RU2425858C1 - Composition for acid treatment of well or bottom-hole formation zone - Google Patents

Abstract

FIELD: oil and gas industry. ^ SUBSTANCE: composition for acid treatment of well or bottom-hole formation zone includes chlorhydric acid, corrosion inhibitor and water. B2 corrosion inhibitor production waste is used as corrosion inhibitor and represents salt aqueous solution containing the following, wt %: ammonium chloride 15-18, aromatic amines 4-5, water is the rest, and B2 corrosion inhibitor at the following component ratio, wt %: chlorhydric acid of 27.5% concentration 80-84.9, B2 corrosion inhibitor production waste 15-20, and B2 corrosion inhibitor 0.05-0.15. ^ EFFECT: lower corrosive activity of composition, which excludes contamination of formation and lower productivity of formation, higher effectiveness of action on formation by slower neutralisation of acid solution, which provides deeper penetration into formation and higher current reservoir recovery, and utilisation of B2 corrosion inhibitor production waste. ^ 1 tbl, 1 ex

Description

The invention relates to the oil and gas industry and can be used to increase the current oil recovery.

The most common formulations for chemical stimulation of a formation are various acid solutions with the addition of corrosion inhibitors and surfactants.

However, such compositions have significant drawbacks - they have high corrosion activity in relation to the equipment of industrial plants, have a high rate of acid interaction with the rocks of the reservoir and, as a result, the penetration of the active reagent into the formation is not deep enough.

A known composition for chemical treatment of the bottomhole formation zone, including hydrochloric acid, a corrosion inhibitor - urotropin, surfactant, urea and water (A.S. 1084421, E21B 43/27, publ. 07.04.84).

The disadvantages of this composition are: a high degree of corrosive effect on the equipment and the fact that its effective use with the formation of a foam acid system is possible only at an elevated temperature of the formation, since urea decomposes under the influence of temperature of 105 ° C with the formation of ammonia and carbon dioxide.

The closest in technical essence and the achieved effect is a composition for acid treatment of a well or a bottom hole of a formation containing hydrochloric acid, a corrosion inhibitor - a mixture of bottoms of aniline, or p-phenethidine, or Santokhin and a hydrophilic organic solvent, as well as water (Patent 2100586, E21B 43/27, publ. 12/27/97).

The disadvantage of this composition is the high corrosivity and significant content of the inhibitory composition - resinous bottoms waste from the production of organic substances mixed with an organic solvent in relation to the main component of the composition - hydrochloric acid, which increases the environmental burden on the subsoil when the composition is exposed to the formation.

The technical result of the present invention is to reduce the corrosivity of the composition, eliminating the formation pollution and reducing its productivity, increasing the effectiveness of the impact on the formation by slowing down the neutralization of the acid solution, providing deeper penetration into the formation and increasing the current oil recovery, as well as the disposal of water-salt solution - waste production of a corrosion inhibitor B2.

The technical result is achieved by the use of a composition for acid treatment of a well or a bottom hole of a formation, including hydrochloric acid, a corrosion inhibitor, and water containing, as a corrosion inhibitor, the waste product of corrosion inhibitor B2, which is a water-salt solution containing, wt.%: Ammonium chloride 15 -18, aromatic amines 4-5, water the rest, and a corrosion inhibitor B2 in the following ratio of components, wt.%:

Hydrochloric acid 27.5% concentration 80-84.9 Corrosion Inhibitor B2 Production Waste 15-20 Corrosion Inhibitor B2 0.05-0 15

It is known that the action of ammonium chloride on the formation rock proceeds according to the following reactions (Ibragimov G.Z., Sorokin V.A., Khisamutdinov NI Chemical reagents for oil production: Handbook of workers. - M .: Nedra, 1986, p. 168).

