Equivalent alkane carbon number EACN

The assessment of surfactant structures and optimal mixtures for potential use in tertiary flooding strategies in North Sea fields has been examined from fundamental investigations using pure oils. The present study furthermore addresses the physico-chemical problems associated with reservoir oils and how the phase performance of these systems may be correlated with model oils, including the use of toluene and cyclohexane in stock tank oils to produce synthetic live reservoir crudes. Any dependence of surfactant molecular structure on the observed phase properties of proposed oils of equivalent alkane carbon number (EACN) would render simulated live oils as unrepresentative. 

Key words hydrophobic oils equivalent alkane carbon number (EACN) surfactant-enhanced remediation... 

Oil contaminants can range in both viscosity and molecular weight. The purpose of this work was to find optimal surfactant formulations to extract low viscosity ( ( 100 cp), high molecular weight (hydrophobic) oils. In surfactant formulation it is common to define the oil molecular weight (hydrophobicity) by virtue of its equivalent alkane carbon number (EACN) aka, how many carbons would there be in an alkane oil of equivalent behavior. Thus, since some crude oils behave similarly to hexane, and since hexane has an alkane carbon number of 6, these crude oils also have an... 

The mixing of a synthetic surfactant and a petroleum soap can be explained in terms of surfactant mixing rules proposed by Wade et al. in 1977 (53). These rules are based on previous studies (54) of the equivalent alkane carbon number (EACN) concept, which show that hydrocarbon behavior toward surfactants is additive and weighted by mole fraction according to the formula ... 

Equivalent Alkane Carbon Number (EACN) Each surfactant or surfactant mixture in a reference series will produce a minimum interfacial tension (IFT) for a different n-alkane. For any crude oil or oil component, a minimum IFT will be observed against one of the reference surfactants. The EACN for the crude oil refers to the n-alkane that would yield minimum... 

It has been established that the behavior of a hydrocarbon in microemulsion formulations can be characterized by its Equivalent Alkane Carbon Number (EACN) (22). This is the number of methylene and methyl carbons making up the molecule. The EACN for MMA should be two and has been determined as such in this laboratory. It is interesting that this correlation seems to apply also to the measured free energies of transfer. This suggests that this previously empirical correlation has a theoretical basis in thermodynamics. Further, in the Li phase, up to a MMA concentration of at least 0.5 M, the free energy of transfer is constant, indicating that the micelle structure is probably not too much different from that at very low MMA concentrations. 

Both oil compositions and surfactant constitutes are complex. Selecting a surfactant for an oil requires a lot of screening work. To make the screening work easier, Cayias et al. (1977) proposed the concept of equivalent alkane carbon number (EACN). EACN is the sum of the mole-fraction-weighted alkane carbon number (ACN) of each pure species, calculated from... 

The expertise with EOR was used for finding suitable microemulsion-forming systems for LNAPL. However, the high polarity of chlorinated hydrocarbons with very low or even negative equivalent alkane carbon numbers (EACN) required novel types of surfactants [56]. The enhanced solubility of surfactants in the oil phase makes most surfactants less effective for solubilisation. DNAPL extraction by mobilisation, however, is problematic owing to the high density of the pollutants, since they may be displaced into deeper soil compartments [57]. This probably happened in at least one field test [58]. 

The above summary of results has dealt entirely with interfacial tensions against alkanes. It is possible to infer a good deal from this about the probable performance of surfactants when employed against crude oils. The first step in the argument is to introduce the concept of equivalent alkane carbon number (EACN). 

The correlations were also extended to oil phases other than n-alkanes. In each case an equivalent alkane carbon number (EACN) was found, which means that any oil or oil mixture behaves similarly to a certain alkane [50]. 

Recently, there have been many studies to explore the selection of demulsifiers by more scientific and/or empirical means for matching the emulsion or oil with the demulsifier properties. Some advances as to what is useful and what is not have been made. Demulsifiers are required to have intermediate solubility in die crude oil or bitumen and not to form strong associations with oflier components of the crude. Sometimes the matching of RSN and equivalent alkane carbon numbers (EACNs) with BS W are used as selection tools. 

