岩石激发极化弛豫时间谱与孔隙结构、渗透率的关系

Estimation of pore size distribution and permeability of shaly sands from induced polarization time spectra

激发极化衰减曲线包含丰富的地层信息,且由多个指数衰减叠加而成.本文采用奇异值分解法对泥质砂岩的激发极化衰减谱进行多指数反演,得到光滑连续的激发极化弛豫时间谱,合适的弛豫时间分布点数为32～6 4 .激发极化弛豫时间谱能够表征饱和NaCl溶液的岩石孔隙结构.结合孔隙度和弛豫时间几何平均值,能够显著提高渗透率的求取精度.

Induced polarization decay curves contain much information, which consist of many exponential decay components. The singular value decomposition method makes it possible to transform induced polarization decay data into relaxation time spectra. The appropriate number of relaxation arrangement points in relaxation data inversion ranges from 32 to 64 The induced polarization relaxation time spectrum can be used to quantitatively estimate the pore size distribution of shaly sands saturated with the NaCl brine. Combining the average induced polarization relaxation time constant with the porosity can markedly improve the accuracy of determining the permeability over using total porosity from core measurements.