RU2407769C1 - Acid composition for treatment of low-permeable terrigenous headers with high carbonate content and method of acid treatment of bottom-hole formation zone with by using it - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: acid composition for treatment of low-permeable terrigenous headers with high carbonate content includes the following, wt %: alkylbenzenesulfoacid containing 12-14 atoms of carbon in alkyl residue, 3.5-5.5, preparation OC-20 2.5-5.5, ammonium chloride 3.5-6.5, 24% solution of inhibited chlorhydric acid 14.0-18.0, methanol 12.0-16.0, grain oil 4.0-8.0, acetic acid 6.0-12.0, citric acid 2.5-4.5, "IKU-118" rust inhibitor 0.1-0.5, and fresh water is the rest. Acid treatment method of bottom-hole zone of terrigenous headers with high carbonate content involves subsequent pumping to the well of flush fluid and 1.5-3.0% solution of ammonium chloride is used as flush fluid in quantity of 0.5-1.0 m³ per 1 m of perforated thickness of the bed, and acid composition in quantity of 0.5-2.0 m³ per 1 m of perforated thickness of the bed, its pushing to the bed by using the above flush fluid in quantity of 1.0-3.0 m³ and liquid for pushing and as the latter there used is fresh or mineralised water or water-oil emulsion, or oil, exposure for reaction during not more than 8 hours and further removal of reaction products; as acid composition there used is the above acid composition or its solution obtained at dilution of the above acid composition with fresh water or with 3-24% solution of inhibited chlorhydric acid in ratio of the above acid composition: fresh water or 3-24% solution of inhibited chlorhydric acid 1:1-1:9 respectively.

EFFECT: increasing acid treatment efficiency.

2 cl, 3 tbl, 2 ex

Description

The invention relates to the oil and gas industry, in particular to compositions and methods for acid treatment of the bottomhole zone of terrigenous and carbonate reservoirs, including low-permeability terrigenous reservoirs with high carbonate content (with carbonate content of 5% or more), can be used in the process of intensifying the operation of production and injection wells, as well as in hydraulic fracturing using acidic solutions.

It is known that acidic compositions containing organic solvents have the ability to even out reaction rates in the formation: to slow down reaction rates in water-saturated interlayers and accelerate them in oil-saturated interlayers due to the oil washing properties of these solvents [1].

A known composition for processing the bottomhole formation zone, which includes, wt.%: An aqueous solution of hydrochloric acid of 10-12% concentration - 10.0-18.0; an aqueous solution of hydrofluoric acid of 1.5-5.0% concentration is 1.5-5.0, the organic solvent is the rest, and the composition contains a mixture of naphthenic and aromatic hydrocarbons as an organic solvent [2].

Closest to the alleged invention in technical essence is a composition for acid treatment of the bottomhole formation zone, the following component composition, wt.%:

A solution of hydrochloric acid 24% concentration or ammonium chloride 1.0-5.0 50% Concentration of Hydrofluoric Acid or ammonium fluoride or ammonium bifluoride 1.0-5.0 Alkylbenzenesulfonic acid 10.0-30.0 Glycol 10,0-40,0

As a glycol, the known composition contains mono-, di- and triethylene glycol [3].

The disadvantages of using these compositions in low-permeability terrigenous reservoirs is that the use of these compositions leads to precipitation and colmatization of the reservoir, especially in conditions of high carbonate content. This is due to the fact that compositions containing a mixture of hydrochloric and hydrofluoric acids form a poorly soluble and insoluble precipitate of silicic acid gel, fluorides, and fluorosilicates as a result of reaction with quartz, clay and carbonate rock [4].

The invention is directed to the creation of a composition for acidizing low-permeability terrigenous reservoirs with high carbonate content, which reduces the risk of precipitation and has a slowed reaction rate with the rock at elevated reservoir temperatures, which allows to increase the coverage of the formation by treatment, as well as low interfacial tension at the border with the hydrocarbon phase and low corrosion rate, which allows to increase the efficiency of acid treatment with its use.

The result is achieved by eliminating fluorine-containing agents from the acid composition, as well as by introducing into it a mixture of organic acids having a relatively low reaction rate with the rock, and a mixture of surfactants that reduce the interfacial tension of the acid composition at the interface with the hydrocarbon phase.

