RU2494244C1 - Treatment method of bottom-hole formation zone - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: in a treatment method of a bottom-hole formation zone, which involves pumping to the formation of acid-oil emulsion of reverse type and acid, as acid-oil emulsion of reverse type there used is emulsion containing the following components, wt %: dispersion medium - hydrocarbon liquid 31-38, emulsifier - reaction products of aliphatic amines of fat acids of hydrated tall oil with hydrochloric acid in terms of amines 0.02-0.08, dispersion medium - synthetic, inhibited hydrochloric acid (10-18%) is the rest.

EFFECT: enlarging application area of the proposed method, use in wider range of formation temperature, use for well any water content of the extracted product, including increased water content, shortening of time required for treatment process, improving efficiency of influence on low-permeability productive zones of the formation, preventing secondary formation of emulsions under formation conditions after treatment, and reducing emulsifier consumption and use of a more technological method of emulsion preparation on a well.

7 cl, 21 tbl, 1 dwg

Description

The invention relates to the oil industry and can be used to intensify oil production from heterogeneous permeability carbonate or terrigenous strata by carrying out acid treatment of the bottomhole formation zone.

A known method of processing the bottom-hole zone of the formation, including the injection of acid into the formation. (1) (Sh.K. Gimatudinov, “Oil production reference book”, M., “Nedra”, 1974, pp. 420-432).

The known method is effective only when processing homogeneous permeability formation. When processing an inhomogeneous formation, mainly highly permeable zones are exposed to chemical exposure, and practically no effect on low-permeability zones of the formation is performed. Therefore, as a result of its implementation, the heterogeneity of the formation in permeability increases even more. The method is not applicable for wells with high water cut of produced products.

A known method of processing the bottom-hole zone of the well, comprising injecting into the formation a plugging material resistant to acid and an acid solution. The injection of the plugging material is carried out with increasing injection pressure, and the acid solution with decreasing injection pressure. In this case, the initial injection pressure of the subsequent solution is planned at the level of the final pressure of the previous injection. The plugging material is injected in a larger volume than the acid solution. The injection of the plugging material and the acid solution is carried out cyclically. At the end of the injection of solutions produce technological exposure. As an insulating material, a gelling solution of polyacrylamide, clay solution or other materials are used. Lower waterlogged intervals overlap with a cement bridge. If it is necessary to isolate several intervals within the exposed part of the reservoir, cover the entire interval with a cement bridge, followed by its drilling and opening with perforation of the productive intervals. (2) (Patent RU No. 2114296, CL ЕВВ 43/27, publ. 1998).

The disadvantages of this method are the complexity and complexity. When conducting work on the isolation of highly permeable intervals (formations) using the recommended grouting materials, a simultaneous irreversible decrease in the permeability of low-permeability reservoir zones is also possible. In addition, during the subsequent operation of the well, for example, when transferring a production well for injection, additional labor-intensive work will be required to open previously isolated zones of the formation (for example, opening them with perforation followed by acid treatment). However, these works usually do not provide a complete restoration of the permeability of isolated intervals.

A known method of processing the bottom-hole zone of the well, comprising sequentially injecting into the formation a plugging material that is resistant to acid under formation conditions, and acid. Studies are preliminarily carried out to determine the injectivity of the isolated formation (interval), according to the results of which the plugging material of the appropriate concentration is prepared. Clay-based material is used as the acid-resistant plugging material. After isolation of the treated interval with the help of two packers, the plugging material is injected into the formation and pressed through with fresh water, followed by technological exposure. The operation is repeated until a significant increase in injection pressure (decrease in injectivity of the well). Then, low permeability production intervals are sequentially isolated with two packers and acid treatments are carried out. (3) (Patent RU No. 2208150, CL ЕВВ 43/27, publ. 2003).

The disadvantages of this method are the complexity and complexity. In the implementation of the method requires additional tripping operations using packers. In addition, the use of clay-based material for isolation of highly permeable zones (formations) can lead to almost complete loss of their permeability.

A known method of processing the bottom-hole zone of a well in a multilayer oil reservoir, comprising sequentially injecting a reverse oil emulsion into all reservoirs, injecting a material dissolving the oil component of the oil emulsion into the intervals of the productive formations and, after technological exposure, the hydrochloric acid treatment of each of the productive formations isolated from other reservoirs using packers. (4) (Patent RU No. 2092686, CL EV 43/27, publ. 1997).

The disadvantages of this method are primarily due to the complexity and complexity of its implementation, which requires repeated tripping operations using packers, as well as a special material that dissolves the oil component of the emulsion - isoprene production waste.

In addition, the inverse emulsion used has a high viscosity, which limits its penetration into the formation and, therefore, reduces the quality of the insulation created by the highly permeable waterlogged intervals. The possibility of a complete restoration of the reservoir properties of low-permeable reservoirs after exposure to a material that dissolves the oil component of the emulsion is not substantiated.

Closest to the invention, in technical essence, is a method for treating the bottom-hole zone of a formation, which includes injecting a reverse oil emulsion and an aqueous solution of acid into the formation, moreover, an emulsion containing the following components, vol.%:

Hydrocarbon fluid from 26 to 40 Oil Soluble Nitrogen Emulsifier Soncor 9601 or Soncor 9701 from 0.4 to 5 An aqueous solution of inhibited 10% hydrochloric acid or clay acid or aqueous solution of 1-10% calcium chloride or sodium rest.

As the hydrocarbon liquid, diesel fuel or paraffin liquid petroleum hydrocarbons, or unstable gas gasoline, or light oil are used.

