Patent Application
20150144535
The present disclosure relates generally to a method, and use of a surfactant, for reducing total acid number (TAN) in produced hydrocarbons. More specifically, the present disclosure relates to a method and/or a use of a surfactant for reducing TAN by forming a precipitate comprising at least some of the acid content from the produced hydrocarbons.
For transportation and refining of produced hydrocarbons it is generally preferable that the acid content in the produced hydrocarbons remains below a particular threshold in order to avoid or reduce corrosion of pipelines and refining facilities. Acids may include carboxylic acids such as naphthenic acids, and acids arising from H2S content in produced hydrocarbons, which may give rise to naphthenic and sulfidic corrosion. One way to quantify the acid content of produced hydrocarbons is by an acidity measurement which yields a Total Acid Number (TAN) for the produced hydrocarbon sample. Specifically, TAN is a measurement of the number of milligrams of potassium hydroxide required for neutralization of acids in a single gram of oil. Produced hydrocarbons may have a TAN number as high as 10-12 in some parts of the world. For transport and refinement, it may be desirable to have a TAN less than 1. In North America, TAN of 1.5-3 is common in produced hydrocarbons. A TAN greater than 1 can reduce the value of produced hydrocarbons.
Methods for reducing TAN may include, for example, caustic washing to remove naphthenic acids in gasoline and kerosene. However, this approach can fail when applied to heavier feedstocks with high TAN due to the formation of very stable emulsions. An approach by refineries involves reacting acid content with alcohols to reduce TAN, however, this process is reversible, which can diminish its effectiveness once the oil is further treated/refined. Acids can be destroyed by thermal treatment or cracking to generate carbon dioxide gas and low acid hydrocarbon content, however, some undesirable side reactions can occur resulting in the formation of sediments and gums that negatively impact the value of the crude. Adsorption on solid surfaces and the use of solvent extraction can also be approaches to extracting naphthenic acids from oil, however, losses in profits due to overall volume reduction can make such processes unattractive. Generally, treatments and processes for reducing high acid content in produced hydrocarbons add time and expense to transportation and refining operations.
A need exists to reduce the TAN in produced hydrocarbons, for example bitumen, to allow for transport and/or refining or processing of the bitumen with reduced or minimized corrosive effects on the associated transport, refining or processing equipment or components.
In one embodiment, a method of for reducing a total acid number (TAN) in produced hydrocarbons, is described, the method comprising: a) introducing a surfactant to the produced hydrocarbons to solubilize, associate, complex, or encapsulate acid in the produced hydrocarbons; separating the surfactant and solubilized, associated, complexed, or encapsulated acid from the produced hydrocarbons; and removing the surfactant and solubilized, associated, complexed, or encapsulated acid.
In a further embodiment of the method or methods outlined above, the surfactant solubilizes, associates, complexes, or encapsulates acid in the produced hydrocarbons at temperatures below a cloud point of the surfactant increasing the temperature above the cloud point to induce precipitation.
In a further embodiment of the method or methods outlined above, the introduced surfactant is soluble in the produced hydrocarbons at temperatures below a cloud point of the surfactant.
In a further embodiment of the method or methods outlined above, the surfactant hydrophilic-lipophilic balance (HLB) is about 1 to 8.
In a further embodiment of the method or methods outlined above, the cloud point is manipulated by addition of salt.
In a further embodiment of the method or methods outlined above, the salt is sodium chloride or ammonium sulfate.
In a further embodiment of the method or methods outlined above, the sodium chloride is added to or above a concentration of between about 30,000 ppm or 80,000 ppm.
In a further embodiment of the method or methods outlined above, the surfactant is precipitated by adjusting the temperature of the produced hydrocarbons to or above about 70° C.
In a further embodiment of the method or methods outlined above, in step b) the surfactant and solubilized, associated, complexed, or encapsulated acid are formed in an aqueous phase or intermediate phase for removal in step c).
In a further embodiment of the method or methods outlined above, in step b) the surfactant and solubilized, associated, complexed, or encapsulated acid are formed in a microemulsion for removal in step c).
In a further embodiment of the method or methods outlined above, the HLD of the produced hydrocarbons following step a) is adjusted to about 0 thereby forming the solubilized, associated, complexed, or encapsulated acid substantially in the intermediate phase.
In a further embodiment of the method or methods outlined above, the HLD of the produced hydrocarbons following step a) is adjusted to be negative thereby forming the solubilized, associated, complexed, or encapsulated acid substantially in the aqueous phase.
