EA006271B1 - Solids-stabilized water-in-oil emulsions and method for using same - Google Patents

Abstract

A method for enhancing the stability of a solids-stabilized water-in-oil emulsion by pretreating the oil prior to emulsification. The pretreatment step can be accomplished by adding dilute acid to the oil, adding a lignosulfonate additive to the oil, sulfonating the oil, thermally oxidizing the oil, thermally treating the oil in an inert environment, and combinations thereof. The emulsion can be used in enhanced oil recovery methods, including using the emulsion as a drive fluid to displace hydrocarbons in a subterranean formation, and using the emulsion as a barrier fluid for diverting flow of fluids in the formation.

Description

The present invention relates to a solids-stabilized water-in-oil emulsion used for improved recovery of crude oil. More specifically, the stability of a solids-stabilized water-in-oil emulsion is enhanced by an oil pretreatment method prior to emulsification. The pretreatment step can be performed by adding dilute acid to the oil, adding a lignosulfonate additive to the oil, sulphonating the oil, thermally treating the oil in an inert atmosphere, thermally oxidizing the oil, and combinations of these methods. The improved emulsion can be used either as a displacement solution to displace hydrocarbons from the subterranean formation, or as a fluid barrier to divert the flow of hydrocarbons into the formation.

It is well known that a significant percentage of oil remains in the subterranean formation after the cost of primary development rises to such an extent that further oil production becomes uneconomical. As a rule, only one-fifth to one-third of the original amount of oil at the place of origin is extracted during initial development. From this point of view, a number of oil recovery enhancement methods (EOR) can be used for further oil production in an economically viable way. These methods are based on the restoration of pressure or the maintenance of pressure and / or mobility of oil.

For example, a reservoir flooding is a method typically used in industry to increase the amount of oil produced from a subterranean formation. Waterfloating involves the simple injection of water into a reservoir, usually through an injection well. Water serves to displace oil from the reservoir into the production well. However, when water flooding is used to divert viscous heavy oils from the formation, the process is inefficient, since the mobility of the oil is much less than the mobility of water. Water quickly flows through the formation to the production well, bypassing most of the oil and leaving it unrecovered. For example, in Saskatchewan, Canada, the initial development of crude oil is reported to be only 2 to 8% of the original oil, presumably located in the reservoir, while flooding gives only an additional 2 to 5% of the oil that is presumed to be seam Consequently, there is a need to either increase the viscosity of the water, or to use another propellant that will not flow through the oil. Since large volumes of the displacing solution are needed, it must be inexpensive and stable under the conditions of flow formation. Oil displacement is most effective when the mobility of the displacement solution is significantly greater than the mobility of the oil, so the greatest need is the need for a method of generating a displacement solution with low mobility in an economically advantageous way.

Oil production can also be affected by extreme changes in rock permeability, for example, when high permeability selection zones between injection wells and production wells allow most of the injected propellant to be rapidly directed to production wells, leaving the oil in other areas relatively unrecovered. There is a need for a low-cost solution that can be injected into such tapping zones (either from injection wells or from production wells) to reduce the mobility of the solution, thereby diverting pressure energy to the oil displaced from adjacent zones with lower permeability.

In some formations, oil production can be reduced due to the cone formation of either gas, above, or water, below the interval where the oil is produced. Consequently, there is a need for a low-cost injection fluid that can be used to establish a horizontal layer of a low-mobility solution, in order to be used as a vertical barrier between the oil production area and the zone where coning takes place. Such a low mobility of the solution would delay the vertical coning of gas or water, while increasing oil production.

For moderately viscous oils, that is, those that have a viscosity of about 20-100 centipoise (cP) - water-soluble polymers, such as polyacrylamides or xanthan gum, are used to increase the viscosity of the water injected to drain oil from the formation. For example, polyacrylamide is added to the water used for flooding oil with a viscosity of 24 cP in the Slippy Hollow Field, Nebraska, USA. Polyacrylamide is also used to increase the viscosity of water used for flooding oil with a viscosity of 40 cP in France’s Chaterenard deposit. In this method, the polymer is dissolved in water, increasing its viscosity.

Although water-soluble polymers can be used to achieve suitable mobility in flooding for oils having a low to moderate viscosity, as a rule, they cannot be cost-effectively used to displace more viscous oils with a favorable change in mobility, i.e. 100 cp or higher. These oils are so viscous that the amount of polymer needed to achieve a suitable mobility ratio is usually not economically acceptable. In addition, as is well known to those skilled in the art, a polymer dissolved in water is often desorbed from

- 1 006271 displacing water on the rock surface in the formation, trapping there and becoming ineffective in lowering the viscosity of the water. This leads to loss of mobility control, deterioration of oil production and an increase in polymer cost. For these reasons, the use of polymer in flooding for the production of oils with viscosities in excess of 100 cP is usually technically or economically disadvantageous. Also, the performance of many polymers is adversely affected by those levels of dissolved ions, which are usually found in formations, which imposes restrictions on their use and / or effectiveness.

The use of water and oil macroemulsions is proposed as a method for producing viscous displacement solutions that can maintain effective mobility control when displacing moderately viscous oils. For example, water-in-oil and oil-in-water macroemulsions are evaluated as propellant solutions to increase oil production for viscous oils. Such emulsions are created by adding sodium hydroxide to acid crude oils from Canada and Venezuela. The emulsions are stabilized using soap films created by the saponification of acidic hydrocarbon components in crude oil using sodium hydroxide. These soap films lower the tension between the oil / water phases, acting as surfactants to stabilize the water-in-oil emulsion. It is well known, therefore, that the stability of such emulsions substantially depends on the use of sodium hydroxide (that is, caustic soda) to produce a soap film in order to reduce the tension between the oil / water phases.

Various tests on the use of caustic soda to produce emulsions demonstrate this technical capability. However, the practical application of this method for oil production is limited by the high cost of caustic soda, the high probability of adsorption of soap films on the formation rock, which leads to the gradual destruction of the emulsion, and the sensitivity of the emulsion viscosity to small changes in salinity and water content. For example, since most formations contain water with a multitude of dissolved solids, emulsions requiring fresh or distilled water often cannot be used according to their original capabilities, since such conditions of low salinity are difficult to achieve in the actual existing formation. Ionic particles can be dissolved from the rock, and the injected fresh water can be mixed with natural water having high salinity, causing destruction of the stabilized emulsion with low surface tension.

Various methods are used to selectively lower the permeability of high permeability selection zones in the method, referred to, as a rule, as profile modification. Typical agents that are injected into the reservoir to reduce the permeability of the contact zones include polymer gels or cross-linked aldehydes. Polymer gels are formed by crosslinking polymers such as polyacrylamide, xanthan, vinyl polymers or lignosulfonates. Such gels are injected into the formation, where crosslinking reactions take place, causing the gels to become relatively rigid, thus lowering the permeability to flow through the treated zones.

In most applications of these methods, the area of the formation that is being processed is a limited area near the well itself, due to the cost and reaction time of the gelling agent. After processing in place, the gels become relatively immobile. This can be a disadvantage, since the displacing solution (for example, water, when water flooding) can find some way around the fixed gel, reducing its effectiveness. Better performance could be expected if the agent for profile modification could slowly move through the formation to overlap the newly emerging selection zones, penetrating significant distances from injection or production wells.

MSKau, in US Pat. No. 5,350014, describes a method for producing heavy oil or bitumen from a formation undergoing thermal production. MSCA describes a method for producing oil or bitumen in the form of an oil-in-water emulsion by carefully maintaining the temperature profile in the locked interval above the minimum temperature, T _s . If the temperature of the oil-injected emulsion is maintained above this minimum temperature, the emulsion is able to flow through the pores of the subterranean formation to collect in the production well. MSCA describes another embodiment of this invention in which an oil-in-water emulsion is introduced into the formation and maintained at a temperature below the minimum temperature. This relatively stationary emulsion is used to form a barrier in order to overlap water-depleted sampling zones in the formation, which are created using thermal methods, including controlling the vertical cone formation of water. However, the method described by MSCA requires careful control of the temperature in the zone of the formation and, therefore, is suitable for use only in thermal extraction methods. Consequently, the method described by MSKau cannot be used for non-thermal (referred to as cold) production of heavy oils.

Recently, a new method was described that uses a new solids-stabilized emulsion for extraction with artificial changes in the physicochemical properties of oil. U.S. Patent No. 5,927,404 describes a method for using a new solid-stabilized emulsion as a displacement solution for MUH. US Patent No. 5855243 Claims a Similar Method

- 2 006271 Coll. Use of a solids-stabilized emulsion, in which the viscosity is reduced by adding gas as a propellant. US Patent No. 5,910,467 claims a new solid-stabilized emulsion described in US Patent No. 5,855,243. US Patent No. 6,066,054 describes a method for using a new solid-stabilized emulsion as a barrier to diverting solution flow in a formation.

The preparation of a solid-stabilized emulsion with optimal properties is the key to the successful use of the MOH emulsion. Two important properties are emulsion stability and its rheology.

The emulsion stabilized by solids must be stable during storage, i.e. the emulsion must be able to remain a stable emulsion without splitting water or oil when it is not subjected to disturbing influences. In addition, the emulsion must be stable under conditions of flow through porous media, that is, in an underground formation. The rheological characteristics of the emulsion are also important. For example, EORM for which this emulsion can be used include injecting the emulsion as a displacement solution or barrier fluid in a subterranean formation. Accordingly, the emulsion should have an optimal viscosity for injection and for use as either a displacement solution or a barrier fluid. When implementing the EOR, and especially when using an emulsion as a displacement solution, it is useful to reconcile the rheology of the emulsion with the rheology of the underground oil that is to be obtained. Oil displacement using a displacement solution is generally more effective when the displacement solution has a higher viscosity than the oil that is to be displaced. In addition to ensuring the stability of a solids-stabilized emulsion, the invention described here will allow the one who uses it to obtain stabilized emulsion solids with a wide range of rheological properties to match the properties of the oil to be obtained.

Since water and oil are readily available at most extraction sites, water-in-oil emulsions are a good alternative for the production of solids-stabilized emulsions for MUN. Some oils have the chemical compositions and physical properties necessary to produce stable, solid-stabilized water-in-oil emulsions with a wide range of solids. The added solids interact with the components of the oil, that is, with polar substances and with asphaltenes, which leads to an increase in their effectiveness as surfactants. This relationship is specific to the type of solids and the composition of the oil to which they are added.

However, if the oil does not contain the appropriate types and sufficient concentrations of polar and asphaltene compounds, the addition of solids is not effective because the solids are not modified adequately and appropriately to function as stabilizers of the oil-water interface. Accordingly, some oils do not form a stable solids-stabilized water-in-oil emulsion with any solids, or some oils can form stable emulsions with only some types of solids, such as silica, and cannot form such the same stable emulsions with other types of solids, for example, with clays and coal dust. The references cited earlier mean that asphaltenes or polar hydrocarbons can be added to these oils to increase their ability to form stable emulsions. See US Patent 5,855,243, column 7, lines 6-10; U.S. Patent 5,927,404 column 6, lines 44-47; US patent 5910467 column 7, lines 3-6. However, this addition is not always successful, since incompatibility between some components of the oil and the added asphaltenes, and polar substances can lead to phase separation or rejection of the added compounds. These cases limit the scope of the inventions described above in the cited US patents.

To expand their scope and to improve the solids-stabilized emulsions described in US Patents 5,927,404, 5,855,243, 5,910,467, 6,068,054, an approach is needed that appropriately modifies the composition of the oil so that it becomes sensitive to adding solids water-in-oil. " The present invention satisfies this need.

In accordance with the present invention, a method is provided for increasing the stability of a solid-stabilized water-in-oil emulsion, the method includes a step of pre-treating at least a portion of the oil before emulsification.

In one embodiment of the present invention, the oil pretreatment step involves the addition of a dilute organic or mineral acid to at least a portion of the oil, prior to emulsification.

In another embodiment of the present invention, the oil pretreatment step involves adding a lignosulfonate additive to at least a portion of the oil, prior to emulsification.

In another embodiment of the present invention, the oil pretreatment step comprises

- 3 006271 in itself sulfonation of at least part of the oil, before emulsification.

In another embodiment of the present invention, the oil pretreatment step involves the heat treatment of at least a portion of the oil, in an inert environment, before emulsification.

