System and method for sealing a well using controlled hydration expansion of a smectite-containing clay mineral

A method of controlled hydration expansion of a smectite-containing clay mineral (SCM) within an aqueous environment in a confined volumetric space within an underground well bore, the method comprising the steps of:

• introducing a positionable delivery body, which includes an amount of an SCM, and an amount of one or more introduced chemical substances, into said volumetric space via an inlet thereinto, the amount of said introduced chemical substances being arranged to react with one or more ionic materials found in solution in said aqueous environment to form a solid product, and to thereby cause a controlled reduction in ionic strength in said aqueous environment, wherein said controlled reduction in ionic strength in the aqueous environment in turn controls hydration expansion of said amount of the SCM into the aqueous environment by consequentially increasing a rate of release of particles of said SCM from the body, said hydration expansion being a movement of the SCM particles between a first condition of the SCM particles being in facing proximity to one another, and a second condition of the SCM particles being spatially separated from one another, and wherein movement from said first condition towards said second condition results in a change in pressure in the confined volumetric space;
• and
• introducing an aqueous flow path modification to limit movement of the SCM particles from the second condition to the first condition so as to maintain the change in pressure in said volumetric space resulting from movement of the SCM particles from the first condition to the second condition,
• wherein the one or more introduced chemical substances comprise either:
• an amount of each member of the group comprising ordinary Portland cement (OPC) and calcium sulfoaluminate cement (CSA), or
• an amount of each of the compounds in each of Group A and Group B, comprising
• Group A alite or tricalcium silicate (Ca3O5Si) (C3S);
• belite or dicalcium silicate (Ca2SiO4) (C2S);
• tri-calcium aluminate (3CaO Al2O3) (C3A);
• tetra-calcium aluminoferrite (4CaO Al2O3 Fe2O3) (C4AF);
• Group B belite or dicalcium silicate (Ca2SiO4) (C2S);
• gypsum or calcium sulfate n-hydrate (CaSO4·n-H2O);
• tetra calcium trialuminate sulfate (Ca4(AlO2)6SO3).