Surfactant-retarded acid

Retarded acid systems can extend the length and number of wormholes. Such systems include slightly gelled acid, chemically modified acid, surfactant-retarded acid, emulsified acid, and foamed acid. However, the time it takes for acid to spend is still short in most cases. Usually, only the formation near the wellbore can be treated effectively. Thus, effective uniform matrix treatment beyond several feet from the wellbore is exceptional. 

Concrete may use plasticizers (e.g., sulphonated melamine and naphthalene formaldehyde condensates), air-entraining agents (aIkyI/aryl sulfonate surfactants), retarders (hydroxy carboxylic acids such as polyethylene glycol mono-p-nonylphenyl ether) and surface washes (benzalkonium chloride) (RAIA 1997). Little has been published on air emissions from concrete additives, their leaching into surface waters appearing to be of greater environmental concern (Ruckstuhl, 2001). 

To control the reaction rate of the acid, retarders such as alkyl sulfonates, alkyl phosphonates and alkyl amines are used to form hydrophobic films on carbonate surfaces. These protective films act as a barrier to slow acid attack. Another method involves the use of foaming agents to stabilize the carbon dioxide foam that is created when CO2 is released as a product of the acidetching reaction. This CO2 foam acts as a barrier to slow acid attack. Yet another method for controlling the acid activity in an oil well is the use of emulsions containing kerosene or diesel as the continuous oil phase and hydrochloric acid as the dispersed aqueous phase. Acid-in-oil emulsions are most commonly used because oil separates the acid from the carbonate surface (and from machine parts, thus reducing the level of corrosion). Moreover, acid reaction rates can be further decreased by surfactant retarders that increase the wettability of the carbonate surface for oil. 

Quite often, acid will form predominantly single wormholes from limited numbers of perforations, without significant branching. That is the case with strong acids, such as HCl. Weaker acids, such as carbox)dic acids (e.g., acetic add), and retarded acid systems tend to create more branching of wormholes, which is desirable but only to a certain extent. Retarded acid systems include viscosified acids (e.g., polymer- or surfactant-gelled acid, emulsified acid, and foamed acid) or chemically retarded (surfactant-retarded) acid. The nature of wormholes created depends on injection rate, temperature, and formation reaction characteristics as well. 

Add retardation can be accomplished by adding unique, usually oilwetting surfactants to acid. These surfactants coat pore surfaces, thereby temporarily preventing or slowing the rate of acid attack on the pore walls. These systems are desirable for the sake of their simplicity. Surfactant-retarded acid is useful in high-temperature appUcations as well. Both HCl and organic acids can be retarded with surfactant. 

Physically retarding acid reaction is accomphshed by thickening (viscosifying) the acid used. Viscous acids include polymer-gelled, surfactant-gelled, emulsified, and foamed acids. Combinations can also be used in addition, surfactant-retarded acid can be gelled or foamed. The intent of viscosifying acid is to slow the rate of acid diffusion outward, to the rock surfaces, and to reduce the rate of fluid loss from wormhole to unreacted matrix. Both of these effects work to increase live acid penetration distance. 

Retarded acid can be chemically retarded (surfactant retarded) slightly gelled or foamed... 

Surfactants have also been of interest for their ability to support reactions in normally inhospitable environments. Reactions such as hydrolysis, aminolysis, solvolysis, and, in inorganic chemistry, of aquation of complex ions, may be retarded, accelerated, or differently sensitive to catalysts relative to the behavior in ordinary solutions (see Refs. 205 and 206 for reviews). The acid-base chemistry in micellar solutions has been investigated by Drummond and co-workers [207]. A useful model has been the pseudophase model [206-209] in which reactants are either in solution or solubilized in micelles and partition between the two as though two distinct phases were involved. In inverse micelles in nonpolar media, water is concentrated in the micellar core and reactions in the micelle may be greatly accelerated [206, 210]. The confining environment of a solubilized reactant may lead to stereochemical consequences as in photodimerization reactions in micelles [211] or vesicles [212] or in the generation of radical pairs [213]. 

An electric conductive rubber base containing carbon black is laminated with an electric conductive cover layer of phosphoric acid ester plasticizer and other ionic surfactants to prepare antistatic mats, where the covers have colors other than black. It is also reported that alkyl acid phosphates act as color stabilizer for rubber. Small amounts of phosphate esters are helpful in restoring reclaimed rubber to a workable viscosity [284,290]. Esters of phosphoric acid are used in the production of UV-stable and flame-retarded alkylbenzenesulfonate copolymer compositions containing aliphatic resins and showing a high-impact strength... 

