The present invention provides compositions and methods for enhancing oil recovery from low permeability subterranean formation using three mechanisms: repressurization; reduction of interfacial tension; and increased permeability. The subject compositions comprise a chelating agent, a biosurfactant, a carbonate or bicarbonate salt, water, and a pH adjusting substance, which when applied to an oil-bearing formation according to the methods of the subject invention, allow for controlled release of carbon dioxide within the formation without complicated machinery or gas-producing microorganisms.

A particulate plugging agent, such as a diverting agent and/or loss circulation material, using a particular polyvinyl alcohol with a certain amount of monovalent metallic salt, which is water-soluble and has a buffer effect even if the environment is acidic, and thus stable, which in particular finds use in various subsurface oil production operations.

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.

In one aspect, a method for plugging a bore includes pumping a slurry composition comprising a swellable phyllosilicate clay in an amount of 70 wt % or less into the bore, and permitting compaction of the phyllosilicate clay in the slurry to plug the bore.

In one aspect, a method for plugging a bore includes pumping a slurry composition comprising a swellable phyllosilicate clay in an amount of 70 wt % or less into the bore, and permitting compaction of the phyllosilicate clay in the slurry to plug the bore.

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.

A method and a drill bit (11) for sealing a blasthole wall (31) are disclosed. The method comprises drilling a blasthole to a rock by a drill bit (11) connected to a hollow drill rod (10); flushing the drill bit (11) and the hollow drill rod (10) via at least one flushing orifice (19); providing a sealant to the hollow drill rod (10); and releasing the sealant to the blasthole wall (31) while lifting the drill bit (11). The drill bit (11) comprises a flushing orifice (19) and a sealant orifice (12), wherein the flushing orifice (19) is below the sealant orifice (12); and the method comprises covering the flushing orifice (19) after completing drilling the blasthole; providing the sealant to the drill bit (11); and releasing the sealant via the sealant orifice (12) while lifting the drill bit (11).

A method and a drill bit (11) for sealing a blasthole wall (31) are disclosed. The method comprises drilling a blasthole to a rock by a drill bit (11) connected to a hollow drill rod (10); flushing the drill bit (11) and the hollow drill rod (10) via at least one flushing orifice (19); providing a sealant to the hollow drill rod (10); and releasing the sealant to the blasthole wall (31) while lifting the drill bit (11). The drill bit (11) comprises a flushing orifice (19) and a sealant orifice (12), wherein the flushing orifice (19) is below the sealant orifice (12); and the method comprises covering the flushing orifice (19) after completing drilling the blasthole; providing the sealant to the drill bit (11); and releasing the sealant via the sealant orifice (12) while lifting the drill bit (11).

Embodiments of the disclosure include swellable smart gel sealants and methods of using smart gel sealants. In certain embodiments, the smart gel sealants reversibly swell when exposed to a certain trigger, such as carbonic acid and/or sulfuric acid. In specific embodiments, the smart gel is comprised within a cement composition.