NL7907884A - METHOD FOR PREPARING A MOTION CONTROLLING SOLUTION FOR USE IN OIL EXTRACTION - Google Patents

Description

0

Process for the preparation of a mobility control solution for use in oil recovery.

Hydrophilic colloids are formed by species of the genus Xanthomonas, consisting of polysaccharides composed of mannose, glucose, glucuronic acid, O-acetyl residues and pyruvic acid bound via acetal bond. These gummy products and their derivatives are widely used in the food industry and for all kinds of industrial applications. Particular attention is paid to the use of gums formed by Xanthomonas species in displacing oil from partially depleted reservoirs.

10 Oil is generally extracted from underground reservoirs through a series of sequential processes.

A new well generally delivers a limited amount of oil, thanks to the internal pressure under which the oil is present in the well.

As this pressure decreases in this way, it becomes necessary to pump up a further amount of oil from the reservoir by mechanical means. With these methods, only about 25% or less of the total amount of oil present in the reservoir can be recovered. Much of the oil is retained in the pores of the formation, in which the oil occurs. Further amounts of oil can be recovered by using secondary recovery methods. In one recovery method, the reservoir is flushed with water by pounding water into a well or a series of vein wells, displacing some of the retained oil from the porous rock and recovering the displaced oil from the surrounding wells. Even after flushing with water, however, approximately 55-60% of the available oil remains in the formation. An explanation for this is that the water has a very low viscosity compared to the crude oil and tends to follow roads with the least resistance 790 7 8 84 * 2 and thereby splits into a number of small streams (fingering) which penetrate the oil as they pass large cavities. In addition, surface forces in the formation can retain the oil and prevent it from being displaced.

In recent years, a number of methods have been developed for recovering further amounts of oil from such reservoirs using the motility control solutions that increase oil displacement by increasing the viscosity or permeability of the displacing liquid. Of interest are the methods of recovering larger amounts of oil using "polymer flushing" with a polysaccharide or polyacrylamide to increase the displacement fluid viscosity. For example, various variants of this method utilize surfactants and co-surfactants to release the oil from the rock. It has been found that polyacrylamides are aware that their viscosity decreases in brine and that they are very sensitive to shear forces. Since, as has been extensively documented in the prior art, xanthan-20 gum is relatively insensitive to salts (does not precipitate under normal conditions and shows no loss of viscosity), is stable under shear forces, stable If a variation in temperature and a stable viscosity is shown over a wide pH range, xanthan gum is in principle a good displacing agent. In addition, xanthan gum is little adsorbed by the elements of the porous rocks and, in low concentrations (100-3000 ppm), gives viscosities favorable for recovering larger quantities of oil (viscosities from 5 x 10 to 90 x 10 ^ Pa. s at a shear rate of 1.32 s The use of solutions of xanthan gum or xanthan gum derivatives for oil recovery is described in U.S. Pat. Nos. 3,243,000, 3,198,268, 3,532,166, 3,305. 016, 3,251,417, 3,319,606, 3,319,715, 3,373,810, 3,434,542, 3,729,460, and 4,119,546.

US Pat. No. 3,305,016 suggests that aqueous solutions containing a sufficient amount of 790 7 8 84 4-3 ψ heteropolysaccharide to increase viscosity can be used as a thickener in the preparation of viscous water flush solutions. The polysaccharide can be prepared, separated, purified and then added. Also, according to this patent, after adding a bactericide (e.g. formaldehyde) to kill the bacteria, the entire culture can be added to the rinse water.

It has been found that various heat treatments result in an increased viscosity or filterability of media obtained as such from cultures of Xanthomonas species as well as of the respective diluted media. According to U.S. Pat. No. 3,501,578, a heat treatment is performed before xanthan is precipitated. In the heat-treated mass, an increase in viscosity of 1.5-3.5 times was noted. U.S. Pat. No. 3,773,752 describes a process in which a dilute fermentation broth is heated after addition of an alkali metal salt until coagulation occurs and the hot solution, preferably after addition of a coagulant such as alum, is filtered. According to the method of U.S. Patent 3,801,502, an alcohol, phenol, ketone or nonionic surfactant is added during the heat treatment. In the process of U.S. Patent 3,355,447, the heat-treated fermentation broth is diluted, filtered and the xanthan is removed by precipitation with alcohol.

