基于OFDM通信的超声扫描成像测井仪

发布时间：2018-04-20 17:09

本文选题：超声成像 + 正交频分复用　；参考：《沈阳工业大学》2015年硕士论文

【摘要】：测井是油气田勘探开发过程中取得地质信息、检测井壁破损情况的重要手段。一个完整的测井系统包括采集、传输、分析、储存等功能，主要由井下仪器、数据传输、地面仪器、辅助设备等四部分组成。随着测井技术的飞速发展，大量的井下仪器需要将数据实时传送到地面仪器中。单芯电缆在提供井下仪器供电的同时，还需要实现井下仪器与地面设备的数据传输与命令控制。由于测井电缆信道环境恶劣，因此测井电缆传输数据可用的频带范围比较窄。为了将井下测量的结构质量的物理量实时地传输到井上处理，提高单芯电缆的利用率，采用正交频分复用技术来解决这些问题。超声波成像测井仪由井下超声探头发送超声波，通过对超声回波的检测，从而得到被测井物理损伤等特性。由于通信速率的限制，井下通信设备不能直接将扫描的模拟量发送到井上仪器，需要先对测井数据进行有效数据提取和数据压缩，通过发送电路将数据编码后载波到单芯电缆上，从而将数据高速地传送到地面仪器中。地面仪器对数据解调后传送到上位机中，通过上位机进行解码并显示，直观显示出井壁厚度损伤等物理状况。本井壁超声成像测井仪主要是对检测油井井壁和其水泥胶情况的专用仪器，满足了对体积、温度等苛刻要求的现场环境要求，系统稳定可靠，，有一定的的实用和参考价值。本文介绍了正交频分复用技术，并对其子载波调制与解调做出了仿真与实验，同时对生产测井信道进行了分析与仿真。充分利用单芯电缆的频带宽度，提高了单芯测井电缆上的通信速率。在此基础上，设计了一套超声波测井仪的发射接收电路和数据传输电路。其中井下仪器的发射接收电路包括升压电路、激励电路、限幅电路、放大电路、滤波电路。传输电路包括耦合电路、滤波电路、模拟前端电路、调制解调电路、接口电路组成。试验表明，通过收发电路可以测得试件厚度并通过通信电路的调制与解调，测井电缆可以在电力传输的同时，可以提供高速、可靠的数据传输。检测电路可以完成对被测试件的超声波检测，有一定的参考价值。
[Abstract]:Logging is an important means to obtain geological information and detect the damage of wellbore in the process of oil and gas field exploration and development. A complete logging system consists of four parts: acquisition, transmission, analysis and storage. It is mainly composed of downhole instruments, data transmission, surface instruments and auxiliary equipment. With the rapid development of logging technology, a large number of downhole tools need to transmit data to surface instruments in real time. While the single core cable provides power supply for underground instruments, it also needs to realize the data transmission and command control between underground instruments and surface equipment. Because of the poor environment of logging cable channel, the band range of cable transmission data is narrow. In order to transmit the physical quantity of structural quality measured in downhole to the well in real time and improve the utilization ratio of single core cable, orthogonal frequency division multiplexing (OFDM) technique is used to solve these problems. The ultrasonic imaging logging tool sends the ultrasonic wave from the downhole ultrasonic probe and obtains the physical damage characteristics of the logging by detecting the ultrasonic echo. Due to the limitation of the communication rate, the downhole communication equipment can not directly send the scanned analog quantity to the well tool, so it is necessary to extract and compress the logging data effectively. The data is transmitted to the ground instrument at high speed by sending the coded carrier to the single core cable. The data are demodulated and transmitted to the upper computer by the ground instrument. The physical condition such as the damage of wellbore thickness is displayed directly by decoding and displaying by the upper computer. The well wall ultrasonic imaging logging tool is mainly a special instrument for detecting well lining and its cement glue. It meets the field environmental requirements such as volume, temperature, etc. The system is stable and reliable, and has certain practical and reference value. This paper introduces orthogonal Frequency Division Multiplexing (OFDM) technology, and simulates and tests its subcarrier modulation and demodulation, and analyzes and simulates the production logging channel. The frequency band width of single core cable is fully utilized and the communication rate on single core logging cable is improved. On the basis of this, a set of transmitting and receiving circuit and data transmission circuit of ultrasonic logging tool are designed. The transmitting and receiving circuits of downhole instruments include boost circuit, excitation circuit, limiting circuit, amplifier circuit and filter circuit. The transmission circuit consists of coupling circuit, filtering circuit, analog front-end circuit, modulation and demodulation circuit and interface circuit. The experiment shows that the thickness of the sample can be measured by the transceiver circuit and the modulation and demodulation of the communication circuit. The logging cable can provide high speed and reliable data transmission while the electric power is transmitted. The detection circuit can complete the ultrasonic detection of the tested parts, which has certain reference value.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.83

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