Methods to monitor a metallic sealant deployed in a wellbore, methods to monitor fluid displacement, and downhole metallic sealant measurement systems

A method to monitor downhole fluid displacement, the method comprising:

• flowing a non-reacting fluid into a wellbore having a metallic sealant deployed along a section of the wellbore;
• exposing the metallic sealant to a reacting fluid to initiate a galvanic reaction;
• measuring, with a downhole temperature sensor deployed in the wellbore, a change in temperature due to heat released by the metallic sealant as a result of the galvanic reaction;
• determining an amount of expansion of the metallic sealant based on the change in the temperature;
• and
• determining a displacement of the non-reacting fluid based on the amount of expansion of the metallic sealant and as a result of the galvanic reaction.

A downhole metallic sealant measurement system, comprising:

• a metallic sealant deployed along a section of a wellbore, wherein a first galvanic reaction is initiated when the metallic sealant is exposed to a reacting fluid, and wherein the first galvanic reaction causes an expansion of the metallic sealant to isolate a section of the wellbore, wherein the metallic sealant is configured to expand as a result of being exposed to the reacting fluid;
• wherein the metallic sealant is configured such that the application of pressure to the metallic sealant exposes a previously unexposed section of the metallic sealant;
• wherein the exposure of the previously unexposed section of the metallic sealant to the reacting fluid initiates a second galvanic reaction;
• a temperature sensor positioned proximate to the metallic sealant and operable to determine a temperature change due to heat released as a result of the first galvanic reaction;
• wherein the temperature sensor is further operable to determine a temperature change due to heat released as a result of the second galvanic reaction;
• and
• a logging tool configured to determine an amount of expansion of the metallic sealant based on the temperature change and as a result of the first galvanic reaction;
• wherein the logging tool is further operable to determine an amount of expansion of the metallic sealant based on the change in the temperature caused by the second galvanic reaction.