This paper investigates the mechanism by which a drill collar enhances the sensitivity of D-T source porosity log-ging using numerical simulation methods and discusses the design scheme for a high-sensitivity wireline D-T source porosity tool based on this mechanism.This study reveals that the drill collar near the detector absorbs thermal neutrons from the borehole direction,increasing the proportion of formation information in the detected signal and thereby improving logging sensitivity.Additionally,the drill collar near the D-T source reduces the average energy of fast neutrons entering the forma-tion,enhancing the porosity sensitivity of the logging instrument,particularly in formations with medium and low porosity.Based on this influence mechanism,new structural features,such as a neutron-source deceleration block and a detector shiel-ding sleeve,were incorporated into the design of the wireline D-T source porosity logging tool,significantly enhancing its po-rosity sensitivity.This research provides theoretical guidance for the application of D-T sources in wireline logging.
关键词
D-T源/中子孔隙度测井/钻铤影响机制/测井灵敏度/数值模拟
Key words
D-T source/neutron porosity logging/influence of drill collar/logging sensitivity/numerical simulation
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