--> ABSTRACT: Lithofacies Distribution and Reservoir Heterogeneity Within Pennsylvanian Phylloid Algal Mounds, Western Orogrande Basin, New Mexico, by Katherine A. Giles and Gerilyn S. Soreghan; #91019 (1996)

Datapages, Inc.Print this page

Lithofacies Distribution and Reservoir Heterogeneity Within Pennsylvanian Phylloid Algal Mounds, Western Orogrande Basin, New Mexico

Katherine A. Giles and Gerilyn S. Soreghan

Pennsylvanian strata within the San Andres Mountains (western Orogrande basin) contain very well-developed phylloid algal bioherms, but these bioherms remain understudied owing to their location within the bounds of the U.S. Army White Sands Missile Range. The exposed Upper Pennsylvanian section within Hembrillo Canyon affords a three-dimensional view of mound structure, and thus an excellent opportunity for characterizing lithofacies distribution and reservoir heterogeneity that may prove useful for exploration/exploitation efforts in analogous petroliferous systems.

The mounds are developed within a mixed carbonate-clastic shallow marine section punctuated by shoaling-upward cycles. Each mound site consists of a stack of individual biohermal growth events characterized by a subtidal wackestone initiation phase, core boundstone phase, and peritidal to subaerially exposed packstone/grainstone terminal phase. Individual biohermal growth events range up to 30 m in thickness; vertical stacking of these bioherms has produced aggregate mounds reaching up to 100 m in stratigraphic thickness and 300 m in diameter. Individual biohermal thicknesses decrease abruptly and markedly away from mound sites, and calcareous mudstones dominate in intermound regions.

The controlling influences of paleogeography and glacioeustasy, respectively, produced the pronounced lateral and vertical heterogeneity characterizing these and analogous phylloid algal mound systems. Reservoirs within these systems are highly compartmentalized: wackestone initiation phases and peritidal to subaerial termination phases that envelope core facies may serve as porosity and permeability barriers that effectively partition the reservoir. Recognition of the scale, character, and probable controls on these lateral and vertical changes is important for effective exploration and exploitation in phylloid algal mound systems.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California