In a further embodiment of the method or methods outlined above, the acid is a carboxylic acid.
In a further embodiment of the method or methods outlined above, the produced hydrocarbons comprise oil, bitumen, diluted bitumen, crude, heavy oil or treated bitumen.
In a further embodiment of the method or methods outlined above, the surfactant is non-ionic.
In a further embodiment of the method or methods outlined above, the surfactant is an ethoxylated or propxylated alcohol, an alkyl polyglycoside, or a combination thereof.
In a further embodiment of the method or methods outlined above, the surfactant is a combination of two or more surfactants.
In a further embodiment of the method or methods outlined above, the introduced surfactant is mixed with the produced hydrocarbons prior to step b).
In a further embodiment of the method or methods outlined above, mixing of the introduced surfactant and the produced hydrocarbons is performed during step b).
In another embodiment, use of a surfactant for separating acid from produced hydrocarbon into an emulsion, microemulsion, intermediate phase, aqueous phase, or precipitate is described.
In a further embodiment of the use or uses outlined above, the surfactant is non-ionic. In a further embodiment of the use or uses outlined above, the acid is a carboxylic acid. In a further embodiment of the use or uses outlined above, the surfactant is an ethoxylated or propoxylated alcohol, an alkyl polyglycoside, or a combination thereof.
In a further embodiment of the use or uses outlined above, the surfactant is a combination of two or more surfactants.
In another embodiment, a method of separating acid from produced hydrocarbons, the method comprises a) introducing a surfactant to the produced hydrocarbons to solubilize, associate, complex, or encapsulate acid in the produced hydrocarbons; and b) forming an intermediate or aqueous phase comprising the surfactant and solubilized, associated, complexed, or encapsulated acid.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the attached Figures. The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
Described herein are methods, techniques, embodiments, systems and apparatuses for reducing total acid number (TAN) in produced hydrocarbons. It will be appreciated that the methods, uses and embodiments described herein are for illustrative purposes intended for those skilled in the art and are not meant to be limiting in any way. In certain non-limiting embodiments, the methods are capable of reducing the TAN in produced hydrocarbons, such as bitumen, and involve the use of a surfactant and take advantage of the cloud point characteristic of the surfactant by precipitating at least some of the acid in the produced hydrocarbons. Removal, or at least partial removal, of the precipitate thereby at least partially reduces the TAN. It will be appreciated that the methods, systems, apparatuses, techniques and embodiments described herein are for illustrative purposes intended for those skilled in the art and are not meant to be limiting in any way. All reference to dimensions, capacities, embodiments or examples throughout this disclosure, including the Figures, should be considered a reference to an illustrative and non-limiting embodiment or an illustrative and non-limiting example.
It will be appreciated that generally, surfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or the interfacial tension between a liquid and a solid. A surfactant can be classified according to the composition of its different chemical functional groups. The hydrophilic part of a surfactant is referred to as the head of the surfactant, while the hydrophobic part of a surfactant is referred to as the tail. Surfactants may be ionic, zwitterionic, or non-ionic. An ionic surfactant carries a net positive (cationic) or negative (anionic) charge that is balanced by a counter-ion of the opposite charge, e.g., benzalkonium chloride is cationic with a chloride counter-ion and sodium lauryl sulphate is anionic with a sodium counter-ion. A zwitterionic surfactant possesses a head with two oppositely charged groups, e.g., lecithin, making the surfactant neutral overall.
Without wishing to be limiting in any way, it is envisioned that some or all of the following steps may be performed when carrying out an embodiment of a method as illustrated in
It will be appreciated that the cloud point may be manipulated using known methods including but not limited to the addition or removal of salt and/or alcohol, in the produced hydrocarbons, the composition of the hydrocarbons, pH, etc.
In a further embodiment, mixing of the introduced surfactant and the produced hydrocarbons may be performed. In one embodiment, a mixing step may be performed during and/or after introduction of the surfactant to the produced hydrocarbons. In another embodiment, a mixing step may be performed during the step of precipitation. In yet another embodiment, mixing may be performed both during and/or after introduction of the surfactant to the produced hydrocarbons, and during the step of precipitation.
