Methods and systems for seismic sensors

Inventors: Masahiro Kamata, Francis Maissant
Original Assignee: Schlumberger Technology Corporation

Patent number: 8027225
Filing date: Mar 10, 2011
Issue date: Sep 27, 2011
Application number: 13/044,552

Methods and systems for determining coil eccentricity of seismic sensors configured or designed for use in seismic signal detection. A direct electrical current is applied to a moving coil of a seismic sensor such that the moving coil is dislocated from a neutral position relative to the magnetic field in the seismic sensor. A predetermined indicator is measured and eccentricity of the coil (δ) relative to the center of the magnetic filed is determined using the predetermined indicator.

Claims

What is claimed is:

1. A system for determining coil eccentricity of one or more seismic sensor configured or designed for use in seismic signal detection, comprising:

at least one seismic sensor, comprising:

a housing;

at least one magnet for creating a magnetic field mounted within the housing;

a moving coil mounted within the housing;

at least one spring assembly connected to the housing and the moving coil for supporting the moving coil for transduction within the magnetic field;

a digital signal processor in communication with the seismic sensor;

a set of instructions executable by the processor that, when executed:

applies to the moving coil of the at least one seismic sensor a direct electrical current such that the moving coil is dislocated from a neutral position relative to the magnetic field in the seismic sensor;

monitors a predetermined indicator relative to the dislocation of the coil from the neutral position; and

determines eccentricity of the coil (δ) relative to the center of the magnetic filed using the predetermined indicator.

2. A system for determining coil eccentricity of one or more seismic sensor according to claim 1, wherein the at least one seismic sensor is configured for positioning on one of on land, within a borehole and at a seabed.

3. A system for determining coil eccentricity of one or more seismic sensor according to claim 1, further comprising an adjustment mechanism for adjusting or correcting the eccentricity of the moving coil.

4. A system for determining coil eccentricity of one or more seismic sensor according to claim 1, wherein the set of instructions, when executed, further performs a step test after dislocating the moving coil from the neutral position.

5. A system for determining coil eccentricity of one or more seismic sensor according to claim 1, wherein the system is configured or designed for quality control (QC) activities during manufacture of the at least one seismic sensor.

6. A system for determining coil eccentricity of one or more seismic sensor according to claim 1, wherein the system is configured or designed for monitoring one or more of:

an amplitude of a response signal of the at least one seismic sensor based on natural oscillation of the moving coil of the seismic sensor;

a sound caused by the moving coil colliding with an end of the seismic sensor;

a waveform that is generated by contact of the moving coil with an end of the seismic sensor; and

total harmonic distortion (THD) of a signal output from the at least one seismic sensor.

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