Inductive pressure transducer

An apparatus for sensing pressure within a tubular member, the apparatus comprising:

• a power supply;
• an oscillator for receiving electrical power from the power supply and generating an alternating current in response thereto;
• an inductor coil for receiving the alternating current and inducing a magnetic field in response thereto;
• the inductor coil being positioned adjacent to an exterior portion of the tubular member for passing the magnetic field into the exterior portion to magnetically couple the inductor coil to the tubular member;
• and
• a detector circuit for sensing a change in the alternating current passing within the inductor coil in response to a pressure change within the tubular member, and for generating an output signal in response thereto.

An apparatus for sensing pressure within a subsea wellhead housing, the apparatus comprising:

• a power supply;
• an oscillator for receiving electrical power from the power supply and generating an alternating current in response thereto;
• an inductor coil for receiving the alternating current and inducing a magnetic field in response thereto;
• an exterior portion of the subsea wellhead housing having a blind hole formed therein, the blind hole having a base which defines a surface of the subsea wellhead housing;
• the inductor coil being sealingly mounted within the blind hole, separated from the base by an air gap, for passing the magnetic field into the exterior portion to magnetically couple the inductor coil to the subsea wellhead housing;
• a detector circuit for sensing an amplitude of the alternating current passing within the inductor coil, which varies in proportion to pressure within the subsea wellhead housing, and for generating an output signal in response to the amplitude of the alternating current;
• and
• means for processing the output signal to provide a readout of the fluid pressure within the subsea wellhead housing.

An apparatus for monitoring fluid pressure within a subsea wellhead housing, the apparatus comprising:

• a power supply;
• a rigid member disposed exteriorly about the subsea wellhead housing and radially spaced therefrom such that any radial movement of the subsea wellhead housing due to the fluid pressure therein will not cause any radial movement of the rigid member;
• a plurality of inductive sensors disposed interiorly about said rigid member, separated from an exterior surface of the subsea wellhead housing by a gap;
• the inductive sensors for receiving electrical power from the power supply and emitting magnetic fields in response thereto, the magnetic fields passing in the gap between the rigid member and the subsea wellhead housing;
• detector circuit for sensing an amount of energy transferred by the magnetic field, and generating an output signal which indicates the amount of energy transferred by the magnetic field, the amount of energy transferred by the magnetic field varying in response to changes in dimension of the gap and in response to changes in the fluid pressure within the subsea wellhead housing;
• and
• means for processing the output signal to determine the fluid pressure within the subsea wellhead housing.

A method for monitoring fluid pressure within a tubular member, the method comprising the steps of:

• positioning an inductive coupling means in proximity to an exterior portion of the tubular member;
• providing electrical power to the inductive coupling means;
• emitting a magnetic field from the inductive coupling means to magnetically couple the inductive coupling means to the tubular member for transferring energy therebetween;
• sensing a net energy transferred between the inductive coupling means and the tubular member;
• generating an output signal which indicates the net energy transferred between the inductive coupling means and the tubular member, which is indicative of the fluid pressure within the tubular member;
• and
• processing the output signal to determine the fluid pressure within the tubular member.