摘要：基于3D有限元素法,对柱状过井眼型洞穴地层的随钻电阻率成像测井响应进行数值模拟;设计单洞穴和多洞穴2种地层模型,考察洞穴直径、洞穴电阻率、洞穴延伸长度对测量信号的影响。为了更加直观地反映不同因素对洞穴的影响,对仪器在多洞穴地层中成像采样过程进行模拟。基于正演结果,利用最大电流对比度概念建立洞穴直径、洞穴延伸长度理论计算模型。研究结果表明,考虑井眼影响时,洞穴直径与测量信号之间呈现出非单调关系;忽略井眼或贴井壁测量时,洞穴直径与测量信号呈现线性关系,大洞穴延伸长度与测量信号具有较好的幂指数关系;在不同洞穴直径下,洞穴与地层电阻率对比度与测量信号呈幂指数关系。

摘要：This paper presents a 2GS/s 10bit CMOS digital-to-analog converter （DAC） that consists of two unit current-cell matrixes for 6MSBs and 4LSBs, respectively, trading off between the precision and size of the chip. Current mode logic （CML） is used to ensure high speed,and a double centro-symmetric current matrix is designed by the Q^2 random walk strategy in order to ensure the linearity of the DAC. The DAC occupies 2.2mm × 2.2mm of die area and consumes 790mW with a single 3.3V power supply.

摘要：针对随钻井径测量对测距的要求,在基本超声波测距原理的基础上,设计实现了一种精度高、盲区小、功耗低的新型超声测距系统。新型超声测距系统采用多次调整比较器阈值的迭代测量方法。检测到反射波信号的最大值。单片机通过测量发射信号到反射波信号最大值的时间差,可以精确地计算发射面到反射面的距离。试验结果表明,系统采用多次调整比较器阈值的迭代测量方法,实现了高精度、盲区小的超声测距。系统测量精度和盲区能够满足井径测量对测距的要求。

摘要：The proposed DAC consists of a unit current-cell matrix for 8MSBs and a binary-weighted array for 4LSBs,trading-off between the precision,speed,and size of the *** order to ensure the linearity of the DAC,a double Centro symmetric current matrix is designed by the Q2 random walk *** achieve better dynamic performance,a latch is added in front of the current switch to change the input signal,such as its optimal cross-point and voltage *** a 12bit resolution,the converter reaches an update rate of 300MHz.

摘要：为一款支持802.11a/b/g协议的WLAN芯片设计了接收机内部的流水线A/D转换器。采用运放共享技术,减少了一半的运算放大器,节省了芯片面积,并降低了功耗。该A/D转换器采样速率为40 MHz,设计精度为10位,使用HJTC 0.18μm 1P6M CMOS工艺流片并测试成功,当输入频率为1 MHz、无杂散动态范围为61.43 dB的正弦信号时,测得输出数字信号的无杂散动态范围为58.6 dB,信号与噪声谐波失真比为52.87 dB,有效位数为8.49位。

摘要：针对随钻电阻率测井仪器中电路系统工作温度高、电路板安装空间狭小、信号灵敏度低等现状,基于开关切换混频原理,设计一种随钻电阻率信号处理系统。依据原有随钻电阻率测井仪器电路系统基本结构和特点,进行优化和改进:通过FPGA对16号进行8分频实现,生成2 MHz信号;设计开关切换混频电路,实现信号由2 MHz向2 kHz的转换。FPGA的引进,降低了对温度的敏感性,压缩了电路板面积,使得随钻电阻率测井仪器可靠性得到提高,能够更加适应井下狭小空间和高温高压的恶劣环境。测试验证表明,幅度比和相位差的测量相对误差都在1%以内,完全满足随钻电阻率测量精度要求。

摘要：A new multi-mode resistivity imaging sonde, with toroidal coils as source, can conduct three resistivity measurements: azimuthal resistivity, lateral resistivity, and bit resistivity measurements. Thus, the logging time and cost are greatly saved. The toroidal coils are simplified as an extended voltage dipole and the response equations are derived for a homogenous formation. Based on 3D FEM, the depth of investigation(DOI), vertical resolution, circumferential azimuthal capacity, borehole diameter, mud resistivity, thickness of target formation, and the resistivity of the surrounding formation and mud invasion are simulated. The results suggest that the three measurement modes of the new sonde are different in vertical resolutions and DOIs. The circumferential detection ability of the azimuth button depends on the contrast between the anomaly and formation resistivity and the open angle of the anomaly. Whether the borehole is truncated at the bit or not has a great influence on the simulation results. The borehole and mud invasion affect the apparent resistivity in all modes, but the effects of resistivity of surrounding formation and thickness of the target formation are only corrected for lateral resistivity measurement.

摘要：本文介绍了直接数字频率合成器的基本原理以及频率合成技术的发展历程.对几种常用的频率合成器技术进行了比较.其中着重讲述了直接数字频率合成器的噪声构成。文中概述了直接数字频率合成器的应用领域.论述了国外主要的直接数字频率合成器供应商的典型产品的性能特点.并介绍了国内相关的研究情况。

摘要：采用0.13μm工艺,设计了一种10 bit精度、无杂散动态范围(SFDR)为54 dBc、最大工作频率达到1.2 GHz的直接数字频率合成器DDFS。采用多通道数据流结构,提高了工作频率;利用QLA技术对ROM查询表进行了优化,压缩了ROM查询表的大小,提高了频谱纯度。

摘要：为了满足多深度探测评价钻井液侵入和识别地层岩性的需要,开发了具有电阻率、伽马等多参数测量功能的随钻一体化测井仪平台。基于相移电阻率、衰减电阻率、总量伽马和成像伽马等测量方法,采用六发两收的八线圈系设计方案,挂接了伽马探管、加速度计和磁通门等传感器,同时采用了由发射电路、接收电路和控制电路组成的模块化电路设计方案,并定义了总线通讯协议,建立起了各功能模块之间的信息传递。开发了测井仪平台的固件程序,不仅能够测量相移电阻率和衰减电阻率数据,还能够测量伽马数据和地层方位信息;开发了平台测试软件,能够对仪器进行标定测试及下井前的启动设置,实现仪器控制指令的下发,测量数据的上传,并对电阻率、伽马、井斜角和工具面等数据进行监测和图形化处理。研制的随钻一体化测井仪平台可以为大斜度井和水平井钻井提供丰富的、高质量的测井数据,为地层评价提供所需要的数据,从而为非常规油气储层开发提供技术支持。