The invention now relates to an improved process for the preparation of a motility control solution for use in oil recovery, with an activity increased by more than 15% and with a filtration ratio of less than 3 through a filter (Millipore filter) with a pore size of 1.2 µm. which method consists in heating an aqueous solution of Xanthomonas biopolymer with a concentration of xanthan equivalents of 0.05-2.0% and a salt content of less than 0.2% for about 2-60 minutes at a temperature of about 60-98 ° C and if the concentration of xanthan equivalents is greater than 3000 ppm, the 790 78 84 * 1 * 4 solution dilutes to a concentration of xanthan equivalents of approximately 100-3000 dpra.

According to a preferred embodiment of the invention, the solution of Xanthomonas biopolymer is a fermentation broth which is practically free of insolubles with a particle size of more than about 3 / m.

Heating for a period of about 5-20 minutes at a temperature of about 80-98 ° C is particularly preferred.

The invention also relates to a process for the preparation of a motility control solution for use in oil recovery, which process comprises the following steps: (a) diluting a complete Xanthomonas fermentation broth to a concentration of xanthan equivalents of 0.14-1.5% with water having a salt content of less than 0.2%, (b) heating the broth over a period of about 2-60 minutes at a temperature of about 77-98 ° C and (c) filtering the broth and recovering a filtrate with an activity greater than 15% and a filter ratio of less than 3 through a filter (Millipore filter) with a pore size of 1.2 µm or even finer.

Particular preference is given to such a method in which the broth is practically free of insolubles with a particle size of more than about 3 / an, wherein step (c) is carried out at a temperature of 77-98 ° C and wherein the heat-treated solution if its concentration of xanthan equivalents is greater than 3000 ppm, is diluted to a concentration of xanthan equivalents of about 100-3000 ppm.

In all cases, the final dilution of the heat-treated solution to the use concentration, if necessary, is preferably carried out with water with a salt content of at least about 0.6%.

While previously described heat treatments 790 7 8 84 5 each aimed at either increasing the viscosity or filterability of complete Xanthomonas fermentation broths, the present invention relates (¾) to an integrated method of preparing the motility control solutions which are characterized by any of said desirable properties, i.e., increased viscosity and improved filterability, as well as improved injectability and good thermal stability.

The invention can be used for the treatment of two types of Xanthomonas biopolymer solutions or broths: solutions or broths practically free of insolubles having a particle size of more than about 3 µm and solutions or broths containing such insolubles. With solutions of the former type, the method according to the invention provides a product suitable for direct injection without filtration, although a filtration can still be used for use in oil fields with low permeability. In the case of Xanthomonas polymer solutions of the latter type, the method according to the invention comprises a filtration step.

The following terminology is used in the description of the method according to the invention. As a measure of xanthan activity, the viscosity of the solution in cP is determined (i cP «10 ~ ^ Pa.s) at 6 min." "* And 25 ° C with a Brookfield Viscosimeter with UL adapter, corresponding to a shear rate of 7.3 s. 1. For a given solution, the dilution (with a saline solution at a concentration of 500 ppm containing NaCl and CaClj in a ratio of 10: 1) is determined to achieve a viscosity of 10 cP In untreated Xanthomonas polymer, this viscosity is observed at a polymer concentration of 0.05% (500 ppm). The dilution factor found for a given solution multiplied by 0.05% gives the concentration of xanthan equivalents of the solution. (also called the active Xanthomonas polymer concentration).

Injectability (not to be confused with the term filterability in this application) is an important property of the motility control solutions. Injectability is correlated with a "Millipore" test, which is described in detail below, a test in which the flow rate through a Millipore filter (pore diameter 0.45-3.0 µm) is measured as a function of volume under a constant overpressure of 276 kPa. The filtration ratio (F.R) is the ratio of the time required to collect the fourth 250 ml motility controlling solution to the time required to collect the first 250 ml motility controlling solution. A filtration ratio of 1.0 indicates that the solution has no tendency to clog pores. An acceptable motility control solution generally has a filtration ratio of 1-3 (for a Millipore filter with a pore diameter of 0.45-3.0 firn) and preferably has a filtration ratio of less than 1.7. The desired filtration ratio and pore size of the filter for a particular motility control solution depend on the permeability of the underground layer of the oilfield from which it is desired to displace oil.

Xanthan-based motility control solutions can be exposed to temperatures below 80 ° C or higher. The thermal stability of these solutions is affected by their salt concentration and also by other factors. Thermal stability is measured as the ratio between the viscosity of the diluted broth after 7 days storage at 80 ° C and the viscosity for the storage period (10 cP).