In another embodiment of the present invention, the oil pretreatment step involves the thermal oxidation of at least a portion of the oil, prior to emulsification.

A combination of these embodiments may also be used. The following describes a method for producing hydrocarbons from a subterranean formation, including:

a) preparation of a solids-stabilized water-in-oil emulsion with pretreated oil;

b) bringing the formation into contact with said solid-stabilized emulsion and

c) obtaining hydrocarbons from the formation using the specified solid-stabilized emulsion.

Solid-stabilized water-in-oil emulsions are described in general terms in US Pat. No. 5,927,404, US Pat. No. 5,855,243 and US Pat. No. 5,910,467. mixing with water until a water-in-oil emulsion stabilized by solids is formed.

As described in the above-mentioned US patents, solid particles must have certain physical properties. The individual particle size should be small enough to adequately cover the surface area of the internal phase of the drop. If the emulsion should be used in a porous subterranean formation, the average particle size should be smaller than the average diameter of the narrowest point in the pores of the subterranean formation. Methods for determining the average particle size are discussed in previously cited US patents. Solid particles can be spherical in shape, or non-spherical in shape. If they are spherical in shape, the solid particles preferably have an average size of about five microns or less, in diameter, more preferably about two microns or less, even more preferably about one micron or less, and most preferably 100 nanometers or less. If the solid particles are non-spherical in shape, they preferably have an average size corresponding to about 200 square microns of surface area, more preferably about twenty square microns or less, even more preferably about ten square microns or less, and most preferably one square micron or less. Solids in the formation conditions should also remain insoluble in both the oil and water phases of the emulsion.

The present invention enables the formation of stable emulsions stabilized by solids, of the “water-in-oil” type on the basis of oil, which otherwise would not have had the corresponding polar and asphaltene compounds to form such stable emulsions. The oil required to prepare a stable emulsion using the method described in US Pat. Nos. 5,927,404, 5,855,243 and 5,910,467 should contain a sufficient amount of asphaltenes, polar hydrocarbons or polar resins to stabilize the solid-oil interaction. But, as noted, some oils do not have the appropriate type or sufficient amount of these compounds in order to make it possible to form stable, solid-stabilized emulsions. As a result of applying the present invention, the oil is pretreated to facilitate the formation of a stable, solid-stabilized water-in-oil emulsion.

The oil used to produce a solids-stabilized emulsion of the present invention may be any type or composition of oil, including, but not limited to, crude oil, refined oil, mixtures of oils, chemically treated oil, or mixtures thereof. Crude oil is unrefined liquid oil.

Refined oil is a crude oil that is refined in various ways, for example, by removing sulfur. Crude oil is the preferred oil used to practice the present invention, more preferably, crude oil is obtained from the same formation where the emulsion should be used. The resulting crude oil may contain formation gas or formation water, or saline mixed with oil. It is preferable to dehydrate crude oil before processing, however, mixtures of oil, gas reservoir and / or brine can also be used in the present invention.

Preferably, formation water is used to produce the emulsion, however, fresh water can also be used, and adjust the ionic content, if necessary, to facilitate the stabilization of the emulsion under formation conditions.

Solid-stabilized water-in-oil emulsions in accordance with the present invention are suitable for use in various MIORs, generally known in the art, including but not limited to, using such an emulsion (a) as you

- 4 006271 testing solutions for displacing hydrocarbons in a subterranean formation; (B) to fill high-permeability zones, with a view to modifying the profile to improve the performance of the subsequent MOU; and (c) to form effective horizontal barriers, for example, to form a barrier to the vertical flow of water or gas, to reduce the coning of water or gas in the area of the well where oil is produced.

In tab. Table 1 provides detailed data describing the physical and chemical properties for three different types of crude oil, which are referred to as # 1 crude oil, # 2 crude oil and # 3 crude oil. Crude oil # 1 and crude oil # 3 have properties that make it possible to form a stable emulsion from water in crude oil with the addition of a solid product, as described in US Pat. water-in-oil emulsion when using the same method.

Table 1

Physical and chemical properties of crude oil

Properties Raw oil #one Raw oil # 2 Raw oil # 3 Density in degrees ANI 16.8 15.5 8.6 viscosity (cp) 4300 2400 384,616 (25 ° C, s ^-1 ) Surface tension (dyn / cm) 2.2 33.7 Sea water Asphaltenes (n-heptane) insoluble 0.1 * 0.02 2.6 13.7 (mass%) Toluene equivalent 0.0 14 20 Sulfur (mass%) 0.12 0.98 3.89 Nitrogen (mass 1%> 0.18 0.07 0.19 Distilled fractions (vol.%) 1C5 / 175 *? Easy.Ligr. - 0.6 0.2 175/250 * Avg Ligr. - 1.3 . - 250/375 * Tyazh.Ligr. 1.Θ0 3.22 1.0 375/530 ’? Kerosene 7.83 12.39 4.8 530/650 °? Easy.Gasoil 9.88 14.27 9.5 650 / 1049’РРСО 38.04 42.41 38.8 1049 °? + Ost. 42.45 25.80 45.7

- 5 006271

Fractions HPLC (mass%)

Extraction by weight 83.8 56.6 66.99 Saturated 41.7 28.51 37.67 1-ring 7.5 11.40 10.07 2-ring 7.0 9.85 12.89 3-ring 7.6 7.96 10.15 4-ring 13.0 16.06 20.93 Polar 23.2 26.23 28.29 Aromatics 17.1 20.27 22.37 Data haegasap Saturated 27.2 19.4 6.4 Aromatics 44.7 44.7 42.5 N30 19.0 30.1 29.0 Asphaltenes (n-pentane) insoluble 8.9 5.8 22.1 (massM Aromas./ Saturation. 1.64 2.3 6.66 NZO / Asphaltenes (insoluble in n- 2.13 5.19 1.33 pentane) OKCH 6.2 6.2 3.13 Determined by HPLC The distribution of acid fractions O) 250 cm 8.5 47.2 22.4 300 cm 23.9 24.5 20.7 425 cm 30.5 15.9 20.4 600 cm 20.4 7.0 14.6 750 cm 16.7 5.4 21.7 Acid aromatics 8.6 17.2 19.0 Metals (ppm) Sa 30-160 4.22 B83 La 10.4-15.5 1.51 31.2 V 0.36-0.31 69.6 4 34 Νί 9.05-13.0 65.6 102

Crude # 2 differs from # 1 and # 3 crude in the following properties:

1. Crude oil # 2 has a high tar / asphaltene ratio,

2. Crude oil # 2 has a high proportion of low molecular weight naphthenic acids and

3. Crude oil # 2 has a low content of calcium and sodium compared to crude oil # 1. These differences mean

1. surfactants, i.e., asphaltenes and acids / resins, which are key components especially important for emulsification, are not readily available for stabilizing water droplets in # 2 crude oil, and

2. Pretreatment of oil to change its physical properties and chemical composition is a possible way to increase the stability of the emulsion.

Accordingly, the present invention describes a method of pre-treating oil to increase the stability of a solid-stabilized emulsion. The following is a description of several embodiments of the present invention. As is understood by any person skilled in the art, an embodiment of the present invention can be used in combination with one or more other embodiments of the present invention, which can lead to a synergistic effect in stabilizing an emulsion stabilized by solids.

Pretreatment of oil with dilute acid

One way to pretreat an oil to increase its ability to form a stable, solids-stabilized water-in-oil emulsion is to pretreat an oil before emulsifying with a diluted mineral or organic acid. This acid pretreatment results in modifications to the oil and to the surface of the solids: (1) The major nitrogen-containing components of the oil are converted to the corresponding salts of a mineral or organic acid. These salts are more surface-active than the basic nitrogen-containing components themselves and thus contribute to improving the stability of a solid-stabilized water-in-oil emulsion; (2) If oil contains naphthenic acids, strong mineral or organic acids displace naphthenic acids from compounds containing basic nitrogen with which they form complexes, while providing high surface activity; (3) Protons from acid act by protonating charged anionic active sites on the surface of solids and, thus, modify the surface of solids to facilitate their interaction with the surface-active components of the oil (either previously existing in the oil or generated by treatment with acid) ;

- 6 006271 (4) If the oil contains calcium and naphthenic acids, mineral or organic acids can replace calcium and free naphthenic acids, which are more surface-active than calcium naphthenates.

Preparation of a solids-stabilized water-in-oil emulsion using pretreatment with dilute acid

To accomplish this embodiment of the present invention, a dilute mineral or organic acid is added to the oil before emulsification. The solids can be added to the oil either before or after the acid pretreatment, but it is preferable to add solids to the oil and then pre-treat the oil with the solids with the acid. After pretreatment with an acid and adding solids, a solid-stabilized emulsion is formed by adding water, in small aliquots or continuously, and mixing, preferably at a rate between 1000-12000 rpm, for a time sufficient to disperse the water in the form small droplets in a dispersive oil medium. It is preferable that the concentration of water in the water-off-emulsion type is from 40 to 80%, more preferably from 50 to 65%, and most preferably 60%.

Acid is added to the oil with agitation, preferably for about 5 to 10 minutes, at a temperature of from 25 to 40 ° C. The preferred acid consumption during processing is between 8 and 30,000 ppm. The diluted acid may be a mineral acid, an organic acid, a mixture of mineral acids, a mixture of organic acids, or a mixture of mineral and organic acids. Preferred mineral acids are hydrochloric and sulfuric acid. However, other mineral acids may be used, including, but not limited to, perchloric acid, phosphoric acid, and nitric acid. The preferred organic acid is acetic acid. However, other organic acids can also be used, including, but not limited to, p-toluenesulfonic, alkyltoluenesulfonic acids, mono-, di-, and trialkylphosphoric acids, mono- or dicarboxylic acids (for example, formic acid), C3-C16 carboxylic acids, succinic acid and naphthenic acid from petroleum. Naphthenic acid from petroleum may also be added to increase the surface activity of the petroleum, or petroleum containing many naphthenic acids may be mixed with oils of interest to provide enhanced surface activity.

The solids are preferably hydrophobic in nature. Hydrophobic silica, marketed under the trademark AeGOSH® K 972 (product of Zebits Chem.), Was found to be an effective material of particles for a number of different oils. Other hydrophobic (or oleophilic) solids can also be used, for example, separated and wetted bentonite clays, kaolinic clays, organophilic clays, or solid asphaltene carbon products. The preferred consumption of solids during processing is from 0.05 to 0.25 wt.% In relation to the mass of oil.

After the emulsion is prepared, its pH value can be adjusted by adding the calculated amount of a weak aqueous base solution to the emulsion for a time sufficient to raise the pH to the desired level. It is desirable to set the pH of the emulsion in the range of 5 to 7. However, setting the pH is optional, since in some cases it is desirable to inject the acid emulsion and allow the formation of the reservoir to bring the emulsion to alkalinity of the reservoir.

Ammonium hydroxide is the preferred basis for adjusting the pH. Strong bases like sodium hydroxide, potassium hydroxide and calcium oxide have a negative effect on the stability of the emulsion. One possible explanation for this effect is that strong bases tend to convert an emulsion, that is, convert a water-in-oil emulsion into an oil-in-water emulsion. Such treatment is undesirable for the purposes of the present invention.

In addition to increasing the stability of a solids-stabilized water-in-oil emulsion, an acid pretreatment method results in an emulsion with a lower viscosity compared to that obtained without an acid pretreatment. Reducing the viscosity helps to improve the properties of the emulsion during injection. Thus, it is possible to reduce the viscosity of a solids-stabilized emulsion by setting the appropriate amount of acid for pre-treatment. This ability to manipulate the viscosity of the emulsion allows the user to optimally coordinate the rheological characteristics of the emulsion with the rheological characteristics of the oil to be extracted in each specific type of EOR used. As noted in US Pat. Nos. 5,855,243 and 5,910,467, gas may also be added to further reduce the viscosity of the emulsion.

Another embodiment of the present invention is the pretreatment of a co-stream or a main batch of petroleum products with a dilute acid, as described above, and subsequently, a co-stream with the main oil stream before adding water and emulsifying. This main stream of oil is preferably raw crude oil, however

- 7 006271 can be any oil, including oil, which is processed to increase its ability to form a stable emulsion, or it is processed to optimize its rheology. If this flow is used with a cocurrent, the amounts of solids and dilute acid needed to process the co-flow are scaled according to the desired quantities in the final emulsion.

