JPH0331875B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a micellar solution for oil recovery that has good salt resistance, has a sufficiently low interfacial tension, and has a high oil recovery rate, and is used in a micellar attack method for recovering oil from underground reservoirs. Conventional technology A type of forced oil recovery (EOR) involves creating a transparent microemulsion from water and oil using a surfactant, and injecting this microemulsion, called a micellar solution, into an underground reservoir to recover oil. There is a micellar attack method. A lot of research has been done on the process and drugs for micellar attack, for example, US Patent No. 3506070, US Patent No. 3613786, US Patent No. 3740343,
It is disclosed in the same No. 3983940, the same No. 3990515, the same No. 4017405, the same No. 4059154, etc. Among these prior art, petroleum sulfonates, alkylaryl sulfonates, dialkyl sulfosuccinates, alkanesulfonates, polyoxyethylene alkyl ether sulfates, α-olefin sulfonates, polyoxyethylene alkyls are used as surfactants for the preparation of micellar solutions. Various surfactants are listed, such as ether, polyoxyethylene alkyl phenyl ether, polyhydric alcohol fatty acid ester, alkyltrimethylammonium salt, and dialkyldimethylammonium salt. There are a large number of oil fields currently being extracted, and the properties of underground reservoirs are also rich in diversity. Therefore EOR
The oil fields that are the subject of
For example, there are many types of oil reservoir water that exist in underground reservoirs, ranging from those with very little inorganic salts to those with extremely high salt concentrations, and the concentrations of polyvalent metal ions also vary. Furthermore, the water used in the production of microemulsions is often brine with a relatively high salt concentration. Therefore, the surfactant used in the micelle solution is required to have salt resistance and hard water resistance. In addition, the micellar solution is required to have salt resistance, hard water resistance, and heat resistance, and the interfacial tension between water and the microemulsion and between the oil and the microemulsion are both sufficiently low. Requirements include that the microemulsion can be easily adjusted to a viscosity slightly higher than that of oil and that the microemulsion remains stable until an oil bank is formed during sweeping of the oil layer. Alkyl ether sulfate is a surfactant that is easily available and has relatively good salt resistance, but has the drawbacks of low interfacial tension lowering ability and poor oil recovery rate. Object and Structure of the Invention An object of the present invention is to provide a micellar solution that has good salt resistance and hard water resistance, has a sufficiently low interfacial tension, and has a high oil recovery rate. That is, the present invention provides a micellar solution for petroleum recovery consisting essentially of oil, water that may contain an inorganic salt, a surfactant, and a surfactant, in which (A) a surfactant having a carbon number of 8 to 20 is used. It is characterized by using 100 parts by weight of alkyl ether sulfate (hereinafter abbreviated as AES) and (B) 1 to 100 parts by weight of internal olefin sulfonate having 10 to 26 carbon atoms (hereinafter abbreviated as IOS). Summary of the invention and description of effects The micelle solution of the present invention contains about 2 to about 90% by weight of oil, about 4 to about 95% by weight of water, and about 1 to about 30% by weight of surfactant.
and about 0.1% to about 20% by weight of a surfactant co-agent. The oil used in the present invention can be petroleum, liquefied petroleum gas, crude gasoline (naphtha), kerosene, light oil, heavy oil, etc.; Given the similarities, it is preferred to use recovered petroleum. The proportion of oil in the micellar solution of the present invention is from about 2 to about 90% by weight, but
Since it is economically disadvantageous to use a large amount of oil, about 3 to about 40% by weight is preferred. Since the water used in the present invention has good salt resistance and hard water resistance as a surfactant, water or brine having an inorganic salt concentration of 0 to about 10% by weight can be used, and preferably, the inorganic salt concentration is about 0.1 to about 10% by weight. It is 8% by weight. Water that can be used in the present invention includes soft water, brine, oil layer water, etc. Examples include rainwater, river water, lake water, groundwater,
Examples include oil reservoir water and seawater. Typical examples of alkali metal salts included in the brine are NaCl, KCl, Na ₂ SO ₄ and K ₂ SO ₄ . Further, examples of divalent metal ions are Mg ions and Ca ions, and up to about 4000 ppm of Mg ions can be tolerated. AES used as component A of the surfactant in the micelle solution of the present invention is prepared by adding an alkylene oxide having 2 to 4 carbon atoms, preferably 2 to 3 carbon atoms, to an aliphatic alcohol having 8 to 20 carbon atoms, preferably 10 to 18 carbon atoms. This is the resulting alkyl ether sulfate ester salt. As the aliphatic alcohol, saturated or unsaturated, linear or branched, primary or secondary alcohols can be used. Preferred alkylene oxides are ethylene oxide and propylene oxide. The number of moles of alkylene oxide added (hereinafter abbreviated as p) is suitably about 0.5 to 20, particularly preferably about 1 to 10. Suitable AESs are alkali metal salts, alkaline earth metal salts, ammonium salts and organic amine salts, with Na salts, K salts, Mg salts, ammonium salts and alkanolamine salts being particularly preferred. Examples of AES suitable for the present invention include a sulfate ester salt of an ethylene oxide adduct of lauryl alcohol (p=3), a sulfate ester salt of an ethylene oxide adduct of a synthetic alcohol having 12 to 15 carbon atoms (p=2),
Examples include a sulfate ester salt of an ethylene oxide adduct of coconut alcohol (p=5) and a sulfate ester salt of an ethylene oxide adduct of beef tallow alcohol (p=4). IOS used as the B component of the surfactant in the present invention has the general formula R-CH=CH-R' (wherein R and R' are each a linear or branched saturated hydrocarbon having 1 or more carbon atoms). is a group, and R and
The essential component is a vinylene type monoolefin having 10 to 26 carbon atoms, preferably 12 to 24 carbon atoms (the sum of the carbon numbers of R' is 8 to 24), and optionally about 33% by weight (about 30% by weight in the olefin). 1/3) It is produced by sulfonating an internal olefin containing the following trisubstituted monoolefin, neutralizing it with an appropriate base, and hydrolyzing it if necessary. IOS produced in this manner typically contains about 10-60% by weight of alkenyl sulfonates with double bonds and about 90-40% by weight of hydroxyalkanesulfonates, while about 80% or more by weight of monosulfonates. , and up to about 20% by weight of disulfonates. Of course, by selecting the sulfonation conditions and hydrolysis conditions, it is also possible to produce IOS with a different component ratio from the above-mentioned component ratios. Generally, as the number of carbon atoms in the internal olefin increases, the proportion of alkenyl sulfonate tends to increase, and as the molar ratio of the sulfonating agent during sulfonation increases, the proportion of disulfonate tends to increase.