The reverse emulsion remains stable for 6 to 35 hours at a temperature of 60 to 100 ° C.

The time of injection of the inverse emulsion during filtration into the formation should not exceed the time of maintaining the stability of the emulsion.

Emulsifiers (Sonkor-9601 or Sonkor-9701) are reaction products of amines and tall oil fatty acids with solvents and additives. As additives, they include nonionic surfactants (AF ₉ -6 or AF ₉ -12). (5) (Patent RU No. 2252515, CL ЕВВ 43/27, publ. 2005).

The disadvantages of the prototype are:

- limited scope: the recommended interval of reservoir temperatures is in a narrow range: from 60 to 100 ° C. It is not intended for use at lower or higher temperatures;

- periods of stability of the emulsions of the prototype from 6 to 35 hours can not be considered optimal. The duration of the processing of low-permeability zones of the formation usually does not exceed 1.5 hours. Therefore, the use of emulsions with periods of stability of the prototype (from 6 to 35 hours) leads to a significant delay in the commissioning of temporarily isolated intervals and, consequently, an increase in the development time of wells after treatment;

- reverse emulsions used according to the prototype can be effectively used for temporary isolation of highly permeable zones of the formation only with a small water cut of the produced products. During the treatment of wells with increased water cut of produced products, simultaneously with the intensification of oil production, water inflows from temporarily isolated zones can also increase, as a result of their treatment, hydrochloric acid released after the emulsion decays;

- for the treatment of low-permeability zones of the reservoir according to the prototype, only aqueous acid solutions are used, which is usually not effective enough. It is known that in this case, only the bottomhole formation zone immediately adjacent to the well is exposed to chemical attack. This is due to the rapid neutralization of hydrochloric acid during its interaction with carbonate rocks;

- used in the prototype emulsifiers stabilize the inverse emulsion not only when using acidic solutions as the dispersed phase, but also aqueous solutions of salts. This can create certain problems in the development of wells after treatment, associated with the possibility of secondary formation of emulsions in the bottomhole formation zone;

- for the preparation of the emulsion of the prototype using a very large amount of emulsifier, up to 5% (by volume). Moreover, for the preparation of, for example, 10 m ^{3 of an} emulsion, 0.5 m ³ or more than 450 kg of emulsifier is required. In addition, special technical means are used (special mixer or UOE-1 unit).

The objective of the present invention is to increase the efficiency of the method due to:

- application of the method in a wider range of reservoir temperatures: from 30 to 110 ° C;

- reduction of processing time;

- application of the method for wells with any, including with increased water cut, of produced products, with the provision, along with the intensification of oil production, to reduce water inflows into the well;

- increasing the effectiveness of impact on low permeable reservoir zones;

- preventing secondary formation of emulsions in reservoir conditions after treatment;

- reducing the flow rate of the emulsifier and the use of a more technological way of preparing the emulsion in the well.

The essence of the present invention lies in the fact that in the known method of processing the bottom-hole zone of the formation, which includes injecting into the formation of an oil acid emulsion of the inverse type and acid, according to the invention, an emulsion containing the following components, wt.%:

Dispersion medium - hydrocarbon liquid from 31 to 38 Emulsifier - Aliphatic Reaction Products hydrogenated tall oil fatty amines hydrochloric acid oils, based on amines from 0.02 to 0.08 The dispersed phase is synthetic, inhibited 10-18% hydrochloric acid rest.

Moreover, the inverse emulsion at temperatures from 30 to 110 ° C has an adjustable stability period of from 0.5 to 5.0 hours.

Moreover, the inverse emulsion is used to limit water inflows into the well.

In addition, the inverse emulsion is used to act on low permeability zones of the formation.

As a dispersion medium, light oil with a low content of asphaltenes and resins, diesel fuel or other light oil products is used.

Interval treatment of the formation is carried out.

Interval treatment of the formation is carried out repeatedly.

In the claimed method, in contrast to the known method, a reverse-type oil-emulsion emulsion is stabilized by a more effective emulsifier — reaction products of aliphatic fatty acid amines of hydrogenated tall oil with hydrochloric acid.

It is known that the main properties of amines are due to the presence of a free electron pair at the N atom. Amines form salts with mineral acids, for example (with hydrochloric acid), - RNH ₃ Cl ^- . (6) (Chemical Encyclopedic Dictionary. Moscow, Soviet Encyclopedia, 1983, p.41, Amines). This reaction is carried out in the process of preparing the emulsion according to the claimed method: dispersed medium preliminarily dissolved in a hydrocarbon liquid) aliphatic fatty acid amines of hydrogenated tall oil react with dispersed hydrochloric acid (dispersed phase). The product of this reaction and the actual emulsifier of the inverse emulsion according to the claimed method are chloramines - RNH ₃ Cl ^- .

The use of this emulsifier provides a pefteacid emulsion of the inverse type while minimizing the consumption of amines in the range from 0.02 to 0.08% of May. According to the prototype method, the consumption of emulsifiers (Sonkor-9601 or Sonkor-9701) is much higher from 0.4 to 5% vol. An important quality of the emulsifier reagent used is that it is formed and is an effective emulsifier only when acidic solutions are used as the dispersed phase. This prevents the secondary formation of emulsions in reservoir conditions after neutralizing the acid and contributes to a more complete extraction of the reaction products from the reservoir after treatment.

The emulsifier used has surface activity, reduces the magnitude of interfacial surface tension at the interface "hydrocarbon liquid-acid solution" and helps to reduce the size of the globules of the dispersed phase (acid solution).

