Water Swellable Cement Sheath on Demand, with Sensing Capability

Abstract

A method of sealing propagating cracks in a sensor-laden cement sheath comprising the steps of monitoring an electrical resistivity of the sensor-laden cement sheath to produce a measured value, wherein the sensor-laden cement sheath comprises a conductive sensor, an on-demand expanding agent, and a cement, activating a heat source when the measured value of the electrical resistivity is greater than an activation threshold, increasing a temperature of the sensor-laden cement sheath with the heat source to an activation temperature, wherein the activation temperature is operable to initiate a reaction between the on-demand expanding agent and water, wherein the activation temperature is greater than a formation temperature, reacting the on-demand expanding agent with water to produce a swelled agent, wherein the swelled agent occupies a greater volume than the on-demand expanding agent, and sealing the propagating cracks in the sensor-laden cement sheath with the swelled agent.

The invention claimed is: 
     
         1 . A composition to produce a sensor-laden cement sheath, the composition comprising:
 a conductive sensor, the conductive sensor operable to create an electrically conductive network;   an on-demand expanding agent, the on-demand expanding agent operable to react with water; and   a cement.   
     
     
         2 . The composition of  claim 1 , wherein the conductive sensor is selected from the group consisting of carbon nanotubes, carbon fibers, graphene, metal fibers, and combinations of the same. 
     
     
         3 . The composition of  claim 1 , wherein the on-demand expanding agent is selected from the group consisting of magnesium oxide, calcium oxide, and combinations of the same. 
     
     
         4 . The composition of  claim 1 , further comprising water-filled vesicles. 
     
     
         5 . The composition of  claim 1 , further comprising thermite. 
     
     
         6 . The composition of  claim 1 , further comprising a metal oxide-type superabsorber. 
     
     
         7 . The composition of  claim 1 , further comprising encapsulated expanding agents.