  Time Reverse Nonlinear Elastic Wave Spectroscopy (TR-NEWS) has been used to
focus acoustic energy, and make measurements correlated with damage in a
variety of industrial materials. Most studies using TR-NEWS in Earth Science
have focused on relatively small objects and may have multiple acoustic
sources. In Earth, within energy extraction settings, the structure and scale
of wellbores makes acoustic focusing challenging. This paper explores the
feasibility of applying TR NEWS for damage detection in wellbores by
constructing a laboratory-scale wellbore, and using TR to focus and make
dynamic linear and nonlinear elastic measurements. After successive cycles of
induced, localized mechanical damage the sample, the hysteretic nonlinear
elastic parameter {\alpha}, increased with damage cycle indicating progressive
mechanical damage. In addition to these strain-dependent changes, TR peak width
and changes to peak amplitude near the damage sites was also observed. To
deploy TR in a wellbore, it will be necessary to choose sensors that are
suitable for the environment, and that can be distributed along the wellbore.
Thus, this paper demonstrates that acoustic TR can be conducted using both an
intrinsic Fabry Perot interferometer fiber optic strain sensor, and an
intrinsic Michaelson interferometer fiber optic strain sensor, as a first step
towards deployable sensing for TR in a wellbore.
