CA1045028A - Micellar dispersions via sulfonating whole or topped crude - Google Patents

Abstract

MICELLAR DISPERSIONS VIA SULFONATING
WHOLE OR TOPPED CRUDE
ABSTRACT OF THE DISCLOSURE
Micellar dispersions useful for displacing crude oil from reservoirs are obtained by first producing crude oil from the reservoir (optionally adding sulfonation agents to the crude oil), then sulfonating the mixture with SO3 (optionally diluted in a diluent), thereafter neutralizing mixture with a mono-valent base (optionally removing the unreacted oil therefrom) (optionally adding liquid, e.g., cosurfactant to obtain the desired viscosity) and thereafter injecting the resulting micellar dispersion into an injection well and displacing it toward a production well to recover crude oil therethrough.

Description

~U4S~?~8 SU~IM~RY OF THE INVENTION
According to the invention, micellar dispersions suitable for the displacement of oil in formations, e.g. in enhanced recovery operations or in well stimulation, are produced from whole crude oils by the treatment wi~h sulfur trioxide.
The resul~ing product mixture (with or without optional removal of a portion of the unsulfonated hydrocarbons and with or without addition of cosurfactant) is neutralized with a monovalent base to form directly a micellar dispersion comprising the sulfonated .
hydrocarbons, at least a portion of the unreacted hydrocarbons ~.
and water.
In one particular aspect the present invention provides in a process for the recovery of oil from an oil-bearing sub-terranean formation by injecting into said formation a micellar dispersion comprised of petroleum sulfonate, hydrocarbon and water; the improvement comprising (a) recovering crude oil; (b) ..
sulfonating the crude oil with sulfur trioxide to form a product comprising petroleum sulfonic acid; (c) neutralizing said product .
with aqueous monovalent base to form a micellar dispersion com- ...
20. prised of petroleum sulfonate having an average equivalent weight of about 350 to about 525; (d) injecting said micellar dispersion into the formation to displace additional oil toward a production well in fluid communication with the formation. ~;
Because the usual steps of refining crude oil to pro- .. `
vide a fractionated feedstock, removing sludge by-product from the sulfonate, and mi~ing together the ingredients of the micellar dispersion are all usually avoided by the invention, great .. ;~
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56~28 1 economic savings in both feedstock utilization and reduced cost

2 of operations can be achieved.

3 Further, by placing the simple apparatus of the invention

4 proximate to the oil reservoir being injected with the micellar dispersion, both feedstock and product transportation savings 6 are also achieved.

8 Figure 1 shows a preferred embodiment of the sulfonation 9 process of the present invention without use of reaction solvent.

DE~CRIPTION OF THE PREF~RRED EMBODIMENTS
11 Starting Materials:
12 Hydrocarbon Feed: It is an important aspect of the pre-13 sent invention that whole crude oil or topped crude oil is sul-14 fonated. Previous processes have sulforlated gas oils without achieving the simplicity of the present invention. Crudes 16 which are particularly useful for the practice of the invention 17 are those which are relatively high in aromatic content but 18 lubricating oil base crudes (low aromatic content) are acceptable.
19 The crude oil may be substituted with non-interfering substituents, e.g., NO3, C12, SO4, etc., but will preferably 21 be a hydrocarbon. Preferred crude oils are those with aromatic 22 portions having molecular weights in the range of from about 200 23 to about 1000, more preferably from about 300 to about 800, and 24 most preferably from about 350 to about 500. The aromatic content of the crude oil is preferably from about 10 to about 95, 26 more preferably from about 20 to about 80, and most preferably 27 from about 25 to about 50 weight percent aromatics as defined . . .

51~2~3 1 in American Petroleum Institute Project 60 Reports 4-7 entitled 2 "Characterization of Heavy Ends of Petroleum". Especially 3 preferred are crude oils wherein the aromatic portion has an 4 aliphatic/aromatic proton ratio of from about 3 to about 20, more preferably from about 4 to about 18.
6 The "aliphatic to aromatic proton ratio" used in the 7 specification is measured on a carbon tetrachloride solution 8 of the sample using a 60MHz nuclear magnetic resonance 9 spectrometer. The basic technique has been described by V. H. Luther and H. H. Oelert, Erdol and Kohle, 24, 216 (1971).
11 All those protons which resonate with a chemical shift between 12 0 and 5 ppm from the tetramethylsilane internal standard are 13 defined as aliphatic protons; those which have a chemical shift 14 between 8.2 and 5 ppm are defined as aromatic protons. Evidence of polynuclear aromatics in crude oil is scattered throughout 16 the petroleum literature.
17 Topped crudes, e.g., those having a portion of the hydro-18 carbons boiling below about 600F. removed, can be utilized in 19 place of the whole crude oil.
Reaction Solvent: The sulfonation of the crude oil feed-21 stock is accomplished using SO3. Though not necessary, the SO3 22 can be diluted with a reaction solvent to promote a more even 23 sulfonation reaction, to solubilize sulfonic acids in unreacted 24 hydrocarbon, and to lower the viscosity of the overall reaction products. Ethylene dichloride (EDC), trichloroethane, nitro-26 benzene, nitropropane, and like solvents are useful for this 27 purpose. The reaction solvent aids in keeping the reaction 28 product stream homogeneous and fluid. Whether or not a reaction 29 solvent is used depends on the crude oil being sulfonated. Heavy 3o viscous crude oils often require a solvent; lighter, less vis-,, . ... ; . , . ,. .. , . ~ ~ . :