The viscosity of the emulsions used is relatively low: under normal conditions, from 250 to 350 MPa · s. With increasing temperature, the viscosity of emulsions decreases significantly. Therefore, the emulsion, heating up in the process of pumping it to the bottom of the well, to the treated object has a reduced viscosity.

All this contributes to a deeper penetration of the emulsion not only into highly permeable isolated zones of the formation, but also, which is very important during subsequent processing, into low permeable productive intervals.

In the claimed method, in contrast to the known method, reverse emulsions with an adjustable stability period in the range from 30 minutes to 5 hours, as well as emulsions that do not collapse (maintain stability) at a given reservoir temperature, are used at temperatures from 30 to 110 ° C. The duration of the stability period of the emulsion at a certain temperature is controlled by the concentration of the emulsifier. In this case, the acid content in the emulsion and the acid concentration are regulated.

In the claimed method, in contrast to the known method, reverse emulsion is used not only for temporary isolation of highly permeable formation zones, but also for limiting water inflows into the well and subsequent (after isolation) deeper chemical effect on low permeable reservoir zones. At the same time, the stability duration of the emulsions used varies depending on their purpose during the treatment of the bottom-hole formation zone:

- for temporary isolation of highly permeable zones of the formation, emulsions with increased periods of stability, for example, from 1.5 to 5 hours, are used.

The duration of these periods, as practice shows, provides not only a single impact on the low-permeable productive zones of the formation, but also conducting multiple interval treatments on wells with large intervals of the exposed part of the formation with an expansion of the chemical coverage of the formation. At the same time, in contrast to the known method, which is used for temporary isolation of emulsions with an unreasonably long period of stability - from 6 to 35 hours, the time of commissioning of temporarily isolated intervals is significantly reduced;

- to isolate highly permeable waterlogged zones of the formation, an emulsion is used, which at a given reservoir temperature does not collapse (maintains stability); subsequently, if it is necessary to use isolated intervals, for example, when transferring a well to injection, the permeability of these intervals can be completely restored by heating the formation to temperatures not less than 20 ° C higher than the value of the formation temperature. In this case, the emulsion loses stability and is completely destroyed and its components are easily removed from the bottomhole formation zone;

- for processing low-permeability productive zones of the formation (after isolation of high-permeability zones) not only hydrochloric acid is used, but reverse emulsions with relatively small periods of stability in the reservoir conditions, for example, from 30 minutes to 1 hour; this significantly increases the efficiency of processing due to the delivery of active acid deep into the reservoir.

The process of preparing an emulsion at a well before processing is technological and does not require the use of special equipment. The work is carried out according to the developed regulations, which determines the modes of injection of the main components of the emulsion (hydrochloric acid, hydrocarbon liquid) through the nozzle chamber with a nozzle with a diameter of 8-10 mm.

To implement the method using the following reagents and commercial products. Light oil with a low content of natural emulsifiers - asphaltenes and resins is used as a dispersion medium. It is allowed to use synthetic light petroleum products: diesel fuel, gas gasoline, kerosene and others.

As the emulsifier using the reaction products of aliphatic amines of fatty acids of hydrogenated tall oil and hydrochloric acid obtained in the process of preparation of the emulsion. Amines of fatty acids of hydrogenated tall oil are produced in the form of a paste with a density of 790 kg / m ³ , which at a temperature of 45 to 55 ° C becomes liquid. They dissolve well in hydrocarbon liquids when they are heated to temperatures of 50-60 ° C. Practically insoluble in water and in aqueous solutions of salts.

As the dispersed phase, synthetic inhibited hydrochloric acid is used, intended for the oil industry. It is recommended to use, for example, technical hydrochloric acid in accordance with GOST 857-95, additionally inhibited (B-2 inhibitor, 0.5%). VOAO Khimprom (Volgograd) or inhibited hydrochloric acid manufactured by Kaustik OJSC (Volgograd) is produced in accordance with TU 2122-066-53501222-2007 (Soling inhibitor, 0.45%). The use of hydrochloric acid obtained from exhaust gases of industrial production is not allowed, since it usually contains a significant amount of various impurities, including mechanical impurities (soot and others.), The amount of which is not regulated. This makes it difficult to prepare inverse emulsions with adjustable periods of stability in reservoir conditions.

For processing reservoirs with a low content of carbonate rocks (less than 20%), the so-called “clay acid” is used as a dispersed phase — an aqueous solution containing a mixture of hydrochloric and hydrofluoric acids. The concentration of these acids is usually located, respectively, in the range, wt.%: From 12 to 13 and from 3 to 2.

In order to justify the optimal compositions of the emulsions used and evaluate their technological properties, laboratory studies and research tests in wells were carried out. In this case, primary amines of fatty acids of hydrogenated tall oil were used, containing mainly C ₁₈ -82%, as well as C ₁₆ -13%.

Laboratory studies were carried out in the laboratory of the LLC Scientific and Production Company (SPC) Technoservis, the licensed laboratory of the LLC Scientific and Production Center (Kotovo, Volgograd Region) and in the laboratory of the Department of Physical, Colloid Chemistry and Quality Management of Kuban State Technological University (g . Krasnodar).

All studies were conducted according to a single method. The following were determined: the stability of the reverse-type oil-emulsion emulsion under sedimentation at temperatures from 30 to 110 ° C, electrical stability, interfacial surface tension at the acid – hydrocarbon liquid interface, and viscosity at various temperatures.

