A large amount of raw echo data is collected by NMR logging, especially in multi-dimensional NMR logging, and a direct inversion for the raw echo data is time-consuming, so the echo data collected need to be compressed before inversion to improve inversion speed. This paper proposes a multi-dimensional NMR data compression method based on Discrete Cosine Transform (DCT). Utilizing the energy concentration characteristics of DCT, the low-frequency information of the echo data is retained to realize the compression of raw echo data. On this basis, a hybrid compression (WAC-DCT) method is proposed, which uses the window averaging method (WAC) to pre-compress the raw echo data, and then uses the DCT compression method to compress the pre-compressed echo data again to achieve a high compression rate. The compression effects of the WAC method, the FastSVD method, the WAC-SVD method, the DCT method and the WAC-DCT method are compared by numerical simulation. The results show that some fluid information is lost in the DCT compression process with a low compression rate. The FastSVD method, the WAC-SVD method and the WAC-DCT method all have the characteristic of a high compression rate. When the number of compressed echoes is very small, the WAC-DCT method has obvious advantage in T₁ distribution. Compared with the case of without compression, the WAC-DCT method not only ensures a high compression rate, but also effectively reduces the inversion time, which has a good application effect in multi-dimensional NMR data compression.

核磁共振测井采集到大量原始回波数据，尤其是多维核磁共振测井，对原始回波数据直接反演耗时，因此在反演前需要对采集的回波数据进行压缩，以提高反演速度. 本文提出了一种基于离散余弦变换（DCT）的多维核磁共振数据压缩方法。利用DCT的能量集中特性，保留回波数据的低频信息，实现对原始回波数据的压缩。在此基础上，提出了一种混合压缩（WAC-DCT）方法，它使用窗口平均法（WAC）对原始回波数据进行预压缩，然后再使用DCT压缩方法对预压缩的回波数据进行再次压缩。以达到高压缩率。WAC方法的压缩效果，通过数值模拟对FastSVD方法、WAC-SVD方法、DCT方法和WAC-DCT方法进行了比较。结果表明，在低压缩率的DCT压缩过程中会丢失一些流体信息。FastSVD方法、WAC-SVD方法和WAC-DCT方法都具有压缩率高的特点。当压缩回波数量很少时，WAC-DCT方法在T ₁分布。与未压缩的情况相比，WAC-DCT方法不仅保证了较高的压缩率，而且有效减少了反演时间，在多维核磁共振数据压缩中具有良好的应用效果。