Methods and compositions for using geopolymers to create storable cementitious slurries used for oil and gas well cementing are provided. The methods of the present disclosure include providing a set-delayed geopolymer cement composition including a geopolymer; activating the set-delayed geopolymer cement composition; introducing the set-delayed geopolymer cement composition into at least a portion of a subterranean formation; and allowing the set-delayed geopolymer cement composition to set in the subterranean formation.

Methods for treating and restoring zonal isolation in a subterranean well involve the use of a well treatment tool that may drill one or more holes in casing and inject a treatment fluid that may seal cracks or fissures in the cement sheath behind the casing. Microannuli may also be sealed. The treatment fluids may be solids free or in the form of suspensions containing solids having a particle size between 1 nm and 100 nm.

Described are a method and composition which use microorganisms for downhole applications, in particular for the maintenance or restoration of the integrity of a cement sheath in a wellbore. The method of cementing a wellbore comprises preparing a cement composition comprising a pumpable slurry of cement, water and a healing agent that comprises one or more microorganisms, delivering the cement composition into the wellbore and allowing the cement composition to set. The method of restoring the integrity of a set cement composition in a wellbore comprises preparing a pumpable slurry that comprises water, a healing agent that comprises one or more microorganisms and optionally cement, pumping the slurry into the wellbore in and around the set cement composition, and allowing the one or more microorganisms to grow and replicate to thereby restore the integrity of the set cement composition. Compositions for carrying out the methods are also described.

The present invention includes well treatment fluids and methods utilizing nano-particles and, in certain embodiments, to sealant compositions and methods utilizing nano-particles. The nano-particles may be incorporated into the sealant composition in different forms, including as discrete nano-particles, encapsulated nano-particles, agglomerated nano-particles, or in a liquid suspension.

A variety of methods and compositions are disclosed, including, in one embodiment, a settable composition comprising: water; and a cementitious component having a calculated reactive index.

A cement composition is disclosed that includes a cement slurry and an epoxy resin system that includes at least one epoxy resin and a curing agent. The cement slurry has a density in a range of from 65 pcf to 180 pcf and includes a cement precursor material, silica sand, silica flour, a weighting agent, and manganese tetraoxide. The epoxy resin system includes at least one of 2,3-epoxypropyl o-tolyl ether, alkyl glycidyl ethers having from 12 to 14 carbon atoms, bisphenol-A-epichlorohydrin epoxy resin, or a compound having formula (I): (OC.sub.2H.sub.3)—CH.sub.2—O—R.sup.1—O—CH.sub.2—(C.sub.2H.sub.3O) where R.sup.1 is a linear or branched hydrocarbyl having from 4 to 24 carbon atoms; and a curing agent.

Cured cements, cement slurries, and methods of making cured cement and methods of using cement slurries are provided. The method of making a modified cement slurry includes adding particles comprising carbon nanotube sponges disposed on sacrificial templates to a cement slurry to form the modified cement slurry and allowing the sacrificial templates to disintegrate, thereby leaving the carbon nanotube sponges dispersed throughout the modified cement slurry.

A method and sealant to seal microcracks as small as 50 μm by causing methyl methacrylate combined with one or more nanoparticles to flow into the microcrack to be sealed.

Cured cements, cement slurries, and methods of making cured cement and methods of using cement slurries are provided. The cured cement comprises cement, carbon nanotube sponges disposed within the cement, and conductive fibers disposed within the cement, in which the conductive fibers interconnect the carbon nanotube sponges and form a conductive web within the cured cement.

A method includes introducing an epoxy resin system to a wellbore defect in a wellbore. The epoxy resin system comprises a polyhedral oligomeric silsesquioxane (POSS) epoxy resin with at least one reactive group and a curing agent. The method includes maintaining the epoxy resin system in the wellbore such that a cured epoxy resin system product forms in the wellbore defect.