JPH0331872B2 - - Google Patents

Description

[Detailed description of the invention]

Technical Field The present invention relates to a micellar solution used in the micellar attack method for recovering oil from underground reservoirs, and more specifically, it is capable of forming microemulsions with low interfacial tension at high salt concentrations, and the viscosity can be easily adjusted. This article relates to a micellar solution for oil recovery with a high oil recovery rate. Prior Art Only a portion of the oil contained in an underground oil reservoir can be recovered by primary recovery methods such as pumping, and most of it remains in the underground reservoir. In order to recover oil that cannot be recovered by this primary recovery method,
Water or gas is injected into underground reservoirs to increase pressure.
Oil can be recovered by making it more fluid, or by heating underground reservoirs by injecting steam or partially burning the oil in the reservoir to reduce the viscosity of the oil and make it more fluid. A variety of tertiary recovery methods have been proposed, including secondary recovery methods in which wastewater is recovered using water, and improved secondary recovery methods that combine these secondary recovery methods or use surfactants or water-soluble polymers. These are commonly referred to as Enhanced Oli Recovery (EOR). Among EOR using surfactants, a method that has been attracting attention in recent years is to create a transparent microemulsion from water and oil such as petroleum or heavy oil, and to deposit this microemulsion, also called a micellar solution, into an underground reservoir. There is a micellar attack method that involves press-fitting and recovering oil. There are many prior arts related to this micellar attack method, such as U.S. Patent No. 3506070 and U.S. Pat.
Examples include No. 3613786, No. 3740343, No. 3983940, No. 3990515, No. 4017405, and No. 4059154. Among these prior technologies,
Surfactants that can be used in the preparation of micellar solutions include petroleum sulfonates, alkylaryl sulfonates, dialkyl sulfosuccinates, alkanesulfonates, polyoxyethylene, and various anionic, nonionic and cationic surfactants. alkyl ether sulfate,
Examples include α-olefin sulfonate, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyhydric alcohol fatty acid ester, alkyltrimethylammonium salt, dialkyldimethylammonium salt, and the like. Micellar solutions require that the interfacial tensions between the oil and the microemulsion and between the oil reservoir water and the microemulsion are sufficiently low and that the viscosity of the microemulsion is low enough to achieve a high oil recovery rate. It is required that the level is the same or slightly higher than that of oil. Furthermore, since the salt concentration of oil layer water varies widely from low to high, the micelle solution is required to have salt resistance suitable for each salt concentration. Object and Structure of the Invention The present invention was made with the aim of solving these problems, and consists essentially of hydrocarbons, water that may contain inorganic salts, a surfactant, and a surfactant auxiliary. In a micellar solution used as an injection fluid for forced oil recovery, the essential component of the surfactant has the general formula R-CH=CH-R' (wherein, R is a linear or It is a branched alkyl group, R' is a straight or branched alkyl group having 1 to 12 carbon atoms, and R and
The sum of R' is 8 to 24, and the number of carbon atoms in R' is about 50% by weight or more, preferably about 60% by weight or more). The number of carbon atoms is 10 to 26, and the content of hydroxyalkanesulfonate is approximately 40% by weight.
The above provides a micelle solution using internal olefin sulfonate (hereinafter abbreviated as IOS) having a disulfonate content of about 20% by weight or less. DESCRIPTION OF THE INVENTION The micellar solutions of the present invention suitable for use as injection fluids for forced oil recovery contain from about 4 to about 90 hydrocarbons.
Weight%, water about 4 to about 92% by weight, carbon number 10 to 30
It is a clear microemulsion containing from about 1% to about 30% by weight of a surfactant consisting essentially of IOS and from about 0.1% to about 20% by weight of a cosurfactant. The water that can be used in the micellar solution of the present invention may be soft water or brine, for example, rainwater,
River water, lake water, groundwater, oil reservoir water and seawater can all be used freely. Since the micellar solution of the present invention uses IOS, which has good salt resistance and hard water resistance, as an essential surfactant component, it can tolerate a salt concentration of about 10% in the brine, and other By using a surfactant and selecting a surfactant, it is possible to use brine up to a concentration of approximately 15%, and the concentration of Mg ions is approximately 5000 PPM for polyvalent metal ions.
(approximately 2.6% as _MgSO4 ) is allowed.
