随钻声波远探测声波速度成像数值模拟与试验

Numerical Simulation and Test of Velocity Imaging for Remote Detection Acoustic Logging While Drilling

  • 摘要: 为了获取井周地层方位声波速度信息,评价地层的非均匀性,设计了不同方向速度模型井,研究了随钻声波远探测的方位声波速度测量性能。不同方向速度模型井包含4个扇区,相邻扇区纵波速度和横波速度均不同。数值模拟了该模型井的声波传播,采用偏极子发射和偏极子接收的测量模式,获得了方位角为0°,90°,180°和270°时的阵列接收波形,从接收波形提取到了井周地层方位声波速度信息,识别到了方位分区的变化。根据不同方向速度模型井的参数设计了试验装置,使用瓦片状方位声源准确测量到2个扇区高速介质的声波速度,识别出2个扇区低速介质的声波速度变化趋势,试验结果与数值模拟结果基本一致。研究结果表明,利用不同方向速度模型井可以对不同方向的声波速度进行评价,为随钻声波远探测进行地质导向和地层各向异性分析提供理论依据。

     

    Abstract: In order to obtain azimuthal acoustic velocity information of formations around wells and evaluate the heterogeneity of the formations, a well model with different velocities in different directions was designed, and the performance of remote detection acoustic logging while drilling (LWD) in measuring azimuthal acoustic velocity was studied. The well model had four sectors, and the velocities of compressional and shear waves in adjacent sectors were different. In addition, acoustic wave propagation of the well model was numerically simulated, and an eccentric transmitter and an eccentric receiver were adopted for measurement. As a result, waveforms recorded by array receivers were obtained with their azimuth angle of 0°, 90°, 180°, and 270°, respectively. Furthermore, azimuthal acoustic velocity information of formations around wells was extracted from the waveforms, and changes in sectors with different azimuths were identified. According to the parameters of the well model with different velocities in different directions, a test device was designed. The tile-like azimuthal acoustic source was used to accurately measure the acoustic velocity of high-speed media in two sectors, and the acoustic velocity variation trend of low-speed media in the other two sectors was identified. The test results were in agreement with the simulation results. The research showed that it is feasible to evaluate acoustic velocity in different directions by the well model with different velocities in different directions, which provides a theoretical basis for geosteering and formation anisotropy analysis by remote detection acoustic LWD.

     

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