Oil acid emulsion was prepared in the following way. The calculated amount of hydrocarbon liquid used as a dispersion medium was heated to 50-60 ° C and the calculated amount of aliphatic fatty acid amines of hydrogenated tall oil was dissolved in it during the mixing of the solution for 15 minutes. The calculated amount of hydrochloric acid was injected into this solution in a flooded stream used as the dispersed phase. An emulsion was then prepared by mixing its components with a paddle mixer at a speed of 3000 rpm for 15 minutes.

The evaluation of the stability period of the emulsion at a certain temperature was carried out at the beginning of the acid release in the lower layer. At the same time, the electrical stability of the emulsion was evaluated using the IHER-1 semi-automatic installation, designed to assess the stability of hydrophobic-emulsion drilling fluids. During these tests, the breakdown voltage between two electrodes lowered into the emulsion was recorded.

The interfacial surface tension at the interface “acid - hydrocarbon liquid with an emulsifier” was determined by the method of counting drops using a thermostatically controlled device design UFNII equipped with a medical syringe and a micrometer screw. In each experiment, measurements were made 20 times (20 drops were formed).

The magnitude of the interfacial surface tension was calculated by the formula

$$\sigma =\frac{v({\rho }_{\mathrm{one}}-{\rho }_2)xg}{\alpha xn}=bx\frac{({\rho }_{\mathrm{one}}-{\rho }_2)xg}{\alpha },$$

where V is the total volume of drops, cm ³ ;

n is the number of drops;

ρ ₁ , ρ ₂ - the density of the solutions of acid and diesel fuel, g / cm ³ ;

g is the acceleration of gravity, cm / s ² ;

α is the constant of the device;

b is the ratio V / n. Coefficient b (V / n ratio) was determined experimentally.

The viscosity of the emulsion was determined using a pre-calibrated viscometer by the time of the expiration of the emulsion. In this case, the equation was used:

µ = µ ₀ ^* (τ / τ ₀ ), where

µ, µ ₀ — viscosity of the emulsion and the reference liquid (glycerin was used), MPa · s;

τ, τ ₀ - the time of the expiration of the emulsion and the reference liquid, min ..

All of the following laboratory results are obtained after processing the data using the least squares method.

The first series of experiments was carried out in order to substantiate the optimal acid content in the emulsion and acid concentration to obtain stable inverse emulsions. The experiments were carried out at a temperature of 80 ° C with synthetic hydrochloric acid in accordance with GOST 857-95, additionally inhibited (B-2, 0.5%) and diesel fuel in accordance with GOST 305-82.

The amount of amines in all experiments was constant and amounted, mg per 100 ml of emulsion: 40,42,44,45,47,48,50.

Tables 1-5 show the results of experiments to substantiate the optimal acid content in the emulsion. In the experiments, hydrochloric acid of 15% concentration was used. The volumetric acid content in the emulsion was: 55.0; 57.5; 60.0; 62.5 and 65.0%.

The stability of the emulsion at 55% content of 15% hydrochloric acid by volume

Table 1 №№ Amine Amount mg / 100 ml The selection of acid from the emulsion with sediment for, h: 0.25 0.5 one 2 3 four 5 one 40 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 2 42 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 3 44 out ^* out ^* out ^* out ^* out ^* out ^* out ^* four 45 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 5 47 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 6 48 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 7 fifty out ^* out ^* out ^* out ^* out ^* out ^* out ^* Note: from ^* - acid is not released, the emulsion is stable.

The stability of the emulsion at 57.5% content of 15% hydrochloric acid by volume

table 2 №№ Amine Amount mg / 100 ml The selection of acid from the emulsion with sediment for, h: 0.25 0.5 one 2 3 four 5 one 40 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 2 42 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 3 44 out ^* out ^* out ^* out ^* out ^* out ^* out ^* four 45 out ^* ots ^* out ^* out ^* out ^* out ^* out ^* 5 47 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 6 48 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 7 fifty out ^* out ^* out ^* out ^* out ^* out ^* out ^* Note: from ^* - acid is not released, stable emulsion

The stability of the emulsion at 60% content of 15% hydrochloric acid by volume

Table 3 №№ Amine Amount mg / 100 ml The selection of acid from the emulsion with sediment for, h: 0.25 0.5 one 2 3 four 5 one 40 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 2 42 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 3 44 out ^* out ^* out ^* out ^* out ^* out ^* out ^* four 45 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 5 47 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 6 48 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 7 fifty out ^* out ^* out ^* out ^* out ^* out ^* out ^* Note: from ^* . - acid is not released, the emulsion is stable

The stability of the emulsion at 62.5% content of 15% hydrochloric acid by volume

Table 4 №№ Amine Amount mg / 100 ml The selection of acid from the emulsion with sediment for, h: 0.25 0.5 one 2 3 four 5 one 40 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 2 42 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 3 44 out ^* out ^* out ^* out ^* out ^* out ^* out ^* four 45 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 5 47 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 6 48 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 7 fifty out ^* out ^* out ^* out ^* out ^* out ^* out ^* Note: from ^* . - acid is not released, the emulsion is stable

The stability of the emulsion at 65.0% content of 15% hydrochloric acid by volume

Table 5 №№ Amine Amount mg / 100 ml The selection of acid from the emulsion with sediment for, h: 0.25 0.5 one 2 3 four 5 one 40 issue * - - - - - - 2 42 issue * - - - - - - 3 44 issue * - - - - - - four 45 issue * - - - - - - 5 47 issue * - - - - - - 6 48 issue * - - - - - - 7 fifty issue * - - - - - - Note: vyd. * - release of acid from the emulsion, the emulsion is unstable

From the above data it follows that a stable emulsion of the inverse type can be obtained with a volumetric acid content in the range from 55 to 62.5%. At a higher acid content, the emulsion loses stability and quickly collapses. The use of emulsions with a lower acid content is impractical according to technological requirements.

