JPS60152794A - Recovery of crude oil - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a micellar attack method for recovering oil from an underground oil-bearing layer, and more specifically, a surfactant fluid is injected from an injection well to form a microemulsion with low interfacial tension in an underground oil-bearing layer. Conventional technology for oil recovery methods that recover oil with a high recovery rate by sweeping the oil layer with the surfactant fluid present as
ced 011 Recovery) (E, 0.R)
One type of method is the micellar attack method, in which a transparent microemulsion is made from water and oil such as petroleum or heavy oil, and this microemulsion, also known as a micellar bath liquid, is injected into an underground oil-bearing layer to recover oil. There are many prior art techniques related to micellar attacks, to name a few: U.S. Pat. No. 3,506,070, U.S. Pat.
No. 740343, No. 3983940, No. 3990
No. 515, No. 4017405 and No. 405915
Examples include No. 4. The use of surfactants is essential for producing micellar solutions used in micellar attack methods, and a number of surfactants have been proposed for this purpose, including petroleum sulfonates, alkyl sulfonates, dialkyl sulfosuccinates, etc. nate, alkanesulfonate, polyoxyethylene alkyl ether sulfate, α-
Olefin sulfonate, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyhydric alcohol fatty acid ester, alkyl) IJ
Various anionic, nonionic and cationic surfactants such as methylammonium salts and dialkyldimethylammonium salts are known.

As an improved method of micellar flooding in which a microemulsion is injected into an oil layer, a method has been proposed in which an aqueous solution containing a surfactant and a surfactant aid is injected into the oil layer, and a microemulsion is formed while sweeping the oil layer. This method requires the formation of a microemulsion in the oil reservoir, so the surfactant water bath solution to be injected must exhibit a sufficiently low oil-water interfacial tension to easily absorb the oil in the reservoir water and petroleum. The viscosity is higher than either, and the viscosity is not too high.
It is required to quickly form a microemulsion upon contact with petroleum. Furthermore, since oil reservoir water varies widely in oil fields, from low salt concentrations to high salt concentrations, surfactants with good salt resistance and hard water resistance are required.

OBJECT AND STRUCTURE OF THE INVENTION The present invention aims to solve the above-mentioned problems. (1) Approximately 1 to 30% by weight of surfactant, approximately 0 surfactant auxiliary
．． injecting a first injection fluid consisting essentially of 1 to 20% by weight, 0 or less than about 90% by weight hydrocarbons and prine from an injection well into a subsurface oil-bearing formation; A method for injecting a viscous aqueous polymer solution as a second injection fluid into an oil reservoir from an injection well, and (3) recovering petroleum displaced by the first and second injection fluids from a production well. As, A, α-olefin sulfonate of carbon 1alO~26 (
(hereinafter abbreviated as AO8) B, internal olefin sulfonate having 10 to 26 carbon atoms (hereinafter abbreviated as IO8) and C0 ethoxylate represented by the general formula [■] or [■], RO + CH2CH2O 7H...CI]R2 Combined O÷C
H2C\yu0yaH...Cl1l- (In both 7 formulas, R1 is an alkyl group or alkenyl group having 10 to 18 carbon atoms, and 1
, R2 is an alkyl group having 6 to 15 carbon atoms, and each of 9, R' and R2 may be linear or branched. m and n are average values, m is about 1 to about 15, n is about 3 to about 1
The number is 5. ) A/B = 1/19 to 9/1 and (
The purpose of the present invention is to provide an improved micellar attack method characterized by using micellar at a weight ratio of A1B)/c = 19/1 to 2/3.

SUMMARY OF THE INVENTION AND DESCRIPTION OF OPERATIONS The first injection fluid used in the present invention contains about 1 to about 3 surfactants.
The present invention is a surfactant fluid containing, by weight, about 0.1% to about 20% by weight surfactant co-agents and brine as essential components, and desirably up to about 90% by weight hydrocarbons. The present invention is characterized in that the first injection fluid contains three types of surfactants with specific specific gravity.

The first component (component A) of the surfactant has 10 to 26 carbon atoms.
, preferably AO8 having 12 to 24 carbon atoms. Suitable AO8 used in the present invention are alkali metal salts, ammonium salts, and organic amine salts. Preferred countercations are Na + K * Mg tNH4 and alkanol ammonium. %KNa salt is inexpensive, and porcelain salt has the advantage of not being affected by polyvalent metal ions in oil reservoir water. Examples of AO8O suitable for the present invention are 1-dodecene sulfonate, 1-tetradecene sulfonate, 1-hexadecene sulfonate, 1-octadecene sulfonate, 1
-Eicosene sulfonate, l-tocosene sulfonate, 1-tetradecene sulfonate, carbon number 10-1 o
s, AO8 having 14 to 16 carbon atoms, A having 14 to 18 carbon atoms
O8, AO8 with 16 to 18 carbon atoms and 20 to 24 carbon atoms
This is AO8.

