岩石激发极化弛豫时间谱实验影响因素分析

Analysis of influence factors to induced polarization relaxation time spectra of rocks

理论和实验研究表明,岩石激发极化弛豫时间谱与地层孔隙结构和渗透率有非常重要的关系。为了更好地应用激发极化弛豫时间谱进行地层评价,必须研究与仪器设计相关的影响因素。为此分析了弛豫时间分布点数、供电时间、供电方向、供电电流及断电时间等参数对岩石激发极化驰豫时间谱的影响。结果表明:弛豫时间常数的分布点数为32～64时较为合适;岩石的弛豫时间谱与供电电流大小和供电方向无关,而与供电时间和断电时间有关;随着供电时间或断电时间的延长,弛豫时间谱逐渐展宽,谱峰数目增加,当供电或断电时间大于 20 s时,弛豫时间谱的变化较小。

Theoretic and experimental results show that the induced polarization relaxation time spectrum relates to the pore structure and permeability of a rock. In order to use the spectrum to characterize the reservoir, the relationships between the spectrum and number of relaxation arrangement points, charging current and direction, charging and discharging time were investigated. It concludes: the optimal number of relaxation arrangement points ranges from 32 to 64; the relaxation time spectrum is irrelevant to the size and direction of charging currents and is related to the time of charging and discharging; the relaxation time spectrum spread out gradually and the number of peaks increases with the time period of charging and discharging; the relaxation time spectrum tends to be invariable if the time period is excess of 20s.