Amidoamine-based gemini surfactants having dual chains connected via an alkenylene or alkynylene linker. Each chain contains a quaternary ammonium head group and an ethoxylated alkyl tail. A water-based drilling fluid containing the gemini surfactant is also provided. As examined by linear swelling and free swelling tests, the gemini surfactant is effective in reducing clay swelling.

A wellbore fluid including a first surfactant, a second surfactant, an activator and an aqueous base fluid is provided. The first surfactant has a structure represented by Formula (I): ##STR00001## where Y.sub.1, Y.sub.2, Y.sub.3, Y.sub.4 are each, independently, a sulfonate, a carboxylate, an ester or a hydroxyl group, m is an integer ranging from 2 to 3, and n, o, and k are each, independently, integers ranging from 2 to 10. The second surfactant has a structure represented by Formula (III): ##STR00002## where R.sub.2 is a C.sub.15—C.sub.27 hydrocarbon group or a C.sub.15—C.sub.29 substituted hydrocarbon group, R.sub.3 is C.sub.1—C.sub.10 hydrocarbon group, and p and q are each, independently, an integer ranging from 1 to 4. A method of using the wellbore fluid for treating a hydrocarbon-containing formation is also provided.

A biocide blend can be used in an oil or gas operation. The biocide blend can include a first biocide of a formaldehyde-releasing biocide and a second biocide of a quaternary ammonium compound. The formaldehyde-releasing biocide can release formaldehyde after introduction into a wellbore. The first and second biocide can possess at least one property that is the same. The first biocide and/or the second biocide can maintain biocidal activity for extended periods of time in high salinity wellbore fluids, be thermally stable, and less expensive than other biocides.

Methods and compositions comprising an emulsion or a microemulsion for use treating an oil and/or gas well are provided. In some embodiments, the emulsion or the microemulsion comprises an aqueous phase, a solvent, a surfactant comprising alkyl polyglycoside, an alcohol, and, optionally, one or more additives.

Draw compounds and draw solutions comprising said draw compounds for use in forward osmosis solvent purification systems. The draw compound may be a linear random, sequential, or block molecular chain consisting of at least one oxide monomer or diol monomer and have a temperature-dependent affinity with a feed solvent. The draw compound may further include a first terminal group and a second terminal group, at least one of the first terminal group and the second terminal group selected from the group consisting of a hydroxyl group, an amine group, a carboxylic group, an allyl group, and a C1 to C14 substituted and unsubstituted alkyl group. The draw compound may also be a branched random, sequential, or block molecular chain consisting of at least one oxide monomer or diol monomer.

Fracturing fluid comprising, in solution in water, a proppant and an associative amphoteric polymer, the said polymer and comprising: 0.01 to 10 mol % of at least one cationic monomer containing a hydrophobic chain, from 0.09 to 89.99 mol % of at least one anionic monomer, and from 10 to 99.9 mol % of at least one nonionic water-soluble monomer, the total amount of monomer being 100 mol %. Fracturing process using this fluid.

Methods of reducing drag in a flowing hydrocarbon include introducing to the flowing hydrocarbon an amount of a solid drag reducing additive effective to improve the flow, the solid drag reducing additive including a polymer particle prepared from at least one polar monomer and a percent by weight (wt%) of liquid of 50 wt% or less. Methods also include producing a solid drag reducing additive that includes forming a polymer from at least one polar monomer by emulsion polymerization; and disrupting the emulsion by adding at least one demulsifier and at least one anti-blocking agent to form the solid drag reducing additive. Compositions include a solid drag reducing additive comprising a polymer prepared from at least one polar monomer and having an average particle size in a range of about 100 .Math.m to about 500 .Math.m, wherein the solid drag reducing additive comprises less than 50 wt% of liquid.

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 multicomponent nanocapsule composition comprising a core particle, an oil phase encapsulating the core particle, and an aqueous phase in which the encapsulated core particle is suspended is provided. The porous particle includes a cationic surfactant encapsulated in a porous particle. The oil phase includes an anionic surfactant and a zwitterionic surfactant. A method of making a multicomponent nanocapsule composition is also provided. A method of treating a hydrocarbon-bearing formation with the multicomponent nanocapsule composition is provided. The method may include providing a multicomponent nanocapsule composition, introducing the multicomponent nanocapsule composition into the hydrocarbon-bearing formation, displacing hydrocarbons from the hydrocarbon-bearing formation by contacting the multicomponent nanocapsule composition with the hydrocarbons, and recovering the hydrocarbons.

The subject invention provides multi-functional biochemical compositions, as well as their use in enhancing oil recovery from an oil-bearing subterranean formation. Advantageously, the compositions and methods of the subject invention are operationally-friendly, cost-effective, and environmentally-friendly. More specifically, in preferred embodiments, the subject invention provides a multi-functional composition for enhanced oil recovery (EOR) comprising one or more surfactants, one or more chelating agents, and one or more solvents.