IOS suitable for the present invention contain about 40% or more, preferably about 45 to 90% by weight of hydroxyalkanesulfonates, and about 20% or less of disulfonates, preferably about 0.1 to 15% by weight. be. When using IOS that satisfies these conditions, microemulsions with sufficiently low interfacial tension can be produced, resulting in improved oil recovery. The IOS used in the present invention is an alkali metal salt,
Selected from ammonium salts and organic amine salts.
Preferred countercations are Na, K, NH ₄ and alkanol ammonium. IOS suitable for this invention
Examples include carbon numbers 12, 13, 14, 15, 16, 18,
20, 22, 24, 12~16, 13~14, 14~16, 14~18~
Mention may be made of IOS's of 15-17, 16-18, 17-20 and 20-24 and mixtures thereof. The micelle solution of the present invention uses AES as a surfactant.
The use of IOS as a minor component in addition to IOS allows the use of high-salt brines for the production of microemulsions, allowing them to be applied to underground reservoirs containing high-salinity reservoir water, yet with sufficiently low interfacial tensions. A microemulsion is obtained having . As a result, high oil recovery is achieved from low to high salt concentrations. To obtain such efficiency, at least 1 IOS per 100 parts by weight of AES must be used.
Parts by weight, preferably 5 parts by weight or more, are required. On the other hand, when the amount of IOS used is increased, the effect of adding IOS becomes constant, so IOS is suitably 100 parts by weight or less, preferably 80 parts by weight or less, per 100 parts by weight of AES. The micelle solution of the present invention contains about 1 to 30% by weight of surfactant, but considering the low oil-water interfacial tension and cost, the surfactant content is about 3 to about 25% by weight.
Preferably, it is % by weight. Since AES used in the present invention is a surfactant that is easily hydrolyzed at a constant temperature and is also easily hydrolyzed even when the pH becomes acidic, preferable results can be obtained when an alkaline substance is used in combination. Preferred alkaline substances include caustic alkali, alkali metal carbonates, alkali silicates, and ammonia. When adding an alkaline substance, the appropriate amount to be used is about 0.1 to 5% by weight in the micelle solution. In the micellar solution of the present invention, the surfactant is an essential component that acts together with the surfactant to form a microemulsion. The surfactant used in the present invention is a compound having an alcoholic hydroxyl group, and preferably has the general formula R″O(CH ₂ CH ₂ O) _o H (where n is a number from 0 to about 3, and R ” is n=
If n is 0, it is an alkyl group or alkenyl group having 3 to 8 carbon atoms, and if n is not 0, it is an alkyl group or alkenyl group having 6 to 15 carbon atoms, a phenyl group, or an alkyl group having 7 to 16 carbon atoms. enyl group, and the aliphatic group may be linear or branched). Specific examples of such alcohols include propanols, butanols, pentanols, hexanols, octanols, polyoxyethylene hexyl ether (=1), polyoxyethylene decyl ether (=2), and polyoxyethylene trimester. Examples include decyl ether (=3), polyoxyethylene butyl phenyl ether (=2), polyoxyethylene nonylphenyl ether (=3), and polyoxyethylene dodecyl phenyl ether (=3). The surfactant used in the present invention is used in the micelle solution in an amount of about 0.1 to about 20% by weight, but from the viewpoint of stability of the microemulsion and ability to lower the oil-water interfacial tension, the amount is about 1 to about 10% by weight. Preferably, % by weight is used. The micelle solution of the present invention uses AES as a surfactant.
and IOS, but other surfactants can also be used supplementarily. Examples of such surfactants include petroleum sulfonates, alkylbenzene sulfonates, paraffin sulfonates, dialkyl sulfosuccinates, alpha-olefin sulfonates, soaps, higher alcohol ethoxylates, alkylphenol ethoxylates, polyhydric alcohol fatty acid esters, fatty acid alkyl sulfonates, Examples include anionic surfactants and nonionic surfactants such as rollamide and polyoxyethylene fatty acid amide. Known thickeners such as water-soluble polymers can be used in the micelle solution of the present invention to adjust the viscosity, if necessary. Examples of such thickeners include heteropolysaccharides produced by microorganisms, naphthalene sulfonic acid formalin condensates, polyacrylamides, polyacrylates, hydroxyethyl cellulose, carboxymethyl cellulose, and the like. The micelle solution of the present invention can be easily produced by a known emulsion production method, and the order of addition of each component, stirring and mixing method, temperature, pressure, etc. can be arbitrarily selected. The method of recovering oil from underground reservoirs using the micellar solution of the present invention is similar to the known micellar attack method, in which the micellar solution is injected from at least one injection well toward an oil-producing well; A seed driving fluid can be introduced to recover the oil. The appropriate amount of micelle solution to be injected at this time is 5 to 25% by volume of the porosity of the underground reservoir. Examples Next, the present invention will be explained in more detail with reference to Examples, but it goes without saying that the present invention is not limited to these Examples. The component proportions in each sample used in the experiment are weight % unless otherwise indicated. Example 1 C ₁₂ - C ₁₅ AES-Na (=3) as surfactant
and C ₁₄ - C ₁₈ IOS-Na 9% mixture with different proportions,
4% n-amyl alcohol as a surfactant;
17% heavy oil A (ASTM, No. 2 oil) as oil and 8% sodium chloride in deionized water as brine.
A microemulsion sample was prepared by weighing out 70% of the aqueous solution in which 70% was dissolved and stirring at 100 rpm for 30 minutes at 71°C. The ability of this sample to form a microemulsion was judged from its appearance. A microemulsion that was formed and uniformly transparent was rated "○", and a sample that was suspended or separated into two phases was rated "x". The interfacial tension was measured using a spinning drop type interfacial tension meter in an appropriately diluted system at 71°C. The viscosity was measured using a Burckfield viscometer at 25
Measured at °C. The obtained results are summarized in the first column along with the proportion of surfactant.
Shown in the table.

