Disclosed are a high-temperature-resistant tertiary amine-grafted silica nano-plugging agent and water-based drilling fluids, relating to oil-gas field drilling. The nano-plugging agent is prepared from a hydrazine compound, a diallyl compound, an enamine compound, silica particle, and an amino-containing silane coupling agent by stepwise reaction. The nano-plugging agent has a grain size of 58-280 nm.

A treatment fluid for performing one or more pre-cementing operations in a wellbore can include a base fluid, a viscosifier, and a crushed glass material. The viscosifier can be dispersed in the base fluid. The crushed glass material can be dispersed in the base fluid for performing one or more cementing operations with respect to the wellbore.

A wellbore fluid comprising an aqueous base fluid and a plurality of nanoparticles suspended in the aqueous base fluid. The nanoparticles are present in the wellbore fluid in an amount effective to have an effect of increasing the density by at least 0.2 lb/gal.

According to embodiments disclosed herein, a method of monitoring a gel fluid composite may include directing the gel fluid composite into a wellbore extending into a subsurface where the wellbore has one or more downhole fractures so that the gel fluid composite enters the one or more downhole fractures, transforming the gel fluid composite from an aqueous phase to a gel phase, irradiating light onto the gel fluid composite so that the fluorescent compounds emit one or more photons, and detecting the one or more photons using a detection device. The gel fluid composite may include a nanosilica gel that includes silica nanoparticles and an activator, wherein the silica nanoparticles have a maximum cross-sectional dimension of from 3 nm to 100 nm, and one or more fluorescent compounds, wherein the one or more fluorescent compounds are dispersed in the nanosilica gel, bonded to the silica nanoparticles, or both.

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.

A method includes disposing a device into a borehole in proximity to a subterranean formation where a filter cake has been formed adjacent thereto, the device comprising a support structure and a shape-memory article disposed at the support structure, the shape-memory article comprising a shape-memory polymer, wherein the device is disposed when the shape-memory article is in a compacted shape; exposing the shape-memory article to a fluid system to cause the shape-memory article to expand and conform to a surface of the borehole; exposing the filter cake to the fluid system; and removing the filter cake with the fluid system. The fluid system comprises a chelating agent, an activator, a non-emulsifier, and water or a brine.

A method of reducing lost circulation includes introducing a lost circulation solution comprising Saudi Arabian volcanic ash, a curing agent, and a resin into a subsurface formation through a wellbore, wherein the Saudi Arabian volcanic ash comprises SO.sub.3, CaO, SiO.sub.2, Al.sub.2O.sub.3, Fe.sub.2O.sub.3, MgO, and K.sub.2O; and allowing the lost circulation solution to thicken within the subsurface formation, thereby forming a barrier between the subsurface formation and the wellbore to reduce lost circulation.

The present specification refers to a patent of invention for a foam formulation and its use in the temporary plugging of pipes, where the foam has volumetric and time stability, is prepared from a solution containing surfactant, co-surfactant, alkaline substance and LDH nanoparticles, is able to have its viscosity increased over time and remain intact for 8 hours or more even under pressure differences of up to 0.1 bar and a temperature of 60° C. and then it is able to disperse simply by using water or even the fluid transported in the pipeline. The LDH nanoparticle reinforced foam of the present invention can be applied in pipes that need to be plugged when they are undergoing maintenance, either to prevent incandescent soldering splashes from coming into contact with an explosive atmosphere or to avoid contamination in the pipe interior, among other applications. The present invention belongs to (but is not limited to) the field of plugs for pipes with explosive atmospheres and can be applied in systems that require temporary plugs that can be easily remover by using water or another solvent.