A Design Of Communication And Control Module For LWD Density Logging Tool

Density Logging While Drilling(LWD)technology plays a critical important role in nowadays Well Logging technology,because complicated oil reservoir can be evaluated during the process of oil exploration and the logging orientation can be guided simultaneously.In the actual logging process,the circumstance is extremely complicated,high demand is put forward for the reliability of tool's communication and the stability of system's acquisition control.Thus,developing a measurement circuit with stable communication and reliable acquisition performences is of great value.Gamma ray is produced in Density LWD tools,and the range of energy spectrum in gamma ray is recorded.According to the different of energy spectrum range,the lithology can be classified,and the deposition can be analyzed.Firstly,this thesis introduces the application environment of Density LWD system,especially the structure and the data acquisition process.Then,according to the requirements of logging,the Communication and Control module is designed,mainly including the communication control circuit and power control circuit.In the Density LWD Communication and Control module,“FPGA+MCU” structure is adopted,it can upload corresponding collection data on the basis of diverse commands.The tools can be controlled by Centre System under this structure in real time.The different function modules in Density LWD tools are connected by Communication and Control module.Under the Communication and Control module's control,data collection work is finished automatically in Density LWD tools,and the essential collection data is also stored.Furthermore,three valid power supplies are selected by priority that is set through power selection circuit in Communication and Control module.After the DC-DC buck circuit convert,the necessary power supply is produced,such as ±12V,±5V,+3.3V,+2.5V,+1.2V.In order to have a well collection circumstance,pivotal voltage,current and charge are monitored by a monitor circuit,and the monitored data is stored in Density LWD tools.Finally,in the thesis a series of experiments are described,which are used to verify the design of Communication and Control module.The communication control experiment,exception handling experiment and store experiment verify the stability of communication control circuit.Then,power supply automatic switchover experiment,monitor experiment verify the reliability of power control circuit.In addition,the experiment that combine all function modules indicates the design of Communication and Control module achieves the expected goal through the acquired data and the data's relevant figure of the tool.