The features of the invention “Acid composition for processing low-permeability terrigenous reservoirs with high carbonation and the method of acid treatment of the bottomhole formation zone with its use” are:

1. Chlorine-containing reagent.

2. As a chlorine-containing reagent, ammonium chloride is used.

3. As a chlorine-containing reagent, 24% inhibited hydrochloric acid is used.

4. Alkylbenzenesulfonic acid.

5. Methanol.

6. Fusel oil.

7. Acetic acid.

8. Citric acid.

9. The drug OS-20.

10. Corrosion inhibitor "IKU-118".

11. Fresh water.

Signs 1-4, 11 are common with the prototype, and signs 5-10 are essential distinguishing features of the invention.

SUMMARY OF THE INVENTION

An acid composition is proposed for low-permeability terrigenous reservoirs with high carbon content, including chlorine-containing reagents and alkylbenzenesulfonic acid containing 12-14 carbon atoms in the alkyl group, which additionally includes methanol, fusel oil, acetic acid, citric acid, and OS-20-ethoxylate natural higher fatty alcohols of the fraction C ₁₆ -C _18, corrosion inhibitor "CGI-118" and fresh water, and as the chlorine-containing reagent used in the composition of ammonium chloride and hydrochloric inhibited . Islota, with the following ratio of components, wt%:

Alkylbenzenesulfonic acid 3,5-5,5 The drug OS-20 2.5-5.5 Chlorine-containing reagent: ammonium chloride 3,5-6,5 24% inhibited hydrochloric acid 14.0-18.0 Methanol 12.0-16.0 Fusel oil 4.0-8.0 Acetic acid 6.0-12.0 Lemon acid 2.5-4.5 Corrosion Inhibitor "IKU-118" 0.1-0.5 Fresh water rest

and a method for acid treatment of the bottomhole formation zone, which includes sequential injection of buffer fluid into the well, which uses a 1.5-3.0% solution of ammonium chloride, in an amount of 0.5-1.0 m ³ per 1 m perforated formation thickness and acid composition in an amount of 0.5-2.0 m per 1 m of perforated formation thickness, pushing it into the formation using 1.0-3.0 m ^{3 of the} indicated buffer fluid and then injecting the liquid for sale in the volume of tubing using fresh or mineralized water or water-oil emulsion, or oil, holding the reaction for no more than 8 hours and subsequent removal of the reaction products, while the specified composition or its solution obtained by diluting the specified composition with fresh water or a 3-24% solution of inhibited hydrochloric acid is used as the acid composition in the ratio of acid composition: fresh water or a 3-24% solution of inhibited hydrochloric acid 1: 1-1: 9, respectively.

For research were used:

1. Inhibited hydrochloric acid containing 24% of the mass. HCl, is produced according to TU 2122-131-05807960-97.

2. Ammonium chloride, is a white powder, the mass fraction of the main substance is not less than 99.6%, is produced according to GOST 2210-73.

3. Alkylbenzenesulfonic acid, grade A, containing 97.0 wt.% Of the basic substance, is produced according to TU 2481-036-04689375.

4. Citric acid, “h.”, Containing at least 99.0 wt.% Of the main substance, is produced according to GOST 3652-69.

5. Acetic acid, containing not less than 99.5 wt.% Of the basic substance, is produced according to GOST 19814-74.

6. Methanol, with a concentration of 99.9%, is produced according to GOST 2222-95.

7. Fusel oil, produced in accordance with GOST 17071-91.

8. The drug OS-20, grade A, is an ethoxylate of natural higher fatty alcohols of fraction C ₁₆ -C ₁₈ , produced according to GOST 10730-82.

9. Corrosion inhibitor "IKU-118", is a glycol solution of surfactants and quaternary ammonium salts, is produced according to TU 2415-020-54651030-2007.

Examples of the preparation of acid formulations

Example 1

6.5 g of ammonium chloride, 4.5 g of citric acid, 12.0 g of methanol, 4.0 g of fusel oil, 6.0 g of acetic acid are dissolved in a 250 ml glass in 37.5 ml of water with stirring with a plastic stick. 18.0 g of hydrochloric acid, 5.5 g of alkylbenzenesulfonic acid, 5.5 g of the preparation OS-20, 0.5 g of the corrosion inhibitor "IKU-118" and mixed until completely dissolved.

