A system is provided that can include a first tube for communicating a fluid through a wellbore. The system can also include a gap between the first tube and a first electromagnetic acoustic transducer (EMAT). The first EMAT can be positioned to magnetically couple with the first tube. The first EMAT can include a magnet and a wire coil positioned around the magnet. The first EMAT can coupled to a power source and positioned to, responsive to receiving a power from the power source, apply a first magnetic force to the first tube for determining a density or viscosity of the fluid.

[Problem to be Solved] To provide a property measuring device for measuring a measurement object, which can highly reliably extract an electric signal serving as the measurement object from an electromagnetic field noise or the like generated by an acoustic wave generating source even if the acoustic wave is a continuous wave, while a high spatial resolution is maintained, by using an acoustic wave as a properly measuring means for measuring an object and method thereof. [Means for Solving the Problem] A property measuring device 100 for measuring a measurement object of the present invention includes: an acoustic wave emitting portion 40 arranged away from a measurement object 90 and emitting an amplitude-modulated acoustic wave; a receiver 50 for receiving an electromagnetic field generated when the acoustic wave is emitted to the measurement object 90; and a measuring portion 60 for extracting at least one type of properties selected from a group consisting of an electric property, a magnetic property, an electromechanical property, and a magnetomechanical property of the measurement object 90, based on at least one measurement selected from a group consisting of measurements of a strength, a phase, and a frequency of the electromagnetic field.

A method is provided for determining at least one material characteristic of a magnetizable metal body by means of a micromagnetic sensor arrangement, which comprises at least one excitation coil having a magnetic core for signal excitation and at least one receiver. The body is magnetized by the sensor arrangement via current or voltage excitation of the sensor arrangement, which comprises at least one sign change between a positive part of a half-wave and a negative part of a half-wave. At least one signal is measured in the receiver, and the signal is Fourier transformed. The material characteristic are determined from at least one Fourier component. The excitation is turned off, and the post-oscillation of the signal is measured in the receiver. At least the part of the signal resulting from the post-oscillation in the Fourier transformation is used.

One measurement device 100 of the present invention comprises: a sound-wave transmission unit 120 that transmits sound waves to a measurement object 10; detection units 130A, 130B that detect electro-magnetic fields which are generated by the measurement object 10 as a result of the sound waves having been emitted from the sound-wave transmission unit, the electro-magnetic fields being from a plurality of mutually different directions or in a plurality of mutually different locations; and an evaluation unit 152 that evaluates characteristics pertaining to the anisotropy of the measurement object 10, on the basis of the results of detection of the electro-magnetic fields by the detection units 130A, 130B.

A magnetic property acquisition unit detects an induced voltage caused by vibration of a measurement sample magnetized by an excitation electromagnet and acquires a magnetic property that indicates a relationship between a magnetic flux density and an external magnetic field. The magnetic flux density is a sum of magnetization of the measurement sample and the external magnetic field. When acquiring the magnetic property of the measurement sample to which pressure is being applied, a control device sets a first magnetic field value as a sweep start value, and performs sweeping with a magnetic field equal to or less than the first magnetic field value. The first magnetic field value is smaller than a second magnetic field value that is acquired before the pressure is applied to the measurement sample, and corresponds to a saturation magnetic flux density of the measurement sample to which the pressure is not being applied.