Limestone

CaCO ₃ + 2NH ₄ Cl = CaCl ₂ + (NH ₄ ) ₂ CO ₃

(NH ₄ ) ₂ CO ₃ = 2NH ₃ + H ₂ O + CO ₂

Calcium bicarbonate

Ca (HCO ₃ ) ₂ + 2NH ₄ Cl = 2NH ₄ (HCO ₃ ) + CaCl ₂

2NH ₄ (HCO ₃ ) = 2NH ₃ + 2H ₂ O + 2CO ₂

Ammonia, in turn, binds to the presence of hydrogen chloride in the hydrochloric acid composition in ammonium chloride, and the resulting carbon dioxide provides a uniform composition of the hydrochloric acid system and its deeper penetration into the formation. Thus, the process of self-generation of the gas system inside the formation is carried out. In addition, the constantly formed ammonium chloride not only helps to slow down the neutralization of the acid solution, which provides deeper penetration into the formation, but also prevents the formation of insoluble compounds of the reaction products of the composition with the rock inside the formation, since the mechanism of action of ammonium chloride is not based on suppressing crystallization centers, but on chemical decomposition of bicarbonate ions with their removal from solution in the form of carbon dioxide.

The aromatic amines contained in the composition (benzylidenebenzylamine, dibenzylamine, tribenzylamine, as well as benzamide and benzaldehyde) are a balanced mixture of several active substances that have inhibitory properties in the environment of hydrochloric acid, which significantly reduces the corrosion activity of the composition, thereby eliminating the formation pollution by gel-like iron compounds, reducing its productivity.

The above composition for acid treatment is optimal, a decrease in the content of components less than the indicated lower limits of their concentrations leads to a decrease in its effectiveness, and an increase above the upper limits of their concentrations does not lead to a significant increase in the effectiveness of the proposed composition.

Hydrochloric acid is a waste of organochlorine production obtained by the gas method (TU 2122-331-05763458-2002).

Water-salt solution is a waste product of the production of a corrosion inhibitor B2. This is a water-salt solution, which is a homogeneous, transparent liquid containing 15-18 wt.% Ammonium chloride and 4-5 wt.% Aromatic amines, water up to 100 wt.%.

Corrosion inhibitor B2 (TU 2499-353-05763458-2003 with amendment 1, 2) is a balanced mixture of several active substances that have inhibitory properties in the environment of hydrochloric acid contained in the composition of the corrosion inhibitor B2, wt.%: Benzaldehyde 25, benzyl alcohol 7, benzylamines 20, Schiff base 45.

The composition is prepared as follows.

Example 1

84.9 g of hydrochloric acid (an aqueous solution containing hydrochloric acid of 27.5 wt.%) Is loaded into a container for the preparation of the composition, and then 15 g of waste from the production of a corrosion inhibitor B2 is added. The mixture is stirred for 30 minutes until a uniform solution is obtained. Then add 0.1 g of inhibitor B2 and again mix for 30 minutes until a homogeneous solution is obtained.

Thus, by varying the ratio of components, formulations 2-10 of table 1 are prepared by analogy with example 1.

The proposed composition for hydrochloric acid treatment of the well is stable during transportation and storage. This composition mixes well with produced water in any ratio, provides effective treatment of the well by slowing down the neutralization of the acid solution, which provides deeper penetration into the formation, and does not form insoluble salts with the rock. An inhibiting system with a sufficiently low content in the composition provides reliable protection of oilfield equipment, both ground and underground, against corrosion. As a result, the service life of oilfield equipment increases, and the risk of an accident decreases.

Laboratory studies to determine the rate of metal corrosion were carried out on samples of 08 KP or St3 grades according to the following procedure.

The corrosion rate of steel was determined in a device consisting of a glass cylinder with a capacity of 400 cm ³ with a mark of 250 cm ³ with a ground stopper, in which a rod with hooks and plates made of carbon steel StZ, St 08KP 50 × 20 × 2 in size and knocked out are freely fixed numbers and holes for hanging on hooks with a diameter of 4 mm, located at a distance of 4 mm from the top edge of the plate.

250 cm ^{3 of the} test composition was poured into the cylinder of the device and a rod with three suspended plates was placed so that the plates were completely immersed in the product solution. The cylinder with the plates was placed in a thermostat and kept for 24 hours at a temperature of 18-20 ° C.

Next, the plates were removed from the solution, washed with plenty of water, removed with a brush or rubber, washed with acetone, then with alcohol, dried in air and weighed.