The flow chart in
A wide variety of surfactants are known in the art. Non-limiting examples of known surfactants may be found in, for example, Surfactants and Interfacial Phenomena, Rosen et al., 2012, John Wiley & Sons; Nonionic Surfactants: Alkyl Polyglucosides, Surfactant Science, Dieter Balzer & Harald Luders, eds., 2000, Taylor & Francis, Vol. 91; and Non-Ionic Surfactants, Pierce L. Wendt & Demario S. Hoysted, eds., 2010, Nova Science Publishers; which are incorporated herein by reference. The introduced surfactant may comprise a non-ionic surfactant, which may comprise a hydrophilic, uncharged head and a hydrophobic tail. In other embodiments, more than one surfactant may be used to achieve a reduction in TAN. For example, the surfactant may be an ethoxylated or propoxylated alcohol, such as Brij® 52 (polyethylene glycol hexadecyl ether) or Pluronic® L61 (a difunctional block copolymer surfactant terminating in primary hydroxyl groups), respectively. Additionally, the surfactant may optionally be an alkyl polyglycoside. In another embodiment, the surfactant may be a combination of surfactants used as a mixture or sequentially.
In a further embodiment, introduction of a surfactant to produced hydrocarbons may solubilize, complex, associate with, or encapsulate acid in the produced hydrocarbons in a temperature range that does not cross the cloud point of the surfactant. Typically, the acid in the produced hydrocarbons, for example bitumen, produced bitumen, treated or diluted bitumen, crude or heavy oil, includes a carboxylic acid, for example, a naphthenic acid.
Without wishing to be bound by theory, it is postulated that introduction of a non-ionic surfactant to produced hydrocarbons may solubilize, complex, associate with, or encapsulate acid in the produced hydrocarbons at temperatures below the cloud point of the surfactant. The non-ionic surfactant may comprise a polar moiety with an affinity for acids, and may form micelles which incorporate acid molecules. Acid content may not necessarily be captured at the centre of the micelles. Rather, acid molecules may form part of the micelles, given that acids are also polar species with some affinity for water and some affinity for oil. Typically, the acid may be a carboxylic acid such as naphthenic acid.
Those skilled in the art will recognize that the cloud point is a physical property of surfactants in a solution, and may be defined as a specific temperature at which the surfactant precipitates, creating a cloudy mixture. For non-ionic surfactants, reaching a cloud point of a solubilized surfactant may require heating. In other cases, or for other surfactants, other physical or chemical property changes may be used to precipitate the surfactant, for example, the introduction of one or more additional reagents and/or compounds, such as salts, may be used to precipitate the surfactant. In another embodiment, cooling or a pH change may be used to precipitate the surfactant.
The addition of salt may be used to precipitate the surfactant. For example, sodium chloride (NaCl) or ammonium sulfate ((NH4)2SO4) may be used to increase the salt content of the produced hydrocarbons, causing precipitation of the surfactant. In a further embodiment, increasing NaCl content in the produced hydrocarbons to more than about 30,000 ppm may be used to precipitate the surfactant.
Those skilled in the art will recognize that the surfactant may have an associated hydrophilic lipophilic balance (HLB) value. As will be appreciated to those skilled in the art, a lower HLB indicates a more oil-soluble (rather than water soluble) compound. In one embodiment, the surfactant may have an HLB value of between about 1 and about 8. However, some surfactants may have an HLB higher than 8, for example, Pluronic® 17R4.
As outlined herein, introduced surfactant may be precipitated from the produced hydrocarbons. In some embodiments, adjustment of the temperature of the surfactant/hydrocarbon mixture, for example by heating, to, or beyond, the cloud point of the surfactant may precipitate the introduced surfactant from the produced hydrocarbons. Alternatively, precipitation of the surfactant may be accomplished by any of a wide variety of known methods for precipitating a compound from a solution, some of which are described above. In some non-limiting embodiments, the surfactant may be precipitated through the addition of an additional reagent such as salt, referred to as “salting out”.
The precipitated surfactant, including precipitated acid, may then be removed from the produced hydrocarbons, wherein removal of the precipitated surfactant and by extension the precipitated acid reduces the TAN of the produced hydrocarbons. Precipitation of the surfactant may also precipitate some of the acid solubilized by, complexed with, associated with, encapsulated by, or part of the surfactant micelles.
It will be appreciated that suitable methods for removing a precipitate from a fluid may be used to remove the precipitated surfactant and/or acid from the produced hydrocarbons. Some non-limiting examples include filtration, gravity separation, distillation, centrifugation, decanting, electrostatic separation and related methods. In one embodiment, gravity separation in a separation vessel may be used for precipitate removal.
