An emulsifier with high temperature resistance, low viscosity and low corrosiveness, and an emulsified acid system comprising the same. The emulsifier includes a viscoelastic surfactant, which is prepared by a quaterization of fatty acid acyl propyl dimethylamine and a halogenated compound; by a quaterization of a long-chain halogenated hydrocarbon and a tertiary amine compound; or by a reaction of the fatty acid acyl propyl dimethylamine with a linking group synthesized by epichlorohydrin and an alkylamine compound.

A method and reactive treatment fluid for treating a wellbore for filter cake removal, including providing the reactive treatment fluid having a viscoelastic surfactant (VES) into a wellbore in a subterranean formation and attacking the filter cake via the reactive treatment fluid.

A method and hydraulic fracturing fluid that is a viscoelastic surfactant (VES) fracturing fluid having a surfactant and an inorganic oxidizer salt for hydraulic fracturing of a geological formation. The VES fracturing fluid is provided through a wellbore into the geological formation to hydraulically fracture the geological formation to form hydraulic fractures in the geological formation. The method includes oxidizing organic material in the hydraulic fractures with the VES fracturing fluid.

Acidizing treatments for carbonate reservoir may include a surfactant comprising one or more of C.sub.8-C.sub.30-alkyloxyglycoside-substituted hydroxysultaine, C.sub.8-C.sub.30-alkylamidopropyl hydroxysulfobetaine, poly(diallyldimethylammonium chloride), C.sub.8-C.sub.30-alkyl amido alkylamine oxide, C.sub.8-C.sub.30-alkyl-amido amine oxide, C.sub.8-C.sub.30-alkyl amine oxide, C.sub.8-C.sub.30-alkyl aryl amine oxide, C.sub.8-C.sub.30-alkyl polyether phosphate, C.sub.8-C.sub.30-alkyl polyether phosphonate, C.sub.8-C.sub.30-alkyl ether phosphonate, C.sub.8-C.sub.30-alkyl amido ammonium propyl sulfonate, C.sub.8-C.sub.30-alkyl amido ammonium vinyl sulfonate, C.sub.8-C.sub.30-alkyl ether sulfonate, C.sub.8-C.sub.30-alkyl amido ammonium propyl sulfonate, C.sub.8-C.sub.30-alkyl ether sulfonate, alpha olefin sulfonate, C.sub.8-C.sub.30-alkyl benzene sulfonate, C.sub.8-C.sub.30-alkyl ethoxy carboxylate, C.sub.8-C.sub.30-alkylphenol ethoxylate carboxylate, and C.sub.8-C.sub.30-alkyl amido ammonium carboxylate. These acidizing treatments may also include an aqueous acid solution or mixture. In these acidizing treatments, the surfactant may be configured to partially or fully adsorb on a carbonate formation to retard the partial dissolution of the formation. Corresponding methods of reducing the reactivity of acidizing treatment may include introducing these acidizing treatments into wellbores such that the acidizing treatments contact carbonate formations.

Viscoelastic compositions suitable for use as diversion agents in a process for acidizing a carbonate-based subterranean oilfield formation are disclosed. The compositions comprise water, a tall oil fatty acid (TOFA)-based amidoamine betaine, a C.sub.1-C.sub.4 alcohol, and propylene glycol. The invention includes an acidizing process that utilizes a mineral acid and an effective amount of the viscoelastic composition. The viscoelastic compositions effectively divert acid flow, thereby optimizing acid utilization and minimizing acid spend. The compositions fully develop formations, stabilize and/or promote formation of worm-like micelles, and maintain a high, stable viscosity during an acidizing process. Surprisingly, the compositions perform well at low surfactant does, high pressures, and temperatures greater than 350° F. The compositions can tolerate higher levels of corrosion inhibitors than known alternatives and can be used in formations having ferric ion contents greater than 10,000 ppm.

A steeply-inclined ultra-thick coal seam gas control method based on a binary composite liquid. The method includes taking a clean fracturing fluid system and a microemulsion as a binary composite liquid. The method includes injecting the binary composite liquid into a coal mass by means of a main hydraulic fracturing and permeability improvement method of hydraulic fracturing and water jet slotting to form a coal mass gas extraction system of binary composite liquid fracturing and permeability improvement. The method includes investigating and analyzing a gas control effect of the steeply-inclined ultra-thick coal seam according to change characteristics and analysis of gas extraction flow rate, change characteristics and analysis of permeability coefficient of coal seam, change characteristics and analysis of gas natural desorption speed of coal mass, change characteristics and analysis of gas concentration of return air flow of working face and theoretical analysis of drilling cuttings index.

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.

A variety of systems, methods and compositions are disclosed, including, in one method, a method may comprise providing a proppant-free fracturing fluid; providing a proppant composition, wherein the proppant composition comprises proppant particulates and degradable thermoplastic particulates; introducing the proppant-free fracturing fluid into a subterranean formation at an injection rate above a fracture gradient to create or enhance at least one fracture in the subterranean formation; introducing the proppant composition into the at least one fracture; and allowing the proppant composition to form a proppant pack in the fracture, wherein the degradable thermoplastic particulates are degradable to generate voids in the proppant pack.

Described herein are methods for treating a subterranean formation penetrated by a wellbore with a retarded acidizing fluid containing an acid and an acid retarding agent, the concentrations of which are adjusted based on measured parameter values of the formation. Also described is a method for treating a subterranean formation by introducing an acid to the formation following the introduction of an acid retarding agent to the formation. Also described is a method for acid fracturing a subterranean formation including reducing the concentration of an acid retarding agent contained in a retarded acidizing fluid over the course of the acid fracturing operation.

A method of recycling a direct emulsion wellbore fluid may include disrupting a direct emulsion comprising an aqueous external phase and an oleaginous internal phase, wherein the direct emulsion is stabilized by a surfactant composition; and separating the aqueous phase and the oleaginous phase.