NL8203952A - PREPARATION FOR ACIDIFYING OIL AND GAS WELLS, AND METHOD FOR USE THEREOF. - Google Patents

Description

* # - 1 - Λ

Preparation for acidifying oil and gas wells, and method for their use.

This invention relates to a composition for acidifying oil and gas wells, and more particularly a composition containing a high molecular weight alcohol and a phosphoric acid ester surfactant, as well as the use thereof.

The general concept of acidifying oil and gas wells has long been practiced, to clean up those wells and stimulate hydrocarbon production. For example, the injection of aqueous solutions of acids such as hydrochloric acid, hydrofluoric acid, acetic acid, etc. is common practice. Mutual solvents such as alcohols, including butoxyethanol in particular, are usually added to oil-source-stimulating acids to improve wetting, reduce surface stresses between acid and oil, and break muddy emulsions. A particularly useful mixture is that of isopropanol and isooctanol as described in U.S. Patent 3,819,520, wherein isopropanol acts as a necessary cosolvent to make the isooctanol soluble, and the combination must be used in relatively high concentration to be effective to be.

Surfactants such as oxyalkylated polyols or oxyalkylated alkylphenols and their sulfated products are known to be used for those purposes in acids, and likewise the oxyalkylated alcohols and the alkyl sulfonates in butanol. Other types of surfactants such as the ethylene oxide adduct of octanol or nonylphenol have been occasionally used.

However, none of the above preparations are as effective as desired. The glycol ethers, the mixed alcohols, etc. are not so good surfactants when wetting oil 8203952 4 if - 2 «4 solids, dispersing solids and reducing surface tension. . And often they form (stabilize) harmful emulsions and are not as effective in promoting oil-acid miscibility as the higher alcohols, which are very slightly soluble in aqueous acid solutions.

Now a new preparation for acidifying oil and gas wells has been found which represents an improvement over the previously known technique, consisting of an additive which, in combination with conventional acid solutions, disperses, solubilizes and emulsifies oil in a superior manner and solids superiorly. The acid composition according to the invention consists of an aqueous acid-15 solution, an aliphatic alcohol with 4-10 carbon atoms (or an alcohol with an equivalent hydrophobic / hydrophilic balance) and so much phosphoric acid ester that the alcohol in the acid solution becomes soluble. In accordance with the invention, at least 75 parts and preferably at least 90 (or even more) 20 parts by volume of aqueous acid solution containing up to about 20 parts by weight of acid are combined with up to 25 parts by volume of a mixture of Cjq alkanols with phosphoric acid ester, which mixture itself contains up to about 8 parts by volume of alkanol on 5 din ester. The additive for the acidic composition according to the invention thus consists of an essentially water-insoluble aliphatic alcohol and a phosphoric acid ester as surfactant.

The invention also provides that a mixture of water and a lower molecular weight (and / or diol) alcohol soluble therein is added to the concentrate as a diluent to make this composition more readily applicable on site, especially at lower ambient temperatures.

Thus, the present invention provides an additive for acidic compositions consisting essentially of a phosphoric acid ester to which is added per 100 parts by volume 20 to 160 parts by volume of an essentially water-insoluble aliphatic alcohol of 4 to 10 carbon atoms and, in an amount of 8203952-3 - approximately equal to the sum of the volumes of phosphoric acid ester and water-insoluble alcohol, a mixture of water and a lower molecular weight alcohol or diol soluble therein, the final mixture being 2 to 20 vol.% water 5.

The aqueous acid solution, incidentally, can contain any conventional acid; the water-insoluble alcohol can be, for example, Cg to Cg and preferably isooctanol, and the phosphoric acid ester is preferably an ester of an oxyalkylated fatty alcohol.

This invention provides an acidification solution that is superior for displacing rock oil. Furthermore, the acidic solution or the additive to be used therein is useful in combination with the known types of treatment, including also as a pre-rinse or a spearhead or as a final rinse (after other solvents, etc.). Furthermore, the concentrate is applicable in the usual oil sources equipment and the supplement can be mixed with the acid solution on site. All this will now become apparent from the following description.

In general, the objects of the invention are achieved by mixing a mixture of a surfactant phosphoric acid ester and an alcohol with an acid solution to be treated with an oil source. For this purpose, the mixture can be added to the acid solution before the injection, but it can also be added to the oil well before or after the acid solution and it is allowed to mix with the acid solution on the spot. The alcohol is chosen such that it is essentially insoluble in water, and therefore also in acid, but is miscible with the oil. The surfactant phosphoric acid ester appears to be uniquely suitable for solubilizing those alcohols and thus providing an acidic solution with exceptional oil displacement.

U.S. Pat. No. 35 3,819,520 has established the benefits of an acidic solution that also contains octanols for oil displacement, wherein. 8203952 - 4 - Pay attention to the surface tension between acid solution and oil phase. The octanols were able to go into the acid solution due to the presence of a clear amount of low molecular weight alcohol which acted as a co-solvent. In this patent a temary phase diagram with 15% HCl, isooctanol and isopropanol at the vertices is found, and it is learned that 22% by volume of isopropanol would solubilize the octanols to 2% by volume in the acid, while 30% by volume. % isopropanol 20 vol.% octanol would solubilize. US patent 3,819,520 also teaches us that for all practical applications there are no alternatives to the octanols, nor to the propanols as a co-solvent. Thus, the solubilization of a higher molecular weight alcohol by a lower alcohol as a co-solvent is not limited only to the C 15 alcohols, but at least 24% by volume of the final acid solution must be added from that addition. to exist.