After mixing, a composition is obtained with the following content of ingredients, wt.%:

Water 37.5 Ammonium chloride 6.5 Lemon acid 4,5 Methanol 12.0 Fusel oil 4.0 Acetic acid 6.0 Hydrochloric acid, 24% 18.0 Alkylbenzenesulfonic acid 5.5 The drug OS-20 5.5 Corrosion Inhibitor "IKU-118" 0.5

Example 2

In a glass with a volume of 250 ml in 37.7 ml of water, 5.0 g of ammonium chloride, 3.5 g of citric acid, 14.0 g of methanol, 6.0 g of fusel oil, 9.0 g of acetic acid are dissolved with stirring with a plastic stick. 16.0 g of hydrochloric acid, 4.5 g of alkylbenzenesulfonic acid, 4.0 g of the preparation OS-20, 0.3 g of the corrosion inhibitor "IKU-118" and mixed until completely dissolved.

After mixing, a composition is obtained with the following content of ingredients, wt.%:

Water 37.7 Ammonium chloride 5,0 Lemon acid 3,5 Methanol 14.0 Fusel oil 6.0 Acetic acid 9.0 Hydrochloric acid, 24% 16,0 Alkylbenzenesulfonic acid 4,5 The drug OS-20 4.0 Corrosion Inhibitor "IKU-118" 0.3

Example 3

In a glass of 250 ml in 37.9 ml of water, 3.5 g of ammonium chloride, 2.5 g of citric acid, 16.0 g of methanol, 8.0 g of fusel oil, 12.0 g of acetic acid are dissolved with a plastic stick while stirring with a plastic stick. 14.0 g of hydrochloric acid, 3.5 g of alkylbenzenesulfonic acid, 2.5 g of the preparation OS-20, 0.1 g of the corrosion inhibitor "IKU-118" and mixed until completely dissolved.

After mixing, a composition is obtained with the following content of ingredients, wt.%:

Water 37.9 Ammonium chloride 3,5 Lemon acid 2.5 Methanol 6.0 Fusel oil 8.0 Acetic acid 12.0 Hydrochloric acid, 24% 14.0 Alkylbenzenesulfonic acid 3,5 The drug OS-20 2.5 Corrosion Inhibitor "IKU-118" 0.1

Example 4 (prototype, composition No. 4 in table 1)

In a Teflon glass with a volume of 250 ml in 20.0 ml of fresh water, 5.0 g of hydrochloric acid, 5.0 g of ammonium fluoride, 30.0 g of alkylbenzenesulfonic acid and 40.0 g of polyglycols are successively dissolved with a plastic stick while stirring with a plastic stick.

After mixing, a composition is obtained with the following content of ingredients, wt.%:

Water 20,0 Hydrochloric acid, 24% 5,0 Alkylbenzenesulfonic acid 30,0 Ammonium fluoride 5,0 Polyglycols 40,0

The content of components in the acid compositions are presented in table 1.

Table 1 The content of components in acid compositions No. p / p Components based on the main substance The content in the acid composition, wt.% one. Sample Numbers one 2 3 4 (prototype) 2. Chlorine Reagent ammonium chloride 6.5 5,0 3,5 - hydrochloric acid 18.0 16,0 14.0 5,0 3. Corrosion Inhibitor "IKU-118" 0.5 0.3 0.1 - four. The drug OS-20 5.5 4.0 2.5 - 5. Monohydric Alcohols - methanol 12.0 14.0 16,0 - fusel oil 4.0 6.0 8.0 - 6. Alkylbenzenesulfonic acid 5.5 4,5 3,5 30,0 7. Carboxylic acids - acetic acid 6.0 9.0 12.0 - lemon acid 4,5 3,5 2.5 - 8. Fluorine-containing reagent - ammonium fluoride - - - 5,0 9. Polyglycols - 40,0 10. Fresh water 37.5 37.7 37.9 20,0

The lower concentration limit of alkylbenzenesulfonic acid and the OS-20 preparation is determined by the necessary interfacial tension of the acid composition at the interface with the hydrocarbon phase (not more than 2.0 mN / m), and the upper one, by economic feasibility. The content of organic acids and chlorine-containing reagents is determined by the required rate of dissolution of the rock during the reaction. The content of monohydric alcohols is determined by the requirements for the pour point - not higher than minus 35 ° C.

In laboratory conditions, the following properties of the proposed composition are determined: the ability to prevent the formation of emulsions and precipitation when mixed with the hydrocarbon phase; interfacial tension at the phase boundary between the proposed composition and the hydrocarbon phase; the corrosion rate of steel in the proposed composition; the rate of dissolution of carbonate rock and bentonite clay at a temperature of 80 ° C, which is typical for most deposits of Western Siberia.

