伽马测井中高温高速数字多道的设计与研究

Design and Research of High Temperature and High-Speed Digital Multi-Channel in Gamma Logging

为了实现深部矿产资源有效探测和精准评价、提高我国矿产资源勘查效率、克服随钻测井时高温环境带来的影响、实现国产造岩元素中子伽马测井仪实用化,设计了脉冲中子伽马测井系统。系统硬件主要由探测器、光电倍增管、前置放大电路、模拟转换器(ADC)、现场可编程门阵列(FPGA)、通信电路组成。考虑到高温运行环境,能谱采集电路采用的芯片为低功耗、耐高温类型,以确保电路在高温状态下正常运行。软件算法采用尖顶成形算法,从而提高采集电路的能谱计数率。经过多次高温试验并更改电路设计,系统在155℃的环境温度下能够正常工作,数据采集速度达到100 MS/s,实现了预期目标。该研究对国内随钻中子伽马测井仪器的发展有着重要意义。

To realize the effective detection and accurate evaluation of deep mineral resources,improve the exploration efficiency of mineral resources in China,the pulsed neutron gamma logging system which can log in high temperature environment while drilling is dosigned.This realized domestic rock-forming element neutron gamma logging tools practice.The system hardware is mainly composed of the detector,photomultiplier,preamplifier,analog to digital converter(ADC),field programmable gate array(FPGA)and communication circuit.Considering that the high-temperature operating environment,the low-power and hightemperature resistant chip is used in the energy spectrum acquisition circuit to ensure the regular operation under the hightemperature state.In order to improve the energy spectrum count rate of the acquisition circuit,the peak shaping algorithm is used in the software algorithm.After many high temperature experiments and circuit design changes,the system can normally work at 155℃and the data acquisition speed reaches 100 MS/s,which achieves the expected goal.The research is of great significance to the development of neutron gamma logging while drilling in China.