The second component (B component) of the surfactant has 10 to 26 carbon atoms.
, preferably 12 to 24 IO8.

IO2 is usually expressed by the general formula % (where R and R' are each a linear or branched saturated hydrocarbon group having 1 or more carbon atoms, and L is the sum of the carbon numbers of R and R'. is 8 to 24, preferably 10 to 22) as an essential component, and if ↓
9 It is produced by fluorinating an internal olefin containing about 33% by weight or less (about 1/3 of the olefin) of a trisubstituted monoolefin, neutralizing it with an appropriate base, and hydrolyzing it if necessary. The IO manufactured in this way
8 is usually a mixture of double-bonded alkenylsulfonates and hydroxyalkanesulfonates, while it is also a mixture of monosulfonates and disulfonates. In the present invention, the weight ratio of alkenyl sulfone)/hydroxyalkanesulfonate is about 1/9 to 3/2.
Preferred is IO8, which is carbonaceous and contains less than about 20% disulfonate by weight. If the content of disulfonate in IO8 is higher than about 20% by weight, the interfacial tension of the microemulsion formed by the first injection fluid in the oil layer is relatively large, resulting in a low oil recovery rate. occurs. IO8 used in the present invention is selected from alkali metal salts, alkaline earth metal salts, ammonium salts and organic amine salts. Preferred countercations are Na, K + Mg
t NH4 and alkanol ammonium. Examples of IO8 suitable for the present invention include carbon atoms of 12 and 13.
, 14 , 15 , 16 , 17° 18 , 20 ,
22, 24, to 12-16, 13~15°14~1
6, 14-18, 15-18, 16-18゜16
~20, 18~20. and 20 to 24 IO8 and mixtures thereof.

The third component (component C) of the surfactant used in the present invention is represented by the following general formula [I] (hereinafter abbreviated as HAE) or [■]
(abbreviated as APF) Rlo-eCH2CH20→: H-... [I) R2
<Σ0 book CH2CH206 "H... [1] (in both formulas,
R is an alkyl group or alkenyl group having 10 to 18 carbon atoms, R2 is an alkyl group having 6 to 15 carbon atoms, and n'
and R2 may both be linear or branched. m and n are average values, m is about 1 to about 15, and n is about 3 to about 15. ) is an ethoxylate shown by

Three typical examples of HAE are polyoxyethylene hexyl ether (m=1), polyoxyethylene octyl ether (m=3), polyoxyethylene decyl ether (m=3.5), and polyoxyethylene dodecyl ether (m=3.5). m=5), polyoxyethylene tetradecyl ether (m=5), polyoxyethylene hexadecyl ether (m=7) and polyoxyethylene octadecyl ether (m=10). A typical example of APE' is polyoxyethylene hexyl phenyl ether (
n = 3), polyoxyethylene octylphenyl ether (n = 5), polyoxyethylene nonylphenyl ether (n = 3, 5 and 8), polyoxyethylene decylphenyl ether (n = 6), polyoxyethylene dodecylphenyl ether (rr-8), polyoxyethylene tetradecylphenyl ether (n=10.) and polyoxyethylene pentadecylphenyl ether (n=
12) Al.

In the present invention, these three types of surfactants (components A, B, and C) are mixed at a specific weight ratio, that is, A/B = 1.
/19~9/1 and (A+8)/C=19/1~2/3
It is essential to use a weight ratio of . A.

When the three components B and C are within this range, the first injection fluid can quickly form a microemulsion in the oil layer, maintain the microemulsion for a long period of time, and further improve the interface of the microemulsion. Since the tension is sufficiently low, sweeping within the oil layer is smooth, and the interface with the polymer bath liquid, which is the second injection fluid, is kept stable. Regarding the relationship between the A component and the B component, if the A component is more than this range, the stability of the microemulsion at low temperature concentration decreases and the oil recovery rate decreases. On the other hand, if the amount of the B component exceeds this range, the interfacial tension of the formed microemulsion will not be reduced, resulting in a decrease in oil recovery.