Examples

The following laboratory tests are presented to demonstrate the effectiveness of pretreatment with acid while enhancing the ability of oil to form stable, water-in-oil emulsions stabilized by solids. In these examples, crude # 2 and other crude oil, # 4 crude, are used for the experiments. None of these crude oils form stable, solids-stabilized emulsions, using the method described in US Pat. Nos. 5,927,404, 5,855,243 and 5,910,467. The physical properties for crude # 4 are given in table. 2. Tests demonstrate that pretreatment with acid enhances the ability of oils to form stable emulsion-stabilized solids. Stable emulsions are formed at pH values ranging from 1.2 to 7.0, and up to 72% by weight of water included in these emulsions.

table 2

Physical and chemical properties of crude oil

Properties

Crude oil 44

Density in degrees ANI

Viscosity (cp) (25 ° С, 1 s - ¹ )

Asphaltenes (insoluble in n-heptane)

Asphaltenes (insoluble in cyclohexane) (mass%)

Toluene equivalent

Sulfur (mass%)

Nitrogen (mass%)

17.2

8500

0.1

3.25

0.0

0.12

0.26

Fractions after distillation (volumes.%)

1C5 / 175 °? Easy.Ligroin - 175/250 °? Mid. Lygroin - 250/375 °? Heavy. Lygroin 0.03 375/530 °? Kerosene 6.09 530/650 °? Easy.Gasoil 8.67 650 / 1049’GRSO 36.48 1049’G + Ost. 48.73 Fractions HPLC (mass) Extract the masses. ·, 84.4 Saturated ' 43.3 1-ring 7.6 2-ring 6.8 3-ring co 7.5 4-ring 12.6 Polar 22.2 Aromatics 15.6

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Data

Saturated 35.4 Aromatics 39.8 N30 15.4 Asphaltene 9.4 Aroma. / Saturated 1.13 MLO / Asf. 1.64 okch 5.4 Determined by HPLC Acid Fraction Distribution (%) ** 250-300 cm 15.4 300-425 cm 14.7 425-600 cm 27.1 600-750 cm 21.5 750+ cm 21.3 Acid aromatics 8.6 Metals (ppm). Sa 400-900 Nah 7.7-15.3 V 0.2-0.9 ΝΪ 11.2-17.9 Mp 13.1 TO 181-935 Md 1.1-25.2

In a typical experiment, a dilute aqueous solution of a mineral or organic acid (concentration from 0.35 to 35%) is added during processing to oil at a rate of from 8 to 30,000 ppm. and mix thoroughly for 10 minutes using a HUappd mixer or homogenizer 811 tubecop. Solids are added after mixing. After pre-treatment with an acid, water is added to the oil, in small aliquots and with stirring, which results in a water-in-oil emulsion stabilized with solids.

Emulsions prepared by pre-treating the oil with a dilute aqueous acid solution are subjected to the following tests:

1. Stability during storage at 25 ° C for 48 h

2. Optical microscopy and / or nuclear magnetic resonance (NMR) for determining the size / size distribution of water droplets

3. Microcentrifugation test - emulsion stability by centrifuging (as described in Appendix 1)

4. Emulsion stability - flow through a layer of sand (this micropercolation test is given in Appendix 1)

5. Rheology of the emulsion using a VgodokieI viscometer (cone (# 51) and plate configuration) at 60 ° C and with a shift in the range from 1.92 to 384 s ^-1 .

The test results for crude oil # 2 using pre-treatment with hydrochloric acid and sulfuric acid are presented in table. 3-6. The results for crude oil # 4, using pretreatment with sulfuric acid and acetic acid, are presented in table. 7

Example 1. Pretreatment of crude # 2 with hydrochloric acid

Crude oil # 2 is used to prepare a 60/40 water-in-oil emulsion with 0.15 wt.% Hydrophobic silica, Lokoy® B 972, but without prior acid treatment. As shown in the table. 3, the emulsion stabilized by solids is stable during storage, however, the emulsion is unstable during microcentrifugation and micropercolation tests, which is proved by a large stratification of water (saline solution) (% Lo). Dispersed water droplets are distributed in size from 1 to 10 microns in diameter.

Then, the effect of pretreatment with hydrochloric acid on the emulsion stabilized with solids is examined. Crude oil # 2 is used to make a water-in-oil emulsion 60/40 stabilized with solids. However, in this example, the oil is pretreated with hydrochloric acid at a rate of 38,000 ppm, followed by the addition of 0.15 wt.% Of Lung® B 972. Dispersed water droplets are distributed in size from 1 to 2 microns in diameter. As shown in the table. 3, pretreatment with hydrochloric acid leads to increased stability during microcentrifugation and micropercolation tests, and, consequently, increases the stability of the emulsion, as indicated by the decrease in the amount of stratified water in both tests.

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Table 3. Pretreatment of crude oil # 2 with hydrochloric acid Pre-treatment procedure: 38,000 ppm HC1 is added to crude oil and mixed with

using the mixer napid for 10 min. HC1 Raw Solid Resist-Diameter Micro- Micro- oil/ the particles chivost drops centrifugal percolation Water (Aegovi®) at giro K972) stored nii Milliond. (mass%) (2 days) (microns) (% B) (% B) 0 40/60 0.15 Sustain 10-1 18 35 38,000 40/60 0.0 Sustain 10-1 0 20 38,000 40/60 0.15 Sustain 2-1 0 five 38,000 33/66 0.15 Sustain 2-1 0 four

LOBO: testing the separation of salt solution (water) during microcentrifugation using Ottawa sand

Example 2. Pretreatment of crude oil # 2 with sulfuric acid

Crude oil # 2 is used to produce a 60/40 emulsion of a water-in-oil type containing 0.15% by weight of Letozy® K 972, without prior acid treatment. As shown in the table. 4, this emulsion, although stable during storage, is unstable during microcentrifugation and micropercolation tests. Dispersed water droplets are distributed in size from 1 to 10 microns in diameter.

A 60/40 water-in-crude emulsion is prepared by pretreatment with sulfuric acid of crude oil # 2, but without the addition of solids. Sulfuric acid is added at a rate of 8750 ppm, relative to the mass of oil. The resulting emulsion is very unstable when microcentrifuging and micropercolation tests.

A 60/40 emulsion of the “water in crude oil” type was prepared by pretreating crude oil # 2 with sulfuric acid at a rate of 8750 ppm, relative to the mass of oil, together with 0.15 wt.% Of Letoty® K 972. How shown in Table. 4, this procedure results in a stable emulsion. Dispersed water droplets are distributed in size from 1 to 2 microns in diameter. The pH of the resulting emulsion is 1.2. Pretreatment of the oil with sulfuric acid results in improved stability during microcentrifugation and micropercolation tests, as shown by a decrease in the amount of stratified water or saline solution (% bo).

A water-in-crude emulsion 60/40 is prepared by pre-treating crude oil # 2 with sulfuric acid in proportion when treating 8750 ppm, relative to the weight of oil, followed by the addition of 0.15% by weight of hydrophilic silica , Летозй® 300 (product IeSizza Sogr.). This procedure does not ensure the stability of a water-in-oil emulsion, since the emulsion has an increased amount of stratified water during microcentrifugation and micropercolation tests. The low performance of hydrophilic silica, Letojay® 300, means that hydrophobic solids are usually necessary to form a stable emulsion using pretreatment with dilute acid.

Table 4. Sulfuric Acid Pretreatment of Crude Oil # 2

Pretreatment procedure: 8750 ppm H ₂ §0 _{4 is} added to the crude oil and mixed using the No. Atsd mixer for 10 minutes.

H ₂ AOR ₄ Crude Oil / Water Particulate Matter (AEGOGI®) B972 Storage stability Diameter drops Kyccentrifuging Perforation ppm (cakes 3) (2 days) (kikron) (% B) (% B) 0 40/60 0.15 steady 10-1 18 35 8750 40/60 0.0 steady 10-1 20 91 8750 40/60 0.15 steady 2-1 0 0 8750 33/66 0.15 steady 2-1 one 2 8750 40/60 0.10 steady 2-1 0 0

40/60

2-1 o

8750

0.075 steady

LOBO: separation of salt solution (water) when testing micropercolation tests using Ottawa sand

- 10 006271

Example 3. The increase in water content in pre-treated sulfuric acid crude oil # 2

As shown in the table. 5, about 70% by weight of water can be included in a water-in-oil emulsion finally stabilized with solids prepared by pretreatment with diluted # 2 sulfuric acid. Over about 72 wt.% Of water, an increase in the size of water droplets is observed. Over about 80% by weight of water, the emulsion phase is stratified into an emulsion and an excess of water. Rheological measurements show that the viscosity of the emulsion increases with increasing water content in the emulsion.

Table 5. The effect of increasing the water content in the emulsion of crude oil # 2, pre-treated with sulfuric acid

ΐ water Storage stability Iterocentrifugation (% L0) Ικρο percation (% B) Diameter of a drop (chichron) Viscosity 35 = C, 9.6 s * ¹ 60 Yes 0 0 <2 15,400 65.5 Yes 0 0 <2 15.888 69.2 la 0 0 <2 20,152 71.4 Yes 0 0 <2 27, Θ52 75 Yes 0 five <2-5 26,214 80 Yes 0 ten <2-10 85 Phase stratified on emulsion and excess oxen

Note:

Solids: 0.15 wt.% Of silicon oxide ЛогоШ® В 972

LOBO: separation of salt solution (water) in micropercolation tests using Ottawa sand

The proportion of sulfuric acid during processing: 8750 ppm

Example 4. The decrease in the content of solids in the emulsion 60/40 type "water in crude oil # 2"

As shown in the table. 6, a stable emulsion is prepared from hydrophobic silica, LegoSH® B 972, at a concentration ranging from 0.025 to 0.15 wt.%. The viscosity of the emulsion decreases with decreasing solids content.

Table 6. The effect of lowering the solids content in the emulsion of crude oil # 2, pre-treated with sulfuric acid

Solid Resilience Micro- Micro- Diameter Viscosity the particles when stored centrifugal rcolation drops 35 ° C (AerozI® giro 9.6 seconds' ¹ B.972) (% B) (% B) (micron) 0.15 Yes 0 0 <2 15400 0.1 Yes 0 0 <2 7864 0.075 Yes 0 0 <2 7536 0, 05 Yes 0 0 <2 8192 0.025 Yes 0 0 <2-5 6389

Note:

Oil / water ratio = 40/60

LOBO: separation of salt solution (water) in a micropercolation test using Ottawa sand

The proportion of sulfuric acid during processing: 8750 ppm

Example 5. Pretreatment of crude oil # 4 with sulfuric and acetic acids

Similar to the results obtained with crude oil # 2, pre-treatment with acid of crude oil # 4 results in increased stability of the resulting solid-stabilized emulsions. As the data table. 7, pretreatment of crude oil # 4 with sulfuric acid at a rate of 8750 ppm, relative to the weight of the oil, followed by the addition of 0.15 wt.% LegoSh® B 972, results in a stable emulsion.

Pretreatment of crude oil # 4 with acetic acid at a processing flow rate of 24,500 ppm, followed by the addition of 0.15% by weight of LegoSh® B 972, also results in a stable

- 11 006271 by a solid-stabilized 60/40 water-in-oil emulsion. The viscosity of the emulsion treated with acetic acid, as observed, is lower than that of the analogue treated only with sulfuric acid, which suggests that the nature of the acidifying agent may affect the viscosity of the emulsion.

