Method of producing resin composite with required thermal and mechanical properties to form a durable well seal in applications

A method of sealing an opening in a well bore, comprising:

• predicting or determining an ambient temperature at a sealing location of the well bore to be sealed;
• formulating, based at least in part on an available delivery system for a sealant to seal the well at the sealing location thereof, a distance of the sealing location from a mixing location thereof, and the well bore temperature at the sealing location thereof, a composite sealant, the formulating of the composite sealant further comprising;
• selecting a fluid material which undergoes an exothermic reaction to change the composite sealant from a fluid to a solid state;
• and
• selecting and intermixing one or more solids with the fluid material to form the composite sealant, wherein the composite sealant has at least one of the following properties:
• a thermal expansion factor of 45 or less;
• an exothermic factor of 1.1 or less;
• a heat flow factor of 5.5 or less;
• a heat duration factor of 55 or less;
• or
• a set time/cool down factor of 1.0 or less;
• wherein the composite sealant can be located at the sealing location in the well bore before hardening of the composite sealant into the solid state.