Multiple charged cationic compounds, which are derived from polyamines through an aza-Michael addition with an α, β-unsaturated carbonyl compound, in a clay treatment composition to reduces clay swelling, clay migration, and sludge formation in a subterranean formation in oil and gas operations are provided. The disclosed methods or compositions are found to be more effective than those methods or compositions commonly used for reducing clay swelling, clay migration, and sludge formation.

A tight oil reservoir CO.sub.2 flooding multi-scale channeling control system and a preparation method, including nanoscale CO.sub.2 responsive worm-like micellar systems and micron-scale CO.sub.2 responsive dispersion gel, are provided. The nanoscale CO.sub.2 responsive worm-like micelle system is prepared by CO.sub.2 reactive monomers and organic anti-ion monomers stirred in water. The micron-scale CO.sub.2 responsive dispersion gel is made of acrylamide, a responsive monomer, a silane coupling agent modified hydroxylated multi-walled carbon nanotubes as raw materials, cross-linked in water. The tight oil reservoir CO.sub.2 multi-scale channel control system, has strong flow control ability during CO.sub.2 displacement, and high-strength carbon nanotubes are introduced into the micro-scale CO.sub.2 responsive dispersion gel, which effectively improves the strength and long-term stability of the dispersion gel, significantly enhances the sealing effect on cracks, and after displacement of the CO.sub.2 of the system, the worm-like micelles revert to spherical micelles with good responsive reversibility.

A tight oil reservoir CO.sub.2 flooding multi-scale channeling control system and a preparation method, including nanoscale CO.sub.2 responsive worm-like micellar systems and micron-scale CO.sub.2 responsive dispersion gel, are provided. The nanoscale CO.sub.2 responsive worm-like micelle system is prepared by CO.sub.2 reactive monomers and organic anti-ion monomers stirred in water. The micron-scale CO.sub.2 responsive dispersion gel is made of acrylamide, a responsive monomer, a silane coupling agent modified hydroxylated multi-walled carbon nanotubes as raw materials, cross-linked in water. The tight oil reservoir CO.sub.2 multi-scale channel control system, has strong flow control ability during CO.sub.2 displacement, and high-strength carbon nanotubes are introduced into the micro-scale CO.sub.2 responsive dispersion gel, which effectively improves the strength and long-term stability of the dispersion gel, significantly enhances the sealing effect on cracks, and after displacement of the CO.sub.2 of the system, the worm-like micelles revert to spherical micelles with good responsive reversibility.

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 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.

Provided is a quaternary ammonium surfmer, that may have the following general formula (I): N.sup.+—R.sup.1R.sup.2R.sup.3R.sup.4 (X.sup.−), where: R.sup.1 and R.sup.2 may independently be H or a C.sub.1-C.sub.3 alkyl, R.sup.3 may be a C.sub.19+ amidoalkyl group, R.sup.4 may be a C.sub.3-C.sub.6 alkyl having a terminal olefin double bond group, and X may be a halogen. Further provided is a method for synthesizing the quaternary ammonium surfmer and a method for recovering hydrocarbons from a subterranean formation that may include injecting a treatment fluid comprising the quaternary ammonium surfmer into the subterranean formation.

Provided is a quaternary ammonium surfmer, that may have the following general formula (I): N.sup.+—R.sup.1R.sup.2R.sup.3R.sup.4 (X.sup.−), where: R.sup.1 and R.sup.2 may independently be H or a C.sub.1-C.sub.3 alkyl, R.sup.3 may be a C.sub.19+ amidoalkyl group, R.sup.4 may be a C.sub.3-C.sub.6 alkyl having a terminal olefin double bond group, and X may be a halogen. Further provided is a method for synthesizing the quaternary ammonium surfmer and a method for recovering hydrocarbons from a subterranean formation that may include injecting a treatment fluid comprising the quaternary ammonium surfmer into the subterranean formation.

A polymeric surfactant for use in chemical enhanced oil recovery, including a terpolymer of a first non-ionic monomer, a second non-ionic monomer, and an ionic monomer, the first non-ionic monomer being a hydrophilic monomer and the second non-ionic monomer being a hydrophobic monomer, the ionic monomer being in a lower proportion than the first and second non-ionic monomers. A method of preparation of polymeric surfactants.

A polymeric surfactant for use in chemical enhanced oil recovery, including a terpolymer of a first non-ionic monomer, a second non-ionic monomer, and an ionic monomer, the first non-ionic monomer being a hydrophilic monomer and the second non-ionic monomer being a hydrophobic monomer, the ionic monomer being in a lower proportion than the first and second non-ionic monomers. A method of preparation of polymeric surfactants.

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.