Relationships
in Heterogeneity, Measured Mechanical / Petrophysical Properties, and Visual ( core and log ) Interpretations to Assess Tight Gas Shale
Reservoirs
Cameron, Michael S.1, S.
Robert Bereskin2, George A. Waters3 (1) Devon Energy,
Oklahoma City, OK (2) Bereskin and Associates, Inc, Salt Lake City, UT (3)
Schlumberger Inc, Oklahoma City, OK
The low matrix permeability of shales
(nanno-darcy scale) implies variability of reservoir quality and depends either
on conductive natural fractures or the ability to create surface area through
various hydraulic fracturing mechanisms. Heterogeneity being the scaling of
measured values along a vertical profile (i.e. geological, petrophysical, or
mechanical) can be interrelated by conducting continuous-strength measurements
on a core and obtaining high resolution profiles that represent rock
properties. Anisotropy in geologic media is directly related to the scaling and
the ordering of the heterogeneity. Effects of heterogeneity (vertical and
horizontal) dominate the geologic material-elastic properties for both
reservoirs and seals. Clues to this relationship are reflected in macroscopic
whole core observations and in borehole image logs. With this knowledge,
completion strategies based on 3 dimensional hydraulic fracture geometries,
both vertically and normal to the preferred fracture plane, can be developed.
Integration of the relationships to insitu stress, heterogeneity, and
laboratory based petrophysical-mechanical properties of geologic material will
result in a greater degree of understanding for tight gas shales.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California