25 Studies of full heat treatment

Xanthomonas fermentation broths teach that the temperature required to achieve an increased viscosity of whole broth is significantly higher than the temperature required for the diluted broth. The complete unmodified broth is much more stable and resistant to reconfiguration of xanthan polymer by heating than the diluted broth. This can be explained by the presence of a higher salt concentration (ionic strength) in the whole broth and by a decreased molecular motility.

35 Further studies teach that although increased 79078 84 7 xgTvfrh * ri activity is achieved by vomiting, heat treated whole broth does not retain its injectability (measured as filtration ratio). Injectability decreases as the heating temperature and heating time increase.

Further studies have further taught that neither chemical treatments (with surfactants, phenols, etc.) nor physical treatments (subject to shear) are effective in improving the injectability of heat-treated whole Xanthomonas fermentation broths.

Research leading to the present invention taught that reconfiguration of Xanthomonas polymer is the main reason for injectability changes due to heat treatment. The configuration of Xanthomonas polymer depends on the treatment temperature, time and salt concentration. In turn, the configuration determines the viscosity, injectability and thermal stability of the Xanthomonas solution.

The novelty of the present invention and the advances in the art achieved with the invention lie in the finding that (a) a significant increase in xanthan activity is obtained by moderate heat treatment (heating at 60-98 ° C) for a short time of about 2-60 min., of a Xanthomonas fermentation broth diluted with deionized water or low salt water, 25 (b) that the moderate heat treatment of a diluted, complete

Xanthomonas fermentation broth causes minimal degradation of Xanthomonas cells and does not significantly affect the injectability of the motility regulating solution and (c) -diluting the motility regulating solution to the use concentration asm xanthan with water with a high salt content, the thermal stability is favorable. affects.

According to a preferred embodiment of the present invention, a complete Xanthomonas fermentation broth which is practically free of insolubles having a particle size greater than about 3 fan. subjected to treatment to obtain a motility control solution having a favorable filtration ratio as described in U.S. Patent 4,119,546.

Complete Xanthomonas fermentation broth which is practically free of insolubles with a particle size greater than about 3 i * m is diluted with deionized water or with naturally occurring water with a salt content of less than 0.2%, to a xanthan concentration of about 0.05-2%. The diluted broth is then heated to a temperature of 60-98 ° C for about 2-60 min., Preferably about 5-20 min. While the mixture is being stirred. diluted to the use concentration (100-3000 ppm xanthan) if necessary, preferably with water with a salt content of at least about 0.6%. The diluent may also contain other additives such as preservatives, surfactants and scale inhibitors or inhibitors.

The integrated method according to the invention thus provides a method for the preparation of motility control solutions for use in oil recovery with the following practical and economic advantages: 1. increased xanthan activity, 2. improved thermal stability (if salt water is used before diluting to the use concentration), 3. Eliminating the need for Xanthomonas cell filtration while maintaining good injectability. Dexterity control solutions prepared from the whole fermentation broths by the method of the invention have filtration ratios which make them suitable for use in most oil fields.

If the subsoil layers are particularly impermeable, low filtration ratio motility solutions (1-3) through finer Millipore filters (pore diameter 0.45-0.65 / wn) should be used. Under those conditions, mobility control solutions should be used which are free 7907884

Q

Of Xanthomonas cells and other insoluble matter.

For this limited alternative method, the fermentation medium can be selected from any of the media described in the literature for the preparation of xanthan. A simple and usable medium 5 containing an extract of "distillers' solubles" (the liquid fraction remaining from the distillation of the crude alcohol formed in alcoholic fermentation; for example, Stimuflav, Hiram Walker), dipotassium hydrogen phosphate, glucose and magnesium sulfate described in Biotech. & Bioeng., XII, 75-83 (1970). The entire Xanthomonas fermentation broth is diluted with water with a salt content of less than 0.2% to a xanthan concentration of 0.05-2.0%, preferably 0.14-1.5%. The pH is optionally adjusted to 6.5 with an alkali metal hydroxide solution. The solution is stirred (preferably by low shear mixing) until the xanthan is evenly dispersed (about 1 h). Low shear mixing provides a higher viscosity solution after heat treatment than when mixed with high shear.

The diluted broth is heated to a temperature of 60-98 ° C, preferably 77-98 ° C, and filtered. With stirring at 77-98 ° C a filtration aid, for example diatomaceous earth (Dicalite Superaid) is added in an amount of approximately four times the xanthan concentration per liter of diluted broth and the broth is filtered through a pressure filter which is heated during the filtration at 77-98 ° C. The total time the broth is at an elevated temperature, including the filtration time, should be about 2-6 min. Filtration can also take place at room temperature after the broth has been kept at the elevated temperature for the selected period of time.

