Application research of all fiber optic microseismic monitoring technology in monitoring water inrush from floor

Abstract

Currently, most fiber optic microseismic monitoring systems in China are based on optical grating sensing technology. However, fiber optic grating wavelength demodulation limits the detection frequency and sensitivity of the system, and there are few successful cases of long-term, continuous and uninterrupted microseismic monitoring. In order to solve the above problems, a new type of all fiber microseismic monitoring system is proposed. Taking the monitoring of water inrush from the floor during the mining process of Pan'er Coal Mine 11023 working face as the engineering background, a comparison is made between the all fiber optic microseismic monitoring system and the ESG microseismic monitoring system. It is found that the all fiber optic microseismic monitoring system has the following advantages. The recorded waveform spectrum features are clearer, showing a high signal-to-noise ratio advantage. The monitoring range for disturbance depth is larger, and the remote monitoring effect is better. The distribution of seismic source positioning results is more reasonable and more in line with the actual mining situation of the working face. During the monitoring of the entire mining cycle of the working face, the relationship between the floor failure and microseismic activity in the fault abnormal area of the 11023 working face is analyzed. Near the fault and coal seam thinning abnormal area, the number and intensity of microseismic events increase. During the initial mining period of the working face, stress is concentrated and released. Due to the influence of mining, the floor is severely damaged. Relatively high energy events are mainly distributed in the floor of the fault anomaly area, with a depth of about 27 meters of damage to the floor. Micro seismic events do not form a line or accumulate in a plane below 60 meters of the 3 coal seam floor. It indicates that cracks have not expanded and no water conducting channels have been formed. The working face can be safely mined.

Keywords

• all fiber microseismic monitoring
• floor water inrush
• disturbance depth
• source positioning
• fault abnormal zone
• microseismic activity
• relatively high energy events