Table 7. Pretreatment of crude # 4 acid

Kypota ^ Solid StaSip- M4KrO- Mzhro Diameter Elm- substances ness price trifu percolation drops bone (AgoaP® at giro 60 ° C Г® 72) storage 9, 6 s (9) (% B) (ykron) Νοηβ 0.15 Yes 0 9 <2-10 5240 Sulfuric 0.15 Yes 0 3.5 <2 2948 Acetic 0.15 Yes 0 0 <2 4095

Note:

Viscosity of crude oil # 4 = 164 cP at 60 ° C, 9.6 s ^-1

LOBO: separation of salt solution (water) in the micropercolation test using Ottawa sand

Sulfuric acid consumption during processing: 8750 ppm

Acetic acid consumption during processing: 24500 ppm

Example 6. The establishment of pH in an emulsion treated with acid

Two approaches are described for obtaining a water-in-oil emulsion with a preferred pH value ranging from 5 to 7:

a) Neutralization of the obtained oil emulsion, treated with acid, with the corresponding amount of base:

Neutralization of the oil, pre-treated with acid, ammonium hydroxide before or after the addition of water, is a preferred way to increase the pH of the emulsion. In contrast, neutralization of the emulsion with sodium hydroxide or calcium oxide leads to destabilization of the emulsion. As noted earlier, a possible explanation for this effect is that ammonium hydroxide is a weaker base than sodium hydroxide or calcium oxide. A strong base tends to invert the emulsion, that is, convert the water-in-oil emulsion into an oil-in-water emulsion. Such treatment is undesirable for the method of the present invention.

B) Reduction in acid consumption during processing to levels sufficient to neutralize the main components of the oil:

Another approach to obtaining an emulsion with a pH value in the range of 5-7 is to reduce the acid consumption during processing to levels sufficient to neutralize the main components of the oil. The acids used in this experiment are hydrochloric, sulfuric, and acetic acid. For crude # 2 and crude # 4, it was found that the acid consumption during processing was 8.7 ppm. is adequate to obtain the required emulsion when the pH value is from 5.5 to 6.5. The list of properties of the emulsion for crude oil # 4, pre-treated 8.75 ppm sulfuric acid are given in table. eight.

Table 8.

List of emulsion properties of a water-in-oil type emulsion prepared by pre-treating # 4 crude oil with 8.75 ppm sulfuric acid

Emulsion properties:

Raw oil

Water

Hydrophobic silica (B 972) Size of water droplets (Medium diameter) Stability during storage Stability during centrifugation

Percolation stability through the sand of Wegs 16% of water stratification Viscosity 3700 сП at 60 ° С, 9.6 s ^-1

PH value 6.2

Example 8. Adding gas to lower the viscosity of a water-in-oil emulsion

Adding CO ₂ to the pre-treated oil emulsion is effective at lowering the viscosity of the emulsion. Experiments are conducted on an emulsion prepared from crude oil # 2, pre-treated 8700 ppm. sulfuric acid and 0.15 wt.% AegoSh® B 972.

The results are shown in Table. 9, it is proved that at a pressure of 500 psi and at an appropriate wt.% Wt.%

0.15 wt.% Microns> 2 weeks

0% water separation

- The temperature of the reservoir is feasible to reduce the viscosity of the emulsion using gaseous carbon dioxide. Other gases like ethane and propane can also lower the viscosity of the emulsion.

Table 9. The effect of CO ₂ on a pre-treated acid stabilized solids emulsion of the type water in crude oil

Tamper emulsion. <° C> Viscosity <cP) at 10 sec ^-1

Viscosity (cp) at 10 sec ^-1

Without CO _g with 500 psi.

inch CO;

Crude oil # 2 35 11213 1671

Pretreatment of oil using sulfonation chemistry

Another way to pretreat oil in order to increase the ability to form a water-in-oil emulsion stabilized by solids is to pretreat oil before emulsification. The sulfonation procedure can lead to chemical modification of the oil and the surface of solids. For example, (1) the sulfonation procedure described here results in sulfur-functionalized oil components, and these components are surface-active and contribute to the formation of a water-out-of-oil emulsion; (2) if naphthenic acids are present in the oil, sulfonation will markedly increase their acidity and activity at the interface using chemically attached sulphonate groups; (3) sulfonate sulfonating agent groups should also functionalize the surface of solids, and thus modify the surface of solids to improve their interaction with the surface-active components of the oil (previously existing in the oil or generated during the sulfonation reaction); and (4) the basic nitrogen-containing components of the oil are converted to the corresponding sulfonates and / or sulfate salts. These salts are more surface-active than the basic nitrogen-containing components themselves, and thus contribute to improving the stability of a solid-stabilized water-out-oil emulsion.

The procedure for the preparation of a stabilized solids emulsion of the type "water-out" using the chemistry of sulfonation

The oil is pretreated with a sulphurizing agent, either before or after the addition of solid particles, and then water is added. Water is added in small aliquots or continuously, and the mixture is subjected to shear mixing, preferably between 1000-12000 rpm, for a time sufficient to disperse the water as small droplets in the dispersed oil medium, usually between 0, 5-24 hours. Preferably, the concentration of water in a water-in-oil emulsion is from 40 to 80%, more preferably from 50 to 65%, and most preferably 60%.

The preferred sulfonating agent is concentrated sulfuric acid. The preferred proportion of sulfuric acid when treated with respect to oil is between 0.5-5% by weight, more preferably between 1 and 3% by weight, relative to the weight of oil. Other sulphurizing agents may be used alone or in combination with other agents. Such sulfonating agents are generally described in E.E. Sps. Zygopabop aib Pe1a1eb Beasboik, 1p1sg5s1spss. You are here, (1965). Other common sulfating agents that may be suitable for use in the present invention include fuming sulfuric acid, sulfur trioxide, alkali disulfate, pyrosulfate, chlorosulfonic acid, and mixtures of manganese dioxide and sulfuric acid. The temperature of the process during sulfonation may be from -20 to 300 ° C, preferably from 10 to 100 ° C, and more preferably from 20 to 60 ° C. The reaction can be accelerated using various methods, including, without limitation, thermal, mechanical, acoustic, electromagnetic, vibrational methods, mixing and spraying.

As is understood by any person skilled in the art, the amount of sulphating agent suitable for use in the present invention can be set according to the nature of the sulphating agent and the content of asphaltenes and tar in oil. Oil containing a large amount of asphaltenes may need less sulfonation than that which contains a small amount of asphaltenes. The amount of asphaltenes in the oil can be determined using standard techniques known in the art. The range of sulfonation can be from 0.01 to 40%, preferably from 0.1 to 10%, and more preferably from 0.1 to 2% by weight of solid particles.

One way to practice this embodiment of the present invention in practice is to first sulphate the oil, and then add solids. However, the addition of solid particles to the oil and the sulfonation of the mixture is preferred. Solids can be silica, clays, hydrophobic particles, and / or non-functionalized and functionalized bitumens and their respective mixtures. Preferred consumption during processing

- 13 006271 solids in relation to oil is from 0.05 to 2.0 wt.% Solids in relation to the mass of oil.

The hydrophobic particles for this embodiment of the present invention are any particles where the hydrophobicity is greater than 50% and less than 99.9%, and the hydrophilic or polar residues are less than 40% and more than 0.1% by weight of particles . Hydrophilic or polar residues may form as a result of the sulfonation of a combination of hydrophobic particles and oil. Examples of hydrophobic particles suitable for use in the present invention include, without limitation, filosilicates, lignin, lignite, coal, hölsonite, silica, dolamite, metal oxides, layered oxides, and quaternary onium exchange filosilicates.

Functionalized and non-functionalized bitumens are also effective solids for the preparation of pre-treated sulfonate solids-stabilized water-in-oil emulsions. In particular, phosphonated bitumen, which is immersed in oil for quite a long time, preferably within 24 hours, at 55 ° C, is an effective solid. Bitumens can be used in their natural state or can be functionalized, or be functionalized with the sulfating agents of the present invention. Non-limiting examples of functional residues are sulfonic acid, phosphoric acid, carboxylic acid, nitric acid or their salts and hydrophilic groups.

After the emulsion is prepared, the pH value of the emulsion can be set in the manner described previously in accordance with the first embodiment of the present invention related to the pretreatment of oil with dilute acid. As previously described, a calculated amount of a weak base is added to the emulsion, and the emulsion is mixed with a shift for a time sufficient to raise its pH to the desired level, preferably within 57. The set pH is optional, because in some cases it is desirable to pump acid emulsion and allow the formation reservoir itself to bring the emulsion to alkalinity of the reservoir. The viscosity of the emulsion during sulfonation increases. However, the viscosity of the emulsion is not a linear function of the addition of the sulfonating agent. The viscosity of the emulsion increases with reduced consumption as a function of sulfonation. Consequently, the user can obtain increasingly stable solids-stabilized emulsions by sulfonation, while maintaining the desired rheological properties. In addition, the viscosity of the emulsion can also be reduced by adding gas, as described in US Patents 5,855,243 and 5,910,467.

Although it is possible to sulfonate the entire amount of oil required to produce such an emulsion, it is also possible to sulfonate the co-flow or the main batch of petroleum products, and subsequently, mix the co-flow with the main oil flow before adding water and emulsifying. This main stream of oil is preferably crude crude, however, it can be any oil, including oil that is processed to improve its ability to form a stable emulsion or processed to optimize its rheology. If this method is used for a co-stream, the amounts of solids and sulphating agent required to process the co-stream are respectively increased to obtain the desired amounts in the final emulsion.

Examples

This embodiment of the present invention is demonstrated using crude oil # 2 and other crude oil, crude oil # 5, since these oils do not form stable, solid-stabilized emulsions using the method described in US Pat. Nos. 5,927,404, 5,855,243 and 5,910,467. However, as shown below through experiments, pretreated oil using sulfonation chemistry enhances the ability of oil to form stable, solids-stabilized water-in-oil emulsions.

In a typical experiment, solids are added to the oil and then sulfurized. Concentrated sulfuric acid is used as a sulphating agent, and is added during processing at a rate of 3 parts of acid per 100 parts of oil. This mixture is stirred on a heating plate connected to a magnetic stirrer, at a temperature of about 50 ° C. Then, water is added to the oil with stirring in small aliquots, which results in the formation of a water-in-oil emulsion stabilized by solids.

These emulsions are subjected to the following tests:

1. Stability during storage at 25 ° C for 48 h

2. Optical microscopy and NMR for determining the size / size distribution of water droplets

3. Stability during centrifugation (described in Appendix 1)

4. Emulsion stability: sand flowing through a layer (micropercolation test procedure is given in Appendix 1)

Example 1

Crude oil # 2 and solids are co-sulphurised as follows: 12 g (g) crude

- 14 006271 oil # 2 and solid particles containing 0.06 g of 2-methylbenzyl tallow intercalated monomorillonite (Otrano1to1® 1665; product from C1 Ctr) and 0.12 g of raw bitumen А8Р-97-021 В111ίη§8 (product from Exhop ) combined in a glass container. The mixture was stirred at 50 ° C for 72 hours. Sulfuric acid was added at a rate of 3 parts of acid per 100 parts of oil, and the mixture was stirred at 50 ° C for 24 hours.

Then, the sulfonated oil and solids are combined with 18 g of synthetic salt solution (contains 9.4 g of sodium chloride, 3.3 g of CaCl ₂ (calcium chloride) · 2H ₂ O, 0.48 g of MdCl ₂ (magnesium chloride) • 6H ₂ O and 0.16 g of potassium chloride per liter of distilled water). Saline is added dropwise over 30 minutes at 5,000 rpm. The emulsion thus obtained is stirred for an additional 15 minutes at a rotation speed of 7500 rpm.

The solids-stabilized oil external emulsion is tested for stability using a micropercolation test, as described in Appendix 1. The sand used in this test is Ottawa sand, and the oil is centrifuged together with sand for one minute at 50 ° C. Dual samples exhibit 0 and 3.2% separation of the salt solution (% LOB) after pumping through the sand layer. Optical microscopy shows a droplet diameter smaller than 20 microns, with most particles having a diameter smaller than 7 microns.

Example 2

Crude oil # 5 and oxidized bitumen (OX-97-29-180; product from 1trepa Oi) are sulfurized together according to the procedure described earlier. However, in this example, oil and bitumen are mixed together for 2.5 hours at 50 ° C before adding the sulphating agent, sulfuric acid at a rate of 3 parts of sulfuric acid per 100 parts of oil.

The sulphonated product is mixed with a synthetic saline solution as described. The resulting mixture has a 60% aqueous phase content. This oil external emulsion has a pH value of 1.6, and then it is neutralized to a pH of 7.3 by adding ammonium hydroxide, and then it is re-mixed using an Aggo \ y 850 mixer at a rotation speed of 350 rpm for 15 minutes. The pH value of the emulsion approaches the pH value for crude # 5. This emulsion demonstrates the absence of saline separation in the micropercolation test. The droplet diameters are smaller than 10 microns, with most water droplets smaller than 5 microns. Rheological tests using conical and plate viscometers demonstrate high emulsion stability, that is, viscosity as a function of the number of cycles remains essentially constant.

