GB2118937A - Alkoxylated alkyl phenol derivatives used as emulsion breakers for crude oil - Google Patents

Abstract

A mixture of compounds of formula <IMAGE> wherein R is H or CH3; R1, R2, R3 independently represent H or isopropyl (i); X is 1-25; m is 0-10; and wherein the CH2 groups limit the aromatic rings via the ortho- or para-positions; provided that when R1 and R2 are both isopropyl and R3 is H, m is 1, and when R2 and R3 are both isopropyl, m is 0, is used as emulsion breaker for crude oil.

Description

SPECIFICATION Emulsion breakers for crude oil The present invention relates to alkoxylated alkyl phenol resins, their production and use as demulsifiers for dewatering and desalting crude oils.

The history of most oilfields shows the gradual infiltratipn of water into oil deposits, and, eventually, water is produced from wells regardless of the method of recovery. This is now a more common occurrence since the practice of water injection methods has become more widespread.

Under conditions of production, high shear forces cause the dispersion of water in oil to form emulsions. These emulsions, considered to be effected by naturally occurring emulsifying agents in the continuous phase, are often extremely stable, and will not resolve on long standing.

It is necessary to facilitate the resolution of these emulsions to obtain dry oil for transport and future processing. It is for this purpose that surface active demulsifying agents, the subject of this invention, are used.

Another process utilising demulsifying agents of the kind hereinafter defined is that of desalting at refineries. In the refining of many crude oils, a desalting operation is necesasry in order to prevent the accumulation of large deposits of salt in stills, and prevent corrosion resulting from the presence of such salts at high still temperatures. In a typical desalting operation, 5%-i 0% of fresh water is added to the crude oil and emulsified therein. A demulsifying agent is added and the treated oil allowed to stand in a quiescent state permitting the salt-laden water phase to separate whereupon it is bled off resulting in 90%~95% of salt removal.

One type of demulsifying agent used in such processes is based on alkylated phenols whereby a mono-para-substituted alkyl phenol is reacted with formaldehyde in a solvent, such as xylene, to form a resin which is then treated with ethylene oxide and/or propylene oxide to achieve the required product.

This type of procedure is described in, for example, US 2499365 and US 4032514.

According to this invention, there is provided a mixture of compounds corresponding to the formula (I)

wherein each R is the same or different and is hydrogen or methyl; R1, R2 and R3 are the same or different and represent hydrogen or isopropyl; each x is the same or different and is an integer from 1 to 25; and m is an integer from 0 to 10, preferably 1 to 6; and wherein the CH2 groups link the aromatic rings via the ortho- or para-positions; provided that when R1 and R2 are both isopropyl and R3 is hydrogen, m is 1, and when R2 and R3 are both isopropyl, m is O.

The products of the invention may be prepared by reacting an isopropyl phenol with ethylene oxide and/or propylene oxide in a molar ratio of 1:1 to 1:25 and then reacting the resulting alkoxylated isopropyl phenol with formaldehyde in a molar ratio of 1:0.7 to 1:1.5 in a high boiling organic solvent and in the presence of an acid catalyst.

While any isomer of isopropyl phenol may be used, we prefer to use a mixture of isopropyl phenols such as is produced by alkylating phenol, e.g. with propylene, under Friedel Craft's alkylation conditions followed by removal of at least part of any unreacted phenol. The maximum amount of unreacted phenol present in the phenols being alkoxylated should be less than 5%, preferably less than 2%. Such a mixture is rich in ortho-isopropyl phenol and also contains para- and meta-isopropyl phenol and some di- and tri-isopropyl phenols. Suitable Friedel Crafts reactions are described in British Patent Specification No. 11461 73.

From 1 to 25 moles of ethylene oxide and/or propylene oxide are used per mole of isopropyl phenol, preferably from 2 to 1 5 moles and most preferably from 3 to 8 moles.

Methods of alkoxylation are well-known. The reaction may be carried out at temperatures of 125 ~1 70 C under pressures of 1-10 atmospheres. An acidic catalyst or a basic catalyst may be used. Suitable acid catalysts include sulphuric, acetic, phosphoric and formic acids and Lewis acid catalysts such as BF3. Suitable basic catalysts include sodium or potassium hydroxides or methoxides.

The amount of catalyst may be 0.05 to 0.5% by weight based on the weight of alkyl phenol.

