WO2014139027A1 - Utilisation d'agents complexants pour la libération contrôlée d'un agent tensioactif lors d'une opération de récupération d'hydrocarbures - Google Patents

Utilisation d'agents complexants pour la libération contrôlée d'un agent tensioactif lors d'une opération de récupération d'hydrocarbures Download PDF

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WO2014139027A1
WO2014139027A1 PCT/CA2014/050275 CA2014050275W WO2014139027A1 WO 2014139027 A1 WO2014139027 A1 WO 2014139027A1 CA 2014050275 W CA2014050275 W CA 2014050275W WO 2014139027 A1 WO2014139027 A1 WO 2014139027A1
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surfactant
composition
formation
hydrocarbon
sequestering agent
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PCT/CA2014/050275
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English (en)
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Laura ROMERO-ZERON
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University Of New Brunswick
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
    • C09K8/02—Well-drilling compositions
    • C09K8/03—Specific additives for general use in well-drilling compositions
    • C09K8/035—Organic additives

Definitions

  • compositions and methods suitable for use in delivery of surfactants in enhanced oil recovery are disclosed.
  • the carrier and/or delivery system includes a sequestering agent into which a surfactant is reversibly received.
  • Surfactants are used in enhanced oil recovery (EOR) processes.
  • EOR enhanced oil recovery
  • Chemically enhanced oil recovery typically involves use of a surfactant during oil production to aid mobilization of the oil trapped by capillary forces in oil reservoirs.
  • Surfactants can reduce the oil/water interfacial tension (IFT) to values of 10 "2 dyne/cm or lower (Morgan et al, 1 979; Hirasaki et al. 201 1 ; Romero-Zeron, L. 201 2).
  • IFT oil/water interfacial tension
  • surfactant effectiveness can be reduced by adsorption at e.g., rock surfaces at the solid/liquid interface (Gale et al., 1973; Green et al, 1998).
  • the inventor has established the feasibility of transporting surfactant into a subterranean oil reservoir and release into the reservoir at the oil saturation zones where it is needed for oil recovery through the use of a carrier.
  • a carrier is cyclodextrin (CD).
  • An example of an environment in which the composition is used is an underground hydrocarbon formation into which a surfactant would normally be injected to aid release of the hydrocarbon during a recovery operation. Because release of the surfactant from the carrier is controlled, a higher proportion of the surfactant can be carried to reach remote distances in the underground operation, where its surfactant properties are desired.
  • the experiments and results presented herein establish advantages obtainable through use of the invention in various contexts.
  • the present specification postulates underlying theories explaining how advantages of the invention are provided. Thus, without being limited to or bound by these theories, the present invention discloses a variety of products and methods for use in oil extraction, particularly in the area of enhanced oil recovery.
  • a surfactant usually has a hydrophobic portion.
  • An example of a sequestering agent is a cyclic molecule having a hydrophobic interior and a relatively hydrophilic exterior. The hydrophobic portion of the surfactant and the agent interior can interact such that the surfactant is reversibly received within the hydrophobic interior of the sequestering agent.
  • the cyclic molecule is a cycle of monosaccharides which form a generally torus-shaped molecule into the interior of which a surfactant tail is received.
  • Such cyclic polysaccharides preferably have at least six monosaccharides, and can be hexoses and/or pentoses.
  • the ring can contain e.g., six, seven or eight monosaccharide units covalently linked together. Specific examples are a-cyclodextrin, ⁇ -cyclodextrin and ⁇ -cyclodextrin.
  • the sequestering agent was ⁇ -cyclodextrin in which the cyclic (ring) oligosaccharides are separate molecules i.e., are not covalently linked to each other.
  • a liquid composition of the invention can include one or more surfactants.
  • the surfactants can be anionic, cationic, zwitterioinic, nonionic, or any combination thereof, by which is meant there can be one surfactant, or more than one, including different surfactants of the same type, different surfactants of multiple types, and different surfactants of the same type and multiple types.
  • a surfactant usually has a tail that has at least a portion that is hydrophobic. Such a hydrophobic portion can be a hydrocarbyl chain or group.
  • a "hydrocarbyl" radical is one which is made up of carbon and hydrogen atoms, specific examples being used in experiments described herein.
  • a hydrocarbyl group of a surfactant typically has at least six carbon atoms (C6), but can have 30 or more carbon atoms.
  • the group can be aliphatic, alicyclic, aromatic, aliphatic, etc.
  • the group can be straight chain or branched C6-C35 alkyl.
  • Disclosure of the range C6-C30 includes disclosure of intermediate members of the range, C7, C8, C9, C10, C1 1 , C1 2, C13, C14, C15, C1 6, C1 7, C18, C19, C20, C21 , C22, C23, C24, C25, C26, C27, C28, C29, C30, C31 , C32, C33 and C34, and this applies to other ranges disclosed throughout this specification such as ranges of components in compositions, temperature ranges, etc. Disclosure of such ranges is further intended to describe intermediate ranges, so C6-C30 also describes C8-C30, C10-C30, C12-C22, C12-C20, C14-C20, C14-C18, etc.
  • hydrocarbyl also includes C6-C30 cycloalkyl, alkylcycloalkyl and cycloalkylalkyl,C6-C18 alkyl aryl and arylalkyl, C6-C30 alkenyl, including alpha-alkenyl and internal alkenyl, and dienyl, trienyl, and C6-C30 alkynyl, including di- and tri-alkynyl.
  • the surfactant includes an anionic surfactant, as exemplified herein.
  • anionic groups are sulfate, a sulfonate, or a carboxylate group. These can be provided in the form of a salt, such as sodium dodecyl sulfate, or the acid form may become ionized when added to an appropriate aqueous medium.
  • the surfactant is or includes an anionic surfactant termed an internal olefin sulfonate, or "IOS". These include (C10-C35) alkenyl sulfonates.
  • the surfactant is or includes a sodium branched alcohol propoxylate sulfate (C n (PO) m S0 4 Na) for the values of n and m mentioned above.
  • the surfactant is one or more of those selected from ethylene oxide-propylene oxide-block polymers, ethoxylated surfactants, propylene oxide surfactants, mixtures of anionic and nonionic surfactants, zwitterionic surfactants, betaine amphoteric surfactants, ethoxylated cationic surfactants, alkyloxylate glycidyl ether sulfonates, alcohol based sulfonates, sodium methyl ester sulfonate, propoxylated sulfate, anionic alkylaryl surfactant based on olefin sulfonic acids, branched alpha olefin sulfonates (AOS), alcohol-alkoxy-sulfate, Guerbet alkkoxy sulfates, alkyl polyglycosides, and mixtures thereof.
  • AOS branched alpha olefin sulfonates
  • the sequestering agent can be selected to have minimum or nil adsorption onto the porous media of the formation, for example, sandstone and/or carbonate rocks.
  • Such determinations in particular instances can be made using media similar to that of the underground area, or of material obtained directly from the area of the formation of interest, by static and/or dynamic adsorption tests.