In contrast, according to the invention, the higher molecular weight alcohols are solubilized with a surfactant phosphoric acid ester. The alcohol can be essentially any water-insoluble alcohol with between 4 and 10 carbon atoms. All such alcohols, in combination with the surfactant phosphoric acid ester, have proven effective in disintegrating and dispersing oil deposits, swallows and emulsions. They essentially provide an oil-free water phase and a water-free oil phase and leave the surfaces of the solids wetted with water without appreciable emulsion formation.

Alcohols with 6 to 8 carbon atoms are preferred because the dispersion of oil swallows with such alcohols is the fastest. Most preferred is a mixture of interrelated, isomeric, branched primary alcohols of the formula Rc-OH, wherein R is a branched heptyl group; this is marketed as "isooctyl alcohol".

The surfactants used to solubilize the higher molecular weight alcohols in the acid solution are categorically surfactant phosphoric acid esters. These are anionic detergents and mixtures of 8203952.

? t · v-. Mono- and di-phosphoric acid esters of alkanols, oxyalkylated alkanols and phenols, etc., in which one or more terminal hydroxy groups are phosphorylated, i.e. compounds according to the general formula of the formula sheet, wherein R is an alkyl phenyl or alkylphenyl group, hydrogen or a phosphate group and wherein X and Y indicate the degrees of propoxylation and ethoxylation, respectively. The surfactant phosphoric acid ester is preferably used in an acid form, but for the purpose of this invention it is partial. neutralized form 10 is equivalent insofar as it changes to the acid form in the acid solution. The particularly preferred surfactant phosphoric acid esters are the esters of oxyalkyl fatty alcohols described in U.S. Pat. No. 3,629,127.

Another preferred series of useful surfactant phosphoric acid esters are the esters of the so-called "Pluronic polyols" described in US Pat. No. 2,674,619.

When preparing the acidification solution, it is preferable that the surfactant 20 and the higher molecular weight alcohol be premixed, thus giving a concentrated addition, which is then mixed with the acidification solution. However, mixing in any other order results in equally good formulations, even if it is less convenient because in the preferred mixing order, the concentrated aggregate can be brought to the wellbore and mixed on site.

When using a surfactant and alcohol concentrate, the presence of a diluent to control pour point and viscosity degree of the mixture is preferred. The diluent is preferably a lower molecular weight water-soluble alcohol or diol, such as methanol, ethanol, n-propanol, isopropanol, t-butanol, ethanediol, etc. Advantageously, the diluent also contains some water for the highly polar surfactant. keep dust in solution, especially in cold weather.

Both when preparing the acidification 8203952 4.

A solution in itself as a concentrated addition therefor preferably contains at least a volume of higher molecular weight alcohol per 4 parts by volume of the surfactant phosphoric acid ester. At that concentration, the acid solution 5 will exhibit superior oil displacement compared to the combination of the individual ingredients with the acid. Preferably, the alcohol to surfactant volume ratio should not exceed 8: 5. Although concentrations beyond that limit are not considered harmful, the ratio of 8: 5 corresponds to the upper limit of the surfactant's ability to solubilize the alcohol in the acid solution. The ratio of 2 parts by volume alcohol to 3 parts by volume surfactant is preferred for most preparations.

When preparing a concentrate 15 to be added later to an acidification solution, the diluting mixture of lower molecular weight alcohol or diol must have enough present to lower the solidification point and viscosity and the highly polar surface -active substance in solution. In general, there is always some discrepancy in the handling of the concentrate when diluted with an alcohol (diol) / water mixture. Preferably, the concentrate thus stabilized consists for at least 50% by volume of an alcohol (diol) / water mixture. The associated water content should be between 2 and 20% by volume to prevent surfactant separation at low temperatures.

When the acidification solution is made up, 0.2 vol.% Of concentrate may be sufficient in its entirety, but a maximum effect of the additive can be seen at 10 to 20 vol.%, Depending on the relative amounts of surfactant. and high molecular weight alcohol, and even the higher percentages work well. A mixture of 95% by volume acid and 5% by volume additive is particularly suitable for most applications and is therefore preferred. This concentration is also particularly advantageous compared to the prior art in that the presence of the additive does not present an important economic problem and the acidic solution obtained in wezan is still at full strength. Higher concentrations, up to 25%, are useful if maximum solubilization of the underground oil is desired.

For a better understanding of the invention there is now a more detailed consideration of the experimental basis therefor.

In order to find the desired surfactant, which was effective for solubilizing 10 higher molecular weight alcohols in acids, a series of initial experiments were conducted with various classes of known surfactants. The experimental procedure included adding about 40 ml of a certain strength acid solution and about 5 ml of surfactant to a 50 ml glass stoppered measuring cylinder. The combination was thoroughly mixed to show solubility. Then 1 ml of the higher molecular alcohol was added. The measuring cylinder was stopped again and shaken. Then the mixture obtained was observed and care was taken to solubilize the alcohol. Then 1 ml of alcohol was added each time and shaken again until no change could be observed. The results of all these tests are presented below.