The concentration of inorganic salts in the water that can be used to prepare the micellar solution of the present invention ranges from 0 to about 15% by weight, especially about 0.5% by weight.
~12% by weight, particularly from about 1% to about 10% by weight are preferred. Typical examples of alkali metal salts contained in water (brine) containing inorganic salts are NaCl, KCl, Na ₂ SO ₄ and K ₂ SO ₄ . For example, seawater has an inorganic salt concentration of about 3.5% and contains about 1600 PPM of divalent metal ions in terms of Mg ions, and such salt concentrations are within the preferred range of the present invention. The IOS that the micellar solution of the present invention contains as an essential component of the surfactant has the general formula R-CH=CH-R' (wherein R is a straight or branched alkyl having 4 to 23 carbon atoms. group, R' is a linear or branched alkyl group having 1 to 12 carbon atoms, and R and
The total number of carbon atoms in R' is 8 to 24, and R' has 1 to 4 carbon atoms in an amount of about 50% by weight or more). type monoolefin as an essential component, and in some cases approx.
It is produced by sulfonating an internal olefin containing less than 33% by weight (approximately 1/3 of the olefin) of a 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 disulfonates in an amount of up to about 20% by weight.
Of course, by selecting the sulfonation conditions and hydrolysis conditions, it is possible to create
It is also possible to manufacture IOS. 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. The IOS used in the present invention requires that the lipophilic group has a long-chain aliphatic group and a short-chain aliphatic group. If it does not have short chain aliphatic groups (i.e.
AOS) has a high viscosity microemulsion, and it is difficult to reduce the viscosity while maintaining interfacial tension and microemulsion stability. On the other hand, if both of the aliphatic groups are long, the salt resistance decreases and it cannot be applied to underground reservoirs with high salt concentration. Therefore, in the above general formula, R' having 1 to 4 carbon atoms is required to account for about 50% by weight or more, preferably R' is linear, and especially R' has 1 to 4 carbon atoms.
-4 is desirably about 60% by weight or more. Moreover, R in the above general formula is preferably linear. Additionally, the amount of disulfonate is preferably less than about 20% by weight, especially less than about 15% by weight, and the amount of hydroxyalkanesulfonate is preferably greater than about 40%, especially from about 45 to 90% by weight. The IOS used in the present invention is an alkali metal salt,
selected from alkaline earth metal salts, ammonium salts and organic amine salts. Preferred countercations are Na,
K, Mg, Ca, NH ₄ and alkanol ammonium. An example of an IOS suitable for the present invention is
12, 13, 14, 15, 16, 18, 20, 22, 24, 12~13,
12~16, 13~14, 14~16, 14~18, 15~17, 16~
18, 16-20, 18-20, 18-24 and 20-24 IOS, and mixtures thereof. The micellar solution of the present invention contains a surfactant from about 1 to
The surfactant content is approximately 30% by weight, but considering the low oil-water interfacial tension and cost, the surfactant content is approximately 3% by weight.
~25% by weight is preferred. The proportion of IOS with 10 to 30 carbon atoms in the surfactant is at least 50
% by weight, preferably 60% by weight or more. The hydrocarbon used as the oil phase component of the present invention can be petroleum, liquefied petroleum gas, crude gasoline (naphtha), kerosene, light oil, heavy oil, etc.; It is preferable to use recovered petroleum, considering that it has a similar composition to the petroleum contained therein. The proportion of hydrocarbons in the micellar solution of the present invention is about 2 to about 90% by weight, but since it is economically disadvantageous to use a large amount of hydrocarbons, an O/W emulsion is preferred, and therefore The proportion is also preferably about 3 to about 40% by weight. In the micellar solution of the present invention, the surfactant auxiliary is an essential component that cooperates 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 RO(CH ₂ CH ₂ O) _o H (where n is a number from 0 to about 4 and R is , n=0
In the case of , it is an alkyl group or alkenyl group having 4 to 8 carbon atoms, and when n is not 0, it is an alkyl group or alkenyl group having 6 to 15 carbon atoms, a phenyl group, or an alkyl phenyl group having 7 to 16 carbon atoms. group, and the aliphatic group may be linear or branched). Specific examples of such alcohols include butanols, pentanols, hexanols, 2-ethylhexanol, other octanols, polyoxyethylene hexyl ether (=1), polyoxyethylene decyl ether (=2), Polyoxyethylene tridecyl ether (=4), polyoxyethylene butyl phenyl ether (=2), polyoxyethylene nonyl phenyl ether (=3),
Polyoxyethyne dodecyl phenyl ether (
=4), etc. 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 contains IOS having 10 to 26 carbon atoms as an essential surfactant component, but other surfactants can be used in combination as an auxiliary component.
