Geometries, Driving Factors, And Connectivity Of Background Fractures At
The Latemar Carbonate Platform (N. Italy): Relevance For Subsurface
Reservoir Modelling
Abstract
Carbonate platform background fracture networks are rarely utilized in
subsurface models, and it is unclear how they relate to regional stress
(other than faults and folds) and burial. We combine structural analysis
and drone imagery to investigate the geometry, kinematics, and
topological characteristics of (background) fractures at the Latemar
platform (both limestones and dolostones; Northern Italy). Deformation
was accommodated by a dense network of mode I and conjugate hybrid
fractures/veins and conjugate reverse faults, all associated with
sub-vertical stylolites. Conjugate fractures and associated sub-vertical
stylolites are organized in two systems, constraining the major stress
fields. Differences lie in the permutation of the position in the space
of the principal stress with depth. Specific burial depth windows are
significant in distinguishing the different spatial positions of the
principal stresses. Changes in overburden provide the major driving
factor in determining the position of background structures that develop
during the burial trajectory. Topologically, background fractures in
lime- and dolostone pavements show distinct characteristics. In
limestone pavements, fractures form a network with a high proportion of
I-node and I-C to C-C branches, resulting in a low to moderate
connectivity (i.e., CB = ~ 1.5). In
dolostones, a complex network with abundant Y-to X- nodes and I-C to C-C
branches is found (moderate to a high degree of connectivity
CB = ~ 1.7). Topological pathways
provide important insights into how background fractures are connected
and shed light on the significance of these features in the context of
subsurface fluid flow.