CO2 injection into subsurface reservoirs for storage engineering is the most important means to reduce greenhouse gases. To satisfy the huge carbon-neutral target, injection and storage engineering exploration is needed for tight reservoirs beyond aquifers or abandoned reservoirs. Later, China carried out an exploration and research project on CO2-ECBM and CO2-EOR demonstration projects in tight reservoirs for the applicability, reliability and coordination of different monitoring technologies. This paper relies on the CO2-ECBM project for a passive monitoring technique of the TS634 well in ShiZhuang City, Shanxi Province, China. The monitoring adopted the three-component grid monitor system with the long-time continuous acquisition, and applied the passive seismic tomography algorithm, and obtained the energy perturbation during reservoir injection. The results integrated the target coal seam configuration, porosity, and permeability distribution of the layer before injection, which well represents the energy distribution and fractures probability distribution caused by fluid perturbation during the injection process. After that, comparing the results of the multi-period processing can illustrate the fluid transport trend and inter-well interconnection direction, and it is consistent with the production well verification. For the first CO2-ECBM demonstration project in China, the passive seismic monitoring technology is used to complete the fluid transport trend analysis with the passive seismic tomography technology as the core, and better presentation results are obtained at a certain scale, which initially verifies the effectiveness of the passive seismic monitoring technology for the ECBM carbon storage project. This study lays a foundation for the development of domestic carbon storage geophysical monitoring technology, and is more likely to improve the accuracy of comprehensive research on multi-dimensional and multi-domain monitoring technology.
Keywords CO2-ECBM Project, Passive seismic tomography, Fluid migration trend, Fractures probability density