Sealant compositions that may be used for creating fluid flow preventing barriers in a subterranean formation. A method may comprise reacting components comprising an oxazoline functionalized polymer and a crosslinking agent in a subterranean formation to create a barrier in the subterranean formation.

A method for zonal isolation in a subterranean formation includes identifying a zone of interest within the subterranean formation, determining a static temperature of the zone of interest, determining a time duration for gelation of a treatment fluid, determining a concentration of a cross-linker in the treatment fluid, determining a volume of the treatment fluid to be delivered to the zone of interest, determining a correlation between cooling of a wellbore near the zone of interest and a delivery rate of the treatment fluid, determining a target wellbore temperature, delivering a cooling stage until the target wellbore temperature is reached, and delivering a treatment stage. Delivering the cooling stage and the treatment stage results in forming, within the zone of interest, a gel that is impermeable to fluid flow.

A method for zonal isolation in a subterranean formation includes identifying a zone of interest within the subterranean formation, determining a static temperature of the zone of interest, determining a time duration for gelation of a treatment fluid, determining a concentration of a cross-linker in the treatment fluid, determining a volume of the treatment fluid to be delivered to the zone of interest, determining a correlation between cooling of a wellbore near the zone of interest and a delivery rate of the treatment fluid, determining a target wellbore temperature, delivering a cooling stage until the target wellbore temperature is reached, and delivering a treatment stage. Delivering the cooling stage and the treatment stage results in forming, within the zone of interest, a gel that is impermeable to fluid flow.

A method for enhanced oil recovery in a reservoir is provided. The method includes injecting a microsphere suspension, including polymeric microspheres dispersed in seawater, into an injection well in the reservoir and injecting a low salinity tailored water (SmartWater) into the injection well in the reservoir. Oil is produced from a production well in the reservoir.

A system and method for water shutoff, including providing a treatment fluid including a polymer and a nitrogen-generating compound through a wellbore into a water zone in a subterranean formation, generating nitrogen gas in the water zone by a reaction of the nitrogen-generating compound, generating foam from the nitrogen gas and the treatment fluid in the water zone to give foamed polymer in the water zone, and sealing the water zone with the foamed polymer.

A system and method for water shutoff, including providing a treatment fluid including a polymer and a nitrogen-generating compound through a wellbore into a water zone in a subterranean formation, generating nitrogen gas in the water zone by a reaction of the nitrogen-generating compound, generating foam from the nitrogen gas and the treatment fluid in the water zone to give foamed polymer in the water zone, and sealing the water zone with the foamed polymer.

A chemical gel system having a polymer and a silicon oxide Janus nanosheets crosslinker for treating thief zones in carbonate formations. The polymer and silicon oxide Janus nanosheets crosslinker may form a crosslinked polymer gel to reduce or prevent water production via thief zones during hydrocarbon production. The silicon oxide Janus nanosheets crosslinker includes a first side having negatively charged functional groups and a second side having amines. The negatively charged functional groups may include negatively charged oxygen groups and hydroxyl groups. Methods of reducing water production in a thief zone using the silicon oxide Janus nanosheets crosslinker and methods of manufacturing the silicon oxide Janus nanosheets crosslinker are also provided.

Provided herein are drilling muds, including water-based drilling muds. The components of the drilling muds are a degradable fluid loss additive, for example, synthetic degradable nanoparticles, a clay mineral, for example, a smectite, and a base fluid, for example, water. Also provide are methods for preventing leak-off during a drilling operation and for automatically cleaning-up filter cake after completion of a drilling process both of which utilize the drilling muds and water-based drilling muds.

Provided herein are drilling muds, including water-based drilling muds. The components of the drilling muds are a degradable fluid loss additive, for example, synthetic degradable nanoparticles, a clay mineral, for example, a smectite, and a base fluid, for example, water. Also provide are methods for preventing leak-off during a drilling operation and for automatically cleaning-up filter cake after completion of a drilling process both of which utilize the drilling muds and water-based drilling muds.

Methods and compositions for performing a sealing operation in a wellbore. An example method introduces a sealant composition into the wellbore while the sealant composition is under shear. The sealant composition comprises a thixotropic material, a conformance gel system, and an aqueous base fluid. The sealant composition is placed into a target location, and applied shear is reduced to the sealant composition when in the target location thereby allowing the sealant composition to thicken in the target location. Fluid flow across the target location is reduced by a fluid seal formed by the thickened sealant composition.