In another embodiment, TAN of produced hydrocarbons may be reduced by performing a method involving the following steps outlined in
In addition, mixing of the introduced surfactant and the produced hydrocarbons may be performed to help increase or optimize the effect of the surfactant and, in turn, TAN reduction.
For example, a mixing step may be performed during and/or after introduction of the surfactant to the produced hydrocarbons. Alternatively, a mixing step may be performed during the step of adjusting the temperature of the produced hydrocarbons to or above the cloud point of the surfactant. Further, mixing may be performed both during and/or after introduction of the surfactant to the produced hydrocarbons, and during the step of adjusting the temperature to or above the cloud point of the surfactant.
The flow chart shown in
Without wishing to be limited by theory, it should be understood that some embodiments of the TAN reduction methods disclosed herein may be performed having regard to hydrophilic-lipophilic deviation (HLD) considerations and may not be dependent on the cloud point but rather separation of the acid solubilized, associated, complexed, or encapsulated with the surfactant via the phase behaviour. This may be accomplished by capturing the surfactant with the solubilized, associated, complexed, or encapsulated acid in a separated phase from the oil, such as an aqueous or intermediate phase or in a emulsion or micro-emulsion.
The choice of surfactant, and the conditions used for TAN reduction (i.e. salt type and concentration in solution and/or added to the solution, the type of oil being processed, the temperature, and the type and concentration of alcohol(s) in and/or added to the solution) affect the HLD of the system, and can be selected so as to achieve a desirable HLD. Contrary to HLB, which is based on the surfactant, the HLD takes into account several different parameters of the system.
There are three phase behaviours common in oil, water and surfactant systems when they form a microemulsion. Two of these phase behaviours are outlined in
In some embodiments, it is desirable to achieve an HLD of, about, or near 0 (Winsor Type III). At an HLD of 0, there is no difference between the hydrophilic and lipophilic interaction energies (Quintero et al. (Optimization of Microemulsion Formulations with Linker Molecules, SPE 165207, 2013)); the surfactant has equal affinity for both the water and oil phases, and oil and aqueous phases separate from one another more quickly under these conditions. An HLD at or near 0 may be beneficial because it allows for separation of surfactant and solubilized, associated, complexed, or encapsulated acid generally formed in the intermediate phase from oil/water mixtures.
In some embodiments, the HLD may be negative (Winsor Type I) which generally results in the surfactant and solubilized, associated, complexed, or encapsulated acid microemulsions forming in the aqueous phase thereby reducing the TAN of the produced hydrocarbons.
A number of conditions can affect the HLD value of a system. The person of skill in the art will be familiar with HLD and how it is calculated (for example, see Salager et al. (Formulacion de microemulsiones por el Método del HLD, Techniques do I'Ingénieur, Vol. Génie des Procédés, articulo J2 157, 1-20 (2001)), Salager and Anton (Chapter 8: Ionic Microemulsions, Handbook of Microemulsion Science and Technology, P. Kumar and K. L. Mittal, eds., Marcel Dekker, New York (1999)), and Quintero et al. (Optimization of Microemulsion Formulations with Linker Molecules, SPE 165207, 2013), each of which is herein incorporated by reference).
For illustrative purposes, HLD may be determined in an oil/aqueous system having a surfactant comprising ethylene oxide unit(s) as follows:
HLD=α−EON+b(sal)−k(ACN)+t(ΔT)+a(A) (1)
where α, k, and t (ct in Tables 1 and 2) are constants related to the surfactant used;
EON refers to the number of ethylene oxide units per molecule of surfactant;
b is a constant of the salt in/added to the system;
sal is the salinity in mass percent in the aqueous phase of the system;
ACN is related to the type of oil/hydrocarbon and the number of carbon atoms in the oil/hydrocarbon, [Quintero et al. (Optimization of Microemulsion Formulations with Linker Molecules, SPE 165207, 2013)];
ΔT is the temperature difference relative to a reference temperature (25° C.);
A represents the weighted percentage of alcohol in/added to the system; and
a is a constant characteristic of the alcohol in/added to the system and the surfactant in/added to the system.
Values for the constants in equation (1) are known in the art, and may be found, for example, in Salager et al. (Formulacion de microemulsiones por el Método del HLD, Techniques do I'Ingénieur, Vol. Génie des Procédés, articulo J2 157, 1-20 (2001)), herein incorporated by reference.
