Design Of Main Control And Data Storage Module Of The LWD Neutron Logging Tool

With the development of the modern MWD(Measurement-While-Drilling)technology,the LWD(Logging-While-Drilling)neutron logging technology makes great progress.As a high-end well logging method,it locates the oil storage with measuring the porosity parameters of the formation during well logging.It has became an important means in logging field.At present,the technology in foreign countries is very mature,but in China still in its infancy,so the study of this technology can effectively promote the development of domestic oil industry.The LWD neutron logging tool is a machine developed with the LWD neutron logging technology,which is composed of two parts: ground control system and underground data acquisition circuit.As the core of underground data acquisition circuit,the function of main control and data storage module covers two aspects: the working process control of neutron data acquisition and the storage of logging data.Firstly,this thesis analyzes the principle of the LWD neutron logging technology.Thereafter,by combing the circuit structure and working flow of the LWD neutron logging tool,the functions and technical specifications of the main control and data storage module are determined.On this basis,the overall design scheme is given.Among the module,the main control part has a basic structure with MCU+FPGA.The works of the thesis include the design of work flow of three working modes(Operation,Scale and Download),the design of communication protocol between the communication module,the process control of neutron data acquisition,the monitoring and recording of instrument status,the control of high voltage and analog module.The data storage part takes FLASH as the basic memory.Its main functions include: data storage area division,logging data storage and high-speed downloading,data area erasing and memory formating.To ensure the data storage module can work accurately and efficiently,the part also designed some functions,such as operation fault tolerance,storage address location and bad block checking.Finally,in order to verify the rationality of the above design,a series of experiments on the module and the results are given in the thesis.The experiments are the system communication experiment,the acquisition process control experiment,the data storage function verification experiment and the high-temperature experiment.Through the analysis of the experimental data,it is proved that the designed module has achieved the expected effect.