What are the Mechanisms
and Timing of Joints in the
Joints, also known as extensional or mode 1 fractures, form
by opening perpendicular to their surfaces and thus provide important fluid
conduits in the reservoir
compartments. A better knowledge of joint
mechanisms
and timing is essential to
effective petroleum production and exploration because early pre- and syn-tectonic joints may be sealed by subsequent processes
and uplift-related joints may not extend to production depths in the
subsurface.
A recent effort to merge traditional, surface-based fracture
studies with new seismic anisotropy studies has resulted in an intriguing
mismatch of hypotheses. Many surface studies have attributed jointing to syn-Laramide compression, post-Laramide
mechanisms
exist, many joints seen in the field and
inferred from seismic data are perpendicular to regional compression
directions. This suggests that recent interpretations have neglected an
important mechanism of jointing, that of rebound in the direction of prior
tectonic compression. This mechanism predicts that many
mechanisms
promises to help unlock the tectonic history of
the