The Research And Test Of The Signal Processing Circuit Of The Electromagnetic Logging While Drilling System

Electromagnetic wave resistivity logging while drilling technology has become a popular tech in recent decades in the field of oil exploitation, as well as the offshore drilling. Due to its important practical value in directional drilling and the detection of stratigraphic boundary, the usage of resistivity LWD is increasing. Compared with the traditional logging technology, electromagnetic wave resistivity LWD is a more accurate, suitable and timely method, which is being the mainstream of international logging tech. In the equipment level, several large oilfield technology companies have made their products go into mass production, while in domestic, the research on this field is just starting out and the design of underground electrical system is still at the experimental stage. Given this background above, this paper carried on research on the basic principle and structure of electromagnetic wave resistivity LWD system, and made the experimental modules to verify the design of signal processing circuit. Meanwhile, in this paper, we established an auto-measure system with the network analyzer and spectrum instrument, and coded the complete set of control software to conduct an overall measurement to the experimental circuits. At last, the functions of signal processing circuit were verified, and more technique data was acquired in this measurement.Several works are done in this paper:Frist, in this paper, we studied on the basic principle of electromagnetic wave resistivity LWD technology, and analyzed the structure as well as the principle of downhole circuit, which is used to achieve the function of resistivity logging. After that, we designed the key module of logging system, the signal processing circuit, and made the experimental circuit. Then, some important technical indexes and measure methods are explained.Second, to conduct a measurement on the test circuit, we designed and realized a auto-measure system in which the vector network analyzer is used. In this system we used the remote control function of the instrument to make an auto-measurement, and a software is coded to control and save the measured Data. This auto-measure system could realize a convenient and rapid measure to the signal processing circuit.At last, an overall measurement to the experimental circuits was conducted and a great many of results were achieved. From the analysis of the results, we can conclude that the design of signal processing circuit, in which the structure of heterodyne is used, is able to complete the target of processing and amplifying the small signal satisfactorily. That makes the signal processing of the next module more convenient.All the experimental results and measured data above are practical and significant to the design of electromagnetic wave resistivity LWD system. Moreover, it can provides sufficient data to support the debugging and improvement of circuit design.