The alkoxylation may use ethylene oxide or propylene oxide alone, or in admixture. When used in admixture, a random mixture of the two oxides may be used or the two oxides may be reacted separately by first ethoxylating and then propoxylating or by reversing this sequence or by a stepwise reaction of each oxide e.g. in the manner:~ EO-PO-EO... etc or PO-EO-PO... etc The resulting alkoxylated product is then reacted with formaldehyde which may be in the form of e.g. formalin or paraformaldehyde in a high boiling organic solvent such as xylene or products known as KEX and Aromasol H. Suitable acid catalysts for this reaction include sulphuric acid hydrochloric acid, citric acid and dodecyl benzene sulphonic acid. The reaction is preferably carried out under reflux, and water produced during the condensation reaction is removed.

After the reaction, the acid catalyst may be neutralised with alkali e.g. sodium hydroxide, potassium hydroxide or sodium carbonate and the desired product is then recovered by distilling off the solvent.

The resulting product is a mixture of compounds which is suitable for use directly without the need to isolate any particular compound. When a mixture of isopropyl phenols is used, it has been found that the formaldehyde reacts with all the alkoxylates from mono- and di-isopropyl phenols which have a free ortho- or para-position, but not with alkoxylates from tri-isopropyl phenols.

The products of the present invention may also be prepared by reacting an isopropyl phenol, or mixture of isopropyl-phenols (as described above), with formaldehyde in a solvent, such as xylene, to form a resin which is then reacted with ethylene oxide and/or propylene oxide.

The compounds of formula (I) are effective emulsion breakers for crude oils in both production and refinery processes. In particular, the compounds find special utility in reducing the basic sediment and water content, known as "grindout" to those skilled in the art, present in crude oil emulsions.

The products produced by the process of the invention may be used alone in many systems.

However some crude oils occur as tight emulsions which are more difficult to demulsify and in these cases, the compounds of the invention may be used in admixture with other demulsifiers in order to produce an oil with the required dewatered specification.

Accordingly the present invention also provides compositions comprising a mixture of compounds of formula (I) in admixture with one or more other demulsifiers such as alkyl phenol resin ethoxylates derived from butyl-, amyl-, octyl- and nonyl-phenols, ethylene oxide-propylene oxide block copolymers, polyalkylene oxide esters of mono- and poly-carboxylic acids, alkoxylated alkyl amines, alkoxylated polyamines, sulphonated systems, polysiloxane derivatives and cationic polyacrylamides.

The ratio of the mixture of compounds of formula (I) to other demulsifier(s) may be from 1:50 to 50:1 preferably from 1:10to 10:1.

The demulsifiers of the invention or demulsifier compositions are preferably formulated as solutions in organic solvents such as kerosene, diesel oil, heavy aromatic naphtha, xylene and mixtures of high boiling components from crude oil distillation procedures available under such tradenames as Aromasol and KEX.

The amount of resinified isopropyl phenol alkoxylate or demulsifier composition, as defined above, may be from 0.1 to 500 ppm, preferably from 1 to 100 ppm, based on the crude oil emulsion to be treated.

The invention is illustrated by the following Examples in which parts and percentages are by weight.

Example 1 Preparation of isopropyl phenol mixture A mixed isopropyl phenol feedstock was prepared by alkylating phenol with 70 to 75 mole percent propylene at 1400C in the presence of a Fuller's Earth catalyst, ofthetradename Fulmont 235, to produce an alkylate (I) of representative isomer levels as follows: Phenol 31.8% 2-isopropylphenol 35.2% 3- and 4-isopropyl phenols 11.8% 2,6-di-isopropylphenol 6.5% 2,5-di-isopropyl phenol 9.1% 2,5- and 3,5-di-isopropyl phenols 1.7% 2,4,5-tri-isopropyl phenol 2.7% 2,4,5-tri-isopropyl phenol 0.4% Other 0.8% The phenol was removed by fractional distillation to a maximum allowable limit of 5% to produce a second alkylate (2) whose composition is represented as follows:: Phenol 1.5% 2-isopropylphenol 57.8% 3- and 4-isopropylphenols 15.9% 2,6-di-isopropylphenol 7.9% 2,4-di-isopropyl phenol 11.0% 2,5- and 3,5-di-isopropyl phenols 1.4% 2,4,6-tri-isopropyl phenol 3.0% 2,4,5-tri-isopropyl phenol 0.5% Other 1.0% Alkylate (2) has an equivalent alkyl content to a C3 6 mono alkyl substituted phenol.

Alkoxylation of isopropyl phenol mixture 100 parts of Alkylate (2) and 0.5 parts of a 50% w/w aqueous solution of potassium hydroxide were charged to an autoclave and heated to 1 100C under reduced pressure to reduce the water content to < 0.1% w/w. The temperature was raised to 1 400C and 200 parts ethylene oxide were slowly introduced to react at 1400 C-i 500 C, the pressure reaching a maximum of 3~4 atmospheres.