Examples of such surfactants include petroleum sulfonates, alkylbenzene sulfonates, polyoxyethylene alkyl ether sulfates, dialkyl sulfosuccinates, lower alpha-olefin sulfonates, paraffin sulfonates, soaps, higher alcohol ethoxylates, alkyl phenol ethoxylates. , anionic surfactants and nonionic surfactants such as polyhydric alcohol fatty acid ester, fatty acid alkylolamide, and polyoxyethylene fatty acid amide. Since the micellar solution of the present invention has a relatively low viscosity,
Although it can be used as it is, if a highly viscous micelle solution is required, a known thickener such as a water-soluble polymer can be used. Examples of such thickeners include heteropolysaccharides produced by microorganisms, naphthalene sulfonic acid formalin condensates, polyacrylamides, polyacrylates, hydroxyethyl cellulose,
Examples include carboxymethylcellulose. 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. The appropriate salt concentration of oil layer water in underground reservoirs to which the micellar solution of the present invention can be applied is 0 to about 15% by weight;
Among these, about 0.1 to about 12% by weight, particularly about 0.5 to about 10% by weight is preferred. Further, the salt concentration of the water used for producing the micelle solution and the salt concentration of the oil layer water do not necessarily have to be the same, but in consideration of changes in salt concentration during sweeping, it is preferable that they be the same. The micelle solution of the present invention has a lipophilic group consisting of two aliphatic groups, a long chain and a short chain, as a surfactant.
Since IOS is used, it has excellent salt resistance and hard water resistance, and can form microemulsions in a wide range of salt concentrations from soft water to brine with high salt concentrations, and between water and microemulsions and between oil and microemulsions. The interfacial tension of both is very small, and the viscosity of the microemulsion is low.
In addition, the viscosity can be adjusted using a thickening agent, so (1) it can be used freely in soft water, seawater, or oil layer water with high salt concentration; (2) the injected micellar solution can be used in underground reservoirs. Almost unaffected by the presence of inorganic salts, (3) Applicable to various oil fields from low viscosity oil to high viscosity oil, (4) Microemulsion is destroyed by oil and water contained in underground reservoirs. Therefore, excellent effects such as a high oil recovery rate can be obtained. 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 The amount of hydroxyalkanesulfonate contained in the active ingredient obtained by sulfonating an internal olefin containing about 75% by weight of surfactants with double bonds in _C2 to _C5 positions was varied. C ₁₅ - C ₁₇ IOS-Na 10.5%, amyl alcohol 4.5% as surfactant, A heavy oil (ASTM No.-2 oil) 17% as oil, and 3% or 8% sodium chloride in deionized water as brine.
Measure out 68% of the dissolved aqueous solution into a beaker.71
A microemulsion was prepared by stirring at 100 rpm for 30 minutes at °C. At this time, the microemulsion forming ability of the sample, the interfacial tension lowering ability of the prepared microemulsion, and the oil recovery rate of the microemulsion were evaluated. The test results are listed in Table-1. IOS used as a surfactant is used as a raw material.
C ₁₅ to C ₁₇ alpha olefins were isomerized to internal olefins using an acid catalyst and then sulfonated. The position of the double bond in olefin after isomerization is _C2 - _C5
Approximately 80% of the cases were located in this position. Samples with different hydroxyalkanesulfonate contents were synthesized by changing the molar ratio of internal olefin and SO ₃ in the sulfonation reaction. 90% hydroxyalkanesulfonate
The contained sample was synthesized by extracting the sultone from the slurry after sulfonation using hexane, and then hydrolyzing it in toluene. In addition, a sample with a hydroxyalkanesulfonate content of 30% was prepared by neutralizing the hexane extraction residue and adjusting the content to a predetermined value. The microemulsion forming ability was evaluated as ○ if the sample was uniformly transparent in appearance, and × if the sample was opaque and suspended. The interfacial tension was measured using a spinning drop type interfacial tension meter in an appropriately diluted system at 71°C. 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 was to load a core sufficiently saturated with brine into a core holder, and then pump heavy oil A at 6c.c./min.
Heavy oil A was pressurized at a speed of
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. First, the microemulsion was injected to 10% pore volume, then the polymer solution was injected 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. The recovered oil was evaluated by recovering the moisture in the core after the test using an azeotropic method using toluene, determining the amount of moisture in the core, and converting it into the amount of oil recovered.

