Compression Algorithm Based On Bulk Acoustic Logging Data

In petroleum well logging, a lot of well logging data cable sent to the well stored andprocessed with a limited bandwidth, especially large acoustic logging data. Therefore, should beto compress it under ensure the main features of the acoustic signal was largely unchanged,reduce the amount of data, logging data transfer rate eventually meet the requirements of thebandwidth of the logging cable.Therefore, this paper designed an improved Embedded Zero tree Wavelet coding(Embedded Zero tree Wavelet, EZW) algorithm to compress the acoustic logging data. TheEZW algorithm proposed by Shapiro is an effective two-dimensional wavelet imagecompression algorithm.But the coefficient of one-dimensional signal in wavelet transformhas a similar tree structure. In this paper, based on the characteristics of the acoustic signalfrequency domain will be designed by the improved EZW algorithm used for the compressionof one-dimensional acoustic logging data. On acoustic data compression, the first will be onedimensional discrete wavelet transform for the original acoustic logging data of sampled, thenanalysis the data structure of wavelet coefficient after the transformation, and then combinedthe data structure to EZW coding of transform coefficient, the result of the output arecharacter-stream and bit-stream. According to the requirement of the subject, the acousticlogging tool (HDST3700single-shot five received is the research object) logging data must bein accordance with the provisions of the frame format to the ground transport, the traditionalrun-length coding encoded bit-stream and character-stream, the compression effect is notobvious, it may even be less than the effect of compression. So this article aims to improvealgorithm of EZW algorithm encoding results, with the improved algorithm character-streamof compression ratio is4:1and the bit-stream compression ratio reached at least2:1, under thepremise that the quality of the signal recovery, to satisfy the requirement for data transfer rate.Through the calculation and verification, the data compression ratio reached to6:1, at thesame time the signal-to-noise ratio is high, reached to the purpose of the research.This Paper uses multiple sets of acoustic logging data test the improved EZW algorithm, the experimental results show that the algorithm in data compression rate and signal-to-noiseratio achieves the expected effect, is a kind of effective method that compress acousticlogging data, and because the multi-resolution characteristic of wavelet transform, can controlthe compression ratio by controlling the output code flow.This paper designed the improved EZW algorithm for acoustic logging, and had obtainedthe good compression ratio and signal to noise ratio, it had the high application value for thelarge capacity logging data transmission with real time.