Example 3

The same experiment was carried out using crude oil # 5 and 2-methylbenzyl talc intercalated monomontrilonite (Otrando1o1® 1665, product from C1t Regulgogtase Mtek, Cagtier8U111e CA) in the form of a powder from solid particles. Crude oil and solids are combined and stirred for 4 hours at 50 ° C before adding sulfuric acid. In another method, this mixture is sulphurized in accordance with the methods described above.

The synthetic saline solution described above is added to the oil and solids, and mixed as described previously. The pH of the resulting emulsion is also set at 7.5 by adding ammonium hydroxide and stirring using an Aggote 850® mixer at a rotation speed of 350 rpm for 15 minutes. The oil outer emulsion has a droplet diameter of the aqueous phase smaller than 10 microns, most of the salt solution drops are smaller than 5 microns. No separation of the salt solution was detected in the micropercolation test described in Appendix 1 using Vegea sand.

Example 4

Crude oil # 2 and untreated bitumen (A8P-97-021, product from 1mt 1 Oh Sotrotabop, Sapaba) are subjected to joint sulfonation. Oil and bitumen is stirred at 50 ° C for 72 hours before adding sulfuric acid. Alternatively, sulfonation is carried out using the steps described above.

A solids-stabilized water-in-oil emulsion is obtained by adding the synthetic saline solution described above and is mixed according to the procedures described above. However, in this example, the pH of the emulsion is not set, but remains acidic. Optical microscopy shows a droplet diameter of the aqueous phase smaller than 10 microns, with most droplets smaller than 5 microns. No separation of the salt solution was detected in the micropercolation test described in Appendix 1 using Ottawa sand.

Example 5

g of crude oil # 2 and 0.06 g of hydrophobic particles, ^ O1A81aGb-050-MN-0010® (methylalcoxysilane coated calcium metasilicate, having a 1 wt.% coating of calcium metasilicate - a product from Ipyeb M1peg1 Sogr.), is subjected to joint sulfonation, as described earlier. In this example, the oil and particles are stirred at 50 ° C for 2.5 hours before adding sulfuric acid.

A solids-stabilized water-in-oil emulsion is obtained by the procedures described above, and the pH of the emulsion is set to 6.1 by the addition of hydroxide.

- 00 006271 ammonium. Optical microscopy shows the diameter of the droplets of the aqueous phase, less than 5 microns. The result of the micropercolation test does not demonstrate any separation of the salt solution after the injection of the emulsion. Rheological tests demonstrate the absence of significant changes in viscosity with an increase in the number of cycles, which indicates a high shear stability.

Example 6

A solids-stabilized water-in-oil emulsion is formed using crude oil # 2 and phosphonated bitumen (Keto 97-149®, product from 1mt 1,011 Sogrogayoi, Sapaba) in the form of solid particles. Oil and solids are added together, and before adding sulfuric acid, the mixture is stirred at 50 ° C for 48 hours, as described above.

The resulting water-in-oil emulsion demonstrates, using optical microscopy, the diameter of the aqueous phase droplets smaller than 5 microns. Micropercolation test indicates the absence of salt solution separation. Rheological tests indicate high emulsion stability, that is, viscosity as a function of the number of cycles remains essentially constant.

Pretreatment of oil using lignosulfonate additives

Another way to pretreat oil to increase its ability to form a stable solids-stabilized water-in-oil emulsion is to add a lignosulfonate additive to the oil before preparing the emulsion. Lignosulfonic acid salts (eg, sodium, potassium, ammonium, calcium, and the like) are surface-active in nature, and when they are added to an oil / water mixture, they will tend to aggregate at the oil / water interface. This effect increases the interfacial activity of the oil and increases the stability of the emulsion.

Preparation treated with lignosulfonate stabilized emulsion solids

In order to practice this embodiment of the present invention, lignosulfonate additives are added to the oil, before or after the addition of solid particles, but before emulsification. For the sake of simplicity and clarity, the present description will mention the addition to the oil of only one type of lignosulfonate additive. However, it should be understood that a combination of various lignosulfonate additives can be used in the practice of this embodiment of the present invention. Lignosulfonate additives are added when processing at a rate between 200-20000 ppm. in relation to the mass of oil, more preferably 500-5000 ppm, and even more preferably 500-1000 ppm, for 5-10 minutes, at 25-40 ° C. The solids are added either before or after the addition of the lignosulfonate additive, followed by the addition of water, in small aliquots or continuously. Then the mixture is subjected to mixing with a shift at a speed in the range between 1000-12000 rpm, for a time sufficient to disperse the water in the form of small drops in a dispersive oil medium. Preferably, the concentration of water in a water-in-oil emulsion is from 40 to 80%, more preferably from 50 to 65%, and most preferably 60%.

During mixing, the temperature of the emulsion rises above the ambient temperature (25 ° C). Temperature control of the emulsion during mixing is not critical, however, a temperature rise between 40 and 75 ° C is preferred.

Both oil-soluble and water-soluble lignosulfonate additives can be used to increase the stability of a water-in-oil emulsion stabilized by solids. Non-limiting examples of water-soluble lignosulfonates are the sulfonate salts of monovalent cations like sodium, potassium, and ammonium. Non-limiting examples of oil-soluble lignosulfonates are the sulfonate salts of divalent cations like calcium, magnesium and iron. The use of water-soluble additives is preferred, due to the ease of delivery and the use of water as a solvent for delivery. A preferred water soluble lignosulfonate additive is ammonium lignosulfonate. In addition, mixtures of lignosulfonate salts can be used to obtain the same or stronger effect.

Hydrophobic silica, Atosh® L 972, has been found to be an effective solid product for several types of oil. The present invention is demonstrated using AetoSh® L-972 with a consumption rate of 0.15% by weight, relative to the mass of oil. Other hydrophobic solids can also be used, like bentonite clays, organophilic clays or solid carbonaceous asphaltene products that are separated and moistened with oil. Hydrophilic solids may also be used. The preferred consumption of solids during processing is from 0.05 to 0.25 wt.% In relation to the mass of oil.

You can first pretreat the oil with a lignosulfonate additive, and then add solids. However, it is preferable to first add solids to the oil, and then add a lignosulfonate additive to the mixture. Optionally, solids can be first treated with lignosulfonate additive, treated solids can be added to

- 16 006271 oil before adding water and mixing. As stated above, either water-soluble or oil-soluble lignosulfonate additives can be used to pretreat solids. The choice as to which type of lignosulfonate additive to use depends on the type of solid product to be processed. As a rule, the hydrophobic solid product is treated with a water-soluble lignosulfonate additive, and the hydrophilic solid product is an oil-soluble lignosulfonate additive. Such a choice makes it possible to impart an appropriate hydrophilic and hydrophobic character to the corresponding modification of the surface of solids.

Although lignosulfonates pretreatment of the entire amount of oil required to obtain the desired emulsion, it is possible with this embodiment of the present invention, it is also possible to pretreat the slug flow or the main batch of oil products, and subsequently, mix the slug flow with the main oil flow before adding water and emulsification. This main stream of oil is preferably crude crude, however, it can be any oil, including oil that is processed to increase its ability to form a stable emulsion or processed to optimize its rheology. If this flow wrap method is used, the amounts of solids and lignosulfonate additives required to process the wake flow are increased accordingly to obtain the desired amounts in the final emulsion.

This embodiment of the present invention can be used in combination with a method of pretreatment of oil with a dilute mineral or organic acid to further improve the surface-active properties of the oil. The addition of dilute acid may occur before or after the addition of lignosulfonate, since the order of addition of the acid and the lignosulfonate additive is uncritical. However, the addition of acid and the addition of lignosulfonate must occur before emulsification. If the addition of lignosulfonate is combined with the addition of acid, the pH of the emulsion can be adjusted by adding the calculated amount of a weak base, as described earlier, to increase the pH to the desired level, preferably to a pH in the range 5-7.

Examples

The present invention is demonstrated in crude oil # 4 and crude oil # 6, because these crude oils do not form stable, solid-stabilized emulsions using the method described in US Patents 5,927,404, 5,855,243 and 5,910,467. Crude oil # 6 is a low viscosity crude oil . In a typical experiment, a lignosulfonate additive is added to the oil during processing at a flow rate of from 0.05 to 0.5% by weight relative to the weight of oil and mixed for 10 minutes using a δίΙνβΓδοη homogenizer at a rotation speed of about 1000 to 12000 rpm . Ammonium lignosulfonate and calcium lignosulfonate are used as lignosulfonate additives in these examples. The solids, either separated bentonite or hydrophilic silica, are added in an amount of 0.15% by weight relative to the weight of the oil, followed by further mixing. Water is then added to the mixture in small aliquots, followed by stirring, to obtain a water-in-oil emulsion stabilized with solids.

Emulsions prepared using the above methods are subjected to the following tests:

1. Stability during storage at 25 ° C for 48 h

2. Optical microscopy and NMR to determine the size / size distribution of water droplets.

3. Stability during centrifugation (see Appendix 1)

4. Emulsion stability: sand flowed through a layer (details of the micropercolation test procedure are given in Appendix 1)

5. Emulsion rheology using the VgookieI® viscometer (cone (# 51) and plate configuration) at 60 ° C, with a shift in the range from 1.92 to 384 s ^-1 .

Example 1. Crude oil # 4

The test results for crude oil # 4, pre-treated with ammonium lignosulfonate or calcium lignosulfonate, are presented in table. 10. Solids stabilized water-in-oil emulsion of 60/40 is formed using pretreatment with lignosulfonate at 0.5 wt.% And hydrophobic silica, LegoSh® B 972, at 0.15 wt.%.

As indicated in the table. 10, pretreatment with lignosulfonate increases the stability of the emulsions, as evidenced by lowering the salt solution stratification (% Lo) during micropercolation tests, as compared to a water-in-oil emulsion untreated with solids.

- 17 006271

Table 10. Effect of 0.5 wt.% Ammonium and calcium lignosulphonate on a solid-stabilized water-in-oil emulsion obtained from crude oil # 4

Lignosulfonate Micropercolation Emulsion viscosity additive stability (% b) (cp) at 60 ° C No ammonium 38 2743 lignosulfonate four 2620 Calcium lignosulfonate eight 2620

Example 2. Crude oil # 6

A 60/40 solids stabilized water-in-oil emulsion is prepared using Crude # 6 and 0.15 wt.% Hydrophobic silica, Letoty® B 972. No pretreatment with lignosulfonate is used. The emulsion is unstable, with 40% water splitting during micropercolation tests. The viscosity of the emulsion at 60 ° C and 9.6 s ^-1 is 983 cP.

However, when the same 60/40 water-in-oil emulsion is obtained using crude oil # 6, pretreated with 0.5 wt.% Ammonium lignosulfonate, the stability of the emulsion increases, and the water separation decreases to 17%. The viscosity of the emulsion at 60 ° C and 9.6 s ^-1 slightly increases to 1064 cP.

Example 3. A mixture of crude oil 50/50 using crude oil # 4 and crude oil # 6

A solid solids stabilized water-in-oil emulsion of 60/40 is prepared using a mixture of 50% crude oil # 4 and 50% crude oil # 6. The solids are hydrophobic silica, Letoty® B 972, in an amount of 0.15% by weight relative to the mass of oil. Untreated, solid-stabilized emulsion has a water separation of 32%. The viscosity for this emulsion, at 60 ° C and 9.6 s ^-1 , is 2129 cP.

The same emulsion is prepared from a mixture of 50/50 crude oil # 4 / crude oil # 6, which is pre-treated with 0.5 wt.% Ammonium lignosulfonate. The solids-stabilized emulsion-treated lignosulfonate shows an increase in stability, as evidenced by a decrease in the salt solution stratification to 5%. The viscosity of the treated emulsion at 60 ° C and 9.6 s ^-1 remains at 2129 cP. The data indicates that the treatment increases the stability of the emulsion without changing its viscosity.

