基于随钻电阻率成像测井的数据压缩方法

Data Compression Method Based on Resistivity Imaging Logging While Drilling

随钻测井作业与钻井作业同步进行,在钻井液滤液还未侵入地层或者侵入井壁很浅时获得测井资料,能准确反映原状地层特征,油气储量评价准确。图像压缩是随钻电阻率测井实时成像的关键技术,通过分析多种图像压缩方法,发现小波编码适合随钻电阻率成像测井,在此基础上,分析嵌入式零树编码和多级树集合分裂编码2种小波变换算法,进行Matlab仿真。多级树集合分裂编码方法在50倍压缩率条件下,能够保持较高的图像质量,可满足随钻电阻率测井实时成像数据压缩需要。

Logging while drilling and drilling operations are carried out simultaneously,logging data are obtained when the formation has not be invaded by the mud or the borehole wall invasion is shallow,which can accurately reflect the characteristics of virgin zone and accurately evaluate oil and gas reserves.Imaging data compression is the key technology of resistivity imaging logging while drilling.Analyzing various imaging data compression methods,it is found that wavelet coding is suitable for resistivity logging while drilling.Two wavelet transformation of embedded zero-tree coding and multi-level tree set splitting coding are analyzed and simulated in detail.The results show that the multi-level tree set splitting coding method can maintain high image quality under the condition of 50 times compression rate,which is suitable for real-time imaging data compression of resistivity logging while drilling.