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精确测定核测井探头的间歇时间,对于下面的定量解释工作是重要的:用自然伽玛测井评定铀矿品位;用伽玛—伽玛测井求地层密度;用中子测井求氢含量(水或烃)。有几种常用的测定间歇时间的经验方法,其中唯有双源法较为可靠。但是,将有关文献中的某些计算公式用于测井探头时,误差竟达50%。本文提出了两个可靠的公式供参考:一是精确的近似式,另一是二步计算式。当用双源法进行测量时,应当考虑本底影响。本文介绍了两种不同的本底校正方法:一种用于中子测井探头,另一种用于自然伽玛测井探头。文中提供了用双源法测定中子测井探头和自然伽玛测井探头的间歇时间的实例。
Accurate determination of the interval time of a nuclear logging probe is important for the quantitative interpretation of the following: uranium grade assessment by gamma ray logging; formation density by gamma-gamma logging; hydrogen production by neutron logging Content (water or hydrocarbon). There are several commonly used empirical methods for determining quiescent time, of which only the dual source method is more reliable. However, when some of the calculations in the literature were applied to logging probes, the error was as much as 50%. This paper presents two reliable formulas for reference: one is the exact approximation, the other is a two-step formula. When using the dual source method for measurements, the background effect should be considered. This article describes two different methods of background correction: one for neutron logging probes and the other for gamma ray logging probes. The article provides an example of using the dual source method to measure the intermittent time of a neutron logging probe and a gamma ray logging probe.