Example I

As a bianco assay, 45 ml of 15% HCl and 5 ml of isooctanol were placed in a 50 ml graduated graduated cylinder

shaken thoroughly. A cloudy dispersion was formed which immediately separated into two immiscible layers. After standing for 5 minutes, there was 6 ml of slightly cloudy oil layer on top of a slightly cloudy water layer. This behavior was considered to be representative of the essentially insoluble high molecular weight alcohol in aqueous acid. Example II

In a closed measuring cylinder, 40 ml of 15% HCl were mixed with 5 ml of "Tretolite AY 31", a liquid consisting of oxyalkylated polyols, oxyalkylated alkyl phenols, sulfated oxyalkyl alcohols and glycol ethers. A clear solution with some foam was formed. After adding 8203952 • - 8 - the first ml of isooctanol, a cloudy dispersion was observed. The second ml of isooctanol gave an opaque dispersion with indications of demixing. The addition of the third, fourth and fifth ml of isooctanol led to the separation of an amber-5 colored emulsion that floated to the top. After the fifth ml, the volume of the upper phase was 7 ml, after standing for 5 minutes. From this it was concluded that with AY 31 as the surfactant there is little or no solubilization of the isopropanol.

Examples III-V

The experiment of Example II was repeated replacing the isooctanol with 5 ml caprylic alcohol, n-octanol and decanol. The results were the same as in Example II, except that with decanol the separation occurred more quickly.

Example VI

The experiment of Example II was repeated with 40 ml of 15% HCl and 5 ml of "Surfonic N-95" (this is an adduct of 9.5 moles of ethylene oxide to nonylphenol). The Surfonic N-95 20 produced lumps and chunks when mixed with the acid. Heating and vigorous stirring resulted in a clear, very foaming solution. The addition of the first ml of isooctanol and shaking resulted in a clear solution, except for. some air bubbles. The second ml of isooctanol gave essentially the same result, albeit with some separation. The third ml gave a cloudy solution that trapped air bubbles and there was separation of an oil layer. With the fourth ml of isooctanol the solution seemed to clarify somewhat but a fifth ml gave an opaque emulsion without foam. After the second ml, all solutions were highly viscous. After standing for 15 minutes with 5 ml of isooctanol, there was a top layer of 3 ml of clear oil on top of an intermediate layer of about 36 ml of cloudy, loose emulsion. Apparently even more isooctanol was being demixed. After one hour three clear layers could be observed: 10 ml on the bottom, 31 ml intermediate layer 35 and 9 ml oil on top. Conclusion: Surfonic N-95 is a weak solubilizer for isooctanol in acid, and it stabilizes 8203952 Λ - 9 emulsions.

Example VII

The above described test was repeated with 40 ml of 15 Z HCl and 5 ml of "Morflo II" (a commercial product considered to be a mixture of oxyalkylated alcohol and alkyl sulfonate in butanol). A clear (slightly cloudy) light brown solution was formed. When successive 1 ml portions of isooctanol were added, the solution turned into: a cloudy dispersion after the first ml, a fog bank after the second ml, and an emulsion surmounted by an oil phase after the third and subsequent ml. After a total of 5 ml of isooctanol, 1.5 ml of the oil phase had separated. After standing for 5 minutes, there was 12 ml of strong emulsion and the rest was cloudy. Conclusion: Morflo II is a poor solubilizer for isooctanol in 15 wt% HCl.

Example VIII

In the same test procedure, 40 ml of 15 Z HCl were mixed with 5 ml of "Klearfac AA-420" (a surfactant phosphoric acid ester). A clear solution with a little foam was formed. The first three 1 ml portions of isooctanol 20 were solubilized, and a clear solution formed.

The fourth ml gave a cloudy but stable mixture and the fifth a stable emulsion. With a total of 5 ml of isooctanol, after 15 minutes, 1 ml of clear oil was left on top. The behavior of this phosphoric acid ester appears to be much better than the previously tested surfactants.

Example IX

A second phosphoric acid ester, going under the name "Klearfac AA-040", was also tested in the same manner. Again, the addition of the first ml of iso-30 octanol resulted in a clear solubilized solution, with slight haze after addition of the second ml. The third ml gave a clearly cloudy dispersion or emulsion, and the fourth ml an emulsion. After the fifth ml of isooctanol, the mixture was completely white and after standing for 15 minutes, 2 ml of slightly cloudy oil had separated on top of the emulsion.

8203952 - 10 - 4 ψ β

Example Σ

Likewise, a third phosphoric acid ester was tested under the name "Klearfac AA-270". To the clear solution, 1 ml portions of iso-5 octanol were successively added, after which shaking was continued. In this case, however, only slight cloudiness of the clear solution occurred when a total of 9 ml had been added, with perhaps a faint mist after 8 ml. But even with 9 ml of isooctanol the mixture was still completely stable and no separation was visible.

φ * 10 Only after adding the 4 to 7 ml there was some foam and some opalescence.

This mixture of 9 ml of isooctanol, 5 ml of Klearfac AA-270 and 40 ml of 15% HCl was left to stand overnight.