lO~S~Z~3 1 cous crudes can be sulfonated with or without a reaction solvent.
2 When using a reaction solvent, concentrations of solvent are 3 typically from about 0 to 20 lbs., more preferably from about 1 4 to 10 lbs., and most preferably from 3 to 8 lbs. of solvent/
lb. SO3. The reaction solvent can be added to either the crude 6 oil stream, the SO3 stream, or to both streams.
7 SO3 Diluent: Either separately or in conjunction with 8 a reaction solvent, the SO3 stream can be diluted with a liquid g or gas, e.g., SO2, refined light paraffins~ crude oil light ends, air, nitrogen, natural gas, or other dry gases; with a ll weight ratio of diluent to SO3 of about 0 to about 10, more 12 preferably about 2 to about 9, and most preferably about 3 to 13 abou~ 8 lbs./lb. SO3.
14 The main purpose of the diluent is to dilute the SO3 in order to promote a more even sulfonation reaction, e.g. to 16 reduce the amount of tri- and higher sulfonates produced.
17 While the SO3 diluent will not ordinarily solubilize the 18 sulfonates in the unreacted hydrocarbons, it has the addi-19 tional advantage of lowering the viscosity of the reaction products.
21 Sulfonation Additives: To optimize oil recovery it is 22 preferable though not absolutely necessary to add one or a 23 mixture of sulfonation additives. These additives may be 24 used either in conjunction with or in the absence of either the aforementioned diluents or solvents. Such sulfonation 26 additives are preferably aromatic hydrocarbons, olefinic hydro-27 carbons, or oxygenated hydrocarbons, and preferably have 28 molecular weights in the range of from about 200 to about lO00, Z~
1 or more preferably from about 300 to about 800, and most 2 preferably from about 350 to about 500. The sulfonation addi-3 tives will be used in amounts of from about 0 to 20, more 4 preferably from about 2 to about 15, and most preferably from about 4 to about 10 pounds of sulfonation additive per 100 6 pounds of crude oil (or topped crude oil) employed as feed to 7 the reactions of the invention.
8 The sulfonation additives can conveniently be incor-9 porated into the crude oil feedstocks before the crude oil feedstock is sulfonated. Thereafter, normal sulfonation 11 reaction procedures are followed and the sulfonation additives 12 themselves are generally sulfonated (or sulfated, in the case 13 of oxygenated hydrocarbons), and exit with the remaining 14 components of the micellar dispersion.
Sulfur Trioxide: The sulfur trioxide useful with the 16 present invention can be of the usual commercial purity 17 though high purity or relatively crude materials may be used 18 in specialized circumstances where warranted by the desired 19 products. The sulfur trioxide should be preferably sub-stantially anhydrous and should be free from substantial 21 quantities of impurities which would cause deleterious side 22 reactions.
23 From about 5 to about 40, more preferably from about 7 24 to about 30, and most preferably from about 8 to about 20 lb.
SO3 per 100 lb. of unsulfonated crude oil will be fed to the 26 reactor zone.
27 Reaction Catalyst: While no catalyst will generally be 28 employed with the present invention, known sulfonation catalysts 29 can be employed where desired.

