In this paper, responses of a new dual-induction resistivity logging-while-drilling （LWD） tool in 3D inhomogeneous formation models are simulated by the vectorfinite element method （VFEM）, the influences of the bo...In this paper, responses of a new dual-induction resistivity logging-while-drilling （LWD） tool in 3D inhomogeneous formation models are simulated by the vectorfinite element method （VFEM）, the influences of the borehole, invaded zone, surroundingstrata, and tool eccentricity are analyzed, and calibration loop parameters and calibrationcoefficients of the LWD tool are discussed. The results show that the tool has a greater depthof investigation than that of the existing electromagnetic propagation LWD tools and is moresensitive to azimuthal conductivity. Both deep and medium induction responses have linearrelationships with the formation conductivity, considering optimal calibration loop parametersand calibration coefficients. Due to the different depths of investigation and resolution, deepinduction and medium induction are affected differently by the formation model parameters,thereby having different correction factors. The simulation results can provide theoreticalreferences for the research and interpretation of the dual-induction resistivity LWD tools.展开更多
直接数字频率合成技术(Direct Digital Synthesize,DDS)具有频率分辨率高、输出频率稳定、功耗低等优点。分析研究了DDS技术的基本原理和DDS芯片AD9850的工作特点,介绍了它在随钻电磁波电阻率测井仪信号源设计中的应用,并给出了它和DSP...直接数字频率合成技术(Direct Digital Synthesize,DDS)具有频率分辨率高、输出频率稳定、功耗低等优点。分析研究了DDS技术的基本原理和DDS芯片AD9850的工作特点,介绍了它在随钻电磁波电阻率测井仪信号源设计中的应用,并给出了它和DSP处理器的硬件接口和程序流程。试验结果表明,利用DDS技术产生的信号能满足测井的需要,为随钻电阻率测井技术提供了新手段。展开更多
影响随钻电磁波电阻率测井仪器响应的因素主要来自两方面:一方面是自身结构因素,包含线圈、天线凹槽、盖板、钻铤等,这些因素通过影响接收线圈感应电动势的幅度,进而对电阻率测量结果产生影响;另一方面因素来自外界环境,包括井眼泥浆、...影响随钻电磁波电阻率测井仪器响应的因素主要来自两方面:一方面是自身结构因素,包含线圈、天线凹槽、盖板、钻铤等,这些因素通过影响接收线圈感应电动势的幅度,进而对电阻率测量结果产生影响;另一方面因素来自外界环境,包括井眼泥浆、围岩、侵入、介电常数以及地层各向异性等,测井过程中的仪器响应,是对井下多种不同介质的综合响应,为了达到探测原状地层电阻率的目的,需要扣除其它因素对仪器响应的影响。因而研究影响随钻电磁波电阻率测井响应的因素,对测井资料的解释与应用是十分必要的。本文以随钻电磁波电阻率仪器WPR(Wave Propagation Resistivity)为算例,建立真实的3维仪器结构,采用3维有限元3 D FEM(Three-Dimensional Finite Element Model)方法,针对真实仪器自身结构以及外界环境因素对仪器响应造成的影响进行了数值模拟,并利用解析解对本文的数值解进行了验证。感应电动势绝对值随着线圈半径、线圈凹槽宽度、天线槽长度、盖板占空比增大而明显增大;随着凹槽深度增加而减小。其中,浅探测模式受以上因素影响较深探测模式更大。此外,感应电动势绝对值受金属钻铤的电导率影响较小。在外界环境因素方面,井眼与泥浆存在使视幅度比电阻率偏小,视相位差电阻率偏大;泥浆电阻率越大,对仪器响应造成的影响越小;各向异性使视幅度比电阻率与视相位差电阻率均偏大;泥浆侵入、围岩、介电常数以及各向异性因素使视幅度比电阻率与视相位差电阻率在数值上差异逐渐增大;泥浆侵入使视相位差电阻率与视幅度比电阻率差异先增大再减小;介电常数影响在高阻地层中更加明显,其中视相位差电阻率受影响更大。展开更多
基金supported by the National Oil and Gas Major Projects(No.2011ZX05020-002)
文摘In this paper, responses of a new dual-induction resistivity logging-while-drilling （LWD） tool in 3D inhomogeneous formation models are simulated by the vectorfinite element method （VFEM）, the influences of the borehole, invaded zone, surroundingstrata, and tool eccentricity are analyzed, and calibration loop parameters and calibrationcoefficients of the LWD tool are discussed. The results show that the tool has a greater depthof investigation than that of the existing electromagnetic propagation LWD tools and is moresensitive to azimuthal conductivity. Both deep and medium induction responses have linearrelationships with the formation conductivity, considering optimal calibration loop parametersand calibration coefficients. Due to the different depths of investigation and resolution, deepinduction and medium induction are affected differently by the formation model parameters,thereby having different correction factors. The simulation results can provide theoreticalreferences for the research and interpretation of the dual-induction resistivity LWD tools.
文摘直接数字频率合成技术(Direct Digital Synthesize,DDS)具有频率分辨率高、输出频率稳定、功耗低等优点。分析研究了DDS技术的基本原理和DDS芯片AD9850的工作特点,介绍了它在随钻电磁波电阻率测井仪信号源设计中的应用,并给出了它和DSP处理器的硬件接口和程序流程。试验结果表明,利用DDS技术产生的信号能满足测井的需要,为随钻电阻率测井技术提供了新手段。
文摘影响随钻电磁波电阻率测井仪器响应的因素主要来自两方面:一方面是自身结构因素,包含线圈、天线凹槽、盖板、钻铤等,这些因素通过影响接收线圈感应电动势的幅度,进而对电阻率测量结果产生影响;另一方面因素来自外界环境,包括井眼泥浆、围岩、侵入、介电常数以及地层各向异性等,测井过程中的仪器响应,是对井下多种不同介质的综合响应,为了达到探测原状地层电阻率的目的,需要扣除其它因素对仪器响应的影响。因而研究影响随钻电磁波电阻率测井响应的因素,对测井资料的解释与应用是十分必要的。本文以随钻电磁波电阻率仪器WPR(Wave Propagation Resistivity)为算例,建立真实的3维仪器结构,采用3维有限元3 D FEM(Three-Dimensional Finite Element Model)方法,针对真实仪器自身结构以及外界环境因素对仪器响应造成的影响进行了数值模拟,并利用解析解对本文的数值解进行了验证。感应电动势绝对值随着线圈半径、线圈凹槽宽度、天线槽长度、盖板占空比增大而明显增大;随着凹槽深度增加而减小。其中,浅探测模式受以上因素影响较深探测模式更大。此外,感应电动势绝对值受金属钻铤的电导率影响较小。在外界环境因素方面,井眼与泥浆存在使视幅度比电阻率偏小,视相位差电阻率偏大;泥浆电阻率越大,对仪器响应造成的影响越小;各向异性使视幅度比电阻率与视相位差电阻率均偏大;泥浆侵入、围岩、介电常数以及各向异性因素使视幅度比电阻率与视相位差电阻率在数值上差异逐渐增大;泥浆侵入使视相位差电阻率与视幅度比电阻率差异先增大再减小;介电常数影响在高阻地层中更加明显,其中视相位差电阻率受影响更大。