The next day, a top layer of 4 ml of clear oil was seen above 15 to 50 ml of clear, stable solution. Thus, 5 ml of Klearfac AA-270 can permanently solubilize at least 5 ml of isooctanol in 15 wt% HCl; and more particularly, that 5 ml of isooctanol can be solubilized in a mixture of 25% by volume surfactant and 75% by volume 15% HCl. This suggests the presence of a particular stoichiometry that may be characteristic of the formation of a coordination complex or the like.

In view of the above examples, the phosphoric acid esters as a class appear far superior to the other types of surfactants for solubilizing isooctanol in dilute hydrochloric acid.

Examples XI - XIV

To check the solubilization (not necessarily the formation of mixtures in thermodynamic equilibrium) of other alcohols by these phosphoric acid esters in dilute acid, 5 ml samples of hexanol, heptanol, n-octanol and n-decanol were measuring cylinders with glass stopper mixed with 40 ml 15% HCl and 5 ml Klearfac AA-270. Except the decanol, they gave all clear solutions, so there was excellent solubilization of the alcohol. The decanol resulted in a cloudy but stable dispersion, characteristic of 8203952-11 - good solubilization.

Examples XV-XVIII

To find other mixtures suitable for practical use, a series of tests was carried out aimed at preparing a concentrate of a high molecular weight alcohol with a surfactant phosphoric acid ester which is mixed to various concentrations in various acidic drilling fluids (with 5 to 20% HCl or with HCl / HF mixtures). The aim was to find a concentrate which can easily be used as an additive to acid drilling mud and which as such can be brought to the well and mixed there with the acid. The concentrate as such should be stable, have a low viscosity for ease of handling, and have a low pour point. In order to combine these practical requirements, the usability of a number of auxiliary liquids was investigated.

In Example XV, 25 ml of surfactant phosphoric acid ester (Klearfac AA-270) was mixed with 25 ml of isooctanol and 50 ml of isopropanol (the latter for reducing the viscosity and freezing point). A clear solution was formed upon stirring. A 5 ml sample thereof was mixed with 95 ml 15% HCl; turbid dispersion resulted in shaking. A clear solution was obtained with 5 ml of the isopropanol solution and shaking. From this it was concluded that a higher surfactant to higher molecular alcohol ratio is required for solubility at lower total concentration.

In Example XVI, a concentrate was made by mixing 35 ml of Klearfac AA-270 with 15 ml of iso-30 octanol and 50 ml of isopropanol. Again a clear solution emerged. With this concentrate, clear solutions were obtained with 0.5, 1.0, 3.0, 5.0 and 10% by volume concentrate in 5% HCl, 10% HCl, 15% HCl and 20% HG1. So there was solubility at all concentrations. Solubility was also observed with HCl / HF mixtures.

In Example XVII, among other things, 8203952

¥ Q

- 12 - find equal viscosity and pour point depressants, 30 ml Klearfac AA-270 mixed with 20 ml isooctanol, and this mixture was found to be soluble in methanol, isopropanol, butanol and ethanediol at all concentrations.

In Example XVIII, a mixture of 300 ml Klearfac AA-270, 200 ml isooctanol, 400 ml isopropanol and 100 ml water was prepared. This clear solution was set aside for determining pour point and other data. The water was added to ensure that the highly IQ polar phosphate would remain in solution when the mixture was cooled.

From the above data, it can be seen that the concentrates of Examples XI through XIV are useful as acid drilling mud additives for avoiding emulsions, wellbore cleaning and stimulation in general, and further as wetting agent, dispersant, mutual solvent and solubilizer. Furthermore, it appears that the amount of concentrate required in the final rinse need only be 0.2% to counteract water / 20 oil emulsions and 10 to 20% by volume for maximum effect. For most applications, 5 vol.% Concentrate in the acid appears to be suitable.

Example XIX

Another commercially available surfactant phosphoric acid ester sold under the name "Pluraflo OF-90" was tested in accordance with Example XI by mixing 40 ml of 15% HCl in a graduated cylinder with 5 ml Pluraflo 0F-90. After mixing, a clear solution was formed, to which successively 1 ml portions of isooctanol were added with shaking. After the third 1 ml, slight opalescence in the otherwise clear, single phase solution was observed. After the 5 or 6 ml, that opalescence had developed to a slight haze. The 7 ml of iso-octanol dissolved in a stable dispersion and the 8 ml of an opaque emulsion. Overall, Pluraflo OF-90 matches Klearfac AA-270, but is likely 8203952-13 - somewhat less concentrated.

Example XX

To evaluate the effect of mixing different classes of surfactants, 20 ml Klearfac AA-270 was mixed with 10 ml Surfonic N-95 (a non-ionic phosphoric acid ester). 5 ml of that mixture was added to 40 ml of 15% HCl to give a clear solution. Once again, adding 1 ml of isooctanol parties resulted in a slight cloudiness after the third ml. The fourth ml 10 cleared up that slight haze again, and the fifth ml produced an opaque emulsion that proved to be unstable. This shows that there is no advantage in mixing different classes of surfactants.

Example XXX

To demonstrate the beneficial effect of the invention, a comparative visual test on the resolving power of a series of six acidification solutions was performed. The first solution was a mixture of 5% by volume of the preparation of Example XV with 95% by volume 15% HCl.