A non-limiting illustrative embodiment may refer to a produced oil containing acid and some water, where the acid resides in the oil phase of the oil/water mixture. A non-ionic surfactant may be added to the oil/water mixture, the surfactant being water soluble. In one possibility, the temperature of the mixture may be increased, which may drive the surfactant into the oil phase where it can solubilize/interact with/capture the acid. When the cloud point of the surfactant is reached, the surfactant and associated acid may then precipitate out of solution in the aqueous phase, at which point the surfactant/acid component can be separated from the produced oil, resulting in a TAN reduction of the produced oil.
In a second possibility, the mixing of the surfactant with the oil/water mixture may produce an oil-in-water emulsion within which the surfactant may solubilize the acid content. When heating is used to reach the surfactant cloud point, the oil-in-water emulsion may destabilize, allowing the surfactant/acid component to precipitate out of solution in the aqueous phase, which can then be separated from the produced oil, resulting in TAN reduction of the produced oil.
It will be appreciated that water may be added to the methods described herein in order to provide for an aqueous phase if necessary or desired.
An example of a method for reducing TAN in bitumen is described in further detail below with reference to
As illustrated, in step 200 a surfactant, for example a non-ionic surfactant, such as an ethoxylated alcohol or propoxylated alcohol, is introduced to produced hydrocarbons [a], having a TAN higher than desired, to produce [b] a hydrocarbon and surfactant mixture. Production of [b] may optionally be assisted by a mixing step. The surfactant in the produced hydrocarbons may form micelles, containing, incorporated or associated to acid, for example a carboxylic acid. In step 210, a precipitation is performed to produce produced hydrocarbons containing a precipitate [c]. A mixing step may optionally be performed during step 210. This precipitation may be triggered by heating the solution to a temperature at or above the cloud point of the introduced non-ionic surfactant, producing a precipitate comprising the surfactant and at least some acid. In step 220, the precipitate is removed from the hydrocarbon and precipitate mixture [c], for example by way of centrifugation or gravity separation in a separation vessel, followed by, for example, skimming, decanting or filtration to produce [d] a hydrocarbon with a reduced TAN.
The method illustrated in the example described herein may be carried out for reducing the TAN of produced hydrocarbons using a surfactant. The produced hydrocarbons may be oil, bitumen, diluted bitumen, or treated bitumen, including bitumen which has been produced from a deposit, such as an oil sands reservoir, and treated or diluted as necessary or desired as would be appreciated by those in the art.
It will be appreciated that the produced hydrocarbons referred to herein may include any produced hydrocarbons including, but not limited to, heavy oil, bitumen, diluted bitumen, or treated bitumen that comprises an acid or acidic component.
It will be appreciated that reference to a surfactant herein encompasses embodiments wherein a single surfactant is intended or a combination of multiple surfactants used in combination or delivered, added, or solubilized sequentially. A combination of surfactants comprising non-ionic, cationic, anionic, or zwitterionic surfactants, or combinations thereof, may be used.
It will be appreciated that reference to precipitation herein encompasses embodiments wherein a precipitation encompasses a co-precipitation including a co-precipitation of surfactant and acid.
An example of surface facilities and processes for reducing TAN in bitumen/produced hydrocarbons is described in further detail below with reference to
As illustrated in the top section of the figure, degassing (i.e. separating gas from oil, water, or an oil/water emulsion), free water knockout (i.e. water separation from oil), and/or other treatment steps (i.e. further oil separation from water) may be performed on produced hydrocarbons (i.e. fluids produced from a hydrocarbon reservoir, optionally including oil/water emulsions and gases) in suitable surface facilities. At various points during hydrocarbon processing (for example, those denoted by a “*” in the top section of
Examples of TAN reduction using a surfactant (i.e. colloidal extraction) technique as described herein is described in further detail below and with reference to
EACN (Equivalent Alkane Carbon Number) Measurement Procedure:
Microemulsions were prepared by mixing 2 ml of aqueous phase and 2 ml of oil phase in 2 dram flat bottom vials. The aqueous phase was prepared by adding the ionic reference surfactant, 30% w/v NaCl solution, and deionized water. In the aqueous phase, the surfactant concentration was maintained at 10% w/v, whereas the amount of NaCl was varied from 0 to 25 g/100 ml. The oil phase consisted of mixtures of diluted bitumen oil (80% bitumen, 20% hexane), and toluene in 1:3, 1:1, 3:1, and 1:0 diluted bitumen oil to toluene mass ratios. All formulations in one data set were mixed and left to equilibrate at room temperature (24° C.) on a flat surface. The phase behavior was recorded after 2 weeks.
