不同井眼偏心距下水平井阵列侧向测井围岩校正研究

Surrounding Rock Influence Correction for Array Laterolog Responses with Borehole Eccentricities in Horizontal Wells

  • 摘要: 为消除围岩对阵列侧向测井仪器响应的影响,使测量结果更为准确,应对其进行校正。为此,建立了水平井三维层状介质模型,应用三维有限元算法研究了不同井眼偏心距下阵列侧向测井的正演响应特性,得到了数值模拟围岩校正图版;对数值模拟结果进行了非线性分析,得到了围岩快速校正公式和校正图版。通过数值模拟发现,阵列侧向测井仪器的探测深度越深,受围岩的影响越大;当井眼偏心程度系数小于20%时,井眼偏心距变化对阵列侧向测井响应的影响可以忽略;当井眼偏心程度系数大于40%后,阵列侧向测井响应受井眼偏心距的影响明显,视电阻率变化幅度最大可达44.8%。对比分析发现,快速校正图版与数值模拟图版具有较好的一致性,采样点最大相对误差小于5.3%。综合研究表明,快速校正图版可用于水平井中阵列侧向测井响应的实时校正。

     

    Abstract: The response of the array lateral logging tool is influenced by the surrounding rock.Therefore,a surrounding rock correction needs to be performed.In this paper,a 3D layered medium model of horizontal well was established as the first step.The forward response characteristics of array laterolog under various borehole eccentricities were studied by using the 3D finite element method,and the correction plate of surrounding rock was obtained.The nonlinear analysis of the numerical simulation plate was carried out,and the fast correction formula and correction plate of the surrounding rock/layer thickness were obtained.Research showed that the deeper the instrument detection depth,the more they are affected by surrounding rock.When the borehole eccentricity was lower than 20%,borehole eccentricity changes had little effect on the response of array lateral logging.However,when the borehole eccentricity was greater than 40%,the response of array laterolog logging was significantly affected by borehole eccentricity,and the maximum change range of apparent resistivity could reach 44.8%.It was found that the fast correction plate was in good agreement with the numerical simulation plate and the relative error of sampling points between the two plates was lower than 5.3%.As shown by the comprehensive study,the fast correction plate could be used for fast and real-time correction of array lateral well response in horizontal wells.

     

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