System and method for wellbore monitoring

A system for monitoring a borehole in an earth formation, comprising:

• a borehole string configured to be disposed within the borehole, the borehole string configured to direct a fluid between the borehole and the earth formation;
• at least one optical fiber sensor disposed on the borehole string at a fixed location relative to the borehole string and including a plurality of measurement units disposed therein along a length of the optical fiber sensor, the at least one optical fiber sensor configured to measure at least one of a strain and a deformation in the borehole string;
• at least one of a distributed temperature sensing (DTS) sensor and a distributed discrete temperature sensing (DDTS) sensor disposed along a length of the borehole and configured to measure a temperature at a plurality of locations along the length;
• and
• a processor configured to interrogate the at least one optical fiber sensor to generate a strain profile of the borehole string based on at least one of the strain and the deformation, interrogate the at least one of the DTS sensor and the DDTS sensor to generate a temperature profile based on the temperature, calculate a thermal effect on the strain profile based on the temperature profile, and subtract the thermal effect from the strain profile to generate a physical strain profile.

A method of monitoring a borehole in an earth formation, comprising:

• disposing a borehole string within the borehole, the borehole string configured to direct a flow of fluid into the earth formation for storage in the earth formation, the fluid including carbon dioxide;
• transmitting an interrogation signal having a nominal wavelength into at least one optical fiber sensor, the optical fiber sensor disposed on the borehole string at a fixed location relative to the borehole string and including a plurality of measurement units disposed therein along a length of the optical fiber sensor;
• receiving a plurality of return signals reflected by the plurality of measurement units, calculating at least one of a strain and a deformation of the borehole string based on a wavelength shift associated with each of the plurality of return signals and generating a strain profile of the borehole string based on at least one of the strain and the deformation;
• interrogating at least one of a distributed temperature sensing (DTS) sensor and a distributed discrete temperature sensing (DDTS) sensor disposed along a length of the borehole to measure a temperature at a plurality of locations along the length, and generating a temperature profile based on the temperature;
• and
• calculating a thermal effect on the strain profile based on the temperature profile, and subtracting the thermal effect from the strain profile to generate a physical strain profile.