If the 1C component exceeds this range in the above relationship between the sum of the A and B components and the C component, the interfacial tension of the formed microemul III will not become small and the oil recovery rate will decrease. Moreover, if the C component is less than this range, the stability of the formed microemulsion over a hair period will not be sufficient, and the oil recovery rate will tend to decrease. , this tendency becomes more pronounced as the salt concentration of the brine and oil layer water increases. Furthermore, when the C component is small, the stability of the interface between the formed V microemulsion and the aqueous polymer solution, which is the second injection fluid, decreases, resulting in a decrease in the oil recovery rate. A.

The preferred range of B and C components is A/B = 1/9 to 1
773 and (A+B)/C=1/1 to 4/1.

The first injection fluid used in the present invention furthermore has as an essential component a surfactant auxiliary. The surfactant is a compound having an alcoholic hydroxyl group, and can be prepared from a pestle consisting of an alcohol having 3 to 8 carbon atoms, an ethylene glycol monoether of an alcohol having 1 to 5 carbon atoms, and a diethylene glycol monoether of an alcohol having 1 to 5 carbon atoms. Alcohol of choice. Specific examples of alcohols suitable for the present invention are propatools, butanols, pentanols, hexanols, 2-ethylhexanols, other octatools, methoxyethanol, ethoxyethanol, glopoxyethanol, butoxyethanol. , diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monozorobyl ether, and diethylene glycol monobutyl ether.

The surfactant used in the present invention is present in the first injection fluid at about 0%
．． It is used in an amount of 1 to 20% by weight, and considering the ease of forming a microemulsion and the ability to lower interfacial tension, about 1% by weight.
．． Preferably, it is used in an amount of 0 to 10% by weight.

Since the first injection fluid used in the present invention uses a surfactant with excellent salt resistance and hard water resistance, brine with a wide range of salt concentrations is used, from soft water to saturated saline (approximately 25% by weight as NaCt). For example, rainwater, river water,
Lake water, groundwater, oil reservoir water, and seawater can all be used freely. The alkali metal salt contained in the brine is NaC
1+ KCL +NaHCO, + NaBr *Na
2804 and 2So4 are typical, and the alkaline earth metal salts are ygct2 and CaC42.

For example, seawater has an inorganic salt concentration of approximately 3.5% and contains divalent metal ions of approximately 1,600 ppm in terms of both ions, and such salt concentration falls within a preferable range.

The first injection fluid used in the present invention may contain other surfactants as long as the effects of the present invention are not impaired. Examples of such surfactants include petroleum sulfonates, alkylbenzene sulfonates, polyoxyethylene alkyl ether sulfonates, dialkyl sulfosuccinates, tsuclafine sulfonates, soaps, polyhydric alcohol fatty acid esters, fatty acid alkylolamides, Examples include anionic surfactants and nonionic surfactants such as oxyethylene fatty acid amide.

Hydrocarbons are not an essential component because the first injection fluid of the present invention forms a microemulsion in the oil reservoir and is swept away by the microemulsion to form an oil puncture. Therefore, if the first injection fluid contains a hydrocarbon, it will be an aqueous surfactant solution, and if it contains a hydrocarbon, it will form a microemulsion. Hydrocarbons that can be used in the present invention include petroleum, liquefied petroleum gas, crude gasoline (naphtha), kerosene, light oil, and heavy oil, but they are cheap, easily available, and petroleum in underground reservoirs. Considering that the composition is similar to
Preference is given to using recovered petroleum. The first injection fluid used in the present invention is permitted to contain less than about 90% by weight hydrocarbons, preferably less than about 4071:% hydrocarbons.

In the present invention, the second injection fluid that is injected into the injection well following the first injection fluid is a water bath liquid of a water bathing polymer and must have a higher viscosity than the first injection fluid. The bath polymer used in the second injection fluid may be natural or synthetic, such as heteropolysaccharides produced by microorganisms, naphthalene sulfonic acid formalin condensates, polyacrylamides, polyacrylates, hydroxyl .

Examples include chill cellulose and carboxymethyl cellulose. The amount of water-soluble polymer in the second injection fluid is selected depending on the viscosity of the first injection fluid, the type and molecular weight of the water-soluble polymer used, and is usually about 0.01 to 1.
A range of weight percent is suitable.

In the oil recovery method of the present invention, at least one injection well and at least one production well are arranged at approximately the same distance from each other, and after injecting a first injection fluid from the injection well,
Subsequently, a second injection fluid is injected. The injection amount of the first injection fluid at this time is 3 to 50% of the porosity of the underground oil-bearing layer.
3i quantity ratio is appropriate.