  • the static adsorption capacity of kaolin for the surfactant(s) of the composition when measured in aqueous NaCI (3 w ⁇ %) at 25°C is reduced by at least about 20%, or about 30%, or about 40%, or about 50%, or about 60%, or about 70%, or about 80% in comparison to the same composition absent the sequestering agent.
  • the static adsorption capacity of a mixture of 5% shale and 95% sand for the surfactant(s) of the composition when measured in aqueous NaCI (3 w ⁇ %) at 25 °C is reduced by at least about 20%, or at least about 30%, or at least about 40%, or at least about 50%, or at least about 60%, or at least about 70%, or at least about 80%, or at least about 90%, or at least about 92% in comparison to the same composition absent the sequestering agent.
  • a composition of the invention can also include a polymer as an additive as may typically be used, for example, in a downhole surfactant composition.
  • a polymer as an additive as may typically be used, for example, in a downhole surfactant composition.
  • Such polymer(s) can be present in a concentration of about 0.1 to about 2 w ⁇ % of the composition, or between about 0.1 and about 1 .5 w ⁇ %, or between about 0.1 and about 1 .0%.
  • Exemplary polymers include, but are not limited to any of the following including combinations thereof: a xanthan gum, scleroglucan, polyacrylamide (PAM), hydrolyzed polyacrylamides (HPAM),a copolymer containing AMPS and acrylamide monomers, a copolymer of vinylpyrrolidone and acrylamide, a ter-polymers of vinylpyrrolidone, acrylamide and acrylate, and a hydrophobically modified polymer.
  • PAM polyacrylamide
  • HPAM hydrolyzed polyacrylamides
  • association of the components can be characterized by the association constant, K a .
  • the K a of a surfactant and sequestering agent can be measured at 25 °C in an aqueous solution containing 1 .05 w ⁇ % total dissolved salts, can be at least 50, or at least 100, or at least 150, or at least 200, or at least 300, or at least 400, or at least 500, or at least 600 or at least 700, or can be between 200 and 900, or between 200 and 800, or between 200 and 700, or between 300 and 700, or between 400 and 700.
  • a sequestering agent of the invention can be dimensioned to reversibly receive one or more surfactant molecules per sequestering agent molecule.
  • the molar ratio of the surfactant to sequestering agent is between about 0.5:1 to about 4:1 , more likely between about 1 :1 and 3:1 .
  • Possible ratios are about 0.7:1 , about 0.8:1 , about 0.9:1 , about 1 :1 , about 1 .1 :1 , about 1 .2:1 , about 1 .3:1 , about 1 .4:1 , about 1 .5:1 , about 1 .6:1 , about 1 .7:1 , about 1 .8:1 , about 1 .9:1 , about 2:1 , about 2.1 :1 , about 2.2:1 , about 2.3:1 , about 2.4:1 , about 2.5:1 , about 2.6:1 , about 2.7:1 , about 2.8:1 , about 2.9:1 or about 3:1 .
  • a surfactant which includes in its structure a straight or branched chain alkyl or alkenyl tail dimensioned to be received within the interior the interior of the cyclic sequestering agent is thought to be particularly effective.
  • the internal cross diameter of the sequestering agent is between about 6.0 A and about 6.5 A.
  • aqueous solution of the composition to be injected downhole is a brine solution.
  • a brine solution in various embodiments contains at least about 1 , about 1 .1 , about 1 .2, about 1 .3, about 1 .4, about 1 .5, about 1 .6, about 1 .7, about 1 .8, about 1 .9, about 2, about 2.1 , about 2.2, about 2.3, about 2.4, about 2.5, about 2.6, about 2.7, about 2.8, about 2.9, about 3, about 3.1 , about 3.2, about 3.3, about 3.4, about 3.5, about 3.6, about 3.7, about 3.8, about 3.9, about 4, about 4.1 , about 4.2, about 4.3, about 4.4, about 4.5, about 4.6, about 4.7, about 4.8, about 4.9, about 5.0, about 5.1 , about 5.2, about 5.3, about 5.4, about 5.5, about 5.6, about 5.7, about 5.8, about 5.9, about 6.0, about 6.1
  • the invention thus includes use of any of the foregoing compositions in recovery of oil from an underground formation.
  • the invention includes use of such composition(s) in remediation of hydrocarbon-contaminated soil.
  • the invention is use of a composition(s) in remediation of soil contaminated with hydrophobic organic chemical wastes including any of the following: naphthalene fluorine, phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)pyrene, waste lubricant oils, naphtlalenepolycyclic aromatics, hydrocarbons, dibenzodioxins, debenzofurans, polychlorinated biphenyls (PCB), hexachlorobenzene (HCB), chlorinated solvents (Carbon tetrachloride, chloroform, trichloride, chloroform, trichloroethane (TCA), trichloroethene (TCE), tetrachloroethene (PCE)), pesticides (DDT, Toxaphene, Aldrin, Dieldrin, Llindane, Heptachlor, Chlordane, Mirex, Endrin,
  • the surfactant and sequestering agent together are present in the composition introduced into a formation in an amount of between about 1 and about 10 w ⁇ % of the composition, or between about 2 and about 10, or between about 3 and about 10, or between about 4 and about 10, or between about 5 and about 1 0, or between about 2 and about 9, or between about 3 and about 9, or between about 4 and about 9, or between about 2 and about 8, or between about 3 and about 8, or between about 4 and about 8 w ⁇ % of the composition, or about 1 , about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9 or about 10 w ⁇ % of the composition.
  • the invention also includes methods, such as a method of treating a hydrocarbon-containing formation.
  • the treatment is typically part of a hydrocarbon recovery operation.
  • Such method can include the step of:
  • hydrocarbon recovery composition (a) delivering a hydrocarbon recovery composition to at least a portion of the hydrocarbon containing formation and/or production pattern wherein the hydrocarbon recovery composition is an aqueous solution containing a sequestered surfactant.
  • the aqueous solution can be a composition of the invention as described herein.
  • the method can include recovering hydrocarbon material from the formation after the delivery step.
  • the empty cavity of the agent can encage or encapsulate oil, aiding in its transport toward the production zone.
  • mobilization of oil through solubility in the core of the surfactant micelles and the mobilization of oil in the cavity of the sequestering agent can synergize to increase oil recovery.
  • the hydrocarbon-containing formation can, for example, contain one or more of a hydrocarbon that is condensate, extra light crude oil, light crude oil, light to medium crude oil, and conventional crude oil.
  • the method can include the step of (b) preparing the composition on site by e.g., admixing sequestering agent and surfactant to form the hydrocarbon recovery composition used in step (a).
  • a e.g., admixing sequestering agent and surfactant to form the hydrocarbon recovery composition used in step (a).
  • other components of the composition needed under the circumstances can be included in the composition or added to the mixture on site.
