JPH0331876B2 - - 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. Although paraffin sulfonate has relatively good salt resistance and is adsorbed to rocks in underground reservoirs to a small extent, microemulsion using paraffin sulfonate has the drawback of high interfacial tension and poor oil recovery. 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 oil recovery consisting essentially of oil, water that may contain an inorganic salt, a surfactant, and a surfactant auxiliary, in which (A) a carbon number of 10 to 22 is used as a surfactant. 100 parts by weight of paraffin sulfonate (hereinafter abbreviated as PS) and (B) carbon number 10
-26 internal olefin sulfonate (hereinafter abbreviated as IOS) is used in an amount of 1 to 100 parts by weight. 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. The water used in the present invention can be water or brine with an inorganic salt concentration of 0 to about 10% by weight, since the surfactant has good salt resistance and hard water resistance.
The inorganic salt concentration is about 0.1 to about 8% by weight. Water that can be used in the present invention includes soft water, brine, oil layer water, etc., and examples thereof include rainwater, river water, lake water, groundwater, oil layer water, and seawater. Examples of alkali metal salts found in brine are NaCl, KCl,
Na ₂ SO ₄ and K ₂ SO ₄ are representative. Examples of divalent metal ions are Mg ions and Ca ions,
Approximately 4000 ppm of Mg ions can be tolerated. The PS used as the surfactant component A in the micelle solution of the present invention has 10 to 22 carbon atoms, preferably
It is an alkanesulfonate having a sulfonic acid group bonded to the secondary carbon and is usually produced by the oxychlorination method of paraffin, especially normal paraffin. Suitable PS salts are alkali metal salts, alkaline earth metal salts, ammonium salts and organic amine salts, especially Na salts, K salts,
Preference is given to Mg salts, ammonium salts and alkanolamine salts. As an example of PS suitable for the present invention,
Carbon number 12, 13, 14, 15, 16, 17, 18, 20, 13 ~
15, 14-16 and 16-18 PS and mixtures thereof. 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 IOS that satisfies these conditions is used, a microemulsion 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. Since the micellar solution of the present invention uses IOS as a minor component in addition to PS as a surfactant, brine with high salt concentration can be used for the production of microemulsions, and it can be used in underground reservoirs containing oil reservoir water with high salt concentration. Microemulsions are obtained which can be applied and have sufficiently low interfacial tensions. the result,
High oil recovery is achieved from low to high salt concentrations. To achieve this effect,
At least 1 part by weight, preferably 5 parts by weight or more of IOS is required per 100 parts by weight of PS. on the other hand,
When the amount of IOS used is increased, the effect of adding IOS remains constant, so IOS is calculated per 100 parts by weight of PS.
A suitable amount is 100 parts by weight or less, preferably 80 parts by weight or less. 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. 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 micellar solution of the present invention contains PS as a surfactant.
Although IOS is used, other surfactants can also be used supplementarily. Examples of such surfactants include petroleum sulfonates, alkylbenzene sulfonates, polyoxyethylene alkyl ether sulfates, dialkyl sulfosuccinates, alpha-olefin sulfonates, soaps, higher alcohol ethoxylates, alkyl phenol ethoxylates, polyhydric alcohols. Examples include anionic surfactants and nonionic surfactants such as fatty acid esters, fatty acid alkylolamides, and polyoxyethylene fatty acid amides. In the micelle solution of the present invention, a known thickener such as a water-soluble polymer can be used 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. At this time, the appropriate amount of injection of the micelle solution is such that the porosity of the underground reservoir is 5 to 25% by volume. 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 _C16 ~ _C18 PS-Na and _C14 ~ as surfactants
9.5% mixture of different proportions of C ₁₈ IOS-Na, 4.5% n-amyl alcohol as surfactant, 20% A heavy oil (ASTM, No. 2 oil) as oil, 8% sodium chloride in deionized water as brine. Weigh out 66% of the aqueous solution dissolved in
A microemulsion sample was prepared by stirring at 100 rpm for 30 minutes. 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 combined with the proportion of surfactant in the first
Shown in the table.

[Table] Example 2 C ₁₆ - C ₁₈ PS-Na7.6% and C ₁₄ as surfactants
~C ₁₈ IOS-Na 1.9%, n-amyl alcohol 4.5% as surfactant, A heavy oil 20% as oil, brine as an aqueous solution of a predetermined amount of sodium chloride dissolved in deionized water, or further added to an aqueous sodium chloride solution. Measure 66% of an aqueous solution of magnesium chloride or calcium chloride into a beaker,
A microemulsion sample was prepared by stirring at 100 rpm at a temperature of 71°C. Evaluation of the microemulsion forming ability of this 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. Subsequently, brine was injected at the same speed and water flooding was performed to recover A heavy oil. 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. Initially, the microemulsion was reduced to 10% pore volume,
followed by polymer solution (xanthan gum 1000ppm)
to 100% pore volume, and finally, brine was injected to 100% pore volume to recover heavy oil A. 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 ₁₄ - C ₁₆ PS-Mg, C ₁₅ - as surfactant
C ₁₇ IOS-NH ₄ and C ₁₆ - C ₁₈ IOS-K, isopropyl alcohol or n-amyl alcohol as surfactant, kerosene or A heavy oil as oil, 5% sodium chloride dissolved in seawater or deionized water as water. A predetermined amount of the aqueous solution shown in Table 3 was measured 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 3.

【table】

[Table] Example 4 C ₁₃ - C ₁₅ PS-K, C ₁₆ - as surfactants
_C18PS −Na, _C13 ~ _C15IOS − _NH4 and _C17 ~
C ₂₀ IOS-K, isopropyl alcohol or n-amyl alcohol as the surfactant, kerosene or heavy oil A as the oil, and an aqueous solution of sodium chloride dissolved in deionized water as the water in a beaker of the specified amount listed in Table 4. Measure it out and heat it for 30 minutes at a temperature of 71℃.
A microemulsion was prepared by stirring at 100 rpm. 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, as a surfactant (A) carbon number
100 parts by weight of 10-22 paraffin sulfonate and
(B) A micelle solution for petroleum recovery characterized by using 1 to 100 parts by weight of an internal olefin sulfonate having 10 to 26 carbon atoms.