REDUCING CONDUCTIVE CASING EFFECT IN TRANSIENT CASED-HOLE RESISTIVITY LOGGING

摘要

A first broadband magnetic field is induced at a first transmitter position in a well bore drilled through a formation. A first formation magnetic field induced by the first broadband magnetic field is detected at a first receiver position. A second formation magnetic field induced by the first broadband magnetic field is detected at a second receiver position. A second broadband magnetic field is induced at a second transmitter position in the well bore. A third formation magnetic field induced by the second broadband magnetic field is detected at the first receiver position. A fourth formation magnetic field induced by the second broadband magnetic field is detected at the second receiver position. A formation property is computed using a function of the first, second, third, and fourth formation magnetic fields, wherein the function reduces the effect of a casing on the computation of the formation property.

主权项

1. A method, comprising
inducing a first broadband magnetic field at a first transmitter position for a transmitter coupled to a tool in a well bore drilled through a formation; detecting at a first receiver position for a first receiver coupled to the tool in the well bore a first formation magnetic field (VR1T1casing) induced by the first broadband magnetic field in the formation; detecting at a second receiver position for a second receiver coupled to the tool in the well bore a second formation magnetic field (VR2T1casing) induced by the first broadband magnetic field in the formation; inducing a second broadband magnetic field at a second transmitter position in the well bore; detecting at the first receiver position in the well bore a third formation magnetic field (VR1T2casing) induced by the second broadband magnetic field in the formation; detecting at the second receiver position in the well bore a fourth formation magnetic field (VR2T2casing) induced by the second broadband magnetic field in the formation; computing a formation property using a function of VR1T1casing, VR2T1casing, VR1T2casing, and VR2T2casing, wherein the function reduces the effect of a casing on the computation of the formation property; using the formation property to plan an activity related to the formation; and executing the plan.