[Table] Example 2 C ₁₂ - C ₁₅ AES-Na (=3) as surfactant
7.2% and C ₁₄ - C ₁₈ IOS-Na 1.8%, n-amyl alcohol 4% as surfactant auxiliary, A heavy oil as oil
17%, an aqueous solution of a predetermined amount of sodium chloride dissolved in deionized water as a brine, or a 70% aqueous solution of magnesium chloride or calcium chloride further dissolved in a sodium chloride aqueous solution in a beaker, and stirred at 100 rpm at a temperature of 71°C. and prepared microemulsion samples. Evaluation of the microemulsion forming ability of the sample and measurement of interfacial tension were carried out in the same manner as in Example 1. The oil recovery test has a permeability of approximately 500 mD and a porosity of approximately 20%.
A Berea sandstone core with a length of 28 cm and a diameter of 3.8 cm was used. The test method is to load a core fully saturated with brine into a core holder, and add 6 liters of A heavy oil.
The brine was pressurized at a rate of cc/min until it no longer flowed out. Then press in brine at the same speed,
Water flooding was carried out and heavy oil A was recovered. Water flooding was continued until the amount of heavy oil A contained in the spilled liquid was below 0.1%. The micellar attack method was carried out by placing the microemulsion to be press-fitted and the core holder in a constant temperature bath and maintaining the temperature at 71°C. First, add 10% microemulsion.
Pore volume followed by polymer solution (xanthan gum
1000ppm) to 100% pore volume, and finally brine
100% pore volume was injected and heavy oil A was recovered. The press-fitting speed was 2 feet/day. To evaluate the recovered oil, the moisture in the core after the test was recovered by an azeotropic method using toluene, and the moisture content of the core was determined and converted to the amount of oil recovered. The results obtained are shown in Table 2.

