Well assembly monitoring

A method of monitoring the size and/or shape of a wellbore of a subsea well assembly, the method comprising:

• providing a subsea well assembly comprising:
• a well foundation fixed to the seabed and defining a wellbore location prior to drilling a wellbore;
• and
• a sensor fixed to the well foundation before drilling the well bore and casing installation;
• and
• monitoring the size and/or shape of the wellbore during initial drilling of the wellbore before casing installation using the sensor,
• wherein the sensor is for monitoring the earth underneath the sensor and/or obliquely to the sensor.

A subsea well assembly, the subsea well assembly comprising:

• a well foundation configured to be fixed to the seabed and to define a wellbore location;
• and
• a sensor fixed to the well foundation before drilling of the wellbore and casing installation;
• and
• wherein the sensor is for monitoring earth underneath the well foundation before and/or during installation of the well foundation for identifying a suitable location for the well foundation to be installed.

A method of monitoring the earth underneath a well foundation of a subsea well assembly, the method comprising:

• providing a well foundation configured to be fixed to the seabed and to define a wellbore location prior to drilling a wellbore;
• providing a sensor fixed to the well foundation before drilling of the wellbore and casing installation;
• monitoring the earth underneath the well foundation using the sensor before and/or during installation of the well foundation;
• and
• identifying a suitable location for the well foundation to be installed using the sensor;
• and
• installing the well foundation.