DPCM Compression for Real-Time Logging While Drilling Data

Logging while drilling (LWD) is a drilling technique which obtains and transmits the logging data during oil/gas drilling operations. Because of the limited available transmission bandwidth of mud channel, how to improve the bandwidth utilization becomes a critical problem in LWD research. In this paper, by discussing the information entropy of real logging data, we find that the original encoding of logging data is inefficient. To prune the data redundancy effectively and to improve the bandwidth utilization, we propose a novel compression method on the basis of Differential Pulse Code Modulation (DPCM). To further improve the compression efficiency with less information loss, we introduce the adjustable compression parameters for different kinds of logging data. Extensive experiments with the real logging data show that our method can give enough precise results with the compression ratio of 50% at least. The experiment results also show that our algorithm has the advantages of alterable compressing ratio, excellent decode quality and low algorithm complexity.