Research And Accomplishment Of Multi-transient Electromagnetics Receiver

With the development of the national economy, the demand of energy is increasing.Energy is the lifeblood of economic development, the oil consumption of China is about50percent of imports. Therefore the importance of finding new large oil and gas resources isprominent. According to the relevant data, the total amount of gas hydrate in marine isconsiderable. And it is enough to meet the human demand for a thousand years. Thereforedeveloping marine oil and gas exploration is becoming a trend.Marine electromagnetic detection, as a complement of the seismic explorationtechnology, can directly detect oil and gas in the oil and gas structures. Marineelectromagnetic detection is increasing its position in the field of ocean exploration.Multi-transient electromagnetic detection system is accompanied by the submarineelectromagnetic probe emerged, if this technology is used in terrestrial a nd marine oil and gasexploration, will greatly reduce the risk of three-dimensional seismic exploration. It will havea very positive impact for our non-seismic method.In this Paper, introduced the principle of Multi-transient electromagnetic detectionsystem, and compared the technical indicators to the foreign mainstream instrument. Throughthese two factors above, clarified the design of the receiving system and the key technologies.Multi-transient electromagnetic receiver system consists of a master control station andmany collecting stations. The master control station is a personal computer with the serial port,and also including the Labview development platform. The main function of the software inthe master control station is accomplished the data and order transmission between thecollecting stations, and the communication protocol is predefined. Besides, the software canrealized the human-computer interaction. The main function of the software is primarily fordetect the communication state of each collecting station, set the operating parameters ofeach collecting station (numbers of acquisition, superimposed times), send control commands, uploading data to master control station and monitor the working status of the collectingstation.The collecting stations using FPGA and MSP430as logic control core, delta-sigmaanalog-to-digital conversion technology to achieve24-bit ADC data synchronous acquisition.In order to meet the large dynamic range requirements of the receiving system, Designed theultra low noise analog signal processing circuit. Using FPGA to fulfil the demand of highspeed data collection, FPGA embedded the interface analog-to-digital converter, high-speedand large-capacity FIFO. In order to improve the signal-to-noise ratio, through MSP430torealize local data superimposed and using magnetic coupling isolation technology. In order toreduce the noise of the collecting station, weaken the interference of digital circuits for analogcircuit, and the technology of grounding have discussed.Aiming at the need of distributed synchronous measurement, referencing commonly usedGPS synchronization technology in the domestic and overseas design. Through the internalFPGA logic control, synchronization control of the timing of the acquisition station is realized.Due to the long-distance wireless communication under outdoors conditions would produce ahigher error rate, so the storage of the data using the form of local storage in collecting station.Local storage circuit using dedicated CH376storage module. These modular designsimplified circuit and improve the stability of the system work.In this paper, analyzed the functional tests of the Multi-transient electromagnetic receiversystem. Tests conducted short-circuit noise test, collecting station acquisition conformancetest, transient electromagnetic signal test and indoor transient electromagnetic modelexperiments. Through these test above, validated the performance of the collecting station.And the final results were analyzed and summarized, and the subsequent design ideas andresearch directions was put forward.