核磁共振T_2谱转换伪毛管压力曲线的矩阵方法

Matrix Method of Transforming NMR T_2 Spectrum to Pseudo Capillary Pressure Curve

针对核磁共振T2谱转换伪毛管压力曲线的常规方法仅是将T2值转换成毛管压力值,从而造成了伪毛管压力曲线转换精度和实用性方面的不足。基于线性变换的概念,提出了从整体上进行转换的矩阵方法。按数据处理方式的不同,给出平均矩阵法、一次矩阵法和坐标矩阵法等3种算法。将10块岩心分成2组:一组8块用于建立转换矩阵;另一组2块用于检验转换效果。结果表明,3种算法转换的伪毛管压力曲线与压汞毛管压力曲线形态一致,符合精度较高;平均矩阵法、一次矩阵法和坐标矩阵法的最大均方误差分别为0.014 4、0.001 9和0.009 1,一次矩阵法的转换效率、可靠性和准确度总体上高于平均矩阵法和坐标矩阵法。核磁共振T2谱转换伪毛管压力曲线的矩阵方法效果良好,具有实用价值。

For the methods of transforming NMR T2 spectrum to pseudo capillary pressure curve only have one coefficient, so the results are deficient in both accuracy and practicability. Matrix method which finishes transformation taking NMR T2 spectrum and pseudo capillary pressure curve as a whole is proposed based on linear transformation. According to different data processing way, average matrix algorithm, one-time matrix algorithm and coordinate matrix algorithm are given. Dividing the 10 cores into two parts, one part containing 8 cores is to establish transformation matrix,the other part containing 2 cores is to inspect the effect of transformation. The results show that the pseudo capillary pressure curves obtained from three algorithms agree well to the mercury injection capillary pressure curves., the maximum mean square error of the three algorithms is 0. 014 4,0. 001 9,0. 009 1,respectively. As a result, the theoretical basis of the matrix method of transforming NMR T2 spectrum to pseudo capillary pressure curve is solid, the algorithms are reasonable, effect of transformation is good, and the method has practical value. The efficiency, reliability and accuracy of transformation of one-time matrix algorithm are better than that of average matrix algorithm and coordinate matrix algorithm.