页岩气水平井LWD曲线的环境因素影响及校正方法

Impacts of Environmental Factors on LWD Curves and Calibration Techniques in Horizontal Shale Gas Wells

  • 摘要: 随钻测井(LWD)曲线受环境因素影响不能准确反映页岩地层的实际特征,导致地质导向钻井精度不够,降低了优质页岩地层的钻遇率。以威远页岩气产业示范区水平井随钻测井曲线为研究对象,采用定量与定性相结合的方法评价了不同环境因素影响下随钻测井曲线的变化特征,构建了校正图版,利用最优拟合和数值迭代等方法建立图版公式化的校正模型,并结合室内页岩岩心数据进行可行性分析,最终形成了适用于页岩地层随钻测井曲线环境因素影响的校正方法。利用该方法处理了威远12口页岩气水平井的随钻测井资料,结果表明,校正后的随钻测井曲线消除了地层电性各向异性、相对夹角、井眼环境、仪器偏离间隙和钻井液密度等环境因素的影响,能够较好地反映所钻遇地层的实际特征。

     

    Abstract: LWD curves can not fully represent the actual characteristics of shale formations due to environmental factors,and so to improve the accuracy of geosteering and to improve the rate of drilling in high-quality shale formations,real-time calibration is needed.Taking horizontal wells with LWD data in Weiyuan Shale Gas Industry Demonstration Zone as research objects,the characteristics of LWD curves under different environment were evaluated quantitatively and qualitatively to construct calibration charts.Optimal fitting,numerical iterative and other techniques were deployed to establish calibration models for relevant charts.Feasibilities of such operations were analyzed by using core data from laboratories.In this way,one complete package of calibration techniques for impacts of environmental factors on LWD curves of shale formationa was obtained.The newly-developed techniques were used in the LWD data processing from shale formation of 12 horizontal wells in the Weiyuan Area.Relevant results showed that such calibration can effectively eliminate the negative impacts of stratigraphic electrical anisotropy,relative angle,borehole environment,instrument deviation,drilling fluid density and other environmental factors to obtain the features of penetrated formations more accurately.

     

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