Self-Adaptive Cement Systems

Abstract

A self-healing cement system includes cement, water and at least one additive that swells in contact with water from reservoir or from formation in the case of a structural failure in the set cement to provide a physical barrier in the zone of failure. Examples of such material include particles of super-absorbent polymer. These additives have the effect of making the cement self-healing in the event of physical failure or damage such as micro-annuli. The self healing property is produced by the contact of the water itself, the potential repair mechanism is thus activated if and when needed in case of start of loss of zonal isolation. Several super-absorbent polymers have been identified such as polyacrylamide, modified crosslinked poly(meth)acrylate and non-solute acrylic polymers.

1 . A composition for well cementing comprising: 
 i. a pumpable slurry of cement,    ii. water and    iii. a material having residual water-absorption properties after the setting of the cement, so that said material is susceptible to swell in contact with underground water in case of failure of the cement matrix.    
   
   
       2 . The composition of  claim 1 , wherein said material is a super-absorbent polymer.  
   
   
       3 . The cement system of  claim 1 , wherein the super-absorbent polymer is selected from the list consisting of polymethacrylate and polyacrylamide or a non-soluble acrylic polymers.  
   
   
       4 . The cement system of  claim 2 , wherein the super-absorbent polymer is added to the slurry dry-blended with the cement.  
   
   
       5 . The cement system of  claim 2 , wherein the super-absorbent polymer is added at a concentration between 0.05% and 3.2% by weight of cement.  
   
   
       6 . The cement system of  claim 2  further comprising a salt.  
   
   
       7 . The cement system of  claim 6 , wherein said salt is sodium chloride or calcium chloride.  
   
   
       8 . The cement slurry of  claim 2 , wherein the super-absorbent polymer is added under the form of particles ranging from 10 μm to 1500 μm.  
   
   
       9 . The cement system of  claim 1 , whereby the material is provided in a capsule that releases the material in response to exposure of the cement to at least one downhole parameter.  
   
   
       10 . The cement system of  claim 1 , whereby the material is provided in a capsule that releases the material when the cement matrix cracks.  
   
   
       11 . The cement system of  claim 1  further comprising at least one additive selected from the list consisting of dispersing agent, fluid loss control agent, set retarder, set accelerator and anti-foaming agent.  
   
   
       12 . The cement system of  claim 2  whereby the material is provided in a capsule that releases the material in response to exposure of the cement to at least one downhole parameter.  
   
   
       13 . The cement system of  claim 2  whereby the material is provided in a capsule that releases the material when the cement matrix cracks.  
   
   
       14 . The cement system of  claim 2  further comprising at least one additive selected from the list consisting of dispersing agent, fluid loss control agent, set retarder, set accelerator and anti-foaming agent.