[Table] Example 3 C ₁₂ - C ₁₃ AES-Na (=3) as surfactant
7.2% and _C15 ~ _C17 IOS−Na1.8%, as alkali
NaOH 1%, Na ₂ CO ₃ 1% or omitted, n-amyl alcohol 4% as surfactant, A heavy oil 17% as oil, 69% or 70% aqueous solution of 8% sodium chloride dissolved in deionized water as brine. % in a beaker and stirred at 100 rpm at a temperature of 71°C.
Microemulsion samples were prepared. Evaluation of the microemulsion forming ability of the sample and measurement of interfacial tension were carried out in the same manner as in Example 1, and measurement of oil recovery rate of the microemulsion was carried out in the same manner as in Example 2. The results obtained are shown in Table 3.

【table】

[Table] Example 4 C ₁₁ - C ₁₅ AES-Mg (=
2), C ₁₆ ~ C ₁₈ AES-K (= 5), C ₁₄ ~ C ₁₆ IOS
-NH ₄ and C ₁₇ - C ₂₀ IOS-K, isopropyl alcohol or n-amyl alcohol as surfactant, kerosene or A heavy oil as oil, and an aqueous solution of sodium chloride dissolved in seawater or deionized water as water, respectively. The predetermined amount listed in Table 4 was weighed into a beaker and stirred at 100 rpm for 30 minutes at a temperature of 71°C to prepare a microemulsion. Evaluation of microemulsion forming ability and measurement of interfacial tension were carried out in the same manner as in Example 1, and measurement of oil recovery rate was carried out in the same manner as in Example 2. The results obtained are shown in Table 4.

【table】

Claims (1)

[Claims] 1. In a micelle solution for oil recovery consisting essentially of oil, water that may contain inorganic salts, a surfactant, and a surfactant aid, (A) an alkyl ether sulfate having 8 to 20 carbon atoms as a surfactant. A micelle solution for oil recovery characterized by using 100 parts by weight and (B) 1 to 100 parts by weight of an internal olefin sulfonate having 10 to 26 carbon atoms.