On completion of the addition, the reaction mixture was stirred until the pressure dropped to 1 atmosphere, evacuated at 11 00C for 30 minutes, and cooled to 500 C. After the pH was reduced to 6-7 by addition of acetic acid, the yield was 298 parts of product having an OH value of 198. The cloud point of the product as a 5% w/w solution in 3:1 water/butane diol mixture was 770C.

Preparation of resinified product.

To a solution of 50 parts of the ethoxylated isopropyl phenol (comprising a material from 5 moles ethylene oxide per mole Alkylate (2) in 25 parts of xylene was added 0.25 parts of dodecyl benzene sulphonic acid sodium salt, 0.36 parts concentrated sulphuric acid and 2.12 parts paraformaldehyde.

The mixture was heated to reflux for 30 minutes, cooled to 600C and a further 2.12 parts paraformaldehyde added (total molar ratio of ethoxylate to formaldehyde 1:1.1). After refluxing for a further 30 minutes, a Dean and Stark extension was fitted to the reaction flask and the temperature raised to 1 65-i 700C such that the water formed during the reaction (2.5 parts) was removed over 30 minutes. This temperature was maintained for 1 and a half hours, after which the mixture was cooled to 900 C, a solution of 0.2 parts sodium hydroxide in 3 parts of water added, and reflux temperature again maintained for 30 minutes to remove excess water. The bulk of the solvent was then removed at 600C/1 5 mm Mg pressure yielding the required product as 51.1 parts of a red-brown syrup.

The water number was found to be 1 6.2.

[The determination of water number, related to hydrophilic-lipophilic characters, is a modification of the procedure published by Greenwald et al in Analytical Chemistry, Vol. 28, Neo.11, p. 1 693 (1956):- 1 part of the demulsifier is dissolved in 30 mis of a mixed benzene-dioxan (4:96) solvent and the solution titrated with distilled water to a persistent turbidity. The recorded titre in mis is the water number].

Examples 2 to 8 Similar products were prepared following the same procedure as outlined in Example 1 with varying reactant ratios as shown in Table 1.

Table 1 Resinified isopropyl phenol alkoxylate demulsifiers

Molar ratio Equivalent %EOin Water* Example Alkylate 2 EO CH2O resin number 2 1.0 3.5 0.85 50 12.8 3 1.0 3.5 1.10 50 12.5 4 1.0 4.4 0.85 55 14.8 5 1.0 4.4 1.10 55 14.7 6 1.0 4.4 1.30 55 13.6 7 1.0 5.4 0.85 60 15.9 8 1.0 5.4 1.10 60 15.7 *Water numbers of non-resinified ethoxylated phenols range from 28-30.

Examples 9-25 Demonstration of demulsifier and desalter activity Demulsification and desalting activity of resinified isopropyl phenol alkoxylates was demonstrated using the "Bottle Test" procedure essentially as described in Chapter VII, pages 33 43 of "Treating Oilfield Emulsions" issued by the Petroleum Extension Service (revised edition, 1974), but using synthetic emulsions.

A brief summary of our modifications is given.

Demulsifier evaluation was conducted by taking the appropriate quantities of crude oil and brine (8% w/w NaCI) and mixing under high shear for a fixed period of time in a Waring Blender. Aliquots of 100 ml emulsion were poured into a 150 ml capacity conical centrifuge tube followed by a specific quantity of the demulsifier as a 1% w/w solution in a mixed xylene-methanol solvent (3:1 by volume).

After sealing, the bottles were shaken manually for a fixed number of times to disperse the demulsifier and then either observed at ambient temperature or placed in a water bath at a prescribed temperature. After allowing for a short warm-up period, the bottles were gently inverted a fixed number of times to aid coalescence of separated water. Then this and subsequent separated water was recorded at period intervals.

Desalter evaluation was conducted by taking an appropriate quantity of crude oil and adding a specific quantity of demulsifier as a 1% w/w solution in a mixed xylene-methanol solvent (3:1 by volume), which was dispersed by mixing in a Waring Blender for a short fixed period of time. An appropriate volume of water was added to the crude oil mixture and the emulsion prepared by again mixing under high shear in the Waring Blender for a fixed period of time. Aliquots of 1 00 ml emulsion were placed in 100 ml capacity conical centrifuge tubes and the subsequent procedure was identical to that described for the demulsifier evaluation.

Oil samples for the determination of basic sediment and water (BS and W, grindout) were taken at half an inch above the interface).

Evaluation of demulsification activity For comparison some commercially available emulsion breakers, prepared by alkoxylating an alkyl phenol resin, were evaluated under the same conditions. These were: Compound X: t-butyl phenol resin treated with 50% mixed ethylene/propylene oxides Compound Y: nonyl phenol resin treated with 50% mixed ethylene/propylene oxides Compound Z: nonyl phenol resin treated with 50% ethylene oxide Conditions:~ 10% emulsion of brine (8% NaCI)/Forties oil Temperature of separation, 400C Settling time, 45 mins Demulsifier dose, 0.06 ml (6 ppm relative to emulsion)

Grindout % brine .