Pretreatment of oil using thermal air oxidation

Another embodiment of pretreatment that can be used to increase the stability of a solid-stabilized water-in-oil emulsion is the thermal treatment of oil, either before or after the addition of solids, in the presence of air or oxygen.

Heat treatment of an oil or a mixture of oil and solids in the presence of air or oxygen causes various reactions that take place in the oil and on the surface of the solids. (1) Aromatic components of petroleum, which have benzyl carbons, and those that have condensed oxidizable rings, include, but are not limited to, naphthalene and anthracene, oxidized to the corresponding acids, ketone or quinone products. The organo-and organo-nitrogen compounds present are oxidized to sulfoxides and nitrogen oxides. Oxygenated compounds are more surface-active than the aromatic components themselves, and are strongly absorbed on the surface of solid particles in order to increase the stability of a solid-stabilized water-in-oil emulsion. (2) If naphthenic acids are present in the form of salts of divalent cations like calcium, oxidation in air can convert these salts into naphthenic acids and the corresponding metal oxide, for example, calcium oxide. Free naphthenic acid can adsorb onto solid surfaces and also increase the stability of a water-in-oil emulsion stabilized by solids. (3) Heat treatment with air blowing dehydrates solid particles and thus modifies the surface of solids in order to improve their interaction with the surface-active components of the oil (previously present in the oil or generated during air oxidation).

Preparation of a stabilized emulsion using thermally oxidized in air oil

For the preparation of a water-in-oil emulsion stabilized with solids using this method, the oil is heat treated for a sufficient time and at a sufficient temperature, if air or oxygen is purged, to allow physical and chemical modification of the oil and solid particles. Preferably, the oil is heated to a temperature between 110-180 ° C., for 15 minutes to 6 hours, with air or oxygen blowing, preferably at a rate of 20 to 100 standard cubic feet per barrel per hour (cubic feet / bbl / h)

Solids may be added prior to the thermal oxidation stage in air, during it or after it, but they must be added before emulsification. However is preferred

- 18006271 first add solids to the oil and then subject the mixture to thermal oxidation in air. The solids may be hydrophilic or hydrophobic in nature. The silica obtained by spraying, sold under the trademark Legosch® B 972 or Legosch® 130 (products from EECi55a Sogr.), Was found to be an effective solid product for a number of oils. Other solid particles, like bentonite clays, separated bentonite clays, kaolinite clays, organophilic clays or solid carbonaceous asphaltenes can also be used.

The amount of solid particles added to the oil can vary from about 1 to 90% by weight of the oil, preferably from 0.01 to 20% by weight and more preferably from 0.05 to 5.0% by weight. At higher concentrations, the mixture of solids and oil is a suspension with a high solids content.

Bentonite clays, such as those mined in Wyoming, Sa, or in various other locations around the world, are particularly suitable for use as stabilizers for a water-in-oil emulsion. After extraction, these clays in nature consist of aggregates of particles that can be dispersed in water, and destroyed under shear to obtain particles having an average size of 2 microns or less. However, each of these particles is a laminated unit containing approximately 100 layers in the form of basic layers of silicates with a thickness of 1 nm, joined together with the help of inclusions in the layers of atoms such as calcium. Through the exchange of atoms such as calcium, sodium or lithium (which are larger and have a strong attraction to water molecules in fresh water), and then bringing the bentonite into contact with fresh water, bentonite can be destroyed to form individual layers thick 1 nm, called the main particles. The chemistry of this delamination process is well known to the expert in the field of clay chemistry. The result of this method of delamination is a gel consisting of divided bentonite clay.

Preferably, the solid is a split or exfoliated bentonite clay, which is obtained as a gel using the exfoliation method described above. The amount of gel added to the oil at the stage of thermal oxidation in air can vary from 5 to 95% of the gel relative to the mass of oil, preferably from 40 to 60%. The mass of solids of bentonite clay in the gel can vary from 1 to 30% relative to the mass of water. When a gel based on bentonite clay is used as solid particles, and it is added to oil and subjected to a thermal oxidation step in air, water is displaced from the reaction vessel in the form of steam. The reaction should be carried out until at least 80% of the water is displaced, preferably until 95% of the water is displaced, and even more preferably until 100% of the water is displaced.

It is preferable to oxidize the co-stream or the main batch of petroleum products together with solids, and subsequently mix the co-stream with the main oil stream before adding water and mixing, that is, before emulsifying. This main stream of oil is preferably crude crude, however it can be any oil, including oil that is processed to increase its ability to form a stable emulsion, or processed to optimize its rheology. If the untreated crude oil is the main stream, it is preferable that the mixing flow is from 0.5 to 5% of the oxidized oil in the main stream of the crude oil, more preferably from 0.1 to 2.5%.

After the air oxidation step and the addition of solid particles, water is added, in small aliquots or continuously, and the mixture is stirred with a shift at 1000-12000 rpm for a time sufficient to disperse water in the form of small droplets in an oil dispersed medium. The temperature of the emulsion during mixing increases above ambient temperature of 25 ° C. Controlling the temperature of the emulsion during mixing is not critical. However, elevated temperatures in the range between 40-70 ° C are preferred.

Catalysts may be used to accelerate the oxidation reaction. Fine catalysts like iron, manganese or nickel, or their oil-soluble salts can be used to catalyze oxidation rates and selective effects on oxidation products. Such oxidation promoting catalysts and techniques for using such catalysts are well known in the art, and therefore will not be discussed here. Oxidation can be carried out at elevated pressures to further catalyze the reaction rate and achieve product selectivity, however, oxidation at ambient pressure is preferred.

The oxidized oil can be additionally treated with dilute mineral or organic acid to impart additional stability with a solids-stabilized water-in-oil emulsion. The preferred acid consumption during processing is between 8 and 30,000 ppm. If this acid pre-treatment step is used, the pH of the resulting emulsion can preferably be set in the range of 5 to 7 by adding a calculated amount of a weak base to the emulsion. However, the establishment of a pH value is optional, since in some cases it is desirable to inject acidic

- 19 006271 emulsion and allow the formation reservoir to bring the emulsion itself to the reservoir alkalinity. Ammonium hydroxide is the preferred basis for establishing the pH value. Strong bases like sodium hydroxide, potassium hydroxide and calcium oxide adversely affect the stability of the emulsion. One possible explanation for this effect is that strong bases tend to reverse the emulsion, that is, convert a water-in-oil emulsion into an oil-in-water emulsion. Such treatment is undesirable for the purposes of the present invention.

Along with an increase in the stability of a solid-stabilized water-in-oil emulsion, treatment with dilute acid lowers the viscosity of the emulsion. This reduction in viscosity helps to improve the properties of the emulsion when it is pumped, and may also be useful in other aspects of the oil-jet recovery facility, for example, to reconcile the rheology of the emulsion with the rheology of underground oil, which must be removed when the emulsion is used as a propellant. Gas may also be added to further reduce the viscosity of the emulsion.

Examples

In a typical experiment, 200 g of oil is placed in a Parra® autoclave or three-neck glass flasks and oxidized at temperatures from 150 to 160 ° C for 2 to 6 hours with continuous air blowing at a flow rate of 80 to 100 cubic feet / barrel / hour The oxidized oil is then mixed in various ways with the untreated oil or other oil subjected to thermal oxidation in air, as explained below in specific examples. Hydrophobic silica, Legos® K 972 is added to the mixture of oxidized oil in an amount of from 0.05 to 0.15 wt.%, Relative to the mass of oil. After the addition of solids, the product is agitated using a Humecoi® homogenizer. Water is then added in small aliquots with stirring to form a water-in-oil emulsion stabilized with solids.

For the preferred case of thermal oxidation in air of a mixture of oil and gel based on split bentonite, the oil and gel are first mixed to form a slurry. Air or gaseous oxygen is blown into the reactor and the temperature is raised to a value between 150 and 170 ° C. Water is expelled as steam and may condense outside for recovery and reuse.

In the optional case of adding acid to the oxidized oil, 10 ppm is added to the oxidized sample. sulfuric acid and stirred for 10 min at 40 ° C. The following is the addition of solids and water with stirring, as described above.

Emulsions prepared by the method mentioned above are subjected to the following tests:

1. Stability during storage at 25 ° C for 48 h

2. Optical microscopy and NMR to determine the size / size distribution of water droplets.

3. Stability during centrifugation (described in Appendix 1)

4. Emulsion stability: sand flowed through a layer (details of the micropercolation test procedure are given in Appendix 1)

5. Emulsion rheology using the VgookieI® viscometer (cone (# 51) and plate configuration) at 60 ° C, with a shift in the range from 1.92 to 384 s ^-1 .

Example 1. Untreated Crude Oil # 4 Blended with Air Oxidized Crude Oil # 4

During processing, Legosh® K 972 is added to the untreated crude oil # 4 in an amount of 0.15 wt.%, Then the water is mixed to form a solid-stabilized emulsion 60/40 “water in crude oil”. This emulsion, although stable during storage, is unstable during centrifugation and micropercolation tests.

Dispersed water droplets are distributed in size from 2 to 40 microns in diameter, and 54% of water separation is observed in the micropercolation test described in Appendix 1 using Vegea sand. The viscosity of the emulsion at 60 ° C and 9.6 s ^-1 is 3644 SP.

Another batch of # 4 crude oil is subjected to thermal oxidation in air according to the procedure described above. Thermally oxidized in air, crude oil # 4 is mixed with untreated crude oil # 4 at 2.5 wt.% The processed oil in the crude oil. Delivery of thermally oxidized in air crude oil # 4 is carried out in toluene, in the ratio 1: 2. Hydrophobic silica, Lego® K 972, is added to the mixture in an amount of 0.15 wt.% Based on the weight of the mixed oil. The addition of water and subsequent mixing should be followed by the preparation of a solid-stabilized water-in-crude emulsion of 60/40. The droplet size distribution determined by NMR indicates that 90% of the water droplets are smaller than 2 microns in diameter. The stability of the emulsion is improved compared with the stability of a solid-stabilized emulsion of untreated crude oil # 4, which proves a reduction to 10% of water separation during micropercolation testing using Vegea sand. The emulsion viscosity is 2452 cps at 60 ° C and 10 s ^-1 . In addition, viscosity profiles are reproduced during the 1 hour shift cycle.

Ethane gas is added to reduce the viscosity of the thermally oxidized in air stable

- 00 006271 solids-lysed water-in-oil emulsions. The viscosity of the resulting emulsion decreases from 2452 to 390 cP at 60 ° C with saturation with ethane at 400 psi. The emulsion is stable with respect to the addition of ethane and a shift at a rate of 10 s ^-1 , for a duration of the experiment of 5 days.

Example 2: Mixtures of oxidized crude # 4 and low viscosity crude # 6

In this experiment, crude oil # 4 and low viscosity crude oil, crude oil # 6, are mixed in various ways. The hydrophobic solid, AegoSh® K 972, adds 0.15% by weight of solid product to the blended oil, along with 10 ppm. sulfuric acid, and stirred for 30 minutes. Then add water in small aliquots and mix to form a 60/40 emulsion of the “water in mixed oil” type. The results are presented in table. 11. As can be seen from these data, an increase in the crude oil content of low viscosity # 6 lowers the viscosity of an emulsion 60/40 of the “water in mixed oil” type from 3644 cps (measured at 60 ° C and 9.6 s ^-1 ) to 983 cP. However, the stability of the emulsions is poor, as evidenced by 30–40% stratification of water during micropercolation testing with the use of Vegea sand.

Table 11 Crude # 4 / Crude oil # 6 % Bb Viscosity, cp 60 ° C, 96 s' ¹ Mixing ratio 100/0 behind 3644 75/25 34 2621 50/50 32 2129 25/75 41 1638 0/100 40 983

Tab. 12 shows the effectiveness of thermal oxidation of oil in air before emulsification in order to increase the stability of the resulting emulsion. Crude oil # 6 is subjected to thermal oxidation in air using the method previously described, and then mixed with untreated crude oil # 4, to obtain a mixture of 75% untreated crude oil # 4 and 25% thermally oxidized in air crude oil # 6. The hydrophobic solid, AegoSh® K 972, is added to the mixture along with 10 ppm. sulfuric acid and stirred for 30 minutes. Water is then added in small aliquots and mixed to form a 60/40 emulsion of the “water in mixed oil” type.

