Print this pageFacies Architecture and Lithologic Heterogeneity: A Precursor to Productivity in the Barnett Shale-Newark East Field, North Central Texas
Michael Cameron1, S. Robert Bereskin2, John
Kieschnick3, and Roberto Suarez-Rivera3
1 Devon Energy,
Oklahoma City, OK
2 Bereskin and Associates, Inc, Salt Lake City, UT
3 TerraTek, Salt Lake City,
The Barnett Shale (Mississippian-north central Texas) has become renowned as a prolific unconventional gas producer since the late 1980's. Since then, production variability has motivated a multidisciplinary study of rock facies distribution and compositional heterogeneity. This approach has led to the understanding of material properties as applied to producibility models.
Concurrent independent avenues of study which include geological/petrological, petrophysical (core and log), geochemical, and geomechanical were applied. Measurements initiated at differing scales were carefully integrated to define principle controls on reservoir producibility.
Four dominant lithofacies were characterized from this integrated methodology and include (1) non-calcareous mudstones, (2) calcareous mudstones, (3) basinal limestones, and (4) silty limestones. While vertical facies profiling commonly occurs as intergradational associations, the mechanical and petrophysical properties reflect a high degree of variability. Total organic carbon measurements utilizing the elemental capture spectroscopy logging tool (ECS) with calibration to core, reflect heterogeneous relationships to facies definition and provide insight to changing geochemical attributes. Continuous profiles of unconfined compressive strength show variability between 1,000 to 40,000 psi. Effective porosities, measured from core, range from 2 to 10% with corresponding permeabilities of 30 to 800 nanodarcies. Completion strategies are of fundamental importance for unconventional reservoirs, and the effectiveness of any stimulation protocol depends on the interrelationship between the heterogeneous mechanical / petrophysical properties and the heterogeneous in-situ stress.
AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005