The optimum design of time delay in time-domain seismic beam-forming based on receiver array

Generally, it is hard to bring high signal-to-noise ratio (SNR) data in seismic prospecting in the mining area especially when noise in the field is strong. To improve the quality of seismic data from complicated ore body, we developed Time-domain Seismic Beam-forming Based on Receiver Array (TSBBRA) method, which can extract directional wave beam in any direction. But only the direction parameter from the target body matches with the direction of reflected waves, the quality of reflected seismic data can be improved. So it's important to determine the direction of reflected waves from target bodies underground. In addition, previous studies have shown that the time delay parameter of TSBBRA can be used to control the direction of the main beam, so it is of great significance for studying the optimization design of the delay time parameter of TSBBRA. The optimum design of time delay is involved in seismic pre-processing, which uses delay and sum in time-domain to form directional reflected seismic beam with the strongest energy of the specified receiving array. Firstly, we establish the velocity model according to the original seismic records and profiles of the assigned exploration area. Secondly, we simulate the propagation of seismic wave and the response of receiver array with finite-difference method. Then, we calculate optimum beam direction from assigned reflection targets and give directional diagrams. And then we synthetize seismic records with a group of time delay using TSBBRA, give the curves that energy varies with time-delay, and obtain the optimum time-delay. The results are as follows: The optimum delay time is 1.125 ms, 0.625 ms, 0.500 ms for reflected wave that form first, second and third target. Besides, to analyze the performance of TSBBRA, we calculated SNR of reflected wave signal before and after TABBRA processing for the given model. The result shows that SNR increased by 1.2~9.4 dB with TSBBRA averagely. In conclusion, the optimum design of time delay of TSBBRA based on wave equation is an effective method to improve SNR of seismic data in the exploration of complicated ore body.