欠平衡条件下深侧向测井电阻率值的校正方法

The Correction Method About Underbalanced Deep Dual Laterolog Data

欠平衡条件下双侧向测井仪器串要通过井口防喷系统下井测量,导致原有双侧向的加长电极不能正常使用,为此需要对其加长电极进行改造。受防喷管长度的限制,改造后的电极系使得深侧向测井电阻率值偏低。由此分析了加长电极长度变化对双侧向电极系数的影响,深侧向电极系数不仅与主电极几何尺寸有关,还与加长电极长度有关。深侧向电极系数与浅侧向电极系数不同,可以被认为是这一推论的2个特例。欠平衡测井时双侧向加长电极的改造并没影响浅侧向电流的回路路径,对浅侧向测井值无影响,实际测量结果也证实了该结论。提出了有效的校正方法,经计算机数值模拟验证证明是正确的,解决了生产中的实际问题。

Dual laterolog under the underbalanced condition is one of the main technical problem.Under the underbalanced condition,dual laterolog tool string should be put down to the well through blowout prevention system of well head,which causes the pristine extension electrode of dual laterolog tool can＇t be used normally.So,the extension electrode must be rebuilt.However,the rebuilt electrode system will make deep dual laterolog resistivity decrease because the length of lubricator is limited.Analyzed is the impact of electrode length changes on the electrode coefficient.The deep laterolog electrode coefficient is not only related with geometry of main electrode,but also with the length of the extension electrode;The deep laterolog electrode coefficient is different from the shallow laterolog electrode coefficient.This is only two special derivations.In the unbalanced logging,the real logging result proves that the extension electrode modification has neither influence on current return path in the shallow laterolog tool,nor influence on the shallow laterolog value.Computer digital simulation proves that the proposed correction method is right,and solves practical production problems.