Wellhead assembly and method

A method for removing or replacing a sensor unit located in a port of a wellhead having a port plug assembly mounted thereon, the port plug assembly comprising:

• the sensor unit comprising a sensor, the sensor unit having first connection elements configured for sealingly and removably mounting of the sensor unit in the port of the wellhead of a hydrocarbon well;
• a spool unit having a through-channel extending between a first end and a second end of the spool unit, second connection elements arranged in the through-channel;
• a flange, the flange configured for sealingly mounting the spool unit to the wellhead such that the through-channel is aligned with the port;
• a plug comprising third connection elements configured for sealingly and removably engaging the second connection elements and fix the plug in the through-channel;
• a transmitter unit arranged in the sensor unit and comprising a wireless signal transmitter;
• and
• a receiver unit arranged on the spool unit and comprising a wireless signal receiver,
• the method comprising:
• mounting a placement and removal tool and a valve unit to the second end and aligning a channel of the valve unit to the end opening;
• inserting an arm of the tool into the spool unit;
• operating the arm to disengage the plug from the spool unit;
• withdrawing the arm and the plug out of the spool unit;
• inserting the arm into the spool unit;
• operating the arm to disengage the sensor unit from the port;
• and
• withdrawing the arm and the sensor unit out of the spool unit.

A method for installing a sensor unit in a port of a wellhead having a port plug assembly mounted thereon, the port plug assembly comprising:

• the sensor unit comprising a sensor, the sensor unit having first connection elements configured for sealingly and removably mounting of the sensor unit in the port of the wellhead of a hydrocarbon well;
• a spool unit having a through-channel extending between a first end and a second end of the spool unit, second connection elements arranged in the through-channel;
• a flange, the flange configured for sealingly mounting the spool unit to the wellhead such that the through-channel is aligned with the port;
• a plug comprising third connection elements configured for sealingly and removably engaging the second connection elements and fix the plug in the through-channel;
• a transmitter unit arranged in the sensor unit and comprising a wireless signal transmitter;
• and
• a receiver unit arranged on the spool unit and comprising a wireless signal receiver,
• the method comprising:
• mounting a placement and removal tool and a valve unit to the second end and aligning a channel of the valve unit to the end opening;
• inserting an arm and the sensor unit into the spool unit and operating the arm to mount the sensor unit inside the port;
• and
• inserting the arm and the plug into the spool unit and operating the arm to mount the plug inside the spool unit.