  • a method of treating a hydrocarbon containing formation can include steps of:
  • a surfactant composition comprising (a) brine, optionally one or more of a co-surfactant and a-co-solvent, (b) a polymer, and (c) a sequestered surfactant, wherein the concentrations of the salt of the composition and the sequestered surfactant in the composition are selected to deliver a predetermined level of surfactant to the formation; and
  • the invention is a method of treating a hydrocarbon containing formation that includes steps of:
  • preparing a surfactant composition comprising (a) brine, and optionally a co- surfactant and/or a-co-solvent, (b) a polymer, and (c) a sequestered surfactant, wherein the concentration of the sequestered surfactant in the composition is selected to deliver a predetermined level of surfactant to the hydrocarbon contained in the rock; and
  • Such method(s) can include determining the chemical composition of the rock, and said selection is further made based on the hydrocarbon saturation in the reservoir or formation production pattern.
  • Such method(s) can include determining the concentration of surfactant to be delivered to the formation based on the interfacial activity between the surfactant aqueous solution and the hydrocarbon in the formation, and basing the selection that determination.
  • Such method(s) can also include determining the temperature within the formation and further basing the selection on that determination.
  • Types of formations relevant to the invention include, but are not limited to, a limestone formation, a mixed limestone-sandstone formation or a shale-limestone formation.
  • the invention can take the form of a kit for the preparation of a controlled release surfactant composition in an underground oil formation.
  • the kit can include:
  • the surfactant of the kit and the sequestering agent can be any of those described in connection with composition(s) of the invention.
  • the invention is a product for preparing a surfactant composition for use in a hydrocarbon recovery operation, the product comprising a surfactant and a sequestering agent.
  • the surfactant and sequestering agent can be provided in a premixed package.
  • the surfactant and sequestering agent could be provided in separate packages. Relative amounts of the surfactant and agent in the packages can be predetermined so that the contents of the first and second packages can be mixed in forming the composition without the need for on-site measuring the surfactant and agent.
  • Another embodiment is a method of providing a treatment fluid comprising composition of the invention, and placing the treatment fluid in at least a portion of a subterranean formation.
  • the composition is contained in an injection fluid and the amount of free surfactant delivered to trapped oil in the subterranean formation during an enhanced oil recovery operation is enhanced over the same injection fluid except for the presence of the sequestering agent.
  • Another embodiment is a method of displacing a hydrocarbon material in contact with a solid material in which the method includes: (i) contacting a hydrocarbon material with the aqueous solution containing a sequestered surfactant as described herein, wherein the hydrocarbon material is in contact with a solid material; (ii) allowing the hydrocarbon material to separate from the solid material thereby displacing the hydrocarbon material in contact with the solid material.
  • the sequestering agent is present in an amount sufficient to decrease the adsorption of the surfactant to the solid material.
  • Method(s) of the invention can be used where hydrocarbon material is unrefined petroleum in a petroleum reservoir and the solid material is a natural solid material in a petroleum reservoir.
  • Embodiments of the invention are exemplified by experiments described below, which were conducted using ⁇ -cyclodextrin ( ⁇ -CD) and complexes formed therewith using model surfactants, such as sodium dodecyl sulfate (SDS), and commercial surfactants for enhanced oil recovery, such as sodium branched alcohol propoxylate sulfates (C n (PO) m S0 4 Na) having various carbon chain lengths and numbers of propoxylate groups (POs).
  • model surfactants such as sodium dodecyl sulfate (SDS)
  • commercial surfactants for enhanced oil recovery such as sodium branched alcohol propoxylate sulfates (C n (PO) m S0 4 Na) having various carbon chain lengths and numbers of propoxylate groups (POs).
  • C n (PO) m S0 4 Na sodium branched alcohol propoxylate sulfates
  • complex formation was studied using surface tension measurements, via optical and SEM microscopy, and 1 H-NMR
  • Figure 1 depicts the molecular structure of ⁇ -CD (adapted from Zhou et al.
  • Figure 2 is a schematic of the instrument used for dynamic adsorption experiments
  • Figure 3 presents a simplified diagram of the experimental set-up used during the displacement tests
  • Figure 4 shows optical microscopic images: (A) ⁇ -CD in free-state; (B) SDS in free-state; (C) 5:95 molar ratio of SDS:B-CD; (D) 10:90 molar ratio of SDS:B-CD; (E) 20:80 molar ratio of SDS:B-CD; and (F) 30:70 molar ratio of SDS: B-CD.
  • A ⁇ -CD in free-state
  • B SDS in free-state
  • C 5:95 molar ratio of SDS:B-CD
  • D 10:90 molar ratio of SDS:B-CD
  • E 20:80 molar ratio of SDS:B-CD
  • F 30:70 molar ratio of SDS: B-CD.
  • Figure 5 shows optical microscopic images of ⁇ -CD (upper left plate), Alfoterra 167-4s (upper right plate), and Alfoterra 167-4s: ⁇ -CD at an equimolar ratio (lower plate);
  • Figure 6 shows scanning electron microscope (SEM) images of (A) ⁇ -CD, (B) SDS and (C) SDS ⁇ -CD inclusion complexes. Scale bar on SEM images represents 100 ⁇ ;
  • Figure 7 shows scanning electron microscopic (SEM) images of (A) (uppermost) ⁇ -CD, (B) (middle) Alfoterra 1 67-4s, and (C) (lowermost) Alfoterra 167- 4s ⁇ -CD inclusion complex at an equimolar ratio;
  • Figure 8 shows 1 H-NMR spectra: (A) (uppermost) ⁇ -CD in free state, (B) (middle) SDS, and (C) (lowermost) SDS:p-CD complex;
  • Figure 9 shows 1 H-NMR spectra: (A) inclusion complex of Alfoterra 167-45/ ⁇ - CD, (B) ⁇ -CD in free-state, and (C) Alfoterra 167-4s in free-state;
  • Figure 10 show the FT-IR spectra of ⁇ -CD in free state, SDS in free-state, and SDS ⁇ -CD complexation
  • Figure 11 shows the FTIR spectra of Alfoterra 167-4s in free-state, ⁇ -CD in free-state, and the inclusion complex of Alfoterra 1 67-4s ⁇ -CD;
  • Figure 12 summarizes static adsorption data of SDS with and without ⁇ -CD onto porous media in brine (3 w ⁇ % NaCI);
  • Figure 13 summarizes the dynamic adsorption data for SDS in free- (bars with dotted infill) and complexed-state (bars with checkered infill) in 2 w ⁇ % NaCI soft brine in adsorbents: 100% sand, 3% kaolin and 97% sand, 5% kaolin and 95% sand, 3% shale and 97% sand, and 5% shale and 95% sand;
  • Figure 14 summarizes dynamic adsorption data for SDS (bars with dotted infill) and SDS: -CD (bars with tiled infill) versus solid adsorbent materials in a 3 w ⁇ % (NaCI) soft brine. Percentages shown indicate reductions of SDS adsorption onto solid surfaces;
  • Figure 15 summarizes dynamic adsorption behavior of Alfoterra 145-4s, Alfoterra 167-4s, and Alfoterra 167-7s in free-state (bars with dotted infill) and complexed-state (bars with crosshatching) in soft brine (2 w ⁇ % NaCI);
  • Figure 16 shows possible (A) mechanisms for anionic surfactant adsorption onto sand surfaces and (B) mechanisms of surfactant adsorption inhibition onto sand by the SDS: -CD complexation;
  • Figure 17 shows possible (A) adsorption mechanism of anionic surfactants onto shale surfaces; (B) adsorption of surfactant via formation of hemicylindrical hemimicelles (C) surfactant adsorption inhibition by hydrophilicity increase (D) surfactant adsorption inhibition by hemimicelles disruption;
  • Figure 18 plots the performance of oil recovery as a function of the capillary number parameter for each of the sandpack systems and SDS in free- and complexed state: (A) 100 % Sand, (B) 5% Kaolin + 95 % Sand, and (C) 5% Shale + 95% Sand in 2 wt% NaCI soft brine;
  • Figure 19 displays a compilation of the oil displacement tests using SDS in free- and complexed state in different porous media blends in soft brine with a concentration of 3 w ⁇ % NaCI;
  • Figure 20 displays the results of the displacement tests conducted with Alfoterra 167-4s in free- and complexed state as cumulative oil recovery as a function of capillary bundle parameter.