The ability of the proposed compositions to prevent the formation of emulsions and precipitation when mixed with the hydrocarbon phase is determined by the separation of the aqueous and hydrocarbon phases after shaking equal volumes of the hydrocarbon phase and the acid composition in a graduated tube, followed by heating to 80 ° C (reservoir temperature) and maintaining at a given temperature in for 30 minutes, followed by pouring the contents of the tube through a sieve with a mesh size of 0.149 mm In the case of the formation of an emulsion, an incomplete separation of the system into phases occurs, which is accompanied by precipitation on the sieve after spilling through it.

The interfacial tension, mN / m, at the border with the hydrocarbon phase (TS-1 kerosene) for the tested compounds is determined using an automatic LCA 2.784.001 stalagmometer according to the procedure attached to the device.

The corrosion rate of steel, g / m ² · hour, is determined in accordance with the generally accepted method - by weight loss of St3 steel plates with a size of 25.0 × 20.0 × 0.5 mm after holding them for 24 hours in the test acid solution at 20 ° C.

The dissolving ability of the proposed composition and composition of the prototype in relation to the rock is investigated by the example of dissolution of carbonate rock and bentonite clay at a temperature of 80 ° C.

Tests for the dissolution of carbonate rock are carried out according to the method, according to which the amount of acid solution (ml) is 2.5 times the surface area (cm ² ) of the rock cube, having sides of 16-20 mm. After manufacturing, cubes of approximately the same size are placed in an oven, where they are kept for two hours and then weighed on an analytical balance to the nearest 0.0001 g. The test acid composition is poured into a Teflon glass, after which the cubes are successively immersed into a fixed contact time - 10, 30, 90 and 300 minutes.

After the contact time of the rock sample has expired, it is removed from the solution, washed with distilled water and placed in a drying oven for two hours, and the next rock sample is placed in the solution. This allows you to observe the dissolution of carbonate rock as acid is consumed.

The solubility of the rock in percent is calculated by the formula:

P _p = (m ₁ -m ₂ ) 100% / m ₁ ,

where m ₁ is the mass of the cube before the experiment, g;

m ₂ is the mass of the cube after the experiment, g.

For the dissolution test of bentonite clay, three paper filters and three clay samples of 2.0 g each are used. The samples are dried to constant weight at a temperature of 105 ° C, then the clay is transferred to a paper filter and weighed on an analytical balance with an accuracy of 0.0001 g The amount of acid solution (ml) is 2.5 times the weight of the sample in grams. Filters with clay are placed in a Teflon funnel mounted on a 100 ml Teflon cup, then the whole system is placed in a heating cabinet. Within 15 minutes, the test solution is heated in a Teflon cup at a temperature of 80 ° C, then the solution is poured into the first funnel and the clay sample is dissolved within 5 minutes, while part of the solution is filtered off. The obtained filtrate is transferred to a second funnel to dissolve the next clay sample, the duration of the second filtration is 10 minutes. Next, the filtrate is transferred to dissolve the third clay sample, the filtering duration of which is 15 minutes.

After filtering, the spent clay is washed in portions with 200 ml of distilled water at a temperature of 80 ° C, then the samples are dried in an oven at a temperature of 105 ° C to constant weight.

The solubility of clay in percent is calculated by the formula:

P _g = (m ₁ -m ₂ ) · 100% / m ₁ ,

where m ₁ - clay mass before the experiment, g;

m ₂ - clay mass after the experiment, g

In the experiments, oil of the Samotlor field was used, with a density at 20 ° С, ρ ₂₀ = 854 kg / m ³ and a dynamic viscosity at 20 ° С, η ₂₀ = 10.6 mPa · s and TS-1 kerosene.

The research results are presented in table 2.

Studies of the emulsifying ability of the proposed acid composition showed that when interacting with oil and kerosene TS-1, emulsions do not form: mixtures of oil (or TS-1) and the proposed composition (compositions 1-3 in table 1, as well as their solutions in fresh water at in the ratio composition: fresh water equal to 1: 1-1: 9, respectively) after shaking, they are completely separated into the aqueous and hydrocarbon phases for 5-30 minutes, and the subsequent spilling of the contents of the tube through a sieve with a mesh size of 0.149 mm leaves no traces on it .

As follows from table 2, at a temperature of 80 ° C, the rate of dissolution of the carbonate rock of the proposed acid composition is lower than in the composition of the prototype 10 minutes after the start of the reaction, however, 130 minutes after the start of the reaction, the proposed compositions are able to maintain a sufficiently high rate of dissolution of the rock while the rate of dissolution of the rock composition of the prototype is significantly reduced. By maintaining the reaction rate with the carbonate rock over time, the total dissolving ability of the proposed compositions is higher than the composition of the prototype. At the same time, an acceptable value of the solubility of bentonite clay is maintained. During the reaction, the proposed compositions do not form insoluble precipitates, while in the composition according to the prototype, a precipitate forms during reaction with carbonate rock. The proposed compositions have lower values of interfacial tension at the border with TS-1 kerosene and a low corrosion rate, which will increase the efficiency of acid treatment.

