随钻高分辨率电阻率成像仪器探测特性研究

The Detection Characteristics of a High Resolution Resistivity Imaging Instrument while Drilling

  • 摘要: 针对现有随钻电阻率成像仪器周向钮扣电极分布少的问题,设计了一种新的钮扣电极分布方案。该仪器周向排布8个圆形钮扣电极,纵向分为2排,且每排钮扣电极直径不同,既能在复合钻进时进行全井眼覆盖扫描成像,又能在滑动钻进时获得8个扇区固定方位的井眼图像;建立了复杂的水平层状地层、含周向异常体地层和水平井地层等3种地层模型,利用有限元方法分析了仪器在不同地层模型中的测井响应特征。分析结果表明:该仪器具有较好的纵向分辨率,钮扣电极的纵向分辨率与其直径相当,可以准确识别方位性高阻地层;水平井地层界面对仪器不同方位测量的影响不同,侧向测量模式在地层界面处的响应与电缆侧向测井类似。该仪器在复杂地层中具有较好的适用性,研究结果对随钻电阻率成像仪器的研发和数据解释具有指导作用。

     

    Abstract: Focusing on the problem of low distribution of circumferential imaging electrodes in existing resistivity imaging instruments while drilling, a new instrument imaging electrode distribution scheme was designed. The new instrument arranges 8 circular imaging electrodes in the circumferential direction. They are placed in 2 rows in the longitudinal direction, and each row of imaging electrodes has different diameters. In this configuration, it is possible that it can not only perform full wellbore coverage scan imaging during composite drilling, but also obtain the borehole images of 8 sectors with fixed orientation during slide drilling. Taking that into consideration, the complex horizontal layered strata, strata with circumferential anomalous bodies and horizontal well stratigraphic models were established, and analyzed the logging response and laws of the instrument in different stratigraphic models by using finite element method. The analysis results showed that this instrument had good longitudinal resolution, the longitudinal resolution of the imaging electrode was equivalent to its diameter, which could identify the azimuthal strata with high resistivity accurately; the horizontal well strata interface had different effects on the various orientation measurements of this instrument. Further, the response of lateral measurement mode at the strata interface was similar to that of cable lateral logging. The instrument scheme has good applicability in complex strata, and in the future, the research results could be used to guide instrument development and data interpretation.

     

/

返回文章
返回