For logging while drilling(LWD)systems,it is necessary to adjust the working state of the downhole tools in real-time according to different operating conditions.In this paper,on the basis of the characteristics of LW...For logging while drilling(LWD)systems,it is necessary to adjust the working state of the downhole tools in real-time according to different operating conditions.In this paper,on the basis of the characteristics of LWD systems,a mud pressure-apperceived downlink system was examined.For the design of this system,a signal acquisition and processing board was created based on a piezoelectric ceramic sensor to acquire the mud pressure signal.The error sources of the downlink command sending process were analyzed,and an error accumulation compensation processing algorithm was proposed to improve the recognition success rate of the downhole system.Moreover,to reduce noise interference on the characteristics of the mud impulse signal,a fi ltering algorithm was proposed based on the empirical mode decomposition method,and the success rate of instruction issuance was determined by identifying feedback instructions.Field tests were conducted to further improve the system,the results of which suggested that the system had good mud adaptability,high recognition success rate,and a certain application value.展开更多
A detector for fast neutrons based on a 10 × 10 cm^2 triple gas electron multiplier （GEM） device is developed and tested. A neutron converter, which is a high density polyethylene （HDPE） layer, is combined wi...A detector for fast neutrons based on a 10 × 10 cm^2 triple gas electron multiplier （GEM） device is developed and tested. A neutron converter, which is a high density polyethylene （HDPE） layer, is combined with the triple GEM detector cathode and placed inside the detector, in the path of the incident neutrons. The detector is tested by obtaining the energy deposition spectrum with an Am Be neutron source in the Institute of Modern Physics （IMP） at Lanzhou. In the present work we report the results of the tests and compare them with those of simulations. The transport of fast neutrons and their interactions with the different materials in the detector are simulated with the GEANT4 code, to understand the experimental results. The detector displays a clear response to the incident fast neutrons. However, an unexpected disagreement in the energy dependence of the response between the simulated and measured spectra is observed. The neutron sources used in our simulation include deuterium-tritium （DT, 14 MeV）, deuterium-deuterium （DD, 2.45 MeV）, and Am Be sources. The simulation results also show that among the secondary particles generated by the incident neutron, the main contributions to the total energy deposition are from recoil protons induced in hydrogen-rich HDPE or Kapton （GEM material）, and activation photons induced by neutron interaction with Ar atoms. Their contributions account for 90% of the total energy deposition. In addition, the dependence of neutron deposited energy spectrum on the composition of the gas mixture is presented.展开更多
A high-efficiency fast neutron detector prototype based on a triple Gas Electron Multiplier（GEM） detector, which, coupled with a novel multi-layered high-density polyethylene（HDPE） as a neutron-to-proton converter...A high-efficiency fast neutron detector prototype based on a triple Gas Electron Multiplier（GEM） detector, which, coupled with a novel multi-layered high-density polyethylene（HDPE） as a neutron-to-proton converter for improving the neutron detection efficiency, is introduced and tested with the Am-Be neutron source in the Institute of Modern Physics（IMP） at Lanzhou in the present work. First, the developed triple GEM detector is tested by measuring its effective gain and energy resolution with55 Fe X-ray source to ensure that it has a good performance.The effective gain and obtained energy resolution is 5.0×104and around 19.2%, respectively. Secondly, the novel multi-layered HDPE converter is coupled with the cathode of the triple GEM detector making it a high-efficiency fast neutron detector. Its effective neutron response is four times higher than that of the traditional single-layered conversion technique when the converter layer number is 38.展开更多
文摘For logging while drilling(LWD)systems,it is necessary to adjust the working state of the downhole tools in real-time according to different operating conditions.In this paper,on the basis of the characteristics of LWD systems,a mud pressure-apperceived downlink system was examined.For the design of this system,a signal acquisition and processing board was created based on a piezoelectric ceramic sensor to acquire the mud pressure signal.The error sources of the downlink command sending process were analyzed,and an error accumulation compensation processing algorithm was proposed to improve the recognition success rate of the downhole system.Moreover,to reduce noise interference on the characteristics of the mud impulse signal,a fi ltering algorithm was proposed based on the empirical mode decomposition method,and the success rate of instruction issuance was determined by identifying feedback instructions.Field tests were conducted to further improve the system,the results of which suggested that the system had good mud adaptability,high recognition success rate,and a certain application value.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11135002,11305232 and 11175076the Foundation of China Spallation Neutron Source:Study and Development of the High-performance and Low-angle Detector
文摘A detector for fast neutrons based on a 10 × 10 cm^2 triple gas electron multiplier （GEM） device is developed and tested. A neutron converter, which is a high density polyethylene （HDPE） layer, is combined with the triple GEM detector cathode and placed inside the detector, in the path of the incident neutrons. The detector is tested by obtaining the energy deposition spectrum with an Am Be neutron source in the Institute of Modern Physics （IMP） at Lanzhou. In the present work we report the results of the tests and compare them with those of simulations. The transport of fast neutrons and their interactions with the different materials in the detector are simulated with the GEANT4 code, to understand the experimental results. The detector displays a clear response to the incident fast neutrons. However, an unexpected disagreement in the energy dependence of the response between the simulated and measured spectra is observed. The neutron sources used in our simulation include deuterium-tritium （DT, 14 MeV）, deuterium-deuterium （DD, 2.45 MeV）, and Am Be sources. The simulation results also show that among the secondary particles generated by the incident neutron, the main contributions to the total energy deposition are from recoil protons induced in hydrogen-rich HDPE or Kapton （GEM material）, and activation photons induced by neutron interaction with Ar atoms. Their contributions account for 90% of the total energy deposition. In addition, the dependence of neutron deposited energy spectrum on the composition of the gas mixture is presented.
基金Supported by National Natural Science Foundation of China(11135002,11305232,11175076)
文摘A high-efficiency fast neutron detector prototype based on a triple Gas Electron Multiplier（GEM） detector, which, coupled with a novel multi-layered high-density polyethylene（HDPE） as a neutron-to-proton converter for improving the neutron detection efficiency, is introduced and tested with the Am-Be neutron source in the Institute of Modern Physics（IMP） at Lanzhou in the present work. First, the developed triple GEM detector is tested by measuring its effective gain and energy resolution with55 Fe X-ray source to ensure that it has a good performance.The effective gain and obtained energy resolution is 5.0×104and around 19.2%, respectively. Secondly, the novel multi-layered HDPE converter is coupled with the cathode of the triple GEM detector making it a high-efficiency fast neutron detector. Its effective neutron response is four times higher than that of the traditional single-layered conversion technique when the converter layer number is 38.
