Automatic event detection and event recovery in low SNR microseismic signals based on time-frequency sparseness

Microseismic monitoring is an effective tool for evaluating the fracturing process and its final results. Event detection is the first step of this monitoring. However, for low SNR microseismic monitoring records, it is difficult to obtain satisfactory results using conventional detection methods. According to time-frequency sparsness of microseismic events, the Renyi entropy method is used to measure sparseness of microseismic monitor records. A target function of event detection is created which takes the number of low entropy value traces as thresholding under time-frequency constraint conditions. This method can detect microseismic events and restore clearer microseismic events simultaneously. Tests on synthesis data and real records show that this method has a good performance in processing low-SNR microseismic records.