  • Cyclodextrin (CD) molecule is a known carrier. It is made up of polymerized monosaccharide glucose units arranged in a donut- or torus-shaped ring arrangement, schematically illustrated in Figure 1 , that results in its having a relatively hydrophobic inner cavity and a relatively hydrophilic exterior. CDs can form inclusion complexes with a guest having a hydrophobic moiety received within the CD cavity (Szejtli, et al., 2004). Examples of molecules that can form inclusion complexes are aromatics, alcohols, halides, fatty acids, and esters, among others.
  • CD is widely used in biomedical drug delivery, as stabilizer, and as solubilizer, among other applications (Stella, et al., 1 997; Szejtli, et al., 1998; Szejtli, et al., 2004).
  • ⁇ -CD was tested as a surfactant carrier. Likewise, the release of the surfactant in porous media through oil displacement test was evaluated.
  • the word “comprise” and “include”, in their various forms, are to be construed as being inclusive and open ended, and not exclusive. Specifically, when used in this specification including claims, the terms “comprises”, “comprising”, “includes” and “including” and variations thereof mean the specified features, steps or components are included. These terms are not to be interpreted to exclude the presence of other features, steps or components. The term “consist”, in its various forms is to be construed as being closed ended.
  • Table 1 and Figure 1 present some of the ⁇ -CD properties and molecular structure.
  • the open hydrophobic cavity of ⁇ -CD makes possible the incorporation of a variety of surfactants structures into the ⁇ -CDs cavities in aqueous solutions (Lu, et al., 1997; Satake, et al., 1986; Palepu et al, 1988).
  • sodium dodecyl sulfate was used as a model surfactant along with known EOR commercial surfactants for complexations with ⁇ -CD.
  • the formation of inclusion complexes surfactants-CD was confirmed through surface tension measurements, optical and SEM microscopy, 1 H-NMR and FTIR spectroscopy.
  • Kinetic analysis was used to determine the stoichiometric ratio and the association constant (Kg) of the complexes.
  • Surfactant adsorption in free- and complex-state onto solid surfaces was evaluated using sandstone, and mixtures of sandstone, clay (kaolin), and shale as the solid adsorbents.
  • Surfactant adsorption was studied using the surface tension method through static and dynamic adsorption tests. The performance of the surfactant delivery system in recovering oil was established through oil displacement tests.
  • Sodium dodecyl sulfate (SDS; Ci 2 H 24 NaS0 4, (>99%) was from Sigma-Aldrich. Samples of commercial monoalkyl branched alcohol propoxy sulfate anionic surfactants (Alfoterra series) were provided by Sasol North America Inc. (Houston, TX, USA). ⁇ -Cyclodextrin (>98.4% and molecular weight of 1 135 g/mol) was purchased from Cyclodextrin Technologies Development Inc. (Florida, USA). Sodium chloride (NaCI) was acquired from Windsor-The Canadian Salt Company Limited (Pointe-Claire, Quebec). All chemicals were used as received without further purification. Sand was obtained from Shaw Resources Company (Nova Scotia, Canada).
  • Kaolin was acquired from Matheson Coleman & Bell Company, (California, USA) and the oil shale samples were provided by the New Brunswick Department of Natural Resources, which were retrieved from one of the New Brunswick's shallow oil shale accumulations. Shale, sand, and kaolin samples were used without further purification. Samples of crude oil with °API of 36 were obtained from the Stoney Creek oil field, located in New Brunswick, Canada. Synthetic soft brine (2 w ⁇ %, 3 w ⁇ %, and 8 w ⁇ % NaCI) and hard brine were used. Table 2 presents the composition of the synthetic hard brines.
  • the mineral composition of the solid adsorbents was determined by X-ray diffraction (XRD) using a spectrometer model D8 Advance manufactured by Bruker Corporation, Germany.
  • the surface area of the solid materials was determined by applying the BET technique using an AUTOSORB-1 analyzer manufactured by Quantachrome Instruments, Florida, USA.
  • the interfacial tension, IFT, between oil and water was measured using a spinning drop tensiometer Model M6500 manufactured by Grace Instrument Company (Houston, TX, USA) equipped with a temperature controller.
  • a drop of crude oil was placed into a capillary glass tube, which contained the surfactant aqueous phase that was placed within the sample holder that was rotated at a speed of approximately 3500 rpm at a constant temperature of 25 °C.
  • brackets signify molar concentrations (M).
  • surfactant: ⁇ -CD and ⁇ -CD in free-state are not surface active and thus do not contribute to surface tension reduction in an aqueous solution. It is possible to determine the concentration of surfactant in free-state in a solution containing inclusion complexes surfactant: -CD from surface tension measurements using a calibration curve of surface tension as a function of surfactant concentration in free-state.
  • surfactant: ⁇ -CD complexes can be formed following stoichiometric molar ratios 1:1 or 2:1 as shown below.
  • K a is the association or binding constant
  • [CD 0 ] and [S 0 ] are the total initial concentrations of ⁇ -CD and surfactant
  • [SCD] and [S] are the inclusion complex concentration and the free surfactant monomer concentration, respectively. From Eq.8, it is expected that for a stoichiometric molar ratio 1:1, S: -CD inclusion complex, the term [S 0 ] - [S] is expected to vary linearly with ( ⁇ - l), with a slope of -— . g units are in M "1 .
  • a plot of [CD] [S] 2 versus [S 2 CD] must follow a positive linear relationship for a 2:1 stoichiometric molar ratio; with a slope * ⁇ /K a .
  • K a units are in M "2 .
  • the best linear relationship determined by the highest squared correlation factor, ff 2 is selected, to establish the stoichiometric ratio and the association (binding) constants of the inclusion complexes.