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S~?28 1 Reaction Temperature: While not narrow~y critical, the 2 temperature in the reaction æone will generally be in the 3 range of from about 80 to about 250, more preferably from 4 about 100 to about 200, and most preferably from about 130 to about 180F.
6 Reaction Pressure: In general, the range of pressuxe 7 will be from about 0.10 to about 150 atmospheres, more 8 preferably from about 0.15 -to about 100 atmospheres, and 9 most preferably from about 0.2 to about 10 atmospheres.
Reaction Time: The reaction time is not narrowly 11 critical and will be determined by standard techniques. In 12 general, times will preferably be from 0.001 to 3600, more 13 preferably 0.01 to 360, and most preferably 0.02 to 60 seconds.
14 Batch or Continuous Basis: The present invention will preferably be practiced on a continuous basis but can be done 16 batchwise.
17 Reaction Apparatus: The reaction apparatus to be used 18 with the present invention is not narrowly critical and a 19 wide variety of reactors may be employed including all of those which are conventionally utilized for the sulfonation of 21 hydrocarbons. For example, falling film, scraped surface, 22 stirred tank, tank with sparger for introduction of SO3 and the 23 like. In those reactions according to the present invention 24 which employs a solvent or diluent, the preferred apparatus is a tubular reactor having an inlet for admitting a stream 26 containing the crude oil plus any additive plus some recycle 27 reaction products, and an inlet for a stream containing the 28 SO3 plus the reaction solvent or diluent. Both streams 29 should be in turbulent flow.

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1 The reactor is preferably made of stainless steel but 2 any metal or non-metal having proper mechanical and corrosio~-3 resistant properties may be utilized.
4 Neutralization: The sulfonic acid in the reaction pro-ducts are neutralized with a monovalent basic compound such 6 as sodium hydroxide, ammonia, ammonium hydroxide, etc.
7 Extraction: While not absolutely necessary to the practice 8 of the present invention, it will generally be preferable to 9 extract the products from the reaction in order to remove excess unreacted hydrocarbons from the micellar dispersions.
11 Extraction can precede or follow neutralization. Preferably, 12 any reaction solvent will first be stripped from the micellar 13 dispersion, the resulting unextracted micellar dispersion is 14 contacted with aqueous alcohol or water to permit extraction of the micellar dispersion. Examples of useful alcohols 16 include those containing from 1 to about 5 carbon atoms, 17 also semi-polar organic compounds such as benzene are useful.
18 The unreacted hydrocarbon and salt contents of the final 19 micellar dispersion are controlled by both the solvent to unextracted micellar dispersion ratio and solvent composition.
21 That is, from about 0.5 to about 5.0 lbs., preferably 1.0 to 22 about 3.0 lbs. and more preferably 1.5 to about 2.0 lbs. of 23 aqueous alcohol solution or (preferably) water is mixed with 24 each lb. of the unextracted micellar dispersion. The aqueous alcohol is preferably isopropyl alcohol/water solution.
26 The mixture resulting after addition of the extraction 27 solvent will separate into either two or three phases; a 28 raffinate phase which consists primarily of unreacted hydro-29 carbons, an extract phase which contains most of the micellar 50~3 1 dispersion product, and possibly (depending on the particular 2 extraction solvent used) a brine phase which contains salts 3 and water.
4 The raffinate phase is processed, e.g., by stripping to recover the alcohol (if any) and water from the unreacted 6 hydrocarbon. The extract phase is fed to a stripper to remove 7 excess water and any alcohol from the micellar dispersion.
8 The brine phase, if any, can be disposed of or can be further 9 processed to recover salts, e.g., ammonium sulfate which can be utilized as fertilizer.
11 Product Specification: The desired petroleum sulfonate 12 in the micellar dispersion has an average equivalent weight 13 within the range of about 350 to about 525, more preferably 14 about 375 to about 475 and most preferably about 390 to about 445. This average equivalent weight range of the petro-16 leum sulfonate is a major quality control parameter. The 17 equivalent weight of the petroleum sulfonate is defined as 18 the sulfonate molecular weight divided by the average number 19 of sulfonate groups per molecule. It indicates the relative amount of monosulfonation and polysulfonation~ i.e., the 21 equivalent weight becomes lower as the polysulfonation increases.
22 Micellar Dispersions: The micellar dispersion contains 23 unsulfonated hydrocarbon, aqueous medium, and petroleum sul-24 fonate. Optionally, cosurfactant and/or electrolyte can be incorporated. Examples of volume amounts include about 0.2%
26 to about 90% hydrocarbon, about 5~ to about 95~ aqueous medium, 27 at least about 4~ of petroleum sulfonate, about 0.01 to about 20%
28 cosurfactant, and about 0.001 to about 5~ (weight ~ based on 29 aqueous medium) of electrolyte. The micellar dispersions can be oil-external or water-external, or intermediate between 31 these.

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1045~32~3 1 The hydrocarbon of the micellar dispersion is unsul-2 fonated crude oil, or topped crude oil. The aqueous medium 3 can be soft water, water containing minor amounts of salts, or 4 brackish water. The cosurfactant can be an amine, aldehyde, ketone, hydroxy-containing compound (including conventional 6 alcohols), ester, ether, etc., containing 1 to about 20 or 7 more carbon atoms. Numerous electrolytes are useful, preferably 8 they are inorganic acids, inorganic bases, and inorganic salts.

