Design And Implementation Of Network Well-Earth Potential Detection System

At present, many large-scale oil and gas fields have already entered a period of high water production, hydraulic fracturing is the primary means of stable development for oil fields. Usually regard hydraulic fracturing fracture geometry as the result of hydraulic fracturing, but there is no effective ways to judging the result of hydraulic fracturing, and very serious impact on the hydraulic fracturing and water distribution judgment. Well-earth ERT (electrical resistance tomography) is the way which comes from medical CT imaging and geophysical technology and applied to the measurement of the geophysical technology as one of the topics at the forefront of technology, for the remaining oil in oil wells tapping potential areas to provide a reliable basis which can provide reliable basis for tapping latent potentialities of the remaining oil. Its underlying principle is the technique by which a strong current is applied to the casing of the water-flood input well on the surface of the earth, the current forms a non-uniform field in underground layer. It reflects underground resistivity distribution by measuring the electrical potential distribution of the earth surface. Therefore, associating the distribution of the underground layer precipitation faces, lithologic characteristics and stratum water salinity, it could make qualitative and semi-quantitative research on propelling front edge of water flooding and the distribution of underground layer residual oil and gas by making use of the resistivity differences. Therefore, the accurate survey for well-earth potential is the core and the important guarantee of well-earth ERT technology. This paper has conducted the thorough research on networked detection system for well-earth potential. System uses multi-channel synchronous sampling ADC collection to 18 channels simultaneously achieve noise suppression and improve the efficiency of field work, applying differential input, analog low-pass filtering, digital FIR filtering, and linear cumulative average number of methods to suppress noise, raising letter noise ratio; because of the natural land in the potential superimposed on the signal measurement will reduce the dynamic range of measurement, feedback compensation used in the design to eliminate the potential impact of natural and ensure a greater dynamic range. In the actual field work, because the number of the electrode is large, the distance is long; the region which the instrument works is large. So design the switch controls equipment which is based on RS485 communication bus. This equipment can switch all test points on the same measurement radius into the network at the same time, to provide reliable collecting information has laid a solid foundation ,through acquisition of the testing point spectrum information and analysis of the information to determine whether the electrode to the test network. And this equipment is makes up of relay signals module and distribution modules which work on various test points for the switching convert. All the switching converter modules adoption of a unified design, and has a good interchangeability of field maintenance performance, the use of RS-485 communication bus makes a good measurement network scalability will be able to meet different production site measurement needs. The twisted pair connections have been connected the switch control units, for the transmission of the relevant directives. Address the multi-channel high-capacity for data transmission, using USB2.0 technology is used for communication between PC hardware and MCU. This transmission is high efficiency. The whole system control, data acquisition, analysis, display and storage operations by the series of PC-based monitoring and control software to complete a sound and can be modified and scalability, which has fully demonstrated the virtual instrument technology advantages and strong vitality. Laboratory tests show that the system of high accuracy, high resolution, and high dynamic range, and has strong anti-jamming capability to meet the design objectives.The text adopted by the key technology of the detail This paper totally includes six chapters. It elaborated the theory, principle and development process in detail. The contents of the paper are as follows: The first chapter is introduction, introduces the research significance and present domestic and foreign situation of the networked well-earth potential detection system, then puts forward the research content of the paper. The second chapter outlines well-earth potential measuring principle, equipment and field survey method. The third chapter analyzes the signal characteristic firstly, provides the basis for the system design. Second, introduces the hardware composition of the system, shows the design and scheme of the key circuit such as conditioning circuit, amplitude transition circuit, multi-channel analog-to-digital conversion circuit, time sequential circuit, USB2.0 interface circuit and feedback compensative circuit, electrodes earthen situation detection and USB2.0 techniques. then, describes the function, front panel and data acquisition flow of the measurement and control software, and introduce three key techniques of the system such as Over sampling technique, FIR digital filter and USB2.0 techniques. Especially, introduces the software design of USB2.0 interface development, including firmware design and EZ-USB GDP design. And the fourth chapter at first analyzes the existing problems in Well-earth potential detection system and proposed a network for the electrode switching mode analyzes the practical data-processing needs for network well-earth potential detection system and proposes a solution for bus, detailed exposition of the electrode switching device design and electrode access to the judgment methods. The fifth chapter tests the system performance, carries on the laboratory model test as well as the practical survey to the detection system, and gives the test result and the conclusion. The sixth chapter is full paper summary. Summarizes the work as well as the work innovation spot, and puts up some questions which should be researched continuously in the future.