JPH0331871B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a micellar solution used in the micellar attack method for recovering oil from underground reservoirs, and more specifically, it can be applied to underground reservoirs containing oil reservoir water with a very wide range of salt concentrations to achieve a high oil recovery rate. This invention relates to a micellar solution for oil recovery that can recover oil. Only a portion of the oil contained in underground oil reservoirs can be recovered using primary recovery methods such as pumping, and the majority remains in the underground reservoirs. 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.
The oil can be recovered by making it more fluid, or by heating the underground reservoir 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 that increase the amount of water used for recovery, 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 Oil 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 a variety of anionic, nonionic, and cationic surfactants, such as petroleum sulfonates, alkylaryl sulfonates,
Dialkyl sulfosuccinate, alkanesulfonate, polyoxyethylene alkyl ether sulfate, α-olefin sulfonate, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyhydric alcohol fatty acid ester, alkyltrimethylammonium salt, dialkyldimethylammonium salt etc. are listed. The micellar solution requires that the interfacial tension between the oil and the microemulsion and between the reservoir water and the microemulsion are sufficiently low to achieve high oil recovery, and that the salt concentration of the reservoir water changes during sweeping. It is required that the microemulsion is kept stable and that the change in interfacial tension is small. 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. Furthermore, since the amount of micellar solution injected into the underground reservoir is very large, the micellar solution must be low cost. The present invention has been made with the aim of solving these problems, and is a method for forced oil recovery consisting essentially of hydrocarbons, water that may contain inorganic salts, surfactants, and surfactant aids. In micellar solutions used as injection fluids, the content of disulfonates as an essential component of surfactants is approximately
The present invention provides a micellar solution using 20% by weight or less of internal olefin sulfonate having 10 to 26 carbon atoms (hereinafter abbreviated as IOS). Micellar solutions of the present invention suitable for use as inflow fluids for forced oil recovery contain about 2% to about 90% by weight hydrocarbons, about 4% to about 92% by weight water, and the essential components of IOS having 10 to 30 carbon atoms. A clear microemulsion containing from about 3 to about 30% by weight of a surfactant and from about 0.1 to about 20% by weight of a cosurfactant. Water that can be used in the micellar solution of the present invention may be soft water, brackish water, or brine, such as 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 component of the surfactant, it can tolerate even 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 NaCI, KCI, 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 contained in the micellar solution of the present invention as an essential component of the surfactant has the general formula R-CH=CH-R' (wherein R and R' are each a linear or branched chain having 1 or more carbon atoms. It is a saturated hydrocarbon group with 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 way typically contains about 10-60% by weight of alkenyl sulfonates with double bonds and about 90-40% by weight of hydroxyl alkanesulfonates;
On the other hand, it contains about 80% by weight or more of monosulfonate and about 20% by weight or less of disulfonate. Of course, by selecting the sulfonation conditions and hydrolysis conditions, it is possible to obtain a different proportion of IOS from the above-mentioned component proportions.
It is also possible to manufacture 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 must have a disulfonate content of about 20% by weight or less.
If the disulfonate content is higher than this, IOS
This impairs the interfacial tension lowering ability of the oil, making it impossible to produce a micelle solution with high oil recovery. A small amount of disulfonate in IOS increases the salt tolerance without impairing the interfacial tension lowering ability and improves the resistance to changes in the salt concentration of the brine, so the content of disulfonate is approximately 0.5-15% by weight. , especially about 1-12% by weight
It is desirable that The IOS used in the present invention is an alkali metal salt,
selected from alkaline earth metal salts, ammonium salts and organic alumine salts. The preferred countercation is
Na, K, Mg, Ca, NH ₄ and alkanol ammonium. An example of an IOS suitable for the present invention is
12, 14, 16, 18, 20, 22, 24, 12-16, 13-14,
13-16, 14-16, 14-18, 15-18, 16-18, 16-
20, 17-20, 18-20 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 a carbon number of 10 to 26 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 works 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 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 aliphatic groups may be linear or branched)