The five other comparative formulations were known commercially available alternatives, namely: 10% by volume of butoxy ethanol in 15% HCl, 35% by volume isopropanol / isooctanol mixture in 15% HCl (according to US Pat. No. 3,819,520 and under the trade name A-Sol), 5% by volume of preparation "AY 31" (see example II) in 15% HCl, 5% by volume "Morflo II" (see example VII) in 15% HCl and 5 vol.% "Surfonic N-95" (see Example VI) in 15% HCl.

Each preparation was used to dissolve the oil from a slate sludge raised from a water-injected well. That sludge contained about 20 wt% heavy hydrocarbons, 70 wt% acid soluble mineral (mainly calcium carbonate) and 10 wt% acid insoluble (clay and quartz). Substantially equal samples of the sludge were immersed in excess of each acidic drilling mud. The phosphoric acid ester and higher alcohol containing solution dissolved the material much faster and dispersed the oil contained therein much faster than. the other preparations. The oil floated freely and the insoluble dispersed well in the water phase.

Example XXII

For further tests, an artificial oil sludge was made by mixing 90 parts of calcium carbonate with 10 parts of kaolin and adding a heavy, waxy oil residue to that mixture until a stiff paste was obtained.

Example XXIII

5 g of this paste was mixed in a beaker glass with 100 ml of 15% HCl. Only slow action was observed, evident from gas bubbles (CO2 released) and oil rise. The small amount of oil released was sticky and emulsified, and the clay remained in the oily lump. This chunk of pasta had not disintegrated after an hour at room temperature.

Examples XXIV - XXVI

A phosphate and higher alcohol-containing concentrate of this invention was prepared and consisted of 30% by volume Klearfac AA-270, 20% by volume isooctanol, 40% by volume isopropanol and 10% by volume water. When the final mixture contains 5% by volume of that concentrate, 100 ml of 1.5 ml of Klearfac, 1.0 ml of isooctanol and 2.0 ml of isopropanol are used.

Such a mixture, with 15 wt% HCl, was prepared, and a mixture of 1.0 ml isooctanol, 2.0 ml isopropanol and 97.0 ml 15% HCl (ie without phosphate),

The latter mixture was cloudy and would separate if not stirred regularly.

5 g of the artificial oil sludge of Example XXII were placed in 100 ml of the two acid solutions. The phosphate-free solution disintegrated the sludge faster than the pure 15% HCl of Example XXIII. It took about 30 minutes for the root ball to disappear. The supernatant was emulsified (a gum) without any indication of dispersion. The materials were found to have been moistened with 8203952. The result was better than nothing, but not enough.

The non-surfactant solution did little better than pure HCl. Most of the isooctanol floated to the surface. No foams were observed. Oil released was in the isooctanol phase. There was no emulsification. After 1 hour, the 5 g sample was not completely disintegrated.

However, with the acidification solution containing both isooctanol and the Klearfac, rapid disintegration of the oil paste took place with the development of a lot of foam.

No emulsification was observed. The solution darkened from the solubilized oil (some free oil in the foam).

A1 the swallow had disappeared after 10 minutes. The solid in the bottom phase was wetted by water.

From the above, it can be concluded that the combination of phosphoric acid ester and high molecular weight alcohol, in a proper weight ratio, is readily soluble in acid and does much better in the disintegration, dissolution and dispersion of oil clogging wells etc. individual ingredients. The new formulation prevents emulsification and foaming better than the surfactant alone, so it is more surfactant.

Examples XXVII - mill. 25 To determine the effect of variation in the ratio of surfactant to higher molecular weight alcohol, the following two concentrates were prepared:

Concentrate 1_ Concentrate 2 20 vol.% Klearfac AA-270 40 vol.% Klearfac AA-270 30 30 vol.% Isooctanol 10 vol.% Isooctanol 40 vol.% Isopropanol 40 vol.% Isopropanol 10 vol.% Water 10 vol.% water 5 ml of concentrate 1 was mixed with 95 ml of 15% HCl to give a cloudy dispersion (emulsion). After adding 5 g of oil sludge from example XXII, a slow reaction occurred with much less foaming than in example 8203952 λ j 6 - * ................... ..... _ ___ __ _ _ mm _ _ ___________ _ XXVI. It took 20 to 30 minutes to break off the oil ball. The slow reaction can be attributed to the excess of isooctanol, namely by wetting the solid in the sludge with oil.

5 ml of the concentrate 2 was mixed with 95 ml of 15% HCl to give a clear acidification solution. About 5 g of oil sludge introduced into this mixture dissolved faster than in that first run, but not as quickly as in Example XXVI. It took about 20 minutes to disperse the sludge.

From those two examples taken together, it can be seen that surfactant phosphoric acid esters such as Klearfac AA-270 higher molecular weight alcohols such as the octanols in acid solutions can solubilize in an amount of 15 to 8 din alcohol on 5 din surfactant. The most

stable solution was achieved with equal amounts of surfactant and higher alcohol if the total concentration of this mixture in the dilute acid is about 25% by volume. If the total concentration is only 5% by volume (which is desirable for economic reasons), the best ratio is about 3 din surfactant to 2 din higher alcohol. Already 1 dl higher alcohol on 4 din surfactant is superior to the surfactant alone. For most purposes, alcohol alone is not acceptable due to slow dissolution. 25 Examples XXIX - XXX

To test several higher alcohols, a series of three concentrates was prepared, containing n-butanol, n-hexanol and n-decanol. Each concentrate contained 30% by volume Klearfac, 20% by volume higher alcohol, 40% isopropanol 30 and 10% by volume water. An acidic solution was prepared from each by diluting 1 volume with 19 parts by volume of 15% HCl.

