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Optimized Design of Spacing in Pulsed Neutron Gamma Density Logging While Drilling

ZHANG Feng;HAN Zhong-yue;WU He;HAN Fei   

  1. School of Geosciences, China University of Petroleum, Qingdao 266580, China
  • Online:2016-05-20 Published:2016-06-03

随钻脉冲中子伽马密度测井最佳源距的优化设计

张锋;韩忠悦;吴赫;韩飞   

  1. 中国石油大学(华东) 地球科学与技术学院,山东 青岛266580

Abstract:

Radioactive source, used in traditional density logging, has great impact on the environment, while the pulsed neutron source applied in the logging tool is more safety and greener. In our country, the pulsed neutron-gamma density logging technology is still in the stage of development. Optimizing the parameters of neutron-gamma density instrument is essential to improve the measuring accuracy. This paper mainly studied the effects of spacing to typical neutron-gamma density logging tool which included one D-T neutron generator and two gamma scintillation detectors. The optimization of spacing were based on measuring sensitivity and counting statistic. The short spacing from 25 to 35 cm and long spacing from 60 to 65 cm were selected as the optimal position for near and far detector respectively. The result can provide theoretical support for design and manufacture of the instrument.

Key words: pulsed neutron, gamma rays, formation density, spacing, optimization design

摘要:

采用脉冲中子源进行密度测井,可避免传统密度测井放射性源对环境的影响,更加安全、环保。目前国内随钻脉冲中子伽马密度技术还处于起步阶段,随钻中子伽马密度仪参数优化设计是提高地层密度测量精度的关键。本研究通过由D-T中子源及2个伽马探测器组成的随钻中子伽马密度仪器,研究了源距对中子伽马密度测井的影响,通过灵敏度和计数比统计性进行源距优化设计,得出最佳短源距为25~35 cm,长源距为60~65 cm,研究结果为随钻脉冲中子伽马密度测井仪器研发提供技术支持。

关键词: 脉冲中子, 伽马射线, 地层密度, 源距, 优化设计