基于改进Iserles渐进法的大斜度井感应测井正演计算

The Computation of Induction Logging in Deviated Wells Based on Modified Iserles Approximation

大斜度井环境中,感应测井仪器发射线圈可用磁偶极子等效,磁偶极子在接收线圈上产生的电磁场,为含有Bessel函数在无穷域的积分表达式。分析了Bessel函数的振荡衰减特性及积分核函数的构成,考虑这类积分的复杂性,引入改进的Iserles渐进法,非常有效地解决了这类积分问题,利用该方法计算了当前常用的双感应仪器在大斜度井中的测井响应,验证了该方法的高效实用性,为大斜度井感应测井响应正演快速准确计算提供了理论参考。

In highly-deviated wells, the transmitting coils of induction lo are equivalent to magnetic dipoles, which generates electromagnetic field that include integral of Bessel function in infinite field. According to the bration of the Bessel function and its attenuation, and taking the compli gging instruments s in receiving coils analysis of the vi- cation of this kind of integration into consideration, these difficulties referring to the modified Iserles approxi- mation method are needed to deal with. The results of this application show the capability of this method in practice, and also provide theory reference to the accurate processing of the induction logging computation when this method is applied efficiently to the commonly used dual-induction instruments in the deviated wells.