A method of sealing a well includes selecting a preexisting fluid pathway between a production platform and a desired sealing location in the well to be sealed, determining, for the well to be sealed, a desired quantity of sealant having known flow qualities, to be delivered in fluid form to the well in the sealing region of the well, determining, based on the flow qualities of the sealant in fluid form and the flow qualities of the preexisting fluid pathway, the time needed to deliver the desired quantity of the sealant in fluid form to the sealing location in the well, determining, based on the time needed to deliver the desired quantity of the sealant in fluid form to the sealing location in the well, whether the sealant will maintain the fluid form, if necessary, change one or more qualities of the sealant so that the desired quantity of the sealant will reach the sealing location in the well while in the fluid form, and transport the quantity of sealant, in fluid form, through the preexisting fluid pathway between a production platform and the desired sealing location in the well to be sealed.

Wellbore synthesis techniques are disclosed suitable for use in geothermal applications. Embodiments are provided where open hole drilled wellbores are sealed while drilling to form an impervious layer at the wellbore/formation interface. The techniques may be chemical, thermal, mechanical, biological and are fully intended to irreversibly damage the formation in terms of the permeability thereof. With the permeability negated, the wellbore may be used to create a closed loop surface to surface geothermal well operable in the absence of well casing for maximizing thermal transfer to a circulating working fluid. Formulations for the working and drilling fluids are disclosed.

Dual-purpose additives that may be used as viscosifying agents and surface active agents in fluids, subterranean treatments and oilfield operations are provided. In one embodiment, the methods comprise: providing a treatment fluid comprising a base fluid and a polymeric dual-purpose additive comprising a base polymer comprising a plurality of monomer units, and one or more hydrophobic groups bonded to at least one of the monomer units; introducing the treatment fluid into at least a portion of a subterranean formation; and depolymerizing at least a portion of the dual-purpose additive to form one or more surface active fragments, each of the surface active fragments comprising one or more of the hydrophobic groups bonded to one or more of the monomer units.

Dual-purpose additives that may be used as viscosifying agents and surface active agents in fluids, subterranean treatments and oilfield operations are provided. In one embodiment, the methods comprise: providing a treatment fluid comprising a base fluid and a polymeric dual-purpose additive comprising a base polymer comprising a plurality of monomer units, and one or more hydrophobic groups bonded to at least one of the monomer units; introducing the treatment fluid into at least a portion of a subterranean formation; and depolymerizing at least a portion of the dual-purpose additive to form one or more surface active fragments, each of the surface active fragments comprising one or more of the hydrophobic groups bonded to one or more of the monomer units.

This disclosure relates a method of reducing water production in a wellbore, which may include introducing an alkaline nanosilica dispersion to the wellbore such that it contacts a water producing zone of the wellbore, introducing a sodium bicarbonate activator to the wellbore such that it contacts the alkaline nanosilica dispersion in the water producing zone, and forming a gelled solid from the water shutoff material in the water producing zone, thereby reducing water production in the wellbore.

The effectiveness of expansive cement systems may be diluted when, during a well cementing operation, commingling takes place between the cement slurry and a spacer fluid, a drilling fluid, or both. Incorporating expansive agents in the spacer fluid or drilling fluid may reduce or negate the loss of expansion at the cement slurry/spacer interface or the cement slurry/drilling fluid interface, thereby promoting zonal isolation throughout the cemented interval.

A wellbore treatment fluid comprising: a base fluid; and an additive comprising: a first polymer bundle selected from the group consisting of cellulose nanofibrils, cellulose nanocrystals, and combinations thereof; and a second polymer, wherein the second polymer attaches to the first polymer bundle by a non-covalent mechanism. A method of treating a portion of a wellbore comprising: introducing the treatment fluid into the wellbore.

A wellbore treatment fluid comprising: a base fluid; and an additive comprising: a first polymer bundle selected from the group consisting of cellulose nanofibrils, cellulose nanocrystals, and combinations thereof; and a second polymer, wherein the second polymer attaches to the first polymer bundle by a non-covalent mechanism. A method of treating a portion of a wellbore comprising: introducing the treatment fluid into the wellbore.

Remediation of a hydrocarbon producing well bore in a subterranean formation includes injecting fluid containing self-degrading particulates into the well bore in order to stop production of hydrocarbon from the well bore prior to commencement of remedial operations and to temporarily seal the well bore from fluid transmission between the well bore and the formation prior to commencement of the remedial operations, and commencing the remedial operations upon the well bore. Examples of the remedial operations include injecting weighted fluid into the well bore, inserting a down-hole tool into the well bore, casing treatment, annulus treatment, well bore wall treatment, cementing, and refracturing. For refracturing, the fluid containing the self-degrading particulates can be injected until a down-hole pressure exceeds a fracture breakdown pressure of new fractures that will be produced by a perforating tool lowered into the well bore.

A method for reducing lost circulation in a subterranean formation. The method includes providing a treatment fluid comprising a base fluid and a lost circulation material comprising red mud. The treatment fluid is introduced into a wellbore within the subterranean formation such that at least a portion of the red mud bridges openings in the subterranean formation to reduce loss of fluid circulation into the subterranean formation.