For practical application, a method is proposed for acidizing the bottom-hole zone of a mixed carbonate-terrigenous formation, which includes injecting a buffer fluid into the well, which is used as a 1.5-3.0% solution of ammonium chloride, in an amount of 0.5-1.0 m ³ per 1 m of perforated thickness of the reservoir, and the proposed acid composition or its solution obtained by diluting the specified composition with fresh water or a 3-24% solution of inhibited hydrochloric acid in the ratio acid composition: water (acid solution) 1: 1-1: 9, respectively about in the amount of 0.5-2.0 m ³ per 1 m of perforated thickness of the formation, pushing it into the formation using 1.0-3.0 m ^{3 of} buffer fluid and liquid for delivery, which is used as a solution of fresh or mineralized water or a water-oil emulsion or oil, exposure to the reaction for no more than 8 hours and the subsequent removal of reaction products.

Table 3 presents the results of a filtration experiment of the proposed acid composition on a core sample - clayey low-permeability sandstone.

Table 3 No. p / p Exposure fluid composition Component Quantity The permeability of the sample for kerosene, μm ² before exposure after exposure one. Forward kerosene injection To stabilize the differential pressure 0,045 2. The injection of composition No. 2 (table 1) Dilution 1: 5 in water, 3 pore volumes 3. Kerosene injection in the opposite direction To stabilize the differential pressure 0,074

As follows from the data presented, the processing of low permeability core with a solution of the proposed acid composition can significantly increase its permeability.

Information sources

1. Smykov VV Resource- and energy-saving technologies for oil production on the example of the fields of the Yamashneft Oil and Gas Production Department, dissertation for the degree of candidate of technical sciences, Almetyevsk. - 2000.

2. RF patent No. 2199661 (ЕВВ 43/27), published February 27, 2003, Bull. No. 6. - analogue.

3. RF patent No. 2243369 (ЕВВ 43/27), published on December 27, 2004, Bull. Number 36. - prototype.

4. Curtis Crowey, Jacques Masmontale, Ron Thomas, Trends in Acid Matrix Processing, Oil Review. Schlumberger. - Autumn. - 1996. S. 20-31.

Claims (2)

1. An acid composition for treating low-permeability terrigenous reservoirs with high carbonate content, including chlorine-containing reagents, alkylbenzenesulfonic acid containing 12-14 carbon atoms and fresh water in the alkyl group, characterized in that it further comprises methanol, fusel oil, acetic acid, citric acid, a preparation OC-20, representing a natural higher fatty ethoxylate alcohols of fraction C ₁₆ -C _18, corrosion inhibitor "CGI-118", and as the chlorine-containing reagent comprises ammonium chloride and hydrochloric acid in the following ratio, wt.%:
Alkylbenzenesulfonic acid 3,5-5,5 The drug OS-20 2.5-5.5 Chlorine-containing reagent: ammonium chloride 3,5-6,5 24% solution inhibited hydrochloric acid 14.0-18.0 Methanol 12.0-16.0 Fusel oil 4.0-8.0 Acetic acid 6.0-12.0 Lemon acid 2.5-4.5 Corrosion Inhibitor "IKU-118" 0.1-0.5 Fresh water Rest 2. The method of acid treatment of the bottom-hole zone of terrigenous reservoirs with high carbonate content, which includes sequential injection of buffer fluid into the well, which is used as a 1.5-3.0% solution of ammonium chloride, in an amount of 0.5-1.0 m ³ per 1 m of perforated formation thickness and acid composition in an amount of 0.5-2.0 m ³ per 1 m of perforated formation thickness, pushing it into the formation using the above buffer fluid in an amount of 1.0-3.0 m ³ and liquids for sale, which use fresh or mineralized water or a water-oil emulsion, or oil, exposure to the reaction for no more than 8 hours and subsequent removal of the reaction products, characterized in that the composition according to claim 1 or its solution obtained by diluting the composition with fresh water is used as the acid composition or a 3-24% solution of inhibited hydrochloric acid in a ratio of composition according to claim 1: fresh water or a 3-24% solution of inhibited hydrochloric acid 1: 1-1: 9, respectively.