  • the compatibility between surfactant and ⁇ -CD was firstly established through optical microscopy. Two or three drops of the corresponding surfactant, ⁇ -CD, and surfactants-CD complexation solutions were placed on a glass slide and allowed to dry overnight under fume hood. The slides were well protected to avoid deposition of solid particles or dust on the glass slides. These cover slides containing the corresponding samples were analyzed using a compact inverted metallurgical microscope; model Olympus GX41 , manufactured by Olympus (Center valley, PA, USA). The images were taken at 200 ⁇ magnification.
  • FTIR spectroscopy was also used to confirm the formation of the surfactants- CD inclusion complex.
  • Spectra of dry samples of surfactant, ⁇ -CD, and surfactant: -CD inclusion complex were acquired.
  • Static adsorption was determined by applying a batch equilibrium adsorption procedure (Muherei et al., 2009).
  • sand 82 g of sandstone (corresponding to a surface area of 0.2398 m 2 /g) was added to 494 ml surfactant solutions contained in glass volumetric flasks.
  • kaolin and shale 0.2 g of crushed samples was added to 12 ml surfactant solutions contained in glass tubes.
  • the amount of sand used was higher than the amount of the other materials, kaolin and shale, with the purpose of reproducing in the sand test a total sand grain surface area similar to the surface area of the kaolin and shale.
  • Adsorption values are reported as mass of surfactant adsorbed per gram of rock and per surface area (m 2 ), respectively. From preliminary testing, the adsorption equilibrium time was determined to be 24 hours. All the surfactant-porous media systems were left for 48 hours to ensure equilibration. After equilibrium was reached, surfactant sample aliquots were taken for surfactant concentration determination before and after adsorption. The surface tension method was applied to analyze the maximum adsorption of surfactant onto solid surfaces. The difference of surface tension values before and after adsorption was calculated to determine the adsorption of surfactant (g) per gram of crushed rock.
  • C ⁇ and C e are the initial and equilibrium liquid phase concentrations of surfactant solutions (g/l), respectively; V is the volume of the surfactant solution (I); and W is the mass of dry adsorbents (kg).
  • Figure 2 depicts a simplified schematic of the experimental set-up of the dynamic adsorption equipment.
  • the key section of the experimental set-up is the adsorption column (diameter: 3.7 cm, height: 37 cm), in which 100 grams of the corresponding solid adsorbents were placed.
  • the surfactant systems were circulated through the column at a flow rate of 1 .0 mL/min at room temperature ( ⁇ 25 °C).
  • the adsorption column was packed by adding alternate layers of the corresponding solid materials (sand, kaolin, and/or shale) to simulate the layered sedimentation process that takes place during rock formation.
  • the concentrations of surfactant and ⁇ -CD before and after adsorption were determined using a Total Organic Carbon (TOC) Analyzer, model TOC-VCPH manufactured by SHIMADZU Scientific Instruments (Shimadzu Corporation, Japan) equipped with a TNM-1 total nitrogen measuring unit.
  • TOC Total Organic Carbon
  • the surfactant solutions were constantly circulated through the packed column and the concentration of surfactant at the effluent were continuously monitored. The flow through the column was maintained until the adsorption equilibrium was reached, after which, samples of the effluent were collected (20 ml aliquots) and centrifuged to separate any solid particles that might be carried out by the effluent. Surfactant adsorption was calculated using Equation 13.
  • FIG. 3 presents a simplified diagram of the experimental set-up used during the displacement tests.
  • the oil displacement experiments were conducted using a Pressure Tapped sandpack and/or core Holder-DCH Series purchased from Temco Inc. (Tulsa, OK, USA).
  • the sandpack dimensions are 4 cm in diameter and 45.3 cm in length. As Figure 3 shows the sandpack holder was set-up horizontally.
  • the internal sandpack sleeve was slowly packed under vacuum in a layered fashion by alternating layers of kaolin and sand to ensure the homogeneity of the unconsolidated packing.
  • An Isco pump Model 1 00DX manufactured by Teledyne Isco, Inc. (Lincoln, NE, USA) was used to inject the fluids through the sandpack system.
  • Basic properties of the sandpack such as permeability, porosity, and pore volume were determined. After which the following injection sequence was applied.
  • Oil displacement was conducted by water flooding (soft brine) until the production of oil ceased.
  • Table 3 presents the composition and surface area of the solid adsorbents as determined by XRD and the BET techniques, respectively.
  • Adsorbents (m 2 /g) ⁇ ⁇ .2 ⁇ o 1 O
  • Kaolin is the solid adsorbent with the largest surface area (20 m 2 /g) followed by shale with 7.0 m 2 /g, and sand with 0.24 m 2 /g. Therefore, kaolin is the solid adsorbent with the highest adsorption capacity in terms of area available for adsorption (adsorption sites).
  • the surface charge of the solid materials shows a significant dependence with the pH of the aqueous solutions surrounding the minerals. For instance, at low pH, the surface charge of silica (quartz) and calcite in aqueous solution is positive, while a negative surface charge develops at high pH. More specifically, silica shows a negative surface charge when the pH of the aqueous solution is increased over the range of 2 to 3.7 (Somasunmuddy, P. 1975; Lui, et al. 2004).
  • the surface of silica presents a weak negative charge; therefore it tends to adsorb organic bases such as cationic surfactants (Lui, et al. 2004; Hirasaki, et al. 2008; and Muherei, et al. 2009).
  • the surface charge of Muscovite responds to the pH of the aqueous media in the opposite direction of silica, thus at low pH it displays a negative charge, while at high pH the surface charge becomes positive (Kapur 1995; Laskowski, J. S. 2013). In the case of the Sylvite mineral, the surface charge is negative for any pH lower than 10.5 (Kapur, P.C. 1995, and Perekh and Miller 1999).
  • the mineral composition of the sand used in this work contains 74 % of quartz, 1 8% of muscovite, and 8% of sylvite and the pH of the brine used in all the experiments is 7.43 ⁇ 0.29, which indicates that the anionic surfactants are exposed to positive (muscovite) and negative (quartz and sylvite) surface charges.
  • the positive sites on the sand will induce the adsorption of surfactant onto the mineral surface by electrostatic attraction.
  • the kaolin used in this work is composed of 100% kaolinite clay, which displays a negative charge on the face of the crystal and a positive charge at the edges of the crystal at neutral pH (Solairaj et al. 2012). Therefore, kaolin is disposed to adsorb anionic surfactants, an adsorption process that is sustained by its large surface area (20 m 2 /g).
  • the shale material contains albite (32%), dolomite (26 %), and clinochlore (7%), besides quartz (20%) and muscovite (7%).
  • the pH dependence of the albite surface charge shows a positive charge at pH lower than 6 (acid region), a neutral surface at pH ranging from 6 to 10, and a negative surface charge at pH higher than 10 (basic region) (Deer et al. 2001 ).
  • Dolomite and clinochlore minerals show the same pH dependence as silica and calcite that is positive at low pH but negative at high pH (Alotaibi et al. 201 1 ).