The more hydrophobic (e.g., long chain length) the oil phase, the higher is the Nqq value. In the case of non-alkane oils, an equivalent alkane carbon number (EACN) is used (Acosta and Bhakta 2009) ( )(A) or/(A) is a factor that takes into account the influence of co-surfactant. It is related to the partitioning of co-surfactant in the two phases. If there is no partitioning of co-surfactant observed in the formulation (e.g., using icc-butanol as noted earlier) or no co-surfactant is present in the system, c )(A) or/(A) is zero (Salager et al. 2005 Acosta and Bhakta 2009) Cj-and aj-are temperature factors, equal to 0.06 and 0.01 K", respectively AT is temperature difference from 25°C and CC is called characteristic curvature of the surfactant. Like HLB, CC is also a measure of the hydrophUicity of surfactant. However, the CC scale is different from that of HLB (Acosta et al. 2008). The smaller the CC value, the more hydrophilic is the surfactant (e.g., the CC value of sodium oleate is -1.7 whereas oleic acid has a CC value of 0) (Acosta et al. 2008). 

Ontiveros, J.F., C. Pierlot, M. Catte et al. 2013. Classification of ester oils according to their equivalent alkane carbon number (EACN) and asymmetry of fish diagrams of C10E4/ester oU/water systems. J Colloid... 

Figure 7.11 Macroemulsion inversion as a function of monolayer spontaneous curvature. The spontaneous curvature is varied by changing the ratio of two surfactants in mixture (a), by varying the equivalent alkane carbon number (EACN), i.e. by mixing two oils in different ratios (b). and by the addition of alcohol (c). All the system are studied over the 2—3—2 transition range see the bars at the top of the plots. The left-hand axis shows the macroemulsion lifetime, denoted as the time for the separation of two-thirds of the disperse phase by volume. The right-hand axis shows the macroemulsion conductivity. All emulsions were prepared at a 1 1 oil-to-water ratio other details of the compositions are shown on the plots. DDS and WITCO TRS10-80 are commercial surfactants (Reproduced by pemiission of Marcel Dekker Inc. from ref. 78)...

The Equivalent Alkane Carbon Number (EACN) is an empirical correlation which helps to evaluate the location of a balanced point for different emulsified oils and oil mixtures. The Calculation of Phase Inversion in Concentrates (CAPICO) method is similar to the EACN. 

It is worth noting here that this difference between the interface and in the bulk is not specific to surfactant mixtures. While oil mixtures of very similar substances, such as n-alkanes, exhibit a linear mixing rule written in terms of equivalent alkane carbon number or EACN [62-64], mixtures of oils containing substances with very different polarities behave in a non-ideal way and exhibit a segregation near the interface, which results in an accumulation most polar oil components close to the interface [65]. 

Crude oils were found to behave as an equivalent alkane as far as the attainment of optimum formulation was concerned. The equivalent alkane carbon number or EACN was then introduced to characterise pure hydrocarbons or mixtures [26]. The EACN of an oil phase is defined as the ACN of the alkane that results in the satisfaction of the correlation in the same conditions of surfactant, salinity, alcohol and temperature. EACN has been experimentally determined for n-alkanes mixtures, resulting in a linear mixing rule on a molar fraction basis, namely... 

For the work described here, n-alkanes are used as the oil phase. The results which these yield can be related to those for other oil structures, including complex mixtures, by employing the concenpt of equivalent alkane carbon number, or EACN (13). 

If the oil phase is not an alkane, but behaves similarly to an alkane, it is characterized by its equivalent alkane carbon number or EACN (136). It has been shown that on an ap-olarity scale, cyclohexane EACN is 3, alkylcyclohexane EACN is equal to its aUcyl group ACN plus 3, while benzene EACN is 0, and alkylbenzene EACN is equal to its aUcyl group ACN. As a matter of fact, the more polar the oil the lower its EACN. For instance the ethyl oleate EACN is about 6. Since it contains a chain, this means that the ester group accounts for a 12-unit reduction in the EACN. Complex hydrocarbon mixtiues can be assigned an EACN too, according to a simple mixing rule which is more or less followed (136,137). 

Alkane carbon number, equivalent (EACN) definition, 392 equation, 282... 

The nature of the oil. This was expressed as ACN (alkane carbon number for alkanes) and EACN (equivalent alkane number for non-alkanes)... 

---