Tables 6-10 show the results of experiments to substantiate the optimal concentrations of hydrochloric acid to obtain stable inverse emulsions. The volumetric acid content in the emulsion in all experiments was constant and amounted to 60%. The acid concentration ranged from 10 to 22.5%. The stability of the emulsion with 10% hydrochloric acid

Table 6 №№ Amine Amount mg / 100 ml The selection of acid from the emulsion with sediment for, h: 0.25 0.5 one 2 3 four 5 one 40 out * out * out * out * out * out * out * 2 42 out * out * out * out * out * out * out * 3 44 out * out * out * out * out * out * out * four 45 out * out. * out * out * out * out * out * 5 47 out * out * out. * out * out * out * out * 6 48 out * out * out * out * out * out * out * 7 fifty out * out * out * out * out * out * out * Note: exc. * - acid is not released, the emulsion is stable. The stability of the emulsion with 15% hydrochloric acid

Table 7 №№ Amine Amount mg / 100 ml The selection of acid from the emulsion with sediment for, h: 0.25 0.5 one 2 3 four 5 one 40 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 2 42 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 3 44 out ^* out ^* out ^* out ^* out ^* out ^* out ^* four 45 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 5 47 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 6 48 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 7 fifty out ^* out ^* out ^* out ^* out ^* out ^* out ^* Note: from ^* - acid is not released, stable emulsion

The stability of the emulsion with 18% hydrochloric acid

Table 8 №№ Amine Amount mg / 100 ml The selection of acid from the emulsion with sediment for, h: 0.25 0.5 one 2 3 four 5 one 40 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 2 42 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 3 44 out ^* out ^* out ^* out ^* out ^* out ^* out ^* four 45 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 5 47 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 6 48 out ^* out ^* out ^* out ^* out ^* out ^* out ^* 7 fifty out ^* out ^* out ^* out ^* out ^* out ^* out ^* Note: from ^* - acid is not released, stable emulsion

Stability of the emulsion with 20% hydrochloric acid

Table 9 №№ Amine Amount mg / 100 ml The selection of acid from the emulsion with sediment for, h: 0.25 0.5 one 2 3 four 5 one 40 issue ^* - - - - - - 2 42 issue ^* - - - - - - 3 44 out ^* - - - - - - - four 45 issue ^* - - - - - - 5 47 issue ^* - - - - - 6 48 out ^* out ^* out ^* issue ^* - - - 7 fifty out ^* out ^* out ^* out ^* out ^* out ^* out ^*

Notes: Iss. ^* - acid evolution, the emulsion is unstable;

out ^* - acid is not released, the emulsion is stable.

The stability of the emulsion with 22.5% hydrochloric acid

Table 10 №№ Amine Amount mg / 100 ml The selection of acid from the emulsion with sediment for, h: 0.25 0.5 one 2 3 four 5 one 40 issue ^* - - - - - - 2 42 issue ^* - - - - - - 3 44 out ^* - - ^* , - - - - four 45 issue ^* - - - - - - 5 47 issue ^* - - - - - 6 48 issue ^* - - - - - - 7 fifty issue ^* - - - - - - Note: Iss. ^* - the allocation of acid from the emulsion, the emulsion is unstable

The data presented in tables 6-10 show that stable inverse emulsions can be obtained at an acid concentration in the range from 10.0 to 18%. At 20% acid concentration, a stable emulsion can only be obtained with an increased concentration of emulsifier, based on amines - at least 50 mg per 100 ml of emulsion. At higher concentrations of acid, the emulsion loses stability and rapidly breaks down.

Based on the above data (tables 1-10), in subsequent studies, the acid content in the emulsion was 60% by volume, and the acid concentration - 15%, was within the established limits. Moreover, the mass content of acid in the emulsion was about 67%.

Table 11 shows the results of experiments to determine the stability of the inverse emulsion depending on the amount of amines (used to obtain the emulsifier). The experiments were carried out at temperatures from 30 to 110 ° C. For the preparation of the emulsion, inhibited hydrochloric acid (Soling inhibitor, 0.45%) manufactured by OJSC Caustic (Volgograd) and diesel fuel according to GOST 305-82 were used. Table 11 also shows the results of experiments using light oil with a small content of asphaltenes and resins as a dispersion medium. In experiments at 60 ° C, an oil sample of the Kotovskoye field was used, and at 80 ° C - an oil sample of the Pamyatno-Sasovskoye field. Data on these oil samples are shown in table 12.

Data on oil samples used in experiments

Table 12 No. of well, field Density, kg / m ³ The content of asphaltenes, wt.% The resin content, wt.% one 2 3 four No. 98, Kotovskoe 804 0.55 3.3 No. 9, Memorial-Sasovskoye 799 0.46 3.12 No. 120, Antipov-Balykleyskoe 798 0.77 2.19

From the results of the experiments (table 1-11), the following conclusions:

1. Emulsions with diesel fuel or oil have approximately the same stability; at the same time, a slightly higher stability of emulsions obtained using light oil is noted, which is confirmed by the results of experiments to evaluate the electrical stability of these emulsions, shown in Table 13 below.