Alcohols shown in 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), and the like. 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 15% 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 optionally be used in combination. Examples of such surfactants include petroleum sulfonates, alkylbenzene sulfonates, polyoxyethylene alkyl ether sulfates, dialkyl sulfosuccinates, alpha-olefin sulfonates, paraffin sulfonates, soaps, higher alcohol ethoxylates, alkyl phenol ethoxylates, Examples include anionic surfactants and nonionic surfactants such as polyhydric alcohol fatty acid esters, fatty acid alkylolamides, and polyoxyethylene fatty acid amides. The viscosity of the micellar solution of the present invention can be adjusted by appropriately selecting the type and blending ratio of each component constituting the microemulsion, but it is also possible to use a known thickener such as a water-soluble polymer. You can also. Such thickeners include, for example, heteropolysaccharides produced by microorganisms, naphthalene sulfonic acid formalin condensates,
Examples include polyacrylamide, polyacrylate, hydroxyethylcellulose, carboxymethylcellulose, 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 for 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 are 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 need 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 contains IOS with a disulfonate content of about 20% by weight or less as an essential component of the surfactant, so it has good salt resistance, resistance to water, and water softening properties, and has a wide range of salts from hard water to brine with high salt concentration. Since the interfacial tension between water and microemulsions and between oil and microemulsions is very small and resistant to changes in salt concentration, (1 )
(2) The injected micellar solution is hardly affected by inorganic salts present in underground reservoirs; (3) It can be used freely in soft water, seawater, and oil reservoir water with high salt concentration.
It can be applied to various oil fields from low viscosity oil to high viscosity oil, and (4) a stable microemulsion can be maintained until an oil bank is formed in an underground reservoir, achieving a high oil recovery rate. You can get excellent effects such as 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 proportions of components in each sample used in the experiment are critical % unless otherwise indicated. Example 1 C ₁₄ - C ₁₈ IOS-Na or petroleum sulfonate (Witco TRS-10) with varying amounts of disulfonate contained in the active ingredient as a surfactant 10.5
%, aluminum alcohol 4.5% as surfactant,
As oil: A heavy oil (ASTM No.-2 oil) 17
%, and 68% of a solution of 8% sodium chloride in deionized water as brine was weighed into a beaker and stirred at 100 rpm for 30 minutes at a temperature of 71°C to prepare a microemulsion. 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 was used as an internal olefin as a raw material in the sulfonation reaction.
The synthesis was performed by changing the molar ratio of SO ₃ to adjust the amount of disulfonate (DS) contained in the active ingredient.
For samples with low disulfonate content,
Furthermore, extraction and purification was performed using isobutyl alcohol to adjust the content to a predetermined value. For evaluation of microemulsion forming ability, samples whose appearance became uniformly transparent at a temperature of 71°C were rated as ○, and samples whose appearance was opaque and suspended were rated as ×. The interfacial tension was measured using a spinning drop type interfacial tension meter at a temperature of 71°C in an appropriately diluted system. 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.
A fuel oil 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 added to 10% pore volume, followed by the polymer solution (xanthan gum).
A 1000 ppm brine solution) was injected to 100% of the pore volume, and finally brine was injected to 100% of the 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] Example 2 C ₁₄ - C ₁₈ IOS-Na 10.5% containing 7% disulfonate (based on active ingredient) as surfactant, 4.5% amyl alcohol as surfactant, 17% heavy oil A as oil, brine An aqueous solution with a predetermined amount of sodium chloride dissolved in deionized water, or an aqueous solution of sodium chloride with CaCl ₂ or
A 68% aqueous solution containing MgCl ₂ dissolved therein 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 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-2.

[Table] Example 3 C ₁₃ C ₁₄ IOS−Na, C ₁₈ ~ as surfactant
C ₂₀ IOS-Mg or C ₂₀ ~ C ₂₂ IOS-K 10.5%, amyl alcohol 4.5% as surfactant, A heavy oil 17% as oil, aqueous solution of 8% sodium chloride dissolved in deionized water as brine68 % 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 the ability of the sample to form a microemulsion, 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-3.

【table】

Claims (1)

[Claims] 1. In a micelle solution for petroleum recovery consisting essentially of hydrocarbons, water which may contain inorganic salts, a surfactant and a surfactant aid, the content of disulfonate as a surfactant is not more than about 20% by weight. number of carbons
A micelle solution for oil recovery characterized by using 10 to 26 internal olefin sulfonates.