Study on energy distribution and attenuation of CO2 fracturing vibration from coal-like material in a new test platform

The complex fracture network generated by CO2 fracturing is conducive to coal seam gas extraction. However, the conventional research carried out experiments on small-size specimens under open environments, resulting in prominent issues such as gas leakage, difficulty obtaining far-field parameters, coupling failure zoning, and energy attenuation. Therefore, a CO2 fracturing experiment was designed and conducted in a new sealed test platform. The differences between the open and closed environment conditions were analyzed using the principal strain field. The influence radii of the crushing, fractured, and elastic zones were defined based on the analysis of the velocity and pressure signal waveforms. The change in the energy distribution was studied using a Short-time Fourier Transform to analyze the velocity signals in different fracturing regions. The frequency band attenuation of fracturing energy at different locations was studied with wavelet analysis. This study can provide a basis for the anti-vibration design of the drilling layout and the formulation of specifications. It can also help to protect roadways during fracturing.