2. The minimum concentration of amines to obtain the inverse emulsion at different temperatures.

3. Emulsions have an adjustable stability period within the entire studied temperature range from 30 to 110 ° C.

4. Recommended periods for the stability of emulsions range from 30 minutes to 5 hours. Emulsions with a shorter stability period do not meet the technological requirements of the method, and the preparation of emulsions with large stability periods is difficult due to the fact that with a further increase in the concentration of amines, the stability of emulsions sharply increases with the formation of stable (non-destructible) emulsions at a given temperature.

5. Emulsions that are not collapsing (preserving stability) at a given temperature are recommended for work to limit water inflows into the well.

Electrical stability of emulsions when using diesel fuel and (or) oil

Table 13 Dispersion medium Amine amount, mg / 100 ml emulsion / breakdown voltage, V thirty 32 34 36 38 40 42 44 46 48 fifty 52 54 56 58 Diesel fuel fifty 60 70 75 80 85 90 95 one hundred 102 105 110 115 117 120 Oil * 80 85 90 95 97 one hundred 105 110 113 115 120 124 129 135 137 Note: oil * is a sample of oil from the Kotovskoye field.

Table 14 shows the results of field trials to assess the stability of emulsions at various temperatures depending on the amount of amines. Data obtained in the course of well treatments. The duration of the stability of emulsions in reservoir conditions was evaluated by the beginning of the growth of the injectivity of the well during the injection of the emulsion into the reservoir, which indicated the beginning of the decay of the emulsion with the release of free acid and its interaction with the reservoir rocks. In this table, to compare the results of laboratory and field studies, the amount of amines is given not only in kg / m ³ , but also, respectively, in mg / 100 ml, as was customary in laboratory studies.

Field tests for evaluating the stability of emulsions

Table 14 №№ Field Well number Reservoir temperature, ° C Amines Amine Stability period, min kg / m ³ mg / 100 ml one Korobkovskoye 570 60 0.39 39 85 2 Memorial Sasovskoye 12 76 0.48 48 92 3 --- "" --- 12 76 0.44 44 35 four Kotovskoe 126 79 0.49 49 80 5 Antipovsko-Balykleyskoe 79 110 0.735 73.5 120

Figure 1 shows the dependences of the stability of emulsions at various temperatures on the concentration of amines obtained from laboratory tests and field tests (data in tables 11 and 14). The conducted studies allow us to conclude that their comparability is quite good. The somewhat increased stability of emulsions according to field data, compared with the results of laboratory studies, is associated with a decrease in the formation temperature as a result of cooling the bottom-hole zone of the formation during the injection of the emulsion into the formation.

Laboratory and field studies have made it possible to justify the concentration of amines to obtain inverse emulsions at temperatures from 30 to 110 ° C with stability periods from 0.5 to 5 hours. They are: for laboratory research in the range from 20 to 80 mg per 100 ml of emulsion, and for field work, respectively, from 0.2 to 0.8 kg / m ³ .

To obtain emulsions that maintain stability (not collapsing) at a given reservoir temperature and are used to limit water inflows into the well, the recommended amine concentration should be at least 20% higher than the amine concentration required to obtain an emulsion with a stability period of 5 hours. These emulsions also have increased electrical stability: the breakdown voltage values for these emulsions exceed 150 volts.

The ability to restore the permeability of isolated zones of the formation using an emulsion that maintains stability at a given formation temperature is confirmed by the following experiments. We prepared two samples of an emulsion of 100 ml each, containing by volume: 60% hydrochloric acid of 15% concentration and 40% of oil from the Kotovskoye field with amines in an amount of 40 mg. One of the samples was sedimented at 40 ° C. The emulsion is stable for 5 hours. Then both samples of the emulsion were placed at sludge at 60 ° C. After 80 minutes, a violation of the stability of the emulsions. Then the emulsion quickly collapsed with the release of acid. Repeated these experiments at 70 ° C. Violation of the stability of the emulsions was noted after 15 minutes. Our experiments show the possibility of breaking emulsions stable at a given formation temperature and completely restoring the permeability of isolated zones of the formation by heating them to temperatures no less than 20 ° C above the value of the formation temperature. At higher temperatures, the decay process of the emulsion is accelerated.

Tables 15-17 show the results of experiments to assess the possibility of formation of an emulsion in reservoir conditions after acid neutralization. In these experiments, in contrast to experiments with hydrochloric acid, the main reaction product of hydrochloric acid with carbonate rocks, an aqueous solution of calcium chloride, was used as the dispersed phase. The concentration of calcium chloride was 2, 5 and 10% (by weight). The stability of the emulsion with a solution of calcium chloride 2% concentration

Table 15 №№ Amine Amount mg / 100 ml The allocation of the solution from the emulsion with sediment for, h: 0.25 0.5 one 2 3 four 5 one 40 issue ^* - - - - - - 2 42 issue ^* - - - - - - 3 44 out ^* - - - - - - four 45 issue ^* - - - - - - 5 47 issue ^* - - - - - 6 48 issue ^* - - - - - - 7 fifty issue ^* - - - - - - Note: Iss. ^* - the allocation of the solution, the emulsion is unstable

The stability of the emulsion with a solution of calcium chloride 5% concentration

Table 16 №№ Amine Amount mg / 100 ml The selection of the solution from the emulsion with sediment for, h 0.25 0.5 one 2 3 four 5 one 40 issue ^* - - - - - - 2 42 issue ^* - - - - - - 3 44 out ^* - - - - - - - four 45 issue ^* - - - - - - 5 47 issue ^* - - - - - 6 48 issue ^* - - - - - - 7 fifty issue ^* - - - - - - Note: Iss. ^* - the allocation of the solution, the emulsion is unstable

The stability of the emulsion with a solution of calcium chloride 10% concentration

Table 17 №№ Amine Amount mg / 100 ml The selection of the solution from the emulsion with sediment for, h 0.25 0.5 one 2 3 four 5 one 40 issue ^* - - - - - - 2 42 issue ^* - - - - - - 3 44 out ^* - - - - - - four 45 issue ^* - - - - - - 5 47 issue ^* - - - - - 6 48 issue ^* - - - - - - 7 fifty issue ^* - - - - - - Note: Iss. ^* - the allocation of the solution, the emulsion is unstable

The data given in tables 15-17 confirm the earlier conclusion that the emulsifier used is a product of the reaction of amines with hydrochloric acid and therefore is not a stabilizer of emulsions with calcium chloride solutions.