  • the surface charge dependence of the minerals contained in shale indicates that a the pH of the brine (7.43 ⁇ 0.29) used in the adsorption tests, the surface of the shale displays positive and negative charges; therefore, anionic surfactants would be also attracted towards the solid interface via electrostatic forces.
  • association constant ⁇ K a The association constant ⁇ K a ) of SDS:B-CD inclusion complexes was determined at various salinities as shown in Table 4.
  • the binding or association constants ⁇ K a ) of the different commercial surfactants Alfoterra series: -CD inclusion complexes in soft brine (2 w ⁇ % NaCI) are summarized in Table 5.
  • the stoichiometric ratio for these surfactant complexes is 1 :1 in low salinity aqueous media containing soft brine with a concentration of 2 w ⁇ % NaCI.
  • Table 5 shows that the binding constant increases as the hydrophobic chain length of the surfactant increases; these observations are in agreement with previous research (Lu et al. 1997). Therefore, stronger interactions between the surfactant and ⁇ -CD are arisen as the length of the hydrophobic tail of the surfactant increases.
  • Figures 4(A) to (F) display the optical microscopic images of ⁇ - CD and SDS in free-state and SDS: -CD inclusion complexes with increasing concentrations of SDS. The images were taken at 200xmagnification.
  • ⁇ -CD in free- state presents a well-defined rod-shaped crystal structure (Figure 4(A)); while the SDS in free-state ( Figure 4(B)) shows a needle-shaped crystalline structure.
  • the SDS: -CD complexations show a very different structure.
  • the inclusion complexes appear as aggregates or clumps that grow as the SDS concentration increases.
  • FIG. 5 displays microscopic images of ⁇ -CD and surfactant in free and complexed-state at equimolar ratios.
  • ⁇ -CD in free-state displays a crystalline rod-like structure well dispersed throughout the film.
  • the sample of Alfoterra 167-4s is well dispersed along the glass slide with a structure showing an irregular curvilinear shape of very small sizes.
  • the inclusion complex is also well dispersed, but showing a structure of larger wavy curvilinear shapes as a result of the complexation.
  • Alfoterra 1 67-4s anionic surfactant (30% active) presents a highly well- organized layer-like crystalline structure. The layers seem to distribute radially from a central point.
  • the crystalline morphology of the inclusion complex (Alfoterra 167- 4s: -CD) displays a more organized flake-like structure if compared with the crystalline structure of the ⁇ -CD in free-state that could be attributed to the formation of the inclusion complexes.
  • the structure of complexation shows in some locations layer-like crystalline features similar to that of the surfactant structure with also suggest the formation of the surfactant ⁇ -CD complex.
  • Figure 8 illustrates the 1 H-NMR spectra of ⁇ -CD in free state, SDS, and the inclusion complex SDS:B-CD and Table 6 presents the 1 H-NMR chemical shifts of free ⁇ -CD and in the complexed state.
  • Protons H3 and H5 located inside the ⁇ -CD cavity in the spectrum of the complexation show up-field chemical shifts ( ⁇ 0) if compared with the spectrum of the ⁇ -CD in free- state. These chemical shifts indicate the formation of the inclusion complex, in which the hydrophobic tail of the SDS is inserted in the ⁇ -CD cavity (Chen and Zhang, 2006; Yallapua et al. 2010). The absence of new peaks in the spectrum of the complexation suggests that the formation of the inclusion complex occurs through a rapid dynamic exchange between the free and complexed states of the ⁇ -CD (Pirnau et al. 2009).
  • Figure 9 displays the spectra for the inclusion complex, ⁇ -CD in free-state, and Alfoterra 167-4s in free-state.
  • the spectrum of the inclusion complex presented in Figure 9(A) displays all the characteristic peaks of the ⁇ -CD in free-state ( Figure 9(B)), however some of the proton signals show up-field chemical shifts ( ⁇ 0), particularly noticeable are the up-field chemical shifts of the internal protons H3 and H5.
  • Table 7 summarizes the 1 H-NMR chemical shifts of ⁇ -CD in free and complexed-state and the difference between the chemical shifts before and after complexation.
  • the inclusion complex spectrum ( Figure 9) also displays characteristic peaks of Alfoterra 167-4s ( Figure 9(C)) such as shift 1 .17 ppm that corresponds to the H in CH-CH 3 and CH-CH 2 groups, shift 1 .03 ppm corresponding to the H in CH 2 , and chemical shit 0.78 ppm assigned to the H to the CH 3 group.
  • the remaining peaks of Alfoterra 1 67-4s in free-state with chemical shifts of 4.42 ppm (CH-O-SO 3 -), 3.51 ppm, 3.39 ppm, and 3.20 pp assigned to the -CH 2 -0- group cannot be distinguished in the inclusion complex spectrum probably due to overlapping.
  • FT-IR spectroscopy was used to validate the formation of the inclusion complex SDS: -CD.
  • the FT-IR spectrum of ⁇ -CD in free-state, SDS in free-state, and the spectrum of SDS- -CD inclusion complex are displayed in Figure 10.
  • the ⁇ - CD in free-state spectrum show characteristic peaks around 3371 cm “1 to 3434 cm “1 and 2943 cm -1 due to the O-H and C-H stretching vibrations.
  • peaks at 1652 cm “1 , 1 164 cm “1 , 1057 cm “1 , and 952 cm “1 correspond to H-O-H, C-O, C-O-C glucose units and C-O-C of the CD rings, respectively (Yallapua et al. 2010).
  • the FT-IR spectrum of SDS in free-state presents absorption bands at 2925 and 2853 cm “1 corresponding to C-H stretching vibrations of asymmetric and symmetric CH 3 and CH 2 ; while, the sharp peak at 1472 cm “1 indicates the bending vibrations of CH 3 and CH 2 deformation. Furthermore, the strongest band at 1 224 cm “1 and 1 254 cm “1 that results from the combination of several overlapping peaks that is generally observed as a double band corresponds to the asymmetric vibrations of the SO 2 head group of the surfactant (Prosser and Franses, 2002).
  • the spectrum of the SDS -CD inclusion complex displays all the representative peaks belonging to ⁇ -CD in free-state with only few distinctive peaks of the SDS such as the peaks at 2922 cm “1 and 2899 cm “1 . Nevertheless, the most intense peaks of the SDS correspond to the polar head group at 1224 cm “1 and 1254 cm “1 , which clearly appear in the spectrum of the inclusion complex.
  • Figure 11 presents the spectra of ⁇ -CD in free-state, Alfoterra 1 67-4s in free- state, and Alfoterra 167-4s/ -CD inclusion complex.
  • the FTIR spectrum of Alfoterra 167-4s in free-state displays an absorption band at 2699 cm "1 that corresponds to the C-H stretching vibration; while the wavelengths 1308 cm “1 and 1 176 cm “1 are attributed to the stretching vibration of the sulfate group and the propylene oxide group (C-O-C) respectively.
