Either surface transportation line integrity monitoring or downhole injection well tubular and rock formation integrity monitoring plays a crucial part in a geological carbon dioxide (CO2) sequestration project, especially in providing early warnings of failure. Various monitoring technologies have been tested and applied in carbon sequestration projects world widely, whereas a lot of them are often low in spatial resolution and time-consuming, or expensive and have system longevity issues. The recent developed coaxial cable Fabry-Perot interferometer sensors have been put forward as a robust and cost-effective solution to carbon sequestration project monitoring strategies. Flexible RG58 coaxial cable is used in the fabrication of Fabry-Perot interferometer strain sensors. The strain sensors were loaded with progressive dynamic loads with the tensile testing machine in laboratory and the sensor measurement results were compared with the electronic extensometer. The sensor characteristics such as measuring range and dynamic response accuracy were analyzed for changing reflection point distance during manufacture, loading speed of the tensile testing machine, and pretensions applied to the sensor before testing. The results show that the coaxial cable Fabry-Perot interferometer strain sensors have steady performance under changing parameters as mentioned above, which means that the sensor accuracy remains invariable. The sensors have engineeringly accepted accuracy and almost real-time response to the dynamic loads applied during the test. And the sensors have large measuring range (up to 10,000 με) due to its excellent ductility. The research proves that the coaxial cable Fabry-Perot interferometer strain sensors can be as a feasible solution to carbon sequestration project monitoring strategies, and is of great value in providing early warnings of failure.
Keywords Carbon sequestration, downhole monitoring, coaxial cable strain sensor, Fabry-Perot interferometer, dynamic load response