EXAMPLE
11 The example which follows is intended to more fully 12 illustrate the invention and is not to be considered as limit-13 ing the invention in any way. Referring to Fig. 1, crude oil 14 ~as specified under the example) is pumped from a well 10, can undergo an optional topping process 11 and either the crude 16 oil 12 or the heavy ends 13 flow into a sulfonation reactor 14 17 after mixing with optional sulfonation additives 15 and/or 18 optionally recycled reactor products 16. SO3 vapor 17 also enters 19 the sulfonation reactor 14 with or without an optional SO3 diluent 18 (as specified in the respective example). Sulfona-21 tion products exiting from reactor 14 flow through cooler 19 22 into neutralization reactor 20 after optional SO2 and H2SO4 removal 23 21 and after optional mixing with recycled neutralized products 24 22. In the neutralization reactor 20 the sulfonated products are neutralized by contact with water 23 and neutralization 26 agent 24 (e.g. ammonium hydroxide). The neutralized products 27 flow through cooler 25 and exit as the micellar dispersion 26.
28 Alternatively, the micellar dispersion 26 may be extracted 29 by mixing with extraction solvent 27 (as described in the reSpective example) and conducted into phase separator 28 for 31 separation into two or three phases.

~09~5~8 1 The plant shown in the drawing is located near the 2 Bridgeport, Illinois (USA) field and is fed feedstock consisting 3 of Bridgeport crude oil (36.5 API Gravity) and 10 pounds of 4 vapor sulfur trioxide per 100 pounds of crude oil. Each mole of sulfur trioxide is diluted with 6 moles of crude oil light 6 ends (those boiling below 150F.) and 5 parts by weight of 7 reaction products are recycled to mix with each weight of 8 fresh crude oil feed. The reaction is carried out at about 150F.
g and one atmosphere pressure for a reaction time of about 15 minutes.
11 Each 110 pounds of reaction products are neutralized 12 with 3.1 pounds of ammonia mixed with 237 pounds of water. A
13 substantial portion of the unreacted hydrocarbon is removed by 14 extracting with water and removing the resulting oil-rich phase. About one volume of n-amyl alcohol is added per 100 16 volumes of the final micellar dispersion.
17 The micellar dispersion (about 0.07 pore volumes) is 18 then injected into the previously water flooded Bridgeport Field.
19 Injection of the micellar dispersion is followed by injection of approximately one pore volume of a drive fluid consisting of 21 500 parts per million (average) of Dow 700 Polymer, a partially 22 hydrolyzed polyacrylamide manufactured by Dow Chemical Company 23 of Midland, Michigan in connate water. Residual oil is dis-24 placed and produced. A portion of the Bridgeport crude oil thus produced is used as feed for production of additional 26 micellar dispersion as described above.

28 It should be understood that the invention is capable of 29 a variety of modifications and variations which will be made .

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1 apparent to those skilled in the art by a reading of the speci-2 fication and which are to be included within the spirit of the 3 claims appended hereto.

Claims (6)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In a process for the recovery of oil from an oil-bearing sub-terranean formation by injecting into said formation a micellar dispersion comprised of petroleum sulfonate, hydro-carbon and water; the improvement comprising (a) recovering crude oil; (b) sulfonating the crude oil with sulfur trioxide to form a product comprising petroleum sulfonic acid; (c) neutralizing said product with aqueous monovalent base to form a micellar dispersion comprised of petroleum sulfonate having an average equivalent weight of about 350 to about 525; (d) injecting said micellar dispersion into the formation to displace additional oil toward a production well in fluid communication with the formation.

2. A process according to Claim 1 wherein said im-provement additionally comprises removing a portion of the un-reacted hydrocarbons after said sulfonation with sulfur trioxide.

3. A process according to Claim 1 wherein said im-provement additionally comprises adding cosurfactant(s) to said micellar dispersion prior to injection to modify the viscosity of said micellar dispersion.

4. A process according to Claim 1 wherein said im-provement additionally comprises sulfonating with sulfur trioxide diluted in hydrocarbon substantially unreactable with said sulfur trioxide.

5. A process according to Claim 1 wherein said sulfur trioxide is diluted in crude oil light ends, natural gas, air, nitrogen, or mixtures thereof.

6. A process according to Claim 1 wherein said im-provement additionally comprises (e) recycling at least a portion of said additional oil for sulfonating as described above.