Calculation of measurement results

The corrosion rate of steel (L), g / m ² h, was calculated by the formula:

L = (m-ml) / (S × 24),

where m is the mass of the plate before the test, g;

ml is the mass of the plate after testing, g;

S is the plate area, m ² .

The area of the plate (S), m ² was calculated by the formula:

S = 2 (av + ac + sun) / 106,

where a is the plate length, mm;

in - the width of the plate, mm;

C - plate thickness, mm.

The arithmetic mean of two parallel measurements was taken as the result of the analysis.

The inhibition efficiency (E) was determined as the ratio of the difference in the corrosion rate of steel in hydrochloric acid and in the studied compounds to the corrosion rate in hydrochloric acid:

E = [(L _o -L _i ) / L _o ] × 100%,

where L _o is the corrosion rate of steel in the medium of hydrochloric acid, g / m ² h;

L _i - the corrosion rate of steel in the medium of the investigated composition, g / m ² h

The results of the studies are shown in table 1. As can be seen from the data of Table 1, the proposed composition exhibits high inhibitory properties with a relatively small amount of inhibitory system with respect to the main component of the composition - hydrochloric acid, which allows it to be used effectively in hydrochloric acid treatment of the well.

Table number 1 No. p \ p The content of components, wt.% Corrosion rate, g / m ² h The efficiency of inhibition,% Hydrochloric acid 27.5% concentration Water-salt solution of production, corrosion inhibitor B2 Corrosion Inhibitor B2 one 2 3 four 5 6 Suggested composition one 84.9 fifteen 0.1 0.15 98.98 2 84.95 fifteen 0.05 0.19 98.7 3 83.9 16 0.1 0.15 98.98 four 82.15 17.7 0.15 0.02 99.86 5 81.87 eighteen 0.13 0.06 99.58 6 81.37 18.5 0.13 0,062 99.57 7 80.86 19 0.14 0.09 99.38 8 80.63 19.3 0,07 0.14 99.04 9 80.0 19.95 0.05 0.12 99.18 10 79.95 twenty 0.05 0.15 98.98 The compositions of the prototype Patent 2100586 Hydrochloric acid 25.3% VAT residue production. + sol. Water one 34 Aniline 1.0 + 10 alcohol. fr. 55 0.41 96.73 2 10 Aniline 3.0 + 16 water-methanol fraction 71.0 0.12 99.18 3 25 P-phenetidine 3.0 + 16 dioxane 56.0 0.02 99.86 four 10 (hydrochloric acid 30% concentration) P-phenetidine 0.9 + 16 ether-aldehyde FR. 86.5 0,07 90.5 5 34 P-phenetidine 3.0 + 16.0 ether-aldehyde FR. 47 0.2 98.64 6 10 Santokhina 3.0 + 16 etherealdehyde FR. 71.0 0,042 98.80 7 34 Santokhina 1.0 + 10.0 dioxane 55 0.21 94.0

The proposed composition in comparison with the known has the following advantages:

- eliminates the aggressive effect of hydrochloric acid on oilfield equipment due to the effective operation of the inhibitory composition system;

- increases the effective impact on the reservoir by slowing down the neutralization of the acid solution and eliminating the formation of insoluble or sparingly soluble compounds in water;

- reduces the environmental load on the environment due to the efficient use of waste from existing production, containing valuable components that functionally act on the formation rock and protect oilfield equipment;

- decreases the cost of production of hydrochloric acid reagent by replacing most of the expensive acid corrosion inhibitor with waste from existing production.

Claims (1)

Composition for acid treatment of a well or a bottom of a formation, including hydrochloric acid, a corrosion inhibitor and water, characterized in that it contains a waste of production of a corrosion inhibitor B2, which is a water-salt solution containing, wt.%: Ammonium chloride, as a corrosion inhibitor 15-18, aromatic amines 4-5, water the rest, and a corrosion inhibitor B2 in the following ratio of components, wt.%:
Hydrochloric acid 27.5% concentration 80-84.9 Corrosion Inhibitor B2 Production Waste 15-20 Corrosion Inhibitor B2 0.05-0.15