Study Of Lossless Logging Data Compression Method Based On Network Transmission

As logging technology fastly developed, the well logging data is becoming more and more big, coupled with restrictions on engineering applications in data transfer bandwidth and demanding requirements of real-time, logging data can not be reliable and real-time transmission to the ground control center, thus it hinders the further development of the well logging technology. Therefore, this issue need to be resolved. Application of data compression techniques reducing the amount of data transmission is one of the most effective ways.In this thesis, on the simulated logging instrument panel platform based on the DSP F2812,realize the simulation of compressing logging data in real-time with Zlib compression algorithm,at the same time the ground host can decompress data correctly and analysis of the downhole environment. Via the transplant of LwIP protocol stack based on the Ethernet controller CS8900A, test and compare with the performance of uIP protocol stack, draw the conclusion is that LwIP protocol stack is more adapt to the actual logging transmission system. This simulation process need to address following issues:firstly guaranteed under the premise of a certain compression ratio, to achieve lossless compression; secondly the compression algorithm should have good fault tolerance, that is, when the event of errors or packet loss occurs in the network transmission process, receiving end is able to correctly decompress the correct data of the back; furthermore, it need compress in real-time, that is, it need to be resolved the problem that compression rate is not less than the sampling rate of the fastest logging instrument; finally it should combine the embedded technology with network logging data transmission system, ensure ground host network can communicate with the downhole tool in real-time, in order to improve the information processing capability.The main research work is as follows:1. According to the logging data compression system design, general lossless compression algorithm is used for logging data compression scheme.2. On the same host platform, assessment test on a variety of mainstream lossless compression algorithm via the logging data samples, finally select the Zlib compression algorithm for the compression of logging data.3. Improve Zlib compression algorithm to achieve independent subcontractors compression, and independent subcontractors decompression. Finally, the compression program is ported to the simulated logging instrument panel based on the DSP F2812,and to optimize and test it to meet the engineering application three indicators,that is, memory consumption, compression rate and real-time.4. To meet the engineering application requirements, the LwIP protocol stack is ported to simulated logging instrument panel based on the DSP F2812with CS8900A Ethernet controller, then evaluate the performance of the LwIP protocol stack, and compared with the uIP protocol stack. The conclusion is that LwIP protocol stack is more adapt to the actual logging transmission system.