Phase Behavior Studies Procedure:
Microemulsions were prepared by mixing 2 ml of a sample of diluted bitumen oil and 2 ml of aqueous phase. The aqueous phase was prepared by adding a non-ionic surfactant, 40% w/v (NH4)2SO4 solution, deionized water, and NaOH solution (in some cases) to 2 dram flat bottom vials. In the aqueous phase, the surfactant concentration was maintained at 1 or 5 g/100 ml, whereas the amount of (NH4)2SO4 was varied from 0 to 21 g/100 ml. Subsequently, 2 ml of oil were added to each aqueous phase. All formulations in one data set were gently mixed 20 times and left to equilibrate at room temperature (24° C.) on a flat surface. Optimum salinities (S*) were identified as the middle phase bicontinuous μE where the excess phases separated in the shortest time. Optimum salinities were observed within the first 15-30 min after preparation. The overall separation time was about 6 hrs, but the phase behavior was recorded after 24 hr.
Results:
Results of TAN reduction and phase behaviour studies are outlined in
Table 1 contains data sets (scans) 1-5. In data set 1, BASF DOS surfactant was used at a concentration of 5 g surfactant/100 mL water, the temperature was 25° C., and no NaOH was used. Salt concentration (ammonium sulfate) was increased moving from vial 1-12. HLD values for each vial are provided. As shown in vial 1-8, TAN was reduced to 1.32 following treatment. Experimental vials are shown in
In data set 2, BASF DO5 surfactant was used at a concentration of 1 g surfactant/100 mL water, the temperature was 25° C., and no NaOH was used. Salt concentration (ammonium sulfate) was increased moving from vial 1-12. HLD values for each vial are provided. As shown in vials 2-7 and 2-8, TAN was reduced to 1.23 and 1.09, respectively. Experimental vials are shown in
In data set 3, BASF DO5 surfactant was used at a concentration of 5 g surfactant/100 mL water, the temperature was 25° C., and 0.0001M NaOH was used. Salt concentration (ammonium sulfate) was increased moving from vial 1-12. HLD values for each vial are provided. As shown in vials 3-7 and 3-9, TAN was reduced to 1.1-1.2 and 1.05-1.15, respectively. Experimental vials are shown in
In data set 4, BASF DO5 surfactant was used at a concentration of 5 g surfactant/100 mL water, the temperature was 70° C., and no NaOH was used. Salt concentration (ammonium sulfate) was increased moving from vial 1-12. HLD values for each vial are provided. As shown in vial 4-2, TAN was reduced to 0.95-1.05. Experimental vials are shown in
Table 2 contains data sets (scans) 6-8. In data set 6, Sasol TDA-6 surfactant was used at a concentration of 1 g surfactant/100 mL water, the temperature was 25° C., and no NaOH was used. Salt concentration (ammonium sulfate) was increased moving from vial 1-12. HLD values for each vial are provided. As shown in vials 6-5 and 6-7, TAN was reduced to 0.77 and 1.22, respectively. Experimental vials are shown in
In data set 7, Sasol TDA-6 surfactant was used at a concentration of 1 g surfactant/100 mL water, the temperature was 25° C., and 0.0001M NaOH was used. Salt concentration (ammonium sulfate) was increased moving from vial 1-12. HLD values for each vial are provided. As shown in vial 7-7, TAN was reduced to 1.2-1.3. Experimental vials are shown in
In data set 8, Sasol TDA-6 surfactant was used at a concentration of 1 g surfactant/100 mL water, the temperature was 70° C., and 0.0001M NaOH was used. Salt concentration (ammonium sulfate) was increased moving from vial 1-12. HLD values for each vial are provided. As shown in vials 8-1 and 8-2, TAN was reduced to 1.32 and 1.35, respectively. Experimental vials are shown in
As will be clear from the data and trends described above and in
Although not shown in the Tables, it should be noted that in certain embodiments, an alcohol may be added to the system. In these cases, the alcohol addition may allow desirable TAN reduction and/or phase behaviour properties to be achieved with the use of less surfactant.
One or more illustrative embodiments have been described by way of example. It will be apparent to persons skilled in the art that a number of variations and modifications can be made without departing from the scope of the invention as defined in the claims.
This application claims the benefit of priority of U.S. Provisional Patent Application No. 61/909,874 filed Nov. 27, 2013, which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61909874 | Nov 2013 | US |
