论文中文题名: | 大容量声波测井数据压缩算法研究 |
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学号: | 201107281 |
保密级别: | 公开 |
学科代码: | 081001 |
学科名称: | 通信与信息系统 |
学生类型: | 硕士 |
学位年度: | 2014 |
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研究方向: | 通信数据处理 |
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论文外文题名: | Compression Algorithm Based on Bulk Acoustic Logging Data |
论文中文关键词: | |
论文外文关键词: | Acoustic Well Logging Data ; Wavelet Transform ; EZW ; Run Length Encoding |
论文中文摘要: |
石油测井中,大量测井数据需要从井下通过传输带宽有限的测井电缆传送至地面存储和处理,声波测井数据的数据量尤其庞大。因此应该在保证声波信号主要特征基本不变的前提下对其进行压缩处理,减少其数据量,使测井数据的传输率最终满足测井电缆的带宽要求。
为此,本论文设计了改进的嵌入式零树小波编码(Embedded Zero-tree Wavelet,EZW)算法来对声波测井数据进行压缩。Shapiro提出的EZW算法是一种较为有效的二维图像小波压缩算法,而一维声波测井信号在小波变换后的系数也具有类似的树结构。本文根据声波信号时频域的特点将所设计的改进EZW算法用于一维声波测井数据的压缩。在对声波数据进行压缩时,首先将经过采样的原始声波测井数据进行一维离散小波变换,分析变换后的小波系数的数据结构,然后结合数据结构对变换系数进行EZW编码,输出的结果为字符流和比特流。根据课题的要求,声波测井仪(课题研究对象为HDST3700单发五收高清声波测井仪)的测井数据必须按规定的帧格式向地面传输,若按照传统的游程编码对字符流和比特流进行编码,压缩效果并不明显,甚至有可能起不到压缩的作用。故本文针对EZW算法的编码结果进行了算法改进,改进后的字符流的压缩比为4:1,而比特流的压缩比至少达到了2:1,在保证恢复的信号质量前提下,满足了对数据传输速率的要求。经过计算和验证,数据压缩比可以达到6:1,同时得到的信噪比也较高,达到了课题研究目的。
论文采用了多组声波测井数据对所设计的改进EZW算法进行实验测试,实验结果表明算法在数据压缩率和信噪比方面均达到了预期的效果,是一种比较有效的声波测井数据压缩方法,并且由于小波变换的多分辨率特性,可以通过控制输出编码流达到控制压缩比的目的。
本文研究设计了针对声波测井的改进EZW算法,取得了较好的压缩比和信噪比,这对大容量测井数据的实时传输具有较高的应用价值。
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论文外文摘要: |
In petroleum well logging, a lot of well logging data cable sent to the well stored and processed with a limited bandwidth, especially large acoustic logging data. Therefore, should be to 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 the bandwidth 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. The EZW algorithm proposed by Shapiro is an effective two-dimensional wavelet image compression algorithm .But the coefficient of one-dimensional signal in wavelet transform has a similar tree structure. In this paper, based on the characteristics of the acoustic signal frequency domain will be designed by the improved EZW algorithm used for the compression of one-dimensional acoustic logging data. On acoustic data compression, the first will be one dimensional discrete wavelet transform for the original acoustic logging data of sampled, then analysis the data structure of wavelet coefficient after the transformation, and then combined the data structure to EZW coding of transform coefficient, the result of the output are character -stream and bit-stream. According to the requirement of the subject, the acoustic logging tool (HDST3700 single-shot five received is the research object) logging data must be in accordance with the provisions of the frame format to the ground transport, the traditional run-length coding encoded bit-stream and character-stream, the compression effect is not obvious, it may even be less than the effect of compression. So this article aims to improve algorithm of EZW algorithm encoding results , with the improved algorithm character-stream of compression ratio is 4:1 and the bit-stream compression ratio reached at least 2:1, under the premise 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 to 6:1, at the same 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-noise ratio achieves the expected effect, is a kind of effective method that compress acoustic logging data, and because the multi-resolution characteristic of wavelet transform, can control the compression ratio by controlling the output code flow.
This paper designed the improved EZW algorithm for acoustic logging, and had obtained the good compression ratio and signal to noise ratio, it had the high application value for the large capacity logging data transmission with real time.
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中图分类号: | TN911.72 |
开放日期: | 2014-06-12 |