The oil recovery method of the present invention has great economic advantages because a microemulsion is formed in the oil reservoir. Furthermore, by using microemulsions as the first injection fluid, the effect can be more reliably exerted since microemulsions are present in the oil layer from the beginning. Therefore, according to the present invention, soft water, seawater, or reservoir water can be freely used in the production of the first injection fluid; (2) the first injection fluid is not affected by the salt concentration of the reservoir water; (3
) The interfacial tension of the microemulsion formed in the oil layer is very small. (4) Excellent effects such as a high oil recovery rate can be obtained.

EXAMPLES The present invention will be explained in more detail with reference to the following 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 specified.

C16~C48Aos-NIL, c1 as eye surfactant
A sample was prepared by mixing 5-c16IO8-Na and polyoxyethylene lauryl ether (n = 3), isobutanol and brine (NaCL 8% or 13%) as a surfactant, and its physical properties and sweeping efficiency ( oil recovery rate)
was measured.

Oral separation stability of the sample was determined for 1 day and 1 day after sample preparation.
The device was left undisturbed for 0 days and 100 days, and the presence or absence of υ layer separation was examined by appearance. Those in which two layers were separated were evaluated as ×.

Next, the sample was placed in a pressure-resistant glass WK with an equal amount of polymer solution, and the state of the interface was judged with the naked eye after leaving it for one day at a gauge pressure of 1 kgI/IM2. A state where the color became cloudy and unclear was rated as ×.

The interfacial tension of the sample was measured by mixing the sample and n-octane at various ratios, and the interfacial tension of the formed microemulsion was measured using a spinning drop type interfacial tension meter, and the lowest value was claimed.

The oil recovery test has a permeability of approximately 500 mD and a porosity of approximately 20%.
The experiment was carried out using a Berea sandstone core with a length of 28 sides and a diameter of 3.81M. The test method is as described below. First, the cores were fully saturated with brine, and then the cores were loaded into a core holder. Next, add 6 n-hexane as oil.
The core was press-fitted with oil at a rate of CC/min until brine no longer flowed out. Subsequently, brine was injected at the same injection speed and water flooding was performed to recover the oil. Water flooding was continued until the oil content in the spilled liquid was below 0.1%.

The micellar attack method was carried out by placing the injection fluid and core holder in a constant temperature bath and maintaining the temperature at 71°C. First injection fluid 15% pore volume, then second injection fluid 100%
Pore volume, finally the grain 100 pore volume is 2 fe
It moved in and out at a rate of @t/day and collected oil. The second injection fluid, an aqueous polymer solution, was prepared by dissolving xanthan gum in brine. The viscosity was adjusted by changing the amount added.

To evaluate the amount of oil recovered, the water in the core after the test was recovered by an azeotropic method using toluene, the amount of water in the core was calculated, and the amount was converted into the amount of oil recovered.

The obtained results are shown in Table 1 along with the composition of the sample. still,
In Table 1, HEC is Hydroxyethyl Cell Table 1 Example 2 Example 1 Gold was repeated with different surfactants and grains.

The composition of the sample is shown in Table 2, and the measurement results are shown in Table 3.

In addition, POE of component C in Table 2 is an abbreviation for polyoxyethylene.

Example 3 AO8, IO8 and ethoxylate as surfactants,
Example 1 was repeated using surfactant aids, n-octane and brine.

The composition of the sample is shown in Table 4, and the results are shown in Table 5.

The sample in this example contains n-octane in an emulsified form.

Claims (1)

[Claims] 1. In recovering petroleum from an underground oil-bearing layer connected to at least one injection well and at least one production well, (1) about 1 to 30% by weight of a surfactant, a surfactant; (2) injecting an aqueous polymer solution with a higher viscosity than the first injection fluid into a second injection fluid; and (3) recovering oil displaced by said first and second injection fluids from a production well, as a surfactant: A, carbon alO~26 α-olefin sulfonate, B, internal olefin sulfonate having 10 to 26 carbon atoms, and C0 ethoxylate represented by general formula 0) or [11), A/B = 1/19 to 9/1 and (A+B)/ C=1
A method for recovering petroleum, characterized in that it uses oil containing a weight ratio of 9/1 to 2A. R' 0(-CH2C) (20ga "-H...[11R
2-C>O+CH2CH2O piece H... [11) (In both formulas, R is an alkyl group or alkenyl group having 10 to 18 carbon atoms! 7"lR2 is an alkyl group having 6 to 15 carbon atoms, R1 and R2 may be linear or branched. m and n are average values, m is a number from about 1 to about 15, and n is a number from about 3 to about 15.)