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 Data Compression Method Based on DPCM for Deep Detection Acoustic Logging

  • 摘要: 远探测声波测井的测井数据量非常大,无法通过电缆实时传输。为解决远探测声波测井实时传输的问题,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: Deep-detection logging is a significant logging method in oil-gas exploration and development. However, its data amount has sharply increased, bringing greater challenge for the cable transmission to upload all data to the ground system in real-time. Compressing the downhole data before uploading can improve the cable transmission and logging speed. The characteristics of the full waveform data in this logging was analyzed and a downhole compression method was proposed. This method is based on a non-uniform quantization and corresponding adaptive coding. The hardware, a downhole compression algorithm and its corresponding ground decompression software were designed to realize the method. Its performance and scalability were tested using water experimental data. The results show that the compression rate of the algorithm is about 50%, the relative distortions at the peak of the full waveform, the first peak of the direct wave and the reflected wave are all within 3%, the execution time and memory usage can meet the requirements of fast acquisition and real-time transmission. In addition, this algorithm has good adaptability and stability in the conditions of different hardware, software and data characteristics. This work is helpful to achieve downhole data compression in deep-detection acoustic logging and improve logging efficiency.

     

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