The results shown in the table. 12, illustrate the effectiveness of this method by the example of a micropercolation test using Vegea sand.

Table 12

Of oil Saline Stratification Viscosity, cp 60's, 96 s' ¹ (% Yoo) 75% Crude Oil # 4 25% Crude Oil # 6 34 2621 75% Crude Oil # 4 25% Thermally Oxidized Crude Oil # 6 sixteen 2620

With the addition of 25% of thermally oxidized in air, crude oil # 6 to untreated crude oil # 4, the stability of the emulsion doubles, as shown by a decrease in the percentage of saline separation from 34 to 16%.

Example 3. Solids-stabilized emulsion produced using # 4 crude oil and split bentonite gel

A mixture of 70 g (g) of crude oil # 4 and 30 g of divided bentonite gel (provides an oil to gel ratio of 70:30, while the concentration of solid particles of bentonite in the gel is 3.5 wt.%) Is oxidized in air at a temperature of 160 ° C for 4 hours with air blowing at a speed of 80 cubic feet / barrel / h. Approximately 25 g of water is expelled from the reactor. The reaction product is used to prepare a water-in-oil emulsion 60/40 stabilized with solids. The air oxidized product is mixed with the untreated crude oil, thereby obtaining a mixture consisting of 2.4 wt.% Of the air oxidized product and 97.6% untreated crude oil.

The resulting 60/40 water-in-oil emulsion demonstrates a 12% separation of the saline solution during micropercolation stability testing. The emulsion is stable with respect to the addition of ethane gas at 400 psig. inch.

A mixture of 30 g of crude oil # 4 and 70 g of divided bentonite gel (30:70 ratio of oil to gel) is subjected to thermal oxidation in air using all the procedures described above.

- 21 006271

Water is displaced from the reactor, resulting in an oily solid product.

A solids-stabilized 60/40 water-in-oil emulsion is prepared using an oily solid product. The amount of oily solid used is 0.1% relative to the mass of untreated crude oil.

The resulting emulsion demonstrates 20% separation of the salt solution during micropercolation stability testing. Dispersed water droplets are less than 4 microns in diameter.

Pretreatment of oil by heat treatment in an inert environment

Another way to pretreat oil in order to increase its ability to form a stable solids-stabilized water-in-oil emulsion is to heat the oil before emulsifying in an inert environment. This embodiment has the additional advantage that it lowers the viscosity of the solid-stabilized water-in-oil emulsions.

Heat treatment can

a) generate asphaltenic solids that, alone and / or in combination with externally added solids, lead to increased stability of solids-stabilized water-in-oil emulsions,

b) lower the viscosity of crude oil, which translates into a lower emulsion viscosity of a solid-stabilized water-in-oil emulsion, and

c) retain or destroy naphthenic acids.

Preparation of solids-stabilized water-in-oil emulsions using thermally treated oil

To improve the physical and chemical properties of the oil in order to form a stable, solids-stable emulsion, the oil can be thermally processed before emulsification in an inert environment, for a sufficient time, and at sufficient temperature and pressure. It is preferable to thermally treat the oil by heating to temperatures ranging between 250-450 ° C, at a pressure of from 30 to 300 pounds per square inch (psi) for 0.5 to 6 hours. Thermal the treatment can be carried out in an inert atmosphere, without gas purging, or alternatively, with continuous exposure to an inert sweep gas. For the preferred method of thermal pretreatment without gas purging, the oil is first flushed with an inert gas, like nitrogen, for 30 minutes, and the autoclave is sealed and heated to the required temperature. For an alternative embodiment of thermal pretreatment with continuous inert gas purging, an inert gas like argon is bubbled through the reactor at a flow rate of 200-450 cubic feet / bbl / hour (cubic feet / bbl / h) during the entire heat treatment process. This method is preferred if a more marked reduction in viscosity is desired. The latter method should lead to a higher percentage of destruction of surface-active naphthenic acids and is less preferred for the preparation of a stable emulsion. The degree of depth of treatment is chosen appropriately, to obtain the optimal reduction of viscosity and retention of naphthenic acids. This degree of depth of processing may vary from one oil to another, but is within the described limits.

After heat treatment, add solids and then water, and mix to form a solid-stabilized water-in-oil emulsion. The addition of solids to the oil before heat treatment is also within the scope of the present invention. However, in the latter case, the likelihood of damage to the processing equipment must be taken into account, and the heat treatment conditions must be optimized to minimize the damage to the equipment.

The water is added in small aliquots or continuously, and the mixture is subjected to shear mixing, preferably between 1000-12000 rpm, for a time sufficient to disperse the water in the form of small droplets in a dispersed oil medium. Preferably, the concentration of water in a water-in-oil emulsion is from 40 to 80%, more preferably from 50 to 65% and most preferably 60%. The temperature of the emulsion during mixing will rise above the ambient temperature (25 ° C). Controlling the temperature of the emulsion while stirring is not critical. However, elevated temperatures in the range between 40-75 ° C are preferred.

As for solids, it is preferable that the solids are hydrophobic in nature. The sprayed silica, marketed under the trademark Aecoy® B 972 (product from Eesicca Co.), was found to be effective for a number of different oils. Other solids can also be used, like bentonite clays, kaolinite clays, organophilic clays or solid carbonaceous asphaltenic solids, which are separated and moistened with oil. The preferred concentration of solids in the oil is in the range from 0.05 to 0.25 wt.%.

- 22 006271

It is preferable to thermally treat the wake to a large level of depth of processing, and then mix the wake with the main oil stream before adding solids, water, and mix to form an emulsion. This main oil stream is preferably unprocessed crude oil, however it can be any oil, including oil, which is processed to increase its ability to form a stable emulsion or it can be processed to optimize its rheology.

For additional stability of a solids-stabilized emulsion prepared with thermally treated oil, it is expected that adding a lignosulfonate additive to the oil before emulsifying from 0.1 to 1.0 wt.% Is particularly useful. This method of increasing the stability of a solids-stabilized emulsion, that is, the addition of a lignosulfonate additive, is described above.

Diluted acid may also be added to the oil before emulsification, which will further increase the stability of the emulsion and lower the viscosity of the emulsion. This dilute acid addition is also described here.

The method of heat treatment of oil before emulsification gives additional benefit in the form of lowering the viscosity of a solid-stabilized emulsion, compared to a solid-stabilized emulsion prepared with a crude oil. This ability to manipulate the viscosity of the emulsion allows the user to optimally match the rheological characteristics of the emulsion with the rheological characteristics of the oil to be extracted, in accordance with the specific type of MUN used. Gas can also be added to further reduce the viscosity of the emulsion.

Another way to reduce the viscosity of a heat-treated, solids-stabilized emulsion is to age the emulsion. A heat-treated, solids-stabilized emulsion can age simply by keeping the emulsion at room temperature or at elevated temperature for a sufficient period of time. The viscosity of the emulsion can be reduced by more than 50% by using this method. The aging process can be accelerated by centrifuging, preferably by repeated centrifuging, which causes a similar decrease in viscosity of the thermally treated stabilized emulsion. Centrifugation is preferably carried out at temperatures between 35 and 80 ° C for 15 minutes to 2 hours at 500-10000 rpm.

Examples

In a typical experiment, 200 g of oil is placed in a Parr autoclave and heated to a temperature of 150 to 450 ° C for 0.5 to 6 hours at pressures ranging from 30 to 280 psi. The pre-heat treatment takes place either in an inert atmosphere, without a gas purge, or, alternatively, with continuous exposure to the purge gas. For thermal pretreatment without gas purging, the oil is first flushed with an inert gas like nitrogen for 30 minutes, and the autoclave is sealed and heated to the required temperature. For thermal pretreatment with continuous purging of inert gas, an inert gas like argon is bubbled through the reactor at a flow rate of 200-450 cubic feet / bbl / h throughout the entire heat treatment process. Hydrophobic silica, Lung® I 972, is then added to the heat-treated oil. Mixing using a 811Hue5oi® homogenizer follows the addition of solids. Finally, water is added to the oil and solids in small aliquots and mixed to form a water-in-oil emulsion stabilized with solids.

The thermal pretreatment method is demonstrated at three levels of processing depth that affect the following properties of oil: (1) total acid number (TAN), (2) the amount insoluble in n-heptane, (3) toluene number (measure of solubility of thermally generated asphaltenes) and (4) viscosity.

Emulsions prepared with thermally treated oil are subjected to the following tests:

1. Stability during storage at 25 ° C for 48 h

2. Optical microscopy and NMR to determine the size / size distribution of water droplets.

3. Stability by centrifugation (as described in Appendix 1)

4. Emulsion stability: sand flowed through a layer (details of the micropercolation test procedure are given in Appendix 1)

5. Emulsion rheology using the VgookieI® viscometer (cone (# 51) and plate configuration), at 35 or 60 ° C and with a shift in the range from 1.92 to 384 s ^-1 .

Example 1

A 60/40 water-in-oil emulsion is prepared using crude oil # 2 without heat treatment, but with the addition of 0.15 wt.% Hydrophobic silica (Leky® I 972). This emulsion, although stable during storage, is unstable during centrifugation and micropercolation tests. Dispersed water droplets are distributed in sizes from 0.4 to 80 microns in diameter.

- 23 006271

Example 2

Crude oil # 2 is heat treated at 360 ° C for 6 hours, at 280 psi, in an inert environment, using a pre-purge with nitrogen. The viscosity of the oil obtained at 35 ° C and 9.6 s ^-1 decreases from 643 centipoise (cP) to 328 cP. The value of OCC decreases from 6.6 to 3.9. The toluene number rises from 14 to 31, while insoluble in n-heptane remains unchanged at a level of 2.7%.

Solid particles, 0.15 wt.% Letoty® K 972, and then water are added to the thermally treated crude oil # 2 and mixed with water to form a water-in-oil emulsion stabilized with solids, as previously described. The resulting solids-stabilized emulsion has a viscosity of 5734 cP at 35 ° C and 9.6 s ^-1 , which represents a 63% decrease in the viscosity of the emulsion, compared to the untreated solid-stabilized emulsion prepared with untreated Crude Oil # 2 and 0, 15% by weight of Letkey® K 972. The size distribution of water droplets determined by heat treatment of a solid-stabilized emulsion determined by NMR shows a narrow size distribution of water droplets ranging from 2 to 10 μm in di a meter. The emulsion is stable in flow, since no stratification of water is observed in the micropercolation test described in Appendix 1. The pH value of the emulsion is approximately 6.2.

Example 3

Heat treatment of # 2 crude oil at 350 ° C for 2 hours, at 90 psi, in an inert environment results in treated oil that has a viscosity at 35 ° C and 9.6 s ¹ decreases from 643 up to 328 cps. The value of OCC decreases from 6.6 to 5.1. The toluene number increases from 14 to 25, while the amount insoluble in n-heptane remains unchanged - 2.7%.

Adding 0.15 wt.% Lekoy® K 972 to thermally treated oil, then water, and mixing, as previously described, results in a stable, solid-stabilized 60/40 water-in-oil emulsion. NMR shows the size distribution of water droplets ranging from 2 to 14 μm in diameter. A 14% water separation during micropercolation testing with a layer of sand and no water separation during microcentrifugation is observed. The pH of the emulsion is 6.2. The viscosity of the emulsion at 35 ° C and 9.6 s ^-1 is 7373 cP, which is a decrease in viscosity by more than half, when compared with a similar solids-stabilized emulsion obtained from crude oil # 2, which was pretreated with dilute acid using the method described above.

Example 4

A water-in-oil type 60/40 emulsion is prepared from other crude oil, crude oil # 4, without any prior heat treatment, but with an addition of 0.5% of £ Lokoy® K 972. Crude oil # 4 does not form stable solid-stabilized emulsions using the method described in US Pat. Nos. 5,927,404, 5,855,243 and 5,910,467. The physical properties of crude oil # 4 are shown in Table. 2. This emulsion, although stable during storage, is unstable during centrifugation and micropercolation tests.

Dispersed water droplets are distributed in size from 2 to 40 microns in diameter, and 54% of water separation is observed in the micropercolation test described in Appendix 1 using Vegea sand. The viscosity of the emulsion at 60 ° C and 9.6 s ^-1 is 3644 SP.

