Study On SNR Of Irregular Seismic Imaging Method Based On A Optimal Stack

As a quick and efficient technology of engineering seismology, seismic imaging method has been used more and more widely in different prospecting missions. However, the general seismic imaging method has some weakness in keep down the noise relatively, because there is no effective use of stack in the alignment of"Single point stimulate single point to receive"; in the other hand, the depth of exploration is a little shallow by seismic imaging method, so it's easy to receive disturbances from the surface. Meanwhile, from the existing de-noising technology of seismic signal, most of those methods are pre-stack de-nosing, they keep down the noise in a certain extent, but ignore that stack itself is a very important and efficient de-noising method. With the deeper going of exploration, the conditions of collecting seismic signal become worse and the random noise in the collected seismic data increase gradually. It's significant that how to keep down the noise effectively and improve the adaptability of seismic imaging method to complex geology conditions like highland, thus to embody its distinguishing feature of fast and efficient.Stack technology sets up on the basis of seismic set of legal, according to the non-coherent of random noise, to keep down the noise effectively through many times of stack. Now the stack technology has been used mainly in the data processing which adopts the multi-coverage and reflection, and has got great effect. With this foundation, this article brings out the basic thought of an irregular seismic imaging method for one thing, that is to use the alignment of"single point stimulate single point", which actually means to induct the stack technology into the general seismic imaging method.Secondly, this article studied the relations between the stack in irregular seismic imaging method and SNR in the seismic data. It shows that the more the stack, the bigger SNR, and they two approach to linear relationship. This proved the validity of this irregular seismic imaging method, at the same time it shows that theoretically the more the seismic traces get in stack, the better effect we will get. But in practice, more stacks mean more input of manual labor, material and financial resources. So this article aims to the practicability of irregular seismic imaging method and brings out a optimal stack algorithm.The idea of the optimal stack algorithm is the premise of stack limited, base on different SNR of different seismic. The mean with additional weight, this is give the big weight to the good SNR, let it have a great contribution to the process of stack, and give the small weight to the bad SNR, let it have a less contribution to the process of stack.This paper using MATLAB work out the optimal stack algorithm, and the results of the performance tests show that:a) The SNR using the optimal stack algorithm is better than conventional stack;b) Along with the increase of the stack number, the optimal stack algorithm more routine stack buff the more obvious, the more stable performance;c) Background noise difference is bigger, namely each seismic records the SNR ratio of the difference between the situation, the optimal stack more obvious gain the effect than conventional stack.In the end the paper on irregular seismic imaging method, and the actual application with conventional seismic imaging method do comparative analysis, the measurement result shows: irregular seismic imaging method in suppressing noise, especially the effect of random noise is obvious.