  • the FTIR spectrum of ⁇ -CD in free-state displays characteristic peaks at 3434 cm -1 and 2943 cm -1 wavelengths corresponding to the stretching vibrations of O-H and C-H, respectively; while peaks at 1652 cm -1 , 1 164 cm -1 , 1057 cm -1 , and 952 cm -1 are attributed to the H-O-H, C-O, C-O-C glucose units and to the C-O-C of the ⁇ -CD rings, respectively.
  • Alfoterra 167-4s -CD inclusion complex spectrum
  • all the sharp peaks belonging to ⁇ -CD appeared on the spectrum and only few characteristic peaks of Alfoterra 1 67-4s are visible (for example: 2044 cm “1 , 2296 cm “1 ).
  • the complexation Alfoterra 167-4s: -CD induces the shifting of the ⁇ -CD IR absorption peaks to higher/lower wavelength numbers, i.e., 3434 to 3392 cm “1 ; 1652 to 1657 cm “1 ; 952 to 953 cm “1 .
  • This IR absorption data confirms the formation of the inclusion complex Alfoterra 1 67-4s: -CD.
  • Table 8 and Figure 12 summarize the adsorption of SDS with and without ⁇ - CD onto porous media in brine (3 w ⁇ % NaCI).
  • the inclusion of SDS into the ⁇ -CD cavity reduces the adsorption of SDS on sand by 19% while the adsorption of SDS on kaolin and oil shale was reduced by 78% and 79%, respectively.
  • These experimental results demonstrate the efficiency of the surfactant delivery system in inhibiting the adsorption of surfactant onto solid surfaces.
  • Figure 13 plots the adsorption data for SDS in free- and complexed-states expressed in mg/g solid as a function of solid adsorbent in soft brine having a concentration of 2 w ⁇ % NaCI.
  • the reduction in surfactant adsorption via complexation ranged from 30% to 74% and the maximum adsorption reduction was observed for the solid mixture containing 95% Sand and 5% Shale.
  • the noticeable adsorption of SDS in free-state onto this solid mixture might be explained by the fact that the shale used in this work contains organic material (kerogen) deposited on the surface of the shale grain.
  • the presence of organic material might promote the flat adsorption of the carbon tail of the surfactant in free-state onto the surface of the shale due to hydrophobic interactions (Somasunkes and Huang, 2000).
  • Adsorption data for SDS in free- and complexed-state in 3 w ⁇ % NaCI soft brine is presented in Figure 14; which shows that the surfactant delivery system significantly reduces the adsorption of SDS towards all solid surfaces tested.
  • Figure 14 shows adsorption reductions ranges from 50% to 92%. The highest SDS adsorption inhibition is observed for the blends of sand-shale with adsorption reductions of 92%.
  • the aforementioned mechanisms of anionic surfactant adsorption onto sand are inhibited by the inclusion complex surfactant: ⁇ -CD by the following proposed mechanisms.
  • the first mechanism is considered to be steric hindrance.
  • kaolinite At neutral pH, kaolinite displays negative surface charge on the face and positive surface charge at the edges (Solairaj et al. 2012); consequently, anionic surfactant molecules are adsorbed onto the kaolin surface due to electrostatic interactions.
  • the shale used in this work contains organic matter (kerogen) deposited on the grain surface.
  • organic matter kerogen
  • the adsorption of surfactant on the solid surface is driven by hydrophobic interactions between the non-polar tail of the surfactant and the organic matter on the shale surface (Somasunkes, P. and L. Huang 2000). Therefore, the hydrophobic tail of the surfactant adsorbs flat onto the solid surface.
  • surfactants can form aggregates and/or hemicylindrical hemimicelles at the shale surface depending on the number of surfactant layers of the aggregates ( Figures 17(A) and (B)). Once these structures are formed, the adsorption of free surfactant monomers increases significantly.
  • each sandpack shows different properties; therefore it was necessary to normalize the experimental data for porosity and permeability using the capillary bundle parameter to remove variations in rock properties (Hirasaki and Pope 1974; Chauveteu 1982; Serigth 2010). As a result, it was possible to compare the experimental performance among different sandpack tests.
  • the capillary bundle parameter is given by the following expression;
  • Table 10 outlines the results obtained from the SDS in free- and complexed state displacement tests using soft brine (2 w ⁇ %).
  • the primary waterflooding stage produces a percentage of oil recovery that ranges from 44% to 76% of the original oil in place (OOIP).
  • chemical flooding was applied by injecting 0.3 PV of surfactant flooding followed by 0.3 PV of polymer flooding.
  • the use of the surfactant delivery system produces higher incremental oil recovery if compared with the conventional surfactant flooding. For instance, the gain in oil recovery due to the application of the surfactant delivery system was 40%, 82%, and 45.5 % in the sand, mixture kaolin-sand, and in the mixture shale-sand, respectively.
  • Figure 18 (A) to (C) plots the performance of oil recovery as a function of the capillary number parameter for each of the sandpack systems and SDS in free- and in complexed state.
  • the application of the surfactant delivery system (SDS:B-CD) produces consistently higher oil recovery during the displacement tests.
  • Table 11 displays the properties of the sandpacks, which were packed using a solid blend containing 5 w ⁇ % kaolin and 95 w ⁇ % sand. Soft brine with a concentration of 8 w ⁇ % of NaCI was used as the injection water. The displacement tests were conducted at room temperature ( ⁇ 25 °C).
  • Figure 20 shows cumulative oil recovery as a function of capillary bundle parameters for the three displacement tests conducted.
  • the baseline displacement test (lowest curve in Figure 20), which consisted in the injection of 0.3 PV of ⁇ -CD solution 1 w ⁇ % concentration, was fitted and the oil production behavior was predicted for a hypothetical total extended waterflooding injection of 65 PV, in order to compare the performance of the baseline against the performances of experimental runs 2 and 3.
  • the total incremental oil recovery due to the injection of ⁇ -CD in free-state was 5% after 1 1 PV of extended waterflooding and a predicted production of 9.5 % after the injection of 65 PV of extended waterflooding.
  • ⁇ -CD The mechanism for oil recovery by ⁇ -CD could be explained by the encapsulation of drops of free mobile oil (discontinuous oil phase) present in the porous media after waterflooding within the ⁇ -CD cavity; therefore these isolated oil drops can be captured by ⁇ -CD and displaced towards the production well.
  • ⁇ -CD for the removal of hydrophobic compounds such as cholesterol from dairy food has been well documented. Santos and co-workers indicated that encaging of cholesterol within the ⁇ -CD cavity is exothermically and energetically favored, and the driving force is the substitution of the high-enthalpy water molecules by the appropriate hydrophobic compound (Santos et al. 201 1 ).
  • the removal of oil presumably occurs through non-bonding interactions between the oil and ⁇ -CD, since ⁇ -CD does not offer any interfacial tension activity and the interfacial tension of the oil/brine system is not changed.
  • Displacement test # 2 which corresponds to the conventional surfactant flooding (dotted line in Figure 20), produced a total incremental oil recovery of 16.5% after 65 PV of extended waterflooding.
  • the experimental data was also fitted and its production projected for a total of 65 PV of extended waterflooding.