SFC-FID is widely used for the analysis of (nonvolatile) textile finish components. An application of SFC in fuel product analysis is the determination of lubricating oil additives, which consist of complex mixtures of compounds such as zinc dialkylthiophosphates, organic sulfur compounds (e.g. nonylphenyl sulfides), hindered phenols (e.g. 2,6-di-f-butyl-4-methylphenol), hindered amines (e.g. dioctyldiphenylamines) and surfactants (sulfonic acid salts). Classical TLC, SEC and LC analysis are not satisfactory here because of the complexity of such mixtures of compounds, while their lability precludes GC determination. Both cSFC and pSFC enable analysis of most of these chemical classes [305]. Rather few examples have been reported of thermally unstable compounds analysed by SFC an example of thermally labile polymer additives are fire retardants [360]. pSFC has been used for the separation of a mixture of methylvinylsilicones and peroxides (thermally labile analytes) [361]. 

By adding an oil-wetting surfactant to an acid, one can promote the temporary formation of a film on formation surfaces thus reducing the rate of rock dissolution. Acids containing these surfactants are known as chemically retarded acids. 

Emulsion oxidation of alkylaromatic compounds appeared to be more efficient for the production of hydroperoxides. The first paper devoted to emulsion oxidation of cumene appeared in 1950 [1], The kinetics of emulsion oxidation of cumene was intensely studied by Kucher et al. [2-16], Autoxidation of cumene in the bulk and emulsion occurs with an induction period and autoacceleration. The simple addition of water inhibits the reaction [6], However, the addition of an aqueous solution of Na2C03 or NaOH in combination with vigorous agitation of this system accelerates the oxidation process [1-17]. The addition of an aqueous phase accelerates the oxidation and withdrawal of water retards it [6]. The addition of surfactants such as salts of fatty acids accelerates the oxidation of cumene in emulsion [3], The higher the surfactant concentration the faster the cumene autoxidation in emulsion [17]. The rates of cumene emulsion oxidation after an induction period are given below (T = 353 K, [RH] [H20] = 2 3 (v/v), p02 = 98 kPa [17]). 

The sulfoxidation of aliphatic hydrocarbons is the easiest method for the synthesis of alkylsulfonic acids. Their sodium salts are widely used as surfactive reactants in technology and housekeeping. Platz and Schimmelschmidt [1] were the first to invent this synthetic method. Normal paraffins (Ci4-Cig) are used for the industrial production of alkylsulfonic acids [2-4]. Olefins and alkylaromatic hydrocarbons do not produce sulfonic acids under the action of sulfur dioxide and dioxygen and retard the sulfoxidation of alkanes [5-9],... 

In recent studies, Friberg and co-workers (J, 2) showed that the 21 carbon dicarboxylic acid 5(6)-carboxyl-4-hexyl-2-cyclohexene-1-yl octanoic acid (C21-DA, see Figure 1) exhibited hydrotropic or solubilizing properties in the multicomponent system(s) sodium octanoate (decanoate)/n-octanol/C2i-DA aqueous disodium salt solutions. Hydrotropic action was observed in dilute solutions even at concentrations below the critical micelle concentration (CMC) of the alkanoate. Such action was also observed in concentrates containing pure nonionic and anionic surfactants and C21-DA salt. The function of the hydrotrope was to retard formation of a more ordered structure or mesophase (liquid crystalline phase). 

Anomolous results have been observed in some emulsion polymerizations—inverse dependencies of N, Rp, and Xn on surfactant concentration. Some surfactants act as inhibitors or retarders of polymerization, especially of the more highly reactive radicals from vinyl acetate and vinyl chloride [Okamura and Motoyama, 1962 Stryker et al., 1967]. This is most apparent with surfactants possessing unsaturation (e.g., certain fatty acid soaps). Degradative chain transfer through allyl hydrogens is probably quite extensive. 

Abstract There is a growing demand for hydrolyzable surfactants, i.e., sirnfactants that break down in a controlled way by changing the pH. Environmental concern is the main driving force behind current interest in these sirnfactants, but they are also of interest in applications where sirnfactants are needed in one stage but later undesirable at another stage of a process. This chapter summarizes the field of hydrolyzable sirnfactants with an emphasis on their more recent development. Surfactants that break down either on the acid or on the alkaline side are described. It is shown that the susceptibility to hydrolysis for many surfactants depends on whether or not the surfactant is in the form of micelles or as free unimers in solution. It is shown that whereas nonionic ester sirnfactants are more stable above the CMC (micellar retardation), cationic ester surfactants break down more readily when aggregated than when present as unimers (micellar catalysis). 

Perfluoroalkyl compounds have been manufactured since the 1950s.The total production of fluorinated surfactants (anionic, cationic and neutral) was 2001 in 1979, whereas in 2000 the total production of PFOS (perfluorooctane sulfonate) alone was nearly 3000t (Shoeib et al., 2004). Together with PFOA (perfluoroocta-noic acid), PFOS is used in refrigerants, surfactants, fire retardants, stain-resistant coatings for fabrics, carpets and paper and insecticides. Surface treatments, such as protection of clothing and carpets constitute the largest volume of PFOS production (Moriwaki, Takata and Arakawa, 2003). PFOA as well is present in several... 

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