论文详情
为解决过套管电阻率测井中测量电极接触电阻的影响问题,以过套管电阻率测井的测量方式、仪器结构等为基础,提出了电极接触电阻测井响应数值模拟计算方法,给出了接触电阻、电表内阻与井壁电势测量值之间的关系。利用KAUFMAN传输线方法计算了金属套管壁的电势分布,利用该分布实现了电极接触电阻测井响应的定量计算。针对目前所使用的单极供电和双极供电2种过套管电阻率测井的测量方式，给出了电极接触电阻测井响应数值算例,结果表明:当任意一个测量电极存在接触电阻时都会引起测井曲线的较大变化,甚至还有可能会出现测井负异常,上、下电极所在的位置为测井曲线的奇异点,在电极附近有可能导致数倍或数十倍的测量误差;并且发现目前使用的2种测量方式的测井曲线存在较大差异,曲线奇异点的位置与测量方式有关。这些结果可用于过套管电阻率测井异常的考察、接触电阻的测井响应分析以及过套管电阻率测井解释等。
In order to solve the influence of the contact resistance for logging tool’s measuring electrode on the measured results in the resistivity logging through casing,based on the measured model and tool’s structure,we proposed a numerical computation method of resistivity logging response through casing when the electrode of logging tool exists the contact resistances and derived the relationship among casing potential,contact resistances of logging tool’s electrodes and inner resistance of voltmeter.The logging responses of the contact resistance for measuring electrodes was calculated quantitatively by casing potential distribution,which is the solution of transmission line equation of Kaufman.The numerical computation examples were provided in accordance with two measured models of resistivity logging through casing.The results show that if there is contact resistivity in anyone of the three measuring electrodes (upper,middle,lower),it will cause a great change in the logging curve.There may even be negative anomaly of logging curve,where the positions of upper and lower electrodes is the singular point of logging curve.The measurement error in the vicinity of the electrodes may be several times or dozens of times larger than that of the regular result.It was found that there are large differences of the measured results with the two measured models of resistivity logging through casing,which cause the different positions of the singular points on the logging curves.With the proposed method we can analyze the logging responses of the contact resistance for measuring electrodes and further give the logging interpretation.
北京市自然科学基金重点项目B类(KZ201510015015)、北京市自然基金(4142016)、北京市教育委员会项目(KM201510015009和KM201410015006)联合资助。