Each acid solution was tested for the ability to decompose artificially oil sludge in the manner of the previous examples. All did well in disintegrating and dispersing the sludge, but the solutions containing n-butanol and n-decanol did not work much faster than surface dust alone, confirming that C ^ -Cj ^ alcohols do the trick, but C 1 -C 6 alcohols are preferred. A1 the higher alcohols (C 1 -C 12) release the oil phase from the sludge without appreciable emulsion formation. That is an improvement over the surfactant treatment alone, even with the slower acting alcohols. This is probably related to the preferred solubility of the higher alcohols in the oil phase of the sludge. For example, isopropanol, which is more water soluble than butanol, in combination with Klearfac does not prevent emulsion formation. Thus, it is clear that the compositions of the invention need a low water solubility alcohol to better penetrate oil sludges and limit the formation of emulsions.

15 Examples XXXI - XXXVII

To determine the recommended water content in the concentrates, a series of three concentrates was prepared, with the following composition:

Concentrate_ 1 2 3 4 5 6_7 20 Vo 1.% Klearfac AA-270 30 30 30 30 30 30 30

Vol% isooctanol 20 20 20 20 20 20 20

Vol% isopropanol 50 48 47 45 40 35 30

Vol.% Water 0 2 3 5 10 15 20

The pour points of these solutions were determined according to ASTM method D-97. The results are shown in table A.

Table A

Concentrate 1 Strong secretion of white solid lumps

30 at -13 ° C

2 Strong separation of white solid lumps at -32 ° C

3 No demixing but high viscosity at -37 ° C

4 No demixing but high viscosity at -37 ° C

35 5 No demixing but high viscosity at -37 ° C

6 No demixing but high viscosity at -37 ° C

7 Brittle separation at -31 ° C, solidified at -37 ° C.

From the above, it is seen that at 8203952 -> - 18 - making concentrates at least 2% water but no more than about 18% water is preferred; then a concentrate is obtained which remains liquid over a wide temperature range. The specific gravities of concentrate 4 5 (5% water) and concentrate 6 (15% water) were found to be 0.925 and 0.950. Concentrate 6 was found to have a flash point of 78 ° C, a focal point of 88 ° C and a viscosity (at 10 ° C) of 38 cp.

Example XXXVIII

To further demonstrate that the phosphoric acid ester and the higher alcohol are also soluble in acid without a diluent and that the solution thus obtained is highly active, 60 ml Klearfac AA-270 was mixed with 40 ml isooctanol, giving a clear viscous gave solution. When it was mixed with 5% hydrochloric acid and 15% strength, it was again found that this mixture was miscible in all proportions with dilute acid. Thus, the lower molecular weight alcohol is not absolutely necessary for solubilizing the higher alcohol in the acid.

5 ml of the above phosphate / alcohol mixture was mixed with 95 ml of 5% HCl and then added to 5 g of artificial oil sludge. The swallow quickly disintegrated and dissolved.

25 ml of this phosphate / alcohol mixture was mixed with 99 ml of 5% HCl and added artificially to a second 5 g sample. Again the mud quickly disintegrated and went into solution.

This was repeated with 3 ml of phosphate / alcohol mixture and 97 ml of drilling fluid (12% HCl and 3% HF). Again the mud quickly disintegrated and went into solution.

From this it was concluded that the combination of phosphoric acid ester and higher alcohol works well, even without lower alcohol.

35 8203952 - 19 -

Examples XXXIX - XL7

To verify the compatibility of the acidic solutions of this invention with other types of acids, a series of eight acidic solutions was made with a mixture of 30% surfactant, 20% isooctanol, 40 as the concentrate % isopropanol and 10% water (Example XXIV), and further with the composition according to Table B.

Table B

Acidic acid solution_1 2 3 4 5_6 7 8 10 Vol.% Concentrate 20 20 20 20 15 20 10 25

Vol.% Glycolic acid 40 - -10 8 - -

Vol.% Sulfamic acid - - - 10 12 - -

Vol.% Acetic acid 40 - - - 15 10 20

Vol.% Citric acid - - 40 - - 10 10 - J5 Vol.% HCl (32%) - 5--

Vol.% NH4HF2 ----- 5 10

Vol% isopropanol 10 10 10 10 10 -

Vol.% Methanol - - - - - 10 - 10 15

Vol% water 30 30 30 50 55 40 55 30 20 As previously indicated, the acids to which the phosphate / alcohol mixtures are added can be any of the acids commonly used in drilling muds of this type. The aqueous acids can contain from less than 5% to 30% by weight of acid, the mixture of surfactant phosphoric ester and higher alcohol remains soluble therein and the acidic solution remains stable. Preferably 7 to 15% by weight of HCl is used for this.