Example Compound separation % W % BS 9 Blank 1 4.3 2.7 10 Compound X 97 0.1 0.4 11 Compound Y 99 0.2 0.4 12 Compound Z 96 0.1 0.5 13 Product of Example 3 90 0.1 0.3 14 Product of Example 5 90 0.1 0.3 15 Product of Example 6 92 0.1 0.3 16 Product of Example 7 96 0.1 0.4 These results demonstrate that resinified isopropyl phenol ethoxylates demulsify crude oil emulsions and produce lower basic sediment plus water figures and thus a cleaner oil phase.

Evaluation of desalting activity Compounds X, Y and Z are as previously defined.

Conditions~ 5% emulsion of water/forties oil Temperature of separation; 600C Settling time, 45 mins.

Desalter dose,0.1 ml (10 ppm relative to emulsion)

Grindout % water Example Compound separation % W % BS 17 Blank 11 - 1.2 18 Compound X 82 0.4 0.6 19 Compound Y 80 0.8 0.3 20 Compound Z 84 0.8 0.4 21 Product of Example 3 80 0.4 0.2 22 Product of Example 4 76 0.2 0.4 23 Product of Example 5 80 0.4 0.1 24 Product of Example 6 76 0.2 0.2 25 Product of Example 7 80 0.3 0.3 These results demonstrate resinified isopropyl phenol ethoxylates desalt crude oil emulsions and produce lower basic sediment and water figures and thus a cleaner oil phase.

Claims (17)

Claims

1. A mixture of the formula (I)

wherein each R is the same or different and is hydrogen or methyl; R1, R2 and R3 are the same or different and represent hydrogen or isopropyl; each x is the same or different and is an integer from 1 to 25; and m is an integer from 0 to 10, and wherein the Ch2 groups link the aromatic rings via the ortho- or para-positions; provided that when R, and R2 are both isopropyl and R3 is hydrogen, m is 1, and when R2 and R3 are both isopropyl, m is 0.

2. A mixture of compounds as claimed in claim 1 in which x is an integer from 2 to 1 5.

3. A mixture of compounds as claimed in claim 2 in which x is an integer from 3 to 8.

4. A mixture of compounds as claimed in any of claims 1 to 3 in which m is an integer from 1 to 6.

5. A composition comprising a mixture of compounds as claimed in any of claims 1 to 4 and a known demulsifying agent.

6. A process for preparing a mixture as claimed in claim 1 which comprises reacting an isopropyl phenol with ethylene oxide and/or propylene oxide in a molar ratio of 1:1 to 1:25 and then reacting the resulting alkoxylated isopropyl phenol with formaldehyde in a molar ratio of 1:0.7 to 1:1.5 in a high boiling organic solvent and in the presence of an acid catalyst.

7. A process as claimed in claim 6 in which a mixture of mono-, di- and tri-isopropyl phenols is used.

8. A process as claimed in claim 7 in which the mixture is produced by isopropylating phenol under Friedel Craft's alkylation conditions followed by removal of at least part of any unreacted phenol, so that said mixture contains less than 5% by weight of unreacted phenol.

9. A process as claimed in any one of claims 6 to 8 in which the molar ratio of isopropyl phenol to ethylene oxide and/or propylene oxide is from 1:2 to 1:15.

10. A process as claimed in claim 9 in which the ratio of isopropyl phenol to ethylene oxide and/or propylene oxide is from 1:3 to 1:8.

11. A process as claimed in any one of claims 6 to 10 which the alkoxylation reaction is carried out at a temperature of 1 250C-i 700C under a pressure of 1~10 atmospheres in the presence of an acidic or basic catalyst.

12. A process as claimed in any one of claims 6 to 11 in which the reaction with formaldehyde is carried out under reflux and water produced during the reaction is removed.

13. A method of demulsifying, dewatering and desalting a crude oil emulsion which comprises adding 0.1 to 500 ppm of a mixture as claimed in claim 1 or a composition as claimed in claim 5.

14. A method as claimed in claim 13 in which 1 to 100 ppm of the mixture or composition are used.

15. A mixture of compounds as claimed in claim 1 substantially as hereinbefore described with reference to any one of Examples 1 to 8.

16. A process as claimed in claim 6 substantially as hereinbefore described with reference to any one of Examples 1 to 8.

17. A method as claimed in claim 13 substantially as hereinbefore described with reference to any one of Examples 9 to 25.