Abstract: Determination
of the Relative Ages and Spatial Parameters of Subsurface Fracture Sets
from Borehole
Data
WU, HAIQING, ATILLA AYDIN, and DAVID D. POLLARD
One of the challenging
problems in the evaluation of subsurface fracture systems is how to use
the information from an observation line (the borehole
) through the fracture
system to determine the temporal and spatial parameters of different fracture
sets including spacing, connectivity, and relative ages. We have conducted
model experiments and investigated outcrop fracture patterns to understand
the relationships among these parameters. Using these relationships, we
have developed a technique applicable to 2D and 3D fracture networks in
the subsurface. Preliminary results from our experimental and outcrop studies,
and from FMS and CBIL log data, show that the relative magnitudes of spacing
and spacing deviation in different fracture sets are significantly different.
These differences provide a basis for inferring the relative ages of the
subsurface fracture sets. The relative ages have important implications
for the geometric evolution of the fracture system and the fracture connectivity
in the rock volume intersected by the
borehole
.
We have also investigated partially
overlapping fracture domains with heterogeneous fracture spacing and connectivity
and have determined their statistical parameters and the corresponding
loading configurations. We propose that the technique described here can
be utilized in reservoir characterization efforts through a conceptual
understanding of how to go from outcrop and model studies to the interpretation
of borehole
data.
AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria