中子伽马曲线受到自然伽马污染影响分析及消除原理

Analysis and Elimination Principle of Neutron Gamma Curve Influenced by Natural Gamma Pollution

中子伽马测井曲线因受到自然伽马污染而失真,导致中子伽马测井曲线无法用于校深,需要消除因自然伽马污染造成的影响。通过分别建立自然伽马测井仪器和中子伽马测井仪器探测的计数与地层放射性强度的关系,分析了中子伽马曲线受到自然伽马污染影响原理,得出了污染影响消除原理。采用二次下井消除自然伽马污染影响,并基于自然伽马、中子伽马测量原理,提出了测量曲线校正公式。此方法有效消除了中子伽马曲线受到自然伽马污染的影响。

Due to the pollution of natural gamma ray,the neutron gamma logging curve is distorted and cannot be used for depth correlation.Through analyzing the relationship between the detection counts and the formation radioactivity of natural gamma ray logging tool and neutron gamma logging tool respectively,it explains how the neutron gamma curve is affected by the natural gamma ray pollution,and the principle of eliminating the natural gamma ray pollution influence on the neutron gamma curve is obtained.The natural gamma ray pollution can be eliminated by running the logging for the second time.Based on the measuring theories of natural gamma ray and neutron gamma,the correction formulas to the logging curve are put forward.The method eliminates the influence of natural gamma ray pollution on neutron gamma curve effectively.