Development Of Portable Automatic Core Scanning Device

Core information is firsthand data to acquire underground geological information in the field of petroleum exploration. Core information is accurate or not directly affects the research. Core gamma scanning device can measure the core from the well quickly in the drilling site, and print out the results in real time. The working period of core catalog and anomaly inspection might be shortening.It's more efficient for lithologic distinvtion, but the cost could be greatly decreased.Aim at the application purpose of petroleum exploration, a portable automatic core gamma scanning device was developed and introduced in the thesis. The protocol instrument has the weight of less than 20kg. It can keep running for more than 8h in field. It can finish the measurement of certain depth and orientation core, and print out the depth and the natural gamma curve of the corresponding depth core. It is a new geophysics instrument for petroleum exploration. And it might make progress in geology technique of China.This thesis has got financial support by State Natural Sciences Fund research project: "Research of Nuclear Geophysics natural gamma field "(Serial number of the project:40774063), major research is core gamma measurement and instrument design.As the detection efficiency and the ability of radiation detector resisting interference of environmental background is so important for continuous measurement and precision to distinguish lithologic in field. Core gamma radiation detector and mechanical transmission equipment are installed in a box, integration. The related electronic units for the detector and the system sofeware are designed and developed.After the optimization geometry parameters of"detector-shielding-core"is calculated and discussed, a low background radiation detector device is designed, which can reduce the impact of environmental background to improve the detecting sensitivity; High stability, low ripple coefficient high voltage power is developed. These circuits can improve the performance of signal-to-noise ratio; A high stability, low power consumption, high signal to noise ratio and high-speed pulse shaping amplifier and a high-resolution capability pulse discriminator are designed; A high stability and high-power power supply circuit for a miniature printer is designed, which has output current up to 3.5A; An eight bit microcontroller as the system control center acqures and processes the nuclear signal pilse, and control the other circuits to work. CH375-chip is used to drive the external U disk device as the data storage unit; A friendly interactive interface is programmed.After complited, protocol system has been made the stability, consistency and accuracy and other performance parameters test, the result is that its precision can be more than 3%, and the short-term stability and the long-term stability is all less than 3%. The system has high accuracy, good stability, and can distinguish the rock well. The equipment is applicated in Sichuan X101 drilling. Application shows that the equipment can measure the depth and the corresponding depth core gamma value and print out the core gamma curve, and the result can match the logging curve well. The accuracy, precision, long-term stability and other key indicators of the instrument are able to meet requirements.