  • Displacement test # 3 (lower dashed line in Figure 20), in which the surfactant delivery system was incorporated into the surfactant flooding, showed an incremental total oil recovery of 21 .1 %.
  • the efficiency of the surfactant delivery system in recovering residual oil can be attributed to the reduced adsorption of surfactant towards the solid surfaces within the sandpack; therefore more surfactant is available for interactions at the oil/brine interface and the IFT of the system can be significantly reduced.
  • Adsorption inhibition via surfactants-CD complexation has been explained through several mechanisms such as steric hindrance, disruption of hemimicelles formation, and self- association of inclusion complexes.
  • anionic surfactants two main category of anionic surfactants: four commercial EOR surfactants -sodium branched alcohol propoxylate sulfates (Cn(PO) m SO 4 Na) having different carbon chain lengths and propoxylate groups (POs)- and a model anionic surfactant, sodium dodecyl sulfate, SDS (Ci2H 2 4NaSO 4 ).
  • the complexation association constant ⁇ K a was found to increase with salinity concentration. A sharp increase in salinity causes changes in the stoichiometric molar ratio of the inclusion complexes and consequently in the value of the binding constant ⁇ K a ).
  • Adsorption of surfactants in free- and in complexed-state was found to increase with the concentrations of kaolin and oil shale in the solid mixture. This is explained by the mineral composition, surface area, and surface charges of these materials.
  • the surfactant delivery system was found to reduce the adsorption of surfactant onto all solid surfaces of the materials tested. Adsorption reductions range from 19% up to 79%.
  • Adsorption of anionic surfactants on the solid surface can also be driven by hydrophobic interactions between the non-polar tail of the surfactant and the organic matter covering the solid surface (i.e. oil shale surface). Therefore, the hydrophobic tail of the surfactant can adsorb flat onto the solid surface.
  • Surfactants can form aggregates and/or hemicylindrical hemimicelles at the solid surface depending on the number of surfactant layers of the aggregates. Once these structures are formed, more surfactant adsorption can occur. These adsorbed surfactant monomers and surfactant aggregates exist in thermodynamic equilibrium with surfactant monomers in the bulk solution. Therefore, significant adsorption of anionic surfactants can occur towards the organic matter and clay minerals contain in the solid surfaces.
  • Encapsulation of the hydrophobic tail group into the ⁇ -CD cavity hinders the above- mentioned surfactant adsorption mechanisms at the solid surfaces because it prevents the hydrophobic interactions between the surfactant tail and the organic matter on the solid.
  • the formation of inclusion complexes also creates disorder and disrupts the packing of hemimicelles structures, attenuating adsorption of surfactants onto the shale surface.
  • Surfactant flooding demonstrates that the surfactant : -CD complex contributes to increasing oil recovery. If the performance of the surfactant delivery system surfactant: -CD is compared with the performance of conventional surfactant flooding at the same experimental conditions, the gain in incremental oil recovery ranges from 28-82 %. This gain in oil recovery was observed for all the sandpack systems evaluated.
  • the baseline displacement test also demonstrates that the injection of ⁇ -CD in free-state is capable of removing free mobile oil droplets (discontinuous beads of mobile oil left behind after waterflooding) from the sandpack through encapsulation within the ⁇ -CD cavity, permitting removal of isolated oil droplets.
  • An advantageous surfactant delivery system for EOR surfactant flooding applications has thus been described. The system is effective in lowering surfactant adsorption - overall surfactant adsorption reductions ranged from 19% to 92% - onto various types of porous media.
  • Silicates Fieldspars. Second ed. Vol. 4A. 2001 , London, UK: The Geological

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Abstract

La présente invention concerne l'utilisation d'agents complexants pour la libération contrôlée d'un agent tensioactif lors d'une opération de récupération d'hydrocarbures, comme la libération de pétrole à partir de formations souterraines. L'agent complexant est une molécule cyclique ayant un intérieur hydrophe et un extérieur relativement hydrophile, et la partie hydrophobe de l'agent tensioactif est reçue de manière réversible dans l'intérieur hydrophobe de l'agent complexant. Un exemple d'agent séquestrant est la β-cyclodextrine.
PCT/CA2014/050275 2013-03-15 2014-03-17 Utilisation d'agents complexants pour la libération contrôlée d'un agent tensioactif lors d'une opération de récupération d'hydrocarbures WO2014139027A1 (fr)

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WO2019195606A1 (fr) * 2018-04-04 2019-10-10 Board Of Regents, The University Of Texas System Émulsions d'alcoxylate
CN110573591A (zh) * 2016-10-06 2019-12-13 杜兰教育基金委员会 用于递送油溶性材料的水溶性胶束
CN110669481A (zh) * 2019-10-22 2020-01-10 石家庄华莱鼎盛科技有限公司 钻井液用抗盐降滤失剂改性树胶树脂
CN113583647A (zh) * 2021-08-02 2021-11-02 南京师范大学 一种表面活性剂-mof复合材料及其制备方法
US11408811B2 (en) * 2020-02-04 2022-08-09 Saudi Arabian Oil Company Methods and systems for determining residual fluid saturation of a subsurface formation
US11713409B2 (en) * 2018-07-06 2023-08-01 China Petroleum & Chemical Corporation Substituted saccharides or glycosides and use thereof in a drilling fluid composition

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CN110573591A (zh) * 2016-10-06 2019-12-13 杜兰教育基金委员会 用于递送油溶性材料的水溶性胶束
CN109501074A (zh) * 2017-09-14 2019-03-22 衢州市中通化工有限公司 一种氟碳脱模剂的制备方法
CN109501074B (zh) * 2017-09-14 2020-10-02 衢州市中通化工有限公司 一种氟碳脱模剂的制备方法
WO2019195606A1 (fr) * 2018-04-04 2019-10-10 Board Of Regents, The University Of Texas System Émulsions d'alcoxylate
WO2019195604A1 (fr) * 2018-04-04 2019-10-10 Board Of Regents, The University Of Texas System Procédés de récupération d'hydrocarbures à l'aide d'émulsions d'alcoxylate
GB2589455A (en) * 2018-04-04 2021-06-02 Univ Texas Alkoxylate emulsions
GB2589454A (en) * 2018-04-04 2021-06-02 Univ Texas Methods for hydrocarbon recovery using alkoxylate emulsions
US11713409B2 (en) * 2018-07-06 2023-08-01 China Petroleum & Chemical Corporation Substituted saccharides or glycosides and use thereof in a drilling fluid composition
CN110669481A (zh) * 2019-10-22 2020-01-10 石家庄华莱鼎盛科技有限公司 钻井液用抗盐降滤失剂改性树胶树脂
US11408811B2 (en) * 2020-02-04 2022-08-09 Saudi Arabian Oil Company Methods and systems for determining residual fluid saturation of a subsurface formation
CN113583647A (zh) * 2021-08-02 2021-11-02 南京师范大学 一种表面活性剂-mof复合材料及其制备方法

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