The final dilution to the xanthan concentration (100-3000 ppm) desired for use can be effected with water, preferably with water with a salt content of at least about 0.6%. The filtration can optionally take place after the final dilution.

Typical sparkling filtrates with a doubled 790 7 3 84 y 10 viscosity have filtration ratios of 1.5-2 through a Millipore filter with a pore diameter of 0.45 µm. In addition, 1000 ml Millipore filtrate is collected within 20 min. This alternative method thus provides mobility control solutions with an increased viscosity, which can be injected into the layers of particularly impermeable oil fields.

The Millipore injectability test.

Prepare 1050 ml of a 500 ppm xanthan-containing solution in a 500 ppm salt-containing solution (with 10: 1 NaCl and CaCl 2) in the following manner:

In a "Waring blender" or other mixing direction of the same type equipped with an adjustable resistance, place an amount of fermentation broth such that the xanthan solid content is 0.525 g. Dilute 1 to 6 with saline.

15 Stir this mixture (subject it to shear) for 2 min at a voltage of 50 V. Dilute in the mixer with saline to 1050 ml and subject the mixture to shear again for 1 min at 50 V. Use a test setup allows the flow rate to be measured by a Millipore filter disc (diameter 20 47 mm, pore size 0.45-20 pxa. \ as a function of the volume when filtering under a constant overpressure of 276 kPa, Use a reservoir that can hold at least 1000 ml filtrate .

Fill the reservoir with 1050 ml of xanthan solution (500 ppm). Set the pressure to an overpressure of 276 kPa. Open the shut-off valve and start recording the volume of filtrate relative to the filtration time (s).

Filtration ratio = time required to collect the 4th portion of 250 ml solution time required to collect the 1st portion of 250 ml solution

The following examples further illustrate the invention.

Example I

A Xanthomonas fermentation broth practically 79078 84 11 free of insolubles having a particle size greater than about 3 / * m can be prepared as follows:

Cells of Xanthomonas campestrls NRRL B-1459a were transferred from an oblique layer of YM agar into 300 ml of YM 5 nutrient solution in a 2.8 L Fernbach flask and shaken in a rotary shaker at 28 ° C for 31 h. A 25 ml portion of the suspension was transferred to a 2.8 L Fernbach flask containing 500 ml of a medium of the following composition: 10 Ingredient g / 1

Glucose Fructose (Isosweet 100, Corn

Products) 10.1

Crude glucose (Cerelose) 25.7 NH.NO. 1.0 4 3 15 MgSO 4 .7H 2 O 0.10

MnSO..HO 0.03 4 2

FeS0..7H_0 0.01 4 2

Anhydrous citric acid 1.0 K2HP04 4.1 20 KH-PO. 0.69 2 4

The Cerelose and the Isosweet 100 were dissolved in distilled water and sterilized separately in an autoclave. The rest of the ingredients were combined, and the mixture brought to pH 6.4 after which it was also sterilized in an autoclave. The individual sterilized mixtures were then combined.

After shaking at 28 ° C for about 33 h, a 200 ml portion of the slurry was transferred to a 4 L mechanically agitated fermenter containing 2 L of the following medium: 790 78 84 4 r 12

Ingredient g / 1

Cerelosis (sterilized separately in autoclave) 25.7

Isosweet 100 (as above) 10.1 5 NH 4 NO 3 1.0

MgSO4.7H20 0.10

MnSO 4.H 2 O 0.03

FeSO4.7H20 0.01

Anhydrous citric acid 1.0 10 CaCl2.2H20 0.20

Na2HP ° 4 3.34

NaH2 PO4 0.70

The sugars were dissolved in 300 ml of water and sterilized separately in an autoclave. The rest of the ingredients were dissolved in 1700 ml of water after which the solution was dissolved

sterilized in an autoclave and the solutions were then combined. Aeration was done at such a rate that 1.5 mmol / l. min. oxygen were supplied. The fermentation took place at 30 ° C for 48 h during which time the pH of the medium was kept between 5.9 and 7.5 by adding a sodium phosphate buffer made with tap water. Ethylenediaminetetraacetic acid was also added to the sodium phosphate buffer to prevent precipitation of calcium phosphate salts. At the end of the fermentation, the viscosity of the fermentation broth was greater than 7,800 cP at a shear rate of 5.27 seconds and the xanthan concentration was greater than 1.5%. Example II

