改进的NMR测井仪中回波检测快速算法

Improved DPSD Algorithm Using NMR Logging

为了减少核磁共振测井回波信号处理算法使用的逻辑资源,并增强算法的实时处理性能,设计了一种基于FPGA的数字相敏检波算法。采用分布式算法,将数字相敏检波算法中乘累加运算转换为查找表和累加器移位操作,充分利用FPGA逻辑资源,提高数据的处理速度。在基于Flash架构的FPGA(A3P1000)的硬件平台上的测试结果表明:改进算法的逻辑资源占用率仅为13%,能使最高频率为4.32 MHz的回波信号的信噪比得到显著提升,算法性能满足井下回波数据处理的时间要求和精度要求。

Reducing the logic resources used in the signal processing algorithm of nuclear magnetic resonance logging and enhancing real-time processing performance of algorithm are not only the development trend of nuclear magnetic resonance logging instrument,but also are the key technical problems of exploration and development of low porosity and low permeability oil and gas resources.An method of implementing DPSD algotithm based on FPGA was designed and realized.Distributed algorithm was adopted in DPSD algotithm,which can convert the operation of tedious multiply accumulate into the operation of looking up table and shift accumulator,making full use of the logic resource of FPGA and improving the data processing,and promoting data processing speed.The test results on the FPGA（A3P1000） hardware platform based on Flash architecture show that the logical resource occupation rate of the improved algorithm is only 13%,and the signal to noise ratio of the echo signal which can make the highest frequency of 4.32 MHz is significantly improved.Algorithm performance meets the requirements of time and accuracy of the data processing in the mine.