本文用Monte Carlo数值模拟方法,针对探测器均在正源距范围内的三探测器密度测井仪器,计算了不同源距探测器的薄层响应曲线,不同密度地层的光子通量与源距的关系,长、中、短源距间的计数交会图。结果表明,源距与密度测井仪器的纵向分辨率、统计误差、灵敏度、泥饼补偿效果有关。为使密度测井仪器具有20cm的纵向分辨率,并有高的测量精度,长、中、短源距应分别选择38、20.5、11cm左右。 In this paper, the Monte Carlo numerical simulation method is used to calculate the thin-layer response curves of detectors with different source distances for three-detector density logging instruments whose detectors are in the positive source distance range. The photon flux and source distance The relationship between the long, medium and short source distance between the count cross chart. The results show that the source distance is related to the longitudinal resolution, statistical error, sensitivity and mud cake compensation effect of the density logging instrument. In order to make the density logging instrument have a vertical resolution of 20cm and a high measuring accuracy, long, medium and short source distances should be respectively selected to be 38, 20.5 and 11cm.