Complete Xanthomonas fermentation broths which were practically free of insolubles with a particle size greater than about 3 microns were subjected to a treatment according to the method of the invention. A portion of each fermentation broth was diluted with deionized water to a xanthan concentration of 0.6% and heated at 80 ° C for 5 min. The heat treated solutions were then further diluted to a viscosity of about 10 cP and compared to similarly diluted solutions that had not been heat treated 790 7 8 84 13. The trial results were as follows:

Broth Heat Filtration Ratio Activity Thermal Treatment (filter with pore enhancement (c) stability of 1.2 μα) 5 1 (a) - 1.06 - 0.77 1 (a) + 1.07 +70% 0 .82 1 (b) - ~ 0.22 2 (b) - 1.01 2 (b) + 1.01 + 65% 10 (a) Final dilution with water containing 0.6% sodium chloride.

(b) Final dilution with water containing more than 500 ppm sodium chloride.

(c) Activity increase = ratio of the 15 dilution needed to measure a viscosity of 10 cP at 6 min. * in the Brookfield Viscometer after heat treatment and the dilution needed to achieve a viscosity of 10 cP at 6 min-1 in the Brookfield Viscosimeter v <5 <5r the heat treatment, times 100.

Example III

A series of Xanthomonas broths with xanthan concentrations greater than 3% were diluted with deionized water to a xanthan concentration of 0.75%, heated at a temperature of 85 ° C for 5 min, and diluted to a viscosity of 10 cP.

25 The results were as follows:

Broth no. Heat treatment Filtration ratio Activity (filter with pore increase, from 1.2 μα) 1 - 1.22 30 + 1.15 +56% 2 - 1.12 + 1.13 +67 3 - 1.12 + 1 , 22 +67 4 - 1.12 35 + ^ 07 +67 79078 84 * tf 14

Broth no. Heat treatment PiItration ratio Activity (filter with pore increase of 1.2 ism) 5 - 1.16 + 1.08 +67% 6 - 1.27 + 1.16 +57 7 - 1.21 + 1, 11 +67 8 - 1.22 10 + 1.09 +84 9 - 2.11 + 1.31 +67 10 - 1.28 + 1.10 +67 11 - 1.37 15 + 1.05 +84 12 - 1.13 + 1.04 +78

Average - 1.28 + 1.13 +70

Example IV

A sample of complete Xanthomonas fermentation broth with an initial FR, for a filter with a 0.65 µm pore, of 2.59 was subjected to a treatment according to the invention to improve viscosity and motility properties. A 25% solution of xanthan in a 500 ppm salt-containing solution (Na: Ca salt = 10: 1 ratio) was heated at 85 ° C for 5 min and then cooled to room temperature and diluted to 0.14% with the same saline, then 5600 ppm of diatomaceous earth were added and the heat-treated, dilute solution was filtered at room temperature under pressure through a pre-coated leaf filter. The sparkling filtrate showed a 40% higher activity and an improved filtration ratio of 1.71 with a filter with a pore size of 0.65 µm.

Example V

A sample of complete Xanthomonas fermentation broth which per se clogged a Millipore filter with 0.45 µm pores, was subjected to a treatment to improve the viscosity and injectability properties. The broth was diluted to a concentration of 1% with brine at a concentration of 500 ppm, after which the diluted broth was heated to 35 ° C and then diluted at 85 ° C to a concentration of 0.14% by adding saline at a concentration of 500 ppm containing a sufficient amount of diatomaceous earth as a filtration aid to increase the rate of subsequent filtrations.

The heat-treated solution was then filtered under pressure at about 85 ° C through a pre-coated leaf filter to give a filtrate yield of 0.15 l / m.

The total time the product was at 85 ° C was 20 min. The sparkling filtrate showed an activity increase of more than 18% and improved injectability, as evidenced by a filtration ratio using a Millipore filter with pores of 0.45 µl of 1.94 and a filtration ratio using a Millipore filter with pores of 0.65 µm of 1.23.

