基于自适应差分脉码调制的远探测声波测井数据井下压缩算法

Downhole Compression Algorithm for Remote Detection Acoustic Logging Data Based on Adaptive Differential Pulse Code Modulation

  • 摘要: 远探测声波测井的测井数据量非常大,给电缆实时上传所有数据和快速测井带来巨大挑战。为解决远探测声波测井实时传输问题,在分析远探测声波测井全波列数据特征的基础上,提出了一种基于差值非均匀量化和自适应编码的井下测井数据压缩算法,设计了实现该算法的硬件系统、井下压缩软件和地面解压缩软件,利用水域试验数据和实际测井数据测试了该算法的基本性能和扩展性能。结果表明:该算法的压缩率约为50%,全波列波形、直达波和反射波首波峰值处的失真度均在3%以内;该算法的执行时间和所需运行存储空间均满足高速采集和实时传输的要求。此外,该算法在不同软硬件环境和数据特性下的适应性和稳定性较好。研究结果表明,采用该算法可以压缩远探测声波测井数据,提高电缆传输速率和远探测声波测井效率。

     

    Abstract: Remote detection acoustic logging has huge amount of data, which brings a great challenge to upload all data in real time for cable and conduct fast logging. In order to solve the problem of real-time transmission of remote detection acoustic logging, a downhole logging data compression algorithm based on differential non-uniform quantization and adaptive coding was proposed after analyzing the characteristics of the full waveform data of remote detection acoustic logging. The hardware system, downhole compression software, and ground decompression software were designed to implement this algorithm. The basic and expansion performance of the algorithm were tested using water experiment data and borehole logging data. The results show that the compression rate of the algorithm is approximately 50%, and the distortions of the full waveform, as well as those in the first-peak region of the direct wave and the reflected wave, are all within 3%. The execution time and required operational storage space of the algorithm can meet the requirements of fast acquisition and real-time transmission. In addition, this algorithm has good adaptability and stability under different hardware and software environments and data characteristics. The results also indicate that the proposed algorithm can compress the remote detection acoustic logging data, improving the cable transmission rate and remote detection acoustic logging speed.

     

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