Journal of Isotopes ›› 2010, Vol. 23 ›› Issue (1): 15-21.DOI: 10.7538/tws.2010.23.01.0015

• 放射性同位素应用技术 • Previous Articles     Next Articles

Monte Carlo Simulation on Compensated Neutron Porosity Logging in LWD With D-T Pulsed Neutron Generator

ZHANG Feng1;JIN Xiu-yun2;HOU Shuang1   

  1. 1.Faculty of Geo-resources and Information, China University of Petroleum, Qingdao 266555, China; 2. Dongxin Oil Recovery Plant, SINOPEC Shengli Oil Field Company, Dongying 257094, China
  • Received:1900-01-01 Revised:1900-01-01 Online:2010-02-20 Published:2010-02-20



  1. 1.中国石油大学(华东) 地球资源与信息学院,山东 青岛 266555;2.中石化胜利油田 东辛采油厂,山东 东营 257094

Abstract: The process of neutron interaction induced by D-T pulsed neutron generator and 241Am-Be source was simulated by using Monte Carlo method. It is concluded that the thermal neutron count descend exponentially as the spacing increasing. The smaller porosity was, the smaller the differences between the two sources were. When the porosity reached 40%, the ratio of thermal neutron count generated by D-T pulsed neutron source was much larger than that generated by 241Am-Be neutron source, and its distribution range was wider. The near spacing selected was 20-30 cm, and that of far spacing was about 60-70 cm. The detection depth by using D-T pulsed neutron source was almost unchanged under condition of the same sapcing, and the sensitivity of measurement to the formation porosity decreases. The results showed that it can not only guarantee the statistic of count, but also improve detection sensitivity and depth at the same time of increasing spacing. Therefore, 241Am-Be neutron source can be replaced by D-T neutron tube in LWD tool.

Key words: D-T pulsed neutron generator, 241Am-Be neutron source, LWD, compensated neutron porosity, Monte Carlo simulation

摘要: 利用蒙特卡罗方法模拟研究了D-T脉冲中子发生器和241Am-Be中子源产生的中子与地层的作用过程,以探讨D-T脉冲中子发生器在随钻中子孔隙度测井中的应用价值。模拟结果显示,使用这两种中子源,热中子计数均随源距增加而呈指数下降;孔隙度较小时,两者的计数差异较小,当地层孔隙度达到40%时,D-T脉冲中子发生器产生的热中子和超热中子计数均比241Am-Be中子源高很多,其分布范围也更宽,近探测器的源距选择20~30 cm,远探测器的源距选择约60~70 cm;D-T脉冲中子发生器用于中子孔隙度测井时对地层孔隙度的灵敏度降低,而相同源距条件下探测深度几乎不变。以上结果提示,利用D-T脉冲中子发生器可以进行补偿中子孔隙度测井,在增加源距的同时既可以保证计数统计性,又可以提高灵敏度和探测深度,在随钻测井仪器设计中可以取代241Am-Be中子源。

关键词: D-T脉冲中子发生器, 241Am-Be 中子源, 随钻测井, 中子孔隙度测井, 蒙特卡罗模拟