Table 18 shows the results of experiments to assess the magnitude of interfacial surface tension at the border "hydrochloric acid - diesel fuel with amines". During the experiments, hydrochloric acid produced by JSC Caustic and diesel fuel according to GOST 305-82 were used.

Table 18 Amines Amount, mg / 100 ml emulsion Interfacial surface tension, mN / m 0 17.4 10 13,2 twenty 10.6 thirty 9.3 40 8.5 fifty 8.3

From the data given in table 18, it follows that the emulsifier used can reduce the magnitude of interfacial surface tension by more than two times.

Table 19 shows the results of experiments to determine the dependence of the viscosity of the emulsion on the amount of amines. The experiments were carried out with hydrochloric acid produced by JSC "Caustic" and a sample of oil from the Kotovskoye field. The dependence of the viscosity of the emulsion on the amount of amines

Table 19 Amine Amount mg / 100 ml 39 41 43 45 47 49 51 53 55 57 The viscosity of the emulsion, MPa · s 138 140 152 190 202 220 250 290 410 516

From the data given in table 19, it follows that with an increase in the concentration of amines, the viscosity of the emulsion increases. This creates favorable conditions for the implementation of the method: for the isolation of highly permeable zones, emulsions with long periods of stability and, therefore, with higher concentrations of emulsifier and with relatively high viscosity, and for the treatment of low-permeability zones of the formation, emulsions with small periods of stability, and, therefore, with small concentrations of emulsifier and lower constant viscosity.

Table 20 shows the results of experiments to assess the change in viscosity of the emulsion depending on temperature. To form an emulsion, hydrochloric acid produced by JSC Caustic and a sample of oil from the Pamyatno-Sasovskoye field were used.

Amines - 40 mg per 100 ml of emulsion.

Emulsion viscosity at various temperatures

Table 20 Temperature ° C thirty 40 fifty 60 70 80 90 Viscosity, MPa · s 187 112 95 83 53 32 25

This leads to the conclusion that, the viscosity of the emulsion with increasing temperature during its injection to the bottom of the well decreases many times.

In practice, the claimed method is implemented by conducting the following operations.

Before processing, preparatory work is carried out:

- design the processing technology with justification of the quantity and quality of the emulsions used, as well as the modes of pumping them into the formation, conduct laboratory experiments with samples of hydrochloric acid and light oil to justify the amount of amines for preparing the necessary emulsions;

- washed the well to the bottom;

- install a string of tubing in the middle of the interval of opening the formation or in its upper part;

- determine the injectivity of the well;

- delivered to the well: oil for preparing emulsions and forcing them into the reservoir, hydrochloric acid, two containers for receiving the prepared emulsions, two pumping units, an acid unit, a mobile steam generating unit (PUF), a “mixer-dispersant” in the form of a nozzle chamber with a fitting diameter from 8 to 10 mm; amines necessary for the preparation of emulsions;

- dissolved in oil, heated with foam to 50-60 ° C, the calculated amount of amines in the mixing process (the pump works "on its own") for 15 minutes;

- dilute hydrochloric acid with water to obtain a solution of 15% concentration;

- the necessary emulsions are prepared according to the applicant’s regulations: at the same time, acid and oil with amines are pumped through the “mixer-dispersant”, the ratio of acid to oil consumption being 3: 2, the total liquid flow rate is in the range from 0.3 to 0.5 m ³ / min, and the discharge pressure is from 8 to 10 MPa;

- prepared emulsions are sent to separate containers;

- tie the pump and acid units with the wellhead with a hard line and pressure test them taking into account the allowable pressure on the production string.

During processing, the following operations are performed sequentially:

- with an open annular space of the well, an emulsion is sequentially injected into the tubing volume to temporarily isolate the highly permeable zones of the formation and part of the emulsion to affect low permeable production intervals;

- close the annulus of the well and continue pumping into the tubing the remainder of the emulsion and squeezing fluid;

- close the well and produce technological exposure, usually within 3 to 5 hours.

The control of the processes of blocking high-permeability zones of the formation and the impact on low-permeability zones is carried out by changing the injectivity of the well during processing.

At low injectivity, the wells are injected into the reservoir before the injection of the first portion of the emulsion and after each portion of the emulsion a small amount of hydrochloric acid, approximately 1 to 1.5 m ³ .

Then, the well is mastered with the removal of reaction products from the formation and examined

inflow to assess the results of processing and justification of the optimal modes of its operation.

Industrial tests of the claimed method are given. The work was conducted in confidence - without publishing data on the emulsifier used. Moreover, the claimed method was called "Method for treating the bottom-hole formation zone with hydrophobic acid emulsions with controlled stability (GCEUS)."

