摘要
正交多极子阵列声波测井仪SL6678遥测上传的数据量极其庞大,但其电缆传输速率还不到100 kb/s。对阵列声波数据在井下采集后进行无损压缩传输,是增加传输带宽的主流解决方案。目前针对声波测井数据的无损压缩方法主要有字典压缩(LZW)及其改进算法、无损DCT,预测编码以及流行的音频无损编码方法,但这些方法压缩率较低,或算法复杂程度高。通过研究采样点高低字节值在波列上的分布规律,提出了一种高位字节进行部分匹配预测编码(PPM)和低位字节预处理后再进行PPM编码相结合的无损压缩方法,并在SL6678上实现了硬件设计和嵌入式软件开发。通过与其他编码方式的实验比较,所提方法的数据压缩率达到约51%,远优于大部分的压缩算法,且较低的算法复杂度易于编程实现。实际测试表明,声波数据的传输速率提高到约200 kb/s。所提方法提高了SL6678井下仪的数据采集质量和传输速率,使其更好地服务于油田的勘探开发工作。
Data volume uploaded by telemetry of cross multi pole array acoustic logging tool SL6678 is very large. But transmission rate by cable is less than 100 kb/s. Mainstream solution is transmitting acquired data down-hole after lossless compression to increase band width. Lossless compressing methods including LZW, lossless DCT and predictive coding and popular audio lossless coding exist lower compression ratio or higher complexity of algorithm. Through studying distribution rule of high and low bytes of samples on wave track, a lossless compression method combining PPM coding in high byte and PPM coding in low byte after pre-processing is proposed in paper implemented in SL6678 by hardware design and. embedded software development. Compared with other coding methods in experiments, the method reaches about 51% compression ratio which is far better than most coding methods. And it is easy for programming by lower complexity. Actual tests show that data transmission rate is improved to about 200 kb/s. Data acquiring quality and transmission rate of SL6678 down-hole tool are improved by the method in this paper which provides better service ability for exploration and development of oilfields.
作者
陈建华
Chen Jianhua(Changqing Branch,China Petroleum Logging Co.,Ltd,Xi’an 710201,China)
出处
《电子测量技术》
2020年第13期81-84,共4页
Electronic Measurement Technology
关键词
测井声波数据传输
无损压缩
PPM算法
acoustic well-logging data transmission
data lossless compression
PPM algorithm