General test for increasing the surface activity of oil

The increase in oil surface activity due to pretreatment can be measured by determining the decrease in interfacial tension between the oil and water. Interfacial tensions are determined using the standard hanging drop method at 25 ° C. The results for raw # 4 and pretreated # 4 crude are below. It should be noted that the interfacial tension results for # 4 crude oil treated with solids and sulfonation cannot be measured using the standard hanging drop technique.

Table 13. Measurement of interfacial tension

Oil Interphase tension dyn / cm Unprocessed crude oil 44 32.3 # 4 crude oil + solids (solids) 32.6 # 4 crude oil + acid pretreatment + solids 15.8 Crude oil # 4 + lignosulfonate + solids 12.5

- 24 006271

Solids = 0.15% by weight of Lekoy® B 972

Lignosulfonate = 0.1 wt.% Ammonium lignosulfonate

Acid pretreatment = 8000 ppm sulfuric acid

The present invention has been described in connection with its preferred embodiments. However, it will be understood by those skilled in the art that many modifications, variations and variations of the present invention are possible without deviating from the true scope of the present invention. Accordingly, all such modifications, variations and variations should be construed as included in the present invention, as defined by the appended claims.

Appendix 1. Micropercolation test for emulsion stability when flowing through porous media

Observing how emulsions that are unstable will form two separate macroscopic phases, the oil / emulsion phase and the aqueous phase, is based on determining the stability of the emulsion as it flows through porous media in a fast, suitable test. A certain amount of emulsion that has completely passed through porous media can be centrifuged for this purpose to form two different phases, the volumes of which can be used as a measure of the stability of the emulsion: the greater the proportion of water or the amount of water in the emulsion itself, which forms a transparent separate phase after passage and centrifugation, the more unstable the emulsion. A convenient parameter for measuring stability, therefore, is the separation of a salt solution or L0, defined as the fraction of water or saline that is in the emulsion and forms a separate aqueous phase. Since this is a proportion, the parameter bo is dimensionless and lies between the unit (maximum instability) and zero (maximum stability). The separation of the salt solution is measured under a given set of conditions.

A commercially available special microcentrifuge tube from sintered ceramics, which consists of two parts, is used as a container for the experiment. The lower part is a tube that picks up any solution flowing from the top tube. The upper part is similar to a conventional polypropylene microcentrifuge tube, except that the lower part is made of sintered ceramics and the pores are small enough not to miss the grains, but to allow easy flow of the solution. In addition, the tubes are provided with caps for each of the parts, one of which also serves as a stand, which makes it possible to facilitate the manipulation and weighing of the upper part, while it is in a vertical position. They are available from RppSupp 8eragiopk. 1ps., Леб1рЫа N1 and sold under the name ’ΌΕΝΤΒΙ-δΕΡ SOEIMYZ.

A heated centrifuge is used to apply pressure to flow the emulsion fluid through a certain amount of sand placed in the upper tube. It is supplied by Vorshkop, 1 ps., (Ti1ka, OK) Mobe1 620. The temperature is not controlled, but stabilized at 72 ° C, under the conditions considered. The rotational speed of the upper part is about 2400 revolutions per minute (rpm), and the sandbag radius is 8 centimeters (cm), which gives a centrifugal force of 520 g. All weights are measured with milligram accuracy.

A small amount of silica gel already weighed in a test tube is placed in the columns. It is removed, and the masses of both measure. Approximately 0.2 grams (g) of sand is weighed into the upper part, and 0.2 ± 0.01 g of oil is added to the upper part. Typical types of sand used for this experiment are Vegea or Ottawa sands. The sand that is used in this test can be replaced in accordance with one's goals. For simplicity, you can use Ottawa's untreated, untreated sand, supplied by the W / BV §1.1 PriscK This gives a convenient, error-forgiving system, since sand particles are rather large and do not contain clay. Alternatively, you can use the fraction that passes through 100 mesh by Tyler, but is held on a 150 mesh sieve, and another fraction that passes through 150 mesh by Tyler, mixed in a ratio of ten to one, respectively. The tube is weighed again, then centrifuged for one minute at full speed in a heated centrifuge. The lower part is removed, and the upper part is weighed again, which gives the amount of sand and oil remaining in the upper part. The sand is now in a state in which it is wetted with oil, with air and oil in the pore space.

Now 0.18 ± 0.02 g of the emulsion is placed on top of the moistened sand, and the upper part is weighed again. The bottom tube is weighed and placed under this tube to capture effluent during centrifugation.

A separate lower tube is filled with 0.2 to 0.5 g of the emulsion alone. It serves as a control for determining whether centrifugation of an emulsion, without passing it through sand moistened with oil, causes separation of the salt solution from the emulsion. This stage is known as microcentrifugation testing, and is also an indicator of emulsion stability.

Then both tubes are centrifuged for a marked time (15 to 45 minutes), depending on the viscosity of the oil and the speed of rotation of the centrifuge. The goal is to set the time for

- 25 006271 which at least 75% of the emulsion reaches the bottom of the tube after passing through the sand. If a smaller amount passes, the assembly is centrifuged for an additional time (several times, if necessary).

After rotation, the mass of the upper and lower parts is again determined. If the emulsion is unstable, the clear aqueous phase will become visible at the bottom of the tube, under the black opaque phase of the emulsion / oil. The volume of water in the lower container is then measured by drawing it into a precision capillary disposable pipette (100-200 microliters) connected to a syringe. They are supplied by Ogittopb ΞοίοηΙίΓίο Co. (under the name \\\\\\\\\\ (11)). The height of the water column is measured and converted to water mass using an appropriate calibration curve for this capillary. Then the water separation can be calculated using these measurements and information on the mass fraction of water in the original emulsion.

Claims (40)

CLAIM 1. A method of increasing the stability of a solid-stabilized water-in-oil emulsion, comprising a step of pre-treating at least a portion of said oil before emulsifying, said step of pre-treating includes at least one of the steps of adding diluted acid to said oil, adding lignosulfonate to said oil, sulfonating said oil, heat treating said oil in an inert environment and thermally oxidizing said oil and. 2. A method of extracting hydrocarbons from a subterranean formation, comprising the steps of (a) preparing a solid-stabilized water-in-oil emulsion by (1) pretreating at least a portion of said oil before emulsifying, said pretreatment stage comprising at least at least one of the steps of adding diluted acid to said oil, adding lignosulphonate to said oil, sulphonating said oil, heat treating said oil in an inert environment and ermicheskogo said oil oxidation, (2) adding solid particles to said oil prior to emulsification, and (3) adding water and mixing to form said solids-stabilized emulsion "water-in-oil"; (b) injecting said solid-stabilized water-in-oil emulsion into said subsurface formation; and (c) extracting hydrocarbons from said subsurface formation. 3. The method of claim 2, wherein said solid-stabilized water-out-of-emulsion is used as a displacement solution to displace hydrocarbons in the specified subterranean formation. 4. The method of claim 2, wherein said solids-stabilized water-out-of-emulsion is used as a barrier solution to divert the flow of hydrocarbons in said underground formation. 5. The method of claim 1 or 2, wherein said pretreatment step comprises adding dilute acid to at least a portion of said oil prior to emulsification, wherein said diluted acid is selected from the group consisting of at least one mineral acid, at least at least one organic acid; mixtures of at least two mineral acids; mixtures of at least two organic acids and mixtures of at least one mineral acid; and at least one organic acid. 6. The method of claim 5, wherein said acid is added to said oil in an amount from about 8 ppm to about 30,000 ppm. 7. The method of claim 5, wherein said method further comprises the steps of determining the pH value of said water-in-oil emulsion, subsequent emulsification and, if necessary, establishing the specified pH so that it falls within approximately from 5.0 to about 7.0. 8. The method according to claim 7, where the specified pH value of the specified emulsion of the type "water-in-oil" set by adding ammonium hydroxide to the specified emulsion. 9. The method of claim 1 or 2, wherein said pretreatment step comprises sulphonating at least a portion of said oil before emulsification. 10. The method according to claim 9, where the specified stage of sulfonation at least part of the specified oil includes adding at least one sulfating agent. 11. The method according to claim 10, where the specified sulfating agent is sulfuric acid. 12. The method of claim 10, where the specified sulfating agent is added during processing to the specified oil in an amount of from about 0.5 to about 5 wt.%. 13. The method according to claim 1 or 2, wherein said pretreatment step comprises adding, before emulsifying, a lignosulfonate additive to at least part of said oil. - 26 006271 14. The method according to claim 13, wherein said lignosulfonate additive is added to said oil in an amount of from about 500 ppm to about 5,000 ppm. 15. The method according to claim 13, wherein said lignosulfonate additive is oil soluble. 16. The method according to claim 13, wherein said lignosulfonate additive is water soluble. 17. The method according to claim 1 or 2, wherein said pretreatment step includes thermal oxidation before emulsifying at least a portion of said oil. 18. The method according to 17, where the specified stage thermal oxidation is carried out at a temperature in the range from about 110 to about 180 ° C. 19. The method according to claim 17, wherein said thermal oxidation step is improved by adding a catalyst. 20. The method of claim 1 or 2, wherein said pretreatment step includes heat treatment before emulsifying at least a portion of said oil in an inert environment. 21. The method according to claim 20, where the specified stage heat treatment is carried out at a temperature in the range from about 250 to about 450 ° C. 22. The method according to claim 20, where the specified stage heat treatment is carried out at a pressure in the range from about 30 to about 300 psi. 23. The method of claim 20, further comprising the step of adding diluted acid to said oil before emulsifying, said diluted acid being selected from the group consisting of at least one mineral acid, at least one organic acid, mixtures of at least two mineral acids, mixtures of at least two organic acids, and mixtures of at least one mineral acid and at least one organic acid. 24. The method according to claim 20, further comprising the step of adding a lignosulfonate additive to said oil prior to emulsification. 25. The method according to claim 20, where the specified stage of heat treatment of the specified oil in an inert environment reduces the viscosity of the specified stabilized solids type emulsion "water-in-oil". 26. The method according to claim 20, further comprising the step of aging said solids-stabilized water-in-oil emulsion after emulsification, with the viscosity of said emulsion decreasing. 27. The method of claim 26, wherein the aging step of said emulsion comprises centrifuging said emulsion at a rotation speed of from about 500 to about 10,000 rpm for about 15 minutes to about 2 hours. 28. The method according to p. 27, where the specified stage of centrifugation of the specified emulsion is repeated. 29. The method of claim 2, wherein said solid particles are hydrophobic solid particles. 30. The method according to claim 2, where the specified stage of adding solid particles to the specified oil is carried out after the specified preliminary stage of processing. 31. The method according to claim 2, where the specified stage of adding solid particles to the specified oil is carried out before the specified preliminary stage of processing. 32. The method according to claim 2, wherein said solid particles contain at least one of functionalized asphalt, non-functionalized asphalt, bentonite clay, gel of bentonite clay, kaolinite clay, organophilic clay, carbonaceous asphaltene solids, filosilicates, lignin, lignite, coal, hilsonite, silica, dolamite, metalloids, layered oxides, and quaternary onium exchange filosilicates. 33. The method according to claim 2, where the specified lignosulfonate additive combine with hydrophilic solid particles. 34. The method according to claim 2, where the specified thermally oxidized oil combined with hydrophilic solids. 35. The method of claim 2, wherein said solid particles are combined with a lignosulfonate additive, and then said combination is added to said oil before emulsification. 36. The method according to claim 2, where these solids are added in the form of a gel containing solid particles and water. 37. The method according to p, where these solid particles contain from about 1 to about 30 wt.% The specified gel relative to the mass of the specified water. 38. The method according to p, where the specified gel is added to the specified oil during processing in the range from about 5 to about 95 wt.% Specified gel from the specified oil. 39. The method according to claim 2, where these solids are added during processing in an amount of from about 0.05 to about 5 wt.%. 40. Solids-stabilized water-in-oil emulsion for use in the extraction of hydrocarbons from a subterranean formation, containing (a) oil in which at least a part of it is pretreated with - 27 006271 at least one of the stages of adding diluted acid to said oil, adding lignosulphonate additive to said oil, sulphonating said oil, thermally treating said oil in an inert environment and thermally oxidizing said oil; (b) water droplets suspended in said oil; and (c) solids that are soluble in said oil and in said water, under the conditions of said underground formation.