超声随钻井径检测仪的信号检测与数字化处理

发布时间：2018-06-23 01:02

本文选题：随钻超声测井 + 压控放大　；参考：《长江大学》2013年硕士论文

【摘要】：在油气田勘探、开发过程中,钻井之后必须进行测井,以便了解地层的含油气情况。测井资料的获取总是在钻井完工之后,利用电缆将仪器放入井中进行测量。然而,在某些情况下,如斜度超过65度的大斜度井或水平井,用电缆很难将仪器放下去。由于钻井过程中要用钻井液循环来带出钻碎的岩屑,钻井液滤液总要侵入地层,所以在钻完之后再测井得到的地层的各种参数与刚钻开地层时有所差别。而用随钻测井获得的地层参数是刚钻开的地层参数,它最接近地层的原始状态,用于对复杂地层的含油、气评价比一般电缆测井更有利。目前,我国随钻测井技术在应用过程中一直面临一系列技术难题,所以研发具有自主知识产权的超声随钻测径仪器具有重要意义。超声随钻井径检测仪主要是通过检测回波时间和回波幅度信息来反映井下井壁的结构和特征。仪器整体设计可以分为以下几个模块：激发与接收模块、信号采集模块、控制处理与存储模块、传输模块、电源模块。激发接收模块：由FPGA产生激励信号激发,换能器接收回波信号送入信号采集模块进行相关处理。信号采集模块：接收来自激发接收模块的回波信号,按回波衰减规律对信号进行压控放大和带通滤波,然后进行电平极性转换后送到A/D转换器对数字化。控制处理与存储模块：根据地面系统发出的命令,产生相应控制指令和时序逻辑,控制井下电路按要求的模式工作,同时将温度信号和井下电源电压信息数字化,然后将检测的回波数据、温度数据、方位信息进行格式编排和数据组帧,进行存储和抽样发送,最后还要在该模块对回波数据进行实时相关处理,提取井径信息。传输模块：主要实现采用QBUS,总线或RS485总线结构与地面系统进行通信和数据传输,同时为了便于井下电路的调试设计一个RS232通信接口,便于与上位机通信。电源模块：提供井下电路需要的三组电源。本文首先介绍了随钻测井技术在国内外的发展情况,通过分析阐述超声测井仪器研制的必要性,指出在仪器研发过程中所需达到的各项指标以及所面临的各项难题；接着提出了系统设计的总体方案,讲述了激发与接收模块、信号采集模块具体硬件电路设计,FPGA控制各模块逻辑时序设计;最后,通过实验验证硬件电路设计的可行性,并提出了本设计中所存在的不足以及值得改进的地方。与传统的电缆超声成像测井仪相比其主要技术改进在于： 1.在电子器件的选择上尽量采用军工级芯片,采用高集成度器件代替分离原件,器件的封装上尽量选用贴片。 2.降低换能器频率,以利于重泥浆环境下的测量。 3.设计了新的激发电路,提高了电声转换的效率,增强了激发声波的能量。 4.根据超声波在介质中随时间的衰减规律,采用高性能压控放大器,随时间的变化对回波信号进行连续可变增益放大,补偿泥浆介质对信号的衰减。
[Abstract]:In the course of exploration in oil and gas fields, well logging must be carried out after drilling in order to understand the oil and gas in the formation. The acquisition of well logging data is always measured in the well after the completion of the drilling. In some cases, in some cases, such as a large inclined or horizontal well with an inclination of more than 65 degrees, it is difficult to put the instrument in a cable. In the course of drilling, drilling fluid should be circulated to bring out the broken bits of rock, and the filtrate of the drilling fluid always invades the stratum, so the parameters of the formation are different from that of the rigid drilling, and the formation parameters obtained by the drilling well logging are the formation parameters of the rigid drilling, which is closest to the original formation. The evaluation of oil and gas in complex strata is more favorable than general cable logging. At present, a series of technical problems have been faced in the application of drilled logging technology in China. Therefore, it is of great significance to develop an ultrasonic drilling measuring instrument with independent intellectual property rights.
The ultrasonic drilling diameter detector mainly reflects the structure and characteristics of the downhole wall by detecting the echo time and echo amplitude information. The overall design of the instrument can be divided into the following modules: the module of excitation and reception, the module of signal acquisition, the module of control processing and storage, the transmission module and the power supply module.
The excitation receiving module is generated by FPGA, and the transducer receives the echo signal and sends it to the signal acquisition module for processing.
Signal acquisition module: receive echo signals from the excitation receiving module, press and amplify the signal according to the law of echo attenuation, and then convert the level polarity to the A/D converter to digitize.
Control processing and storage module: according to the commands issued by the ground system, the corresponding control instructions and timing logic are generated, and the downhole circuit is controlled to work according to the required mode. At the same time, the temperature signal and the downhole power supply voltage information are digitized. Then the detected echo data, the temperature data, and the azimuth information are arranged and the data group frames are entered. Row storage and sample sending, and finally, the real-time correlation processing of echo data is carried out in the module, and the well diameter information is extracted.
Transmission module: the main realization is to use QBUS, bus or RS485 bus structure to communicate with the ground system for communication and data transmission. At the same time, in order to facilitate the debugging of the downhole circuit, a RS232 communication interface is designed to facilitate communication with the host computer.
Power module: three sets of power supply for downhole circuits.
This paper first introduces the development of drilled logging technology at home and abroad, analyzes and expounds the necessity of the development of ultrasonic logging instruments, points out all the indicators needed in the process of research and development of the instrument and the difficult problems it faces, and then puts forward the overall plan of the system design, and describes the excitation and reception modules and the signal acquisition. The module specific hardware circuit design, FPGA control the logic timing design of each module. Finally, the feasibility of the hardware circuit design is verified by the experiment, and the shortcomings in this design and the place to be improved are put forward.
Compared with the traditional cable ultrasonic imaging logging tool, its main technical improvement lies in:
1. in the selection of electronic devices, we should use military chip as far as possible and replace the original parts with high integration devices.
2. reduce transducer frequency to facilitate measurement in heavy mud environment.
3. a new excitation circuit is designed, which improves the efficiency of the electro acoustic conversion and enhances the energy of the excited sound wave.
4. according to the attenuation law of ultrasonic wave in the medium with time, the high performance pressure control amplifier is used. The continuous variable gain amplification is carried out to the echo signal with the change of time to compensate the attenuation of the mud medium to the signal.
【学位授予单位】：长江大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TE927.9;TN911.7

【参考文献】