The additives for acid solutions according to the invention are applicable to all acid leaching from oil and gas wells. They can be used in rinsing producing wells with water, as well as in other secondary and tertiary productions. The acidic solution is injected into the oil-containing formation with the phosphate / alcohol additive in a producing well, whereupon production proceeds again. In other cases, the acidic liquid is injected into the well and then plain water. In both cases, the combination of surfactant and alcohol can be mixed with the acid solution or injected before or after the acid solution; combinations of these are also possible. These methods can also be used in combination with "spear points" or "rinses" of other known solvents, for example, aromatic solvents to remove asphaltenes and other heavy deposits, various sulfur solvents and the like.

The primary value of injecting this additive for the acidic solution is to displace the oil for the acid from it, resulting in less mixing and optionally emulsification. Such plug flow also dissolves organic deposits that would otherwise block the flow of the acid through the oil-containing layers.

Injuring such a supplement would also break emulsions that tend to be produced by naturally occurring emulsifiers. It would appear that the breaking of the emulsions, the removal of organic deposits and the acidification can be adjusted as needed with the concentration of the additive and whether it is administered continuously or by pulses.

The advantages of mixing the additive with the acid are the solubilization of the oil in contact therewith and the improved displacement of the oil by the acid, leaving the solid moistened with water. Injecting the additive of the invention after the acid is valuable for displacing oil and organics that have not come off in the previous treatments. This is especially true if that supplement had not previously been applied. A portion surcharge after acid rinse is especially valuable in wells that are rinsed with water, and frees up more pore space for water to flow through.

The amount of acid can range from a few hundred to many thousands of liters. However, the treatment is primarily intended for the zone immediately surrounding the wellbore, so that somewhat smaller volumes are usually used. Preferably between 2 and 20 m are used. Otherwise 8203952> 9% - 21 - said: 100 to 7000 liters per meter that the formation is thick, as recommended in U.S. Patent 3,548,945.

If a "spear point" or pre-rinse 5 of this addition precedes acid rinsing, the volume of this spear point should be between 1% (with the larger amounts of acid) and 100% (with the smaller volumes) of the amount of acidification. solution. In such cases, the ratio of surfactant to higher alcohol can also be adjusted, taking into account the individual oil deposits.

About the same volumes should be used as with the final rinse.

When cleaning injection wells, ie removing clogging sludges, emulsions, etc., where acidification of the formation is not the primary objective, it is often advantageous to reduce the total volume of the acidic solution and the concentration of the increase the surcharge. This is economised to keep costs down. Furthermore, as in Example XV, the ratio of higher alcohol to phosphoric acid ester can be chosen higher to keep costs low (since that ester is the more expensive substance).

As already indicated, the primary use of the compositions of the invention is in oil wells, but they are also sometimes useful in treating gas wells and gas condensate wells. Many gas wells give a little oil, as many oil wells give some gas. Thus, organic deposits can form in and around gas wells. Many gas wells also provide some water, so mineral deposits can also form in and around gas wells. When gas wells are acidified to remove such mineral deposits and otherwise increase the gas flow, the oil present in the formation can emulsify with the acid, just as in oil wells. In such applications, the ability to foam the compositions of the invention is an advantage for recovering the acid and using 8203952 nitrogen for that purpose. Thus, it is evident that many considerations that make the use of the surfactant combination and higher aXkohoX aXs worthwhile in acidifying oil sources worthwhile also apply to gas and gas 5 condensate sources.

The use of the additive according to the invention and the advantages thereof in the acidification of wells appear to be clearer from the following examples. Example XLVI

"Surfonic N40" (ethoxylated nonyXphenoX with 4 mol of ethylene oxide per mole and a terminal hydroxy group) was used, which is practically insoluble in 15 wt% HCl but does emulsify in it. 25 ml of this Surfonic N-40 was mixed with 25 ml "Pluraflo 0F-90" and 50 ml iso-15 propanol. Dezetoesiag gave a clear solution at a concentration between 2 and 10% by volume with 15% HCl. 5 g of oil sludge was added to a combination of 5 ml of this supplement with 95 ml of 15% HCl. The rate at which this dissolved was not as high as with the previously described isooctano1 combinations, but the results were acceptable because the solid was wetted with water and no thick emulsion layer floated to the top. The test was repeated without ethoxylated nonylphenol to give an unacceptable heavy viscous oil layer on top. The conclusion is that "Surfonic N-40" is useful, but not as good as the unbranched higher alco caves.

Although preference is given to the oil-soluble essentially water-insoluble monovalent alcohols, other alcohols with the same solubility and the same hydrophilic / lipophilic balance as the straight-chain Cg-Cg alcohols can be used. For example, solubility and HLB of the very high molecular weight fatty alcohols (at 12 to 22 ° C), the polypropylene and polybutylene glycols, the alkyl substituted phenols and the fatty acids with 12 to 22 carbon atoms are shifted into the usable range by reacting them with a little ethylene oxide . The al 8203952-23 thus obtained substances having at least one terminal hydroxy group and the best solubility in oil can be represented by the general formula

RjR2-0 - / - "CH2CH2-0 r5 ^ CH2CH2OH

5 wherein R 1 is a methyl or g-hydroxyethyl group, R 2 is a hydrocarbon chain of 11 to 21 carbon atoms, polypropylene oxide, polybutylene oxide chain, fatty acid residue of 11 to 22 carbon atoms, or an alkylphenyl group of 8 to 21 Is 10 carbon atoms in the alkyl group, and wherein X is a number from 3 to 5 10.

