基于水平井电阻率测井的井间夹层反演方法及应用

Interlayer Inversion Method and Its Application Based on Horizontal Well Resistivity Logging

  • 摘要: 为了掌握夹层的空间分布特征,揭示剩余油分布规律,开展了井间夹层识别与预测研究。首先,根据岩心资料确定了夹层类型,并结合测井资料建立了夹层识别标准;然后,依据电测井原理构建反演算法,反演得到了水平井井轴外夹层的展布情况。研究发现,利用密度相对值与自然伽马相对值交会或补偿中子相对值与自然伽马相对值交会,能够识别研究区2类夹层;反演的钙质夹层厚度绝对误差为0.018 m,泥质夹层厚度绝对误差为0.017 m;钙质夹层较为发育,分布广,厚度变化大;泥质夹层分布数量相对较少,以顺物源北东向分布。研究结果表明,利用水平井电阻率反演井轴外夹层的分布,结合直井联合控制确定的夹层井间展布,可以提高夹层井间预测精度,为研究剩余油分布和挖潜提供依据。

     

    Abstract: In order to study the spatial distribution characteristics of interlayers and reveal the distribution pattern of remaining oil, interlayers between wells were predicted and identified. Firstly, the types of interlayers were determined from core analysis, and the identification criteria was established along with logging data.Then, an inversion algorithm was designed on the basis of electric logging for the distribution of interlayers beyond horizontal wellbore. The results demonstrate that the intersection of relative density or relative value of neutron with relative value of gamma can identify two types of interlayers in the target area with absolute errors of 0.018 m and 0.017 m in the inversed thickness of calcareous interlayers and muddy interlayers, respectively. The calcareous interlayers are more developed, with wide distribution and varied change in thickness, while the muddy interlayers are fewer, with a distribution in the northeast orientation. This study, which can provide a reference in studying the distribution and tapping potential of remaining oil, proves that the prediction of interlayer distribution between wells can be more accurate after the interlayer distribution beyond the wellbore is inversed on the basis of horizontal-well resistivity and the inter-well distribution of interlayers determined with the joint control of vertical wells.

     

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