中文摘要：

针对中子伽马密度测井中利用单探测器信息进行含氢指数校正计算密度结果的不稳定问题,开展双源距含氢指数校正方法研究;采用蒙特卡罗方法模拟热中子、伽马分布与密度和含氢指数的响应规律,建立热中子、俘获伽马以及氢俘获伽马计数比进行含氢指数校正的密度计算模型,对比不同粒子含氢指数校正效果以及井径、矿化度的影响.模拟结果表明：含氢指数校正后密度准确度明显改善;其中,热中子含氢指数校正后的密度精度和准确度最高,氢俘获校正密度准确度略高于俘获伽马,但其密度精度远小于热中子和俘获伽马.双源距含氢指数校正密度误差随着井径和地层水矿化度的增大而增大;其中,热中子校正受井径和矿化度影响最小,氢俘获和总俘获伽马校正方法受影响较大.研究结果为随钻测井准确计算中子伽马密度提供了校正方法.

英文摘要：

To resolve unstable density measurements using single detector hydrogen index correction calculation in neutrongamma density logging,a dual-spacing hydrogen index correction method is studied. The neutron and gamma ray distribution in different hydrogen index and formation conditions is simulated by a Monte Carlo method. A hydrogen index correction calculation model is established by the dual-spacing count rate ratio of capture gamma ray, hydrogen capture gamma rny and thermal neutron. The results of hydrogen index correction and the impact of caliper and salinity are compared. As a result, the accuracy in the density measurements after hydrogen index correction has improved significantly. Among them, the precision and accuracy from thermal neutron correction is the highest. The accuracy from hydrogen capture gamma correction is slightly higher than that of the capture gamma; on the contrary, the precision of hydrogen capture gamma is far less than that of the capture gamma and the thermal neutron. The error of dual-spacing hydrogen index correction in-creases with the increasing caliper and salinity. The results from thermal neutron correction are less sensitive to caliper and salinity, while the results from capture gamma and hydrogen capture gamma correction are considerably are on the opposite. The research provides correction methods for obtaining neutron gamma density accurately in LWD.