Deformation measurement method and apparatus

A method for measuring deformation of an elongate body defining an axis, the method including, in a processing device:

• a) determining, from a sensor connected to an end of an optical fibre, sensed electromagnetic radiation received from first and second strain sensitive optical fibre portions, the first strain sensitive optical fibre portion being coupled to the body and at least partially aligned at a first angle relative to the axis, and the second strain sensitive optical fibre portion being coupled to the body and at least partially aligned at a second angle relative to the axis, the second angle being opposite to the first angle relative to the axis, wherein the second strain sensitive optical fibre portion is a portion of the same optical fibre as the first strain sensitive optical fibre portion;
• and,
• b) determining deformation of the body using the sensed electromagnetic radiation, the deformation including any axial or torsional deformation.

A method for measuring deformation of a portion of tubing for use in a drilling operation, the method including, in a processing device:

• a) determining, from a sensor connected to an end of an optical fibre, sensed electromagnetic radiation received from first and second strain sensitive optical fibre portions, the first strain sensitive optical fibre portion being coupled to the portion of tubing and at least partially aligned at a first angle relative to an axis of the tubing, and the second strain sensitive optical fibre portion being coupled to the portion of tubing and at least partially aligned at a second angle relative to the axis of the tubing, the second angle being opposite to the first angle relative to the axis, wherein the second strain sensitive optical fibre portion is a portion of the same optical fibre as the first strain sensitive optical fibre portion;
• and,
• b) determining deformation of the portion of tubing using the sensed electromagnetic radiation, the deformation including any axial or torsional deformation.