Design Of Digital Gamma Spectrum Acquisition Circuit For Geochemical Elemental Logging Tool With Controllable Neutron Source

With the continuous development of industry,there is a growing demand for oil.At the same time,the proportion of complex reservoirs in total oil and gas reserves is also increasing.In order to solve the problem of petroleum exploration under current conditions,the study of nuclear logging is increasingly active.As an important branch of nuclear logging,geochemical elemental logging plays a key role in the logging operation in complex and harsh formation environment.The geochemical elemental logging method can obtain the content of the main elements in the formation by instrument measurement,and analyze the proportion of these elements,so as to realize the quantitative evaluation of the components in the reservoir.This principle makes the geochemical elemental logging has unique advantages.Geochemical elemental logging tool with controllable neutron source is one of the most advanced tools in the field of geochemical elemental logging.The core part of the tool is gamma spectrum acquisition circuit.This thesis takes the digital gamma spectrum acquisition circuit for geochemical elemental logging tool with controllable neutron source as the research topic,and the gamma spectrum acquisition circuit is digitized from hardware and software.The goal is to improve the performance of the tool,improve the ability to process data,and extend the service life of the tool.By introducing the background of geochemical elemental logging and the development process in this field at home and abroad,and according to the current situation of digital gamma spectrum acquisition circuit for geochemical elemental logging tool with controllable neutron source,and the technical requirements of a sub-project from UESTC and an oil company,the research objectives of the thesis are proposed,and the method of full data acquisition is tried.Finally,the thesis completed the design of three parts.(1)According to the overall structure of the tool,some analog circuits in the signal processing module,gamma spectrum acquisition module,processing module and communication module of the gamma spectrum acquisition circuit are designed digitally,and the components of the circuit are optimized.(2)The availability of trapezoidal shaping algorithm is verified by a mathematical software and the algorithm is applied in the data processing of digital gamma spectrum acquisition circuit.(3)Through the software design of the master chip,the whole process control of the gamma spectrum acquisition circuit is realized,and the functions of data acquisition and processing,communication and spectrum stabilization are completed.At last,the thesis introduces the single circuit board test and the joint test with the ground system of the digital gamma spectrum acquisition circuit for geochemical elemental logging tool with controllable neutron source.The test results are analyzed in detail.It is verified that the circuit works stably and the functions of each part are realized normally.The design in this thesis meets the expected research objectives.