Example VI

A Xanthomonas fermentation broth containing insolubles with a particle size greater than 3 µm can be prepared in the following manner:

Cells of Xanthomonas campestrls NRKL B-1459a from an oblique layer of YM agar are transferred into 300 ml of YM 25 broth in a 2.8 L Fernbach flask and shaken in a rotary shaker at 28 ° C for 31 h. A 25 ml portion is then transferred to a 2.81 Fernbach flask containing 500 ml of a medium of the following composition:

Ingredient q / 100 g solution

30 Part A

x Distillers' soluble extract 18 Κ.ΗΡΟλ 0.5 2 4

Anti-foaming agent (GE 60) 0.08

Distilled water 57 35 pH 7.1 Individually sterilized in a car claaf 790 78 84%> 16

Ingredient q / 100 g solution

Part B

Glucose 2.5

MgSO4 0.01 5 Distilled water 22 pH 4.25 x The extract was prepared by a 10% by weight aqueous suspension of the dried solubles which were distilled from a crude alcohol (distillers' dried solubles) 5 min. 10, then cool, supplement the solution with fresh water to compensate for the evaporation losses, add 4% diatomaceous earth as a filtration aid and filter under vacuum.

After shaking for 33 hours at 28 ° C, a 200 ml portion is transferred to a 4 L mechanically agitated fermenter containing 2 L of the above medium.

It is aerated at a rate such that 1.5-3.5 mmol / 1 min oxygen is supplied. The fermentation is carried out at 30 ° C until the reducible sugar content is 0.3%, the viscosity is at least 4500 cP and the xanthan concentration is at least 1.0%.

The treatment of the Xanthomonas fermentation broth according to the present invention takes place as follows:

The whole broth is mixed with water containing 500 ppm of salt (sodium chloride and potassium chloride in a ratio of 10: 1) to a xanthan content of 750 ppm. The diluted broth is stirred at a slow shear rate for about 1 h until the xanthan is evenly dispersed and then heated at a temperature of about 95 ° C for about 5 minutes.

Dicalite Superaid (3 g / l diluted broth) is added with stirring at a temperature of about 95 ° C and the broth is filtered through a test sheet filter with vertical filter blades using a cotton cloth without pre-coating as filter medium. The filter area was 23.25 cm. The filter 1 79071 84 was electrically heated to 93-98 ° C before and during the test. The filtration took place under a constant overpressure of 276 kPa. The first filtrate was recycled until it became clear. The filtrate was cooled to 20-30 ° C. With this treatment, a filtrate having a viscosity of about 30 cP and a filtration ratio was obtained by filtration through a Millipore filter with a pore size of 0.45 m and 1.2 im less than 2, which are typical results for such a mixture.

10 79078 84

Claims (11)

1. Process for the preparation of a motility control solution for use in oil recovery, having more than 15% greater activity and having a filtration ratio of less than 3 when using a filter (Millipore filter) with a pore size of 1.2 / n, characterized in that an aqueous solution of Xanthomonas biopolymer with a concentration of asm xanthan equivalents of 0.05-2.0% and with a salt content of less than 0.2% for a period of time of about 2-60 min. is heated to a temperature of about 60-98 ° C and that if the concentration of xanthan equivalents is greater than 3000 ppm, the solution is diluted to a concentration of xanthan equivalents of about 100-3000 ppm. 2. Process according to claim 1, characterized in that the solution of Xanthomonas biopolymer is practically free of insolubles with a particle size of more than about 3 µm. Process according to claim 2, characterized in that the solution of Xanthomonas biopolymer is a fermentation broth. 4. Method according to claim 3, characterized in that the heating is carried out at a temperature of about 80-98 ° C for about 5-20 min. A method according to any one of the preceding claims, characterized in that the dilution takes place with water with a salt content of at least about 0.6%. Process for the preparation of a mobility control solution for use in oil recovery, characterized in that (a) a complete Xanthomonas fermentation broth is diluted to a concentration of xanthan equivalents of 0.14-1.5% using water with a salt content of less than 0.2%, (b) heat the broth over a period of about 2-60 minutes at a temperature of about 77-98 ° C and (c) filter the broth and a filtrate recovered with an activity greater than 15% and a filtration ratio of less than 3 using a filter (Millipore filter) 79078 84 'A with a pore size of 1.2 µm. Process according to claim 6, characterized in that the complete fermentation broth is practically free of insolubles with a particle size of more than about 3 am. Process according to claim 6 or 7, characterized in that / step (c) is carried out at a temperature of 77-98 ° C. 9. Process according to claims 6-8, characterized in that the heat-treated solution is diluted to a concentration of xanthan equivalents of approximately 100-3000 ppm, if the concentration of xanthan equivalents is previously more than 3000 ppm. 10. Process according to claim 9, characterized in that the heat-treated solution is diluted with water with a salt content of at least about 0.6%. 11. Methods, substantially as described in the description and / or the examples. 20 79078 84