多探测器密度测井泥饼影响的研究

INFLUENCE OF MUDCAKE ON MULTIDETECTOR DENSITY LOGGING

传统的密度测井仪器垂向分辨率差 ,计数率统计起伏较大 ,测量精度不高 ,受泥饼和井眼影响严重 ,对邻层影响无法补偿。为了提高密度测井的测量精度 ,更好地补偿井眼和泥饼的影响 ,国外一些石油公司相继推出了三个探测器的密度测井仪器。在影响三探测器密度测井精度的众多因素中 ,泥饼仍然是其中一个重要的影响因素。文章利用MonteCarlo方法计算泥饼在含有和不含重晶石时 ,三个探测器处光子通量随泥饼厚度和泥饼密度变化的关系 ,定性和定量地分析了泥饼厚度、泥饼密度对三个探测器光子通量的影响规律 ,进而得出了求取地层密度的泥饼校正公式 ,这为核测井数据处理方法的研究提供了一种新的探索途径。

The conventional density logging tools are of some disadvantages, such as poor vertical resolution, a large undulant range of counting rate statistics, low measure accuracy, being seriously affected by mudcake and wellbore, and being unable to compensate the influence on adjacent layers, etc. In order to raise the measure accuracy of density logging and to compensate the influences of mudcake and well-bore, the three-detector density logging tools were put out by some foreign oil companies in succession. In many factors affecting the accuracy of the three-detector density logging, the mudcake is still an important one. The change of three-detector photon flux with the mudcake thick and density was investigated by use of Monte-Carlo method under the circumstances of the barite's being and being not contained in the mudcake; the law of the influence of the mudcake thick and density on the three-detector photon flux was qualitatively and quantitatively analyzed; then a mudcake correction formula of acquiring formation density was derived, thus providing a new probing way for the research on the data processing methods of nuclear logging.