[Table] In Table 1, sample numbers 3 to 6 are examples of the present invention, sample number 1 is a reference example that forms a microemulsion at a low salt concentration, and sample number 2 is a comparative example of hydroxyalkanesulfonate. An example will be shown in which salt tolerance deteriorates as the amount decreases. Example 2 As a surfactant, 70% hydroxyalkanesulfonate and disulfonate obtained by sulfonating an internal olefin containing approximately 75% by weight of double bonds in _C2 to _C5 positions are used as active ingredients. C ₁₈ - C ₁₆ IOS-Na 10.5% containing 8%, 4.5% amyl alcohol as surfactant, 17% heavy oil A as oil, sodium chloride, calcium chloride, magnesium chloride in seawater or deionized water as brine. A predetermined amount of dissolved 68% was weighed into a beaker and stirred at 25° C. and 100 rpm for 30 minutes to prepare a microemulsion. Evaluation of the microemulsion forming ability of the sample, measurement of the interfacial tension of the microemulsion, and oil recovery test of the microemulsion were conducted in the same manner as in Example 1. The test results are listed in Table-2.

[Table] Example 3 As a surfactant, a sulfonated internal olefin was used under different isomerization conditions of C ₁₆ alpha olefin, ie, catalyst amount and reaction time. Table 3 shows the positions and ratios of double bonds in the C ₁₆ internal olefin after isomerization.

[Table] C ₁₆ IOS-Na 10.5% made by sulfonating internal olefins of sample numbers 13 and 14, amyl alcohol 4.5% as surfactant, A as oil
A microemulsion was prepared by weighing 17% heavy oil and a 68% aqueous solution of 8% sodium chloride dissolved in deionized water as brine into a beaker and stirring at 71° C. and 100 rpm for 30 minutes. Using this sample, an oil recovery test was conducted in the same manner as in Example 1. As a result, the oil recovery rate of the microemulsion using the sulfonated internal olefin of sample number 13 was 93%, whereas the oil recovery rate of sample number 14 was 93%. In the case of the sulfonated internal olefin, it was 90%. The difference in recovery rate due to the difference in the position of the double bond in the raw material olefin is small, but when applied to an actual scale, it becomes a difference that cannot be ignored. It is preferable that the starting olefin has many double bonds at _C2 to _C5 positions. Example 4 C ₁₃ C ₁₄ IOS−Mg, C ₁₄ ~ as a surfactant
C ₁₈ IOS-Na or C ₁₈ - C ₂₀ IOS-K 10.5%, amyl alcohol 4.5% as surfactant aid, A heavy oil 17% as oil and an aqueous solution of 8% sodium chloride in deionized water as brine68 % was measured in a beaker and stirred at 100 rpm for 30 minutes at a temperature of 71°C to prepare a microemulsion. Evaluation of the microemulsion forming ability of the sample, measurement of the interfacial tension of the microemulsion, and oil recovery test using the microemulsion were conducted in the same manner as in Example 1. The test results are listed in Table-4.

【table】

[Table] Example 5 C ₁₆ - C ₁₈ IOS used in Example 2 as surfactant
-The viscosity of the microemulsion using Na was measured. The viscosity of samples based on the composition shown in Sample No. 9 with different surfactant additives and samples with hydroxyethylcellulose added as a thickener were measured. Microemulsions using C ₁₆ -C ₁₈ IOS-Na formed uniform microemulsions even when the surfactant was changed or a thickener was added. The viscosity was measured at 25°C using a Bruckfield viscometer. The test results are listed in Table-5.

【table】

Claims (1)

[Claims] 1. In a micelle solution for petroleum recovery consisting essentially of a hydrocarbon, water which may contain an inorganic salt, a surfactant, and a surfactant aid, the surfactant has the general formula R-CH= CH-R' (wherein, R is a linear or branched alkyl group having 4 to 23 carbon atoms, and R' is a linear or branched alkyl group having 1 to 12 carbon atoms. and R and
The total number of carbon atoms in R' is 8 to 24, and R' has 1 to 4 carbon atoms in an amount of about 50% by weight or more). 26. A micelle solution for petroleum recovery characterized by using an internal olefin sulfonate having a hydroxyalkanesulfonate content of about 40% by weight or more and a disulfonate content of about 20% by weight or less.