consisting primarily of CO2 and N2. Data interpretation suggests degasification of the coal reservoir due to fault breach. Adjacent igneous sills, emplaced over the last 37 my, may have reacted with Paleozoic carbonate rocks to modify CO2 distribution within the study area.
AAPG Search and Discovery Article #90055©2006 AAPG Rocky Mountain Section Meeting, Billings, Montana