For the treatments used synthetic technical hydrochloric acid produced by OJSC "Caustic" (inhibitor Soling, 0.45%) or OJSC "Khimprom" (inhibitor B-2, 0.5%). Before treatment, the acid was diluted with water to 15% concentration. The volumetric acid content in the emulsion was 60%.

As a dispersion medium used oil Kotovskogo, Pamyatno-Sasovskogo or Antipovsko-Balykleiskogo fields.

OAO LUKOIL-Volgogradneftegaz (now a branch of OAO RITEK TPP Volgogradneftegaz) conducted industrial tests of the claimed method with the aim of limiting water inflows into the well and affecting low-permeability zones of the productive formation through well No. 126 of the Kotovskoye field.

Production facility: Evlan-Libyan horizon, open bore 2506-2494 m, reservoir temperature 75 ° C, reservoir pressure 24.95 MPa. The water content of the extracted products is 86%.

Used 10 m ³ emulsion. Amines amount - 6.5 kg (0.65 kg / m ³ ).

10 m ³ emulsions were also used to influence the low-permeability reservoir zones of the formation. Amines - 4.5 kg (0.45 kg / m ³ ).

During processing, the prepared emulsion was sequentially pumped into the reservoir.

At the beginning of injection, there was a decrease in the injectivity of the well to 9 m ^{3 /} day. Then, after the decay of the emulsion intended for processing low-permeability zones of the formation and the release of free acid to interact with the formation rocks, the injectivity of the well increased to 283 m ^{3 /} day. After treatment, the flow rate of the well increased from 3 t / day. up to 20 t / day. At the same time, the well switched to gushing with anhydrous oil. The well worked with an increased flow rate for 2 years, additional production amounted to over 8 thousand tons of oil. (A copy of certificate No. 1 is attached).

Also, industrial tests of the claimed method were conducted in order to increase the productivity of well No. 78 of the Antipovsk-Balykleisky OAO “LUKOIL-Volgogradneftegaz” (now a branch of OAO RITEK TPP Volgograd-Neftegaz).

Production facility: Evlan-Libyan horizon, perforation interval 4747-4753 m, reservoir temperature 110 ° C, reservoir pressure 39.1 MPa. For processing used 10 m ³ emulsion. The amount of amines is 7.35 kg (0.735 kg / m ³ ), which provided an emulsion with a two-hour stability period under reservoir conditions.

Before treatment, the well was slightly overfilled, the average flow rate was 0.03 tons / day. After treatment, the well switched to gushing with a flow rate of 17.9 tons / day. The well worked for 2 years with an increased flow rate, additional oil production amounted to 10 thousand tons of oil. (A copy of certificate No. 2 is attached).

LLC Volgodeminoil JV also conducted industrial tests of the claimed method in 5 wells of the Pamyatno-Sasovskoye field (No. 3, 6, 8, 12 and 15 Platovsky). Interval treatments of the bottom-hole formation zone were performed for all wells.

The volume of each portion of the emulsion used to treat the formation, depending on the specific conditions, was varied in the range from 5 to 10 m ³ . The amount of amines in emulsions for temporary isolation of high-permeability zones of the formation for these wells with reservoir temperatures from 74 to 77 ° C ranged from 0.48 to 0.49 kg / m ³ , and in emulsions for exposure to low-permeability zones of the formation - from 0.44 up to 0.46 kg / m ³ .

The analysis of the performed treatments showed that they have high efficiency and are characterized by: a significant increase in productivity and permeability coefficients, a decrease in the depression on the formation during the operation of wells in various operating modes, and an increase in the power of drained intervals.

Comparative characteristics of the results of gas-dynamic studies carried out before and after repair and insulation works are presented in table 21. (A copy of certificate No. 3 is attached).

Hence the conclusion about a sufficiently high efficiency of the claimed method.

Information sources:

1. Gimatudinov Sh. K., "Reference book on oil production", M., "Nedra", 1974, p. 420-432).

2. Patent RU No. 2114296, cl. ЕВВ 43/27, publ. 1998 year

3. Patent RU No. 2208150, cl. ЕВВ 43/27, publ. 2003 year

4. Patent RU No. 2092686, cl. ЕВВ 43/27, publ. 1997 year

5. Patent RU No. 22255215, cl. ЕВВ 43/27, publ. 2005 - prototype.

6. "Chemical Encyclopedic Dictionary". Moscow, “Soviet Encyclopedia”, 1983, p.41, “Amines”.

Claims (7)

1. The method of processing the bottom-hole zone of the formation, including the injection into the formation of an oil acid emulsion of the inverse type and acid, characterized in that as an oil acid emulsion of the inverse type, an emulsion containing the following components, wt.%:
Dispersion medium - hydrocarbon liquid from 31 to 38 Emulsifier - Aliphatic Reaction Products hydrogenated tall oil fatty amines hydrochloric acid oils for amines from 0.02 to 0.08 Dispersed phase - synthetic inhibited 10-18% hydrochloric acid Rest 2. The method according to claim 1, characterized in that the inverse emulsion at temperatures from 30 to 110 ° C has an adjustable stability period for from 0.5 to 5.0 hours 3. The method according to claim 1, characterized in that the inverse emulsion is used to limit water inflows into the well. 4. The method according to claim 1, characterized in that the inverse emulsion is used to affect the low-permeability zones of the formation. 5. The method according to claim 1, characterized in that as the dispersion medium, light oil with a small content of asphaltenes and resins, diesel fuel or other light oil products is used. 6. The method according to claim 1, characterized in that the interval processing of the reservoir. 7. The method according to claim 1, characterized in that the interval processing of the formation is carried out repeatedly.

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