Examples XLVII-LIII

A number of field tests with the preparations according to the invention have been carried out. In each run, the supplement contained 30 vol% Klearfac AA-270, 20 vol% isoocta-15 nol, 40 vol% isopropanol, and 10 vol% water. The results are shown in Table C.

Table C

Type Place Formation / Full ratio Production (Co., TX) depth thing acid / (in barrels) 20 '_ surcharge before / after wiw * Cass Haynes Mitchell / 950/50 10407 65 atm 1350 m 10482 28 atm

gas ** Panola Pettit / 475/25 250 MCFD / 600 MCFD

1900 m 25 oil *** Rusk Woodbine / 1140/60 10 oil; 211 wall 00 m ter / 56 oil; 168 water barrels oil Wood Subclarks- 950/50 11 oil; 32 wave / ter / 16 oil; 30 1200 m. 70 water barrels gas Marion Travis Peak / 950/50 300 MCFD, 42 atm 2600 m 1.2M MCFD, 120 atm gas Henderson Rodessa / 2850/150 10 MCFD /

35 2100 m 710 MCFD

oil Cherokee Woodbine / 950/50 19 oil; 28 watts 1100 m ter / 59 oil; 28 water s wiw = water injection source 40 * a gas = gas production source oil = oil production source 8203952 - 24 -

Example LIV

A water-injected well in 3

Smith County, Texes, which was used to infuse 320 m water of 140 atm per day in the Paluxy formation at a depth of 200 m per day, was treated with a mixture of 2000 liters of 15% HCl containing 5 vol% addition according to examples XLVII -LIII and contained 800 liters of xylene. The xylene and the acid solution were mixed and then injected into the formation and allowed to act for an hour. A mixture of salt water and displacer 10 was used to rinse out that formation and then 3 more 14 m acidic solution (with 5% vol. Surcharge) was injected.

After this they continued to inject ordinary water.

3

For that treatment, the well received 320 m of water from 3,140 atm per day, then 720 m from 35 atm.

From the above it should be clear that in addition to the advantages of economy with the surcharge according to the invention, its application also leads to savings in the operation of injection wells and an increased production of gas and oil-producing wells.

20 8203952

Claims (20)

Acidic acid solution, suitable for treating dietary and / or gas sources, consisting of 5 (a) acid diluted with water, (b) an aliphatic alcohol of 4 to 10 carbon atoms, and (c) an effective amount of surface active phosphorus salt ester which solubilizes that alcohol in the aqueous acid. 2. Acidic acid solution according to claim 10 1, composed of at least 75 parts by volume of aqueous acid with a strength of up to 20% by weight and up to 25 parts by volume of the mixture of the aliphatic alcohol and the surfactant phosphoric acid ester, which mixture on 5 parts surfactant contains up to 8 parts by volume of alcohol. The acidic solution according to claim 1 or 2, wherein the acid is HCl, HF, acetic acid, sulfamic acid, citric acid, glycolic acid, or a mixture thereof. Acidic acid solution according to any one of the preceding claims, wherein the aliphatic alcohol has from 6 to 8 carbon atoms. Acid solution according to any one of the preceding claims, wherein the surfactant phosphoric acid ester is an ester of an oxyalkylated fatty alcohol. Acidic acid solution according to claim 25, wherein the aliphatic alcohol is an octanol. Acidic acid solution according to claim 6, the dilute acid of which is 15 wt% HCl and the surfactant phosphoric acid ester is Klearfac AA-270 or Puraflo OF-90. Acidic acid solution according to any one of the preceding claims, which also contains an effective amount of water-soluble alcohol of lower molecular weight and / or a diol. 9. Acidic acid solution according to any one of claims 2 to 8, composed of at least 90 parts by volume of dilute acid with up to 10 parts by volume of said mixture. 10. Surcharge for an acidic solution, 8203952% - 26 - consisting of an aliphatic alcohol with 4 to 10 carbon atoms and a surfactant phosphoric acid ester. The supplement of claim 10, additionally containing (a) a water-soluble alcohol of lower molecular weight and / or a diol and (b) water. The supplement of claim 11, wherein the lower molecular weight alcohol or diol is methanol, ethanol, n-propanol, isopropanol, t-butanol and / or ethanediol. The supplement of claim 10, 11 or 12, wherein the alcohol has from 6 to 8 carbon atoms and the surfactant phosphoric acid ester is an ester of an oxyalkylated fatty alcohol. The supplement of any one of claims 15 to 13, wherein the volume ratio of alcohol to surfactant is between 1: 4 and 8: 5. The supplement of claim 14, wherein the volume ratio of alcohol to surfactant is about 2: 3. A supplement according to any one of claims 11 to 15 containing up to 50% by volume of water-soluble alcohol and water. The supplement of claim 16, which contains between 2% and 20% by volume of water. A method of treating an oil and / or gas-containing formation, wherein said formation is treated with an aqueous solution, characterized in that the aqueous solution is a solution according to any one of claims 1 to 10. 19. Acid solution or supplement therefor, mainly according to description and / or examples. 20. Method for treating an oil and / or gas-containing formation, substantially according to description and / or examples. 35 8203952