An acid-generating fluid includes a thermally activated strong acid precursor. The thermally activated strong acid precursor can include a component selected from aldehydes, ketones, and combinations thereof, in combination with a precursor of a compound adapted to react to liberate sulfur dioxide; or it can include sulfur dioxide in combination with a precursor of a compound adapted to react to liberate a component selected from aldehydes, ketones, and combinations thereof.

Described are methods and compositions for treating a subterranean formation. The method comprising introducing into the subterranean formation via a well-bore a diverter composition, the diverter composition comprising a combination of at least one deformable particle and at least one non-deformable particle; and allowing the diverter composition to block the flow of at least a portion of a treatment fluid from a first location within the well-bore to a second location.

Described are methods and compositions for treating a subterranean formation. The method comprising introducing into the subterranean formation via a well-bore a diverter composition, the diverter composition comprising a combination of at least one deformable particle and at least one non-deformable particle; and allowing the diverter composition to block the flow of at least a portion of a treatment fluid from a first location within the well-bore to a second location.

Systems and methods for sealing a lost circulation zone associated with a subterranean well include a drill string with a circulating port and a lost circulation material. A lost circulation shape is a hollow body having an outer skin and an open interior chamber. The outer skin includes a plurality of perforations that extend through the outer skin, providing fluid communication between an exterior of the lost circulation shape and the open interior chamber. The plurality of perforations are sized to prohibit a passage of lost circulation material between the exterior of the lost circulation shape and the open interior chamber.

A reversible gel composition including nanosilica and polyethylene oxide, the nanosilica and polyethylene oxide present at concentrations operable to allow for the reversible gel composition to be a flowable liquid at pH greater than about 8 and operable to allow for the reversible gel composition to be a substantially solid gel at pH less than about 8.

A reversible gel composition including nanosilica and polyethylene oxide, the nanosilica and polyethylene oxide present at concentrations operable to allow for the reversible gel composition to be a flowable liquid at pH greater than about 8 and operable to allow for the reversible gel composition to be a substantially solid gel at pH less than about 8.

Polyacrylamide (PAM)-coated nanosand that may be a relative permeability modifier (RPM) and that is applied to treat a wellbore in a subterranean formation. The treatment may be for excess water production. The PAM-coated nanosand is PAM-hydrogel-coated nanosand. The PAM-coated nanosand os nanosand coated with PAM hydrogel. The PAM hydrogel includes crosslinked PAM in water. Application of the PAM-coated nanosand may reduce water production from the subterranean formation into the wellbore. The PAM hydrogel of the PAM-coated nanosand may expand in a water zone of the subterranean formation to restrict water flow into the wellbore. The PAM hydrogel of the PAM-coated nanosand may contract in an oil zone of the subterranean formation so not to significantly restrict crude oil flow into the wellbore.

Release of hydrochloric acid, hydrofluoric acid and fluoroboric acid into a well may be controlled by introducing into the well an aqueous fluid containing ammonium chloride, ammonium bifluoride, ammonium fluoroborate, ammonium tetrafluoroborate or a mixture thereof and a breaker. After being introduced into the well, the ammonium salt reacts with the breaker and the acid is released into the well.

Release of hydrochloric acid, hydrofluoric acid and fluoroboric acid into a well may be controlled by introducing into the well an aqueous fluid containing ammonium chloride, ammonium bifluoride, ammonium fluoroborate, ammonium tetrafluoroborate or a mixture thereof and a breaker. After being introduced into the well, the ammonium salt reacts with the breaker and the acid is released into the well.

A method is provided including: introducing a first diverter material comprising polyvinyl alcohol and a plasticizer into or adjacent to a permeable zone of a subterranean formation; introducing a second diverter material into or adjacent to the permeable zone of the subterranean formation, wherein at least a portion of the first diverter material comprises particles larger than particles of the second diverter material; and allowing the first diverter material and the second diverter material to at least partially divert at least a portion of a treatment fluid to a different portion of the subterranean formation.