A stable, aqueous composition containing a crosslinked, nonionic, amphiphilic polymer capable of forming a yield stress fluid in the presence of a surfactant is disclosed. The yield stress fluid is capable of suspending insoluble materials in the form of particulates and/or droplets requiring suspension or stabilization.

Amidoamine-based gemini surfactants having dual chains connected via an arylene or heteroarylene 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 polyacrylamide-based symmetric branched polymer surfactant and a process for preparing the same and use thereof are provided. The surfactant has an acrylamide structure unit, an anionic monomer structure unit, an optional non-ionic monomer structure unit, a branched structure unit, and an optional cationic monomer structure unit. The branched structure unit has at least one of structures represented by formula (1) or formula (2):

##STR00001##

The polymer surfactant can realize both the high viscosity of the aqueous solution and the low oil water interfacial tension, and can be used as the oil displacement agent in the tertiary oil recovery.

A wellbore fluid may include a gemini surfactant, a zwitterionic surfactant, an activator, and an aqueous base fluid. The gemini surfactant may have a structure represented by formula (I): ##STR00001## where R.sup.1 is a C.sub.1-C.sub.10 hydrocarbon group, m and o are each, independently, an integer ranging from 1 to 4, and n is an integer ranging from 8 to 12.

The present disclosure relates to delivery and release systems wherein a plurality of particles is provided, and the particles are formed of a vehicle component and a cargo component. The systems and methods particularly can be useful in delivery of various chemicals to a petroleum reservoir. The vehicle component can undergo a change in situ such that at least a portion of the cargo component is released.

The invention discloses a core-shell structured non-ionic nanoemulsion system and the preparation and use thereof. The system comprises a non-ionic gemini surfactant, an oil phase material, a solubilizer, and water; wherein the microemulsion has a core-shell structure, with the outer shell being the non-ionic Gemini surfactant, and the inner core being the oil phase material. The non-ionic Gemini surfactant is di(octylphenol polyoxyethylene ether)-substituted dicarboxylic acid diphenyl ether having the structural formula: ##STR00001## The non-ionic nanoemulsion system of the present invention is homogeneous and transparent, and has a spherical core-shell structure with nanometer-sized (3-40 nm) droplets, narrow particle size distribution, low tendency to agglomerate, good stability, and both an ultra-low interfacial tension and the ability to reduce viscosity of crude oil.

Amidoamine-based gemini surfactants having dual chains connected via an arylene or heteroarylene 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.

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 hydrocarbon well remediation/stimulation treatment based on an Y-Grade natural gas liquid injection fluid mixture, including prescribed amounts of gas, nanoparticles with wettability alteration properties, foaming agents (including nanoparticles with foam stabilization properties), and solvent additives. The fluid mixture may be tuned to address multiple factors contributing to production decline, such as liquid blockage, wettability properties, fines/debris/scale build-up and organic deposits, reservoir heterogeneity/permeability, and/or reservoir fluid and hydrocarbon compositions, resulting in hydrocarbon production enhancement. The treatment is typically applied with a Huff-n-Puff process, however may also be applied with a flooding process.

The anionic cocogem surfactant of formula (I) for an oil production process of increased efficiency

##STR00001##

wherein each R1 and R2 is independently selected from hydrogen or C1-C18 straight or branched alkyl optionally substituted by OH; each R3 is independently selected from hydrogen; C1-C25 straight or branched alkyl or alkenyl optionally comprising inter-chain amido-group; aromatic group optionally substituted by C1-C25, preferably C5-C20, more preferably C5-C15 straight or branched alkyl, preferably selected from phenyl and diphenylether; or C10-C20 straight or branched alkenyl, alkadienyl or alkatrienyl; Z is C1-C18 straight or branched alkylene optionally substituted by one or two C1-C6 alkyl or preferably C3-C6 cycloalkyl, optionally comprising (EO).sub.n and/or (PO).sub.m groups, wherein EO is ethylene-oxide i.e. —CH.sub.2CH.sub.2O—, and PO is propylene-oxide, i.e. —CH(CH.sub.3)CH.sub.2O—, wherein n and m is independently an integer of from 0 to 30 and n+m is an integer of from 1 to 30; and/or [NH(R4)].sup.+ quaternary ammonium, wherein R4 is hydrogen, C1-C6 alkyl, preferably methyl or ethyl; R5 is hydrogen or C1-C6 alkyl, preferably methyl or ethyl; An is one or more groups selected from SO.sub.3.sup.−, Cl.sup.− or CO.sub.2.sup.−; i is an integer of 0 or 1; p is an integer of 2 or 3; j is an integer of 2 or 3.