Patent ID: 8165825
Filing Date: 2012-04-24
Classification: E21B,G01B,G01N

Abstract:
1. A method for electromagnetically measuring physical parameters of a pipe (CS) by means of a measuring arrangement comprising a transmitter coil and a receiver coil, both coils being coaxial to and longitudinally spaced from each other, the measuring arrangement being adapted to be positioned into the pipe and displaced through the pipe, the pipe physical parameters being the pipe inner diameter (ID) and the pipe ratio of magnetic permeability to electrical conductivity (μ 2 /σ 2 ), the method comprising the steps of: a1) exciting the transmitter coil by means of a transmitter current (I a2) measuring a receiver voltage (V a3) determining a transimpedance (V wherein the method further comprises the steps of: b) repeating the excitation step a1), the measuring step a2), the transimpedance and the measurement ratio determination step a3) for at least a second excitation frequency (f c) calculating a prediction function vector ([G d) applying a minimizing algorithm onto the measurement ratio vector ([M