RU2702784C1 - Composition for inhibiting salt deposition - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to compositions for preventing inorganic deposits of calcium and barium, which can be used in oil industry, in particular in wells and on well equipment, in oil collection, preparation and transportation system. Composition for preventing loss of calcium carbonate, calcium sulphates and barium, which are difficult to dissolve in water, including oxyethylidene diphosphonic, nitrilotrimethylphosphonic acids, monoethanolamine, methanol and water, additionally contains hydrolysed polyacrylonitrile in form of its solution with density from 1.1 to 1.3 g/cm³ in following ratio of components, wt%: oxyethylidenediphosphonic acid – 8.0–12.0, nitrilotrimethylphosphonic acid – 2.0–3.0, monoethanolamine – 10.0–12.0, hydrolysed polyacrylonitrile in form of said solution with density of 1.1 to 1.3 g/cm³ (on dry) — 0.38–0.63, methanol – 36.0–44.0, water – balance.

EFFECT: high inhibiting power and low corrosion aggressiveness.

1 cl, 5 tbl

Description

The invention relates to compositions for preventing inorganic deposits of calcium and barium, which can be used in the oil industry, in particular, in wells and downhole equipment, in a system for collecting, preparing and transporting oil.

A known composition for the prevention of hydrated, salt deposits and corrosion according to the patent of the Russian Federation 2504571, C09K 8/528, publ. 01/20/2014, including a surfactant, alcohol and mineralized water, additionally contains a polymer: a copolymer of pyrrolidone or caprolactam, a terpolymer based on N-vinyl-2-pyrrolidone, polyacrylamide, hypane, polypropylene glycol, polyoxypropylene polyol, dimethylaminoethyl methacrylate, ether brand Laprol hydroxy ethyl cellulose; scaling inhibitor: substituted aminopolycarboxylic or phosphonic acid, disodium salt of ethylenediaminetetraacetic acid and sodium salt of aminomethylene phosphonic acid, hexametaphosphate or sodium tripolyphosphate, ammonium chloride or nitrate; alcohol in the form of a mixture of formalin or urotropine, or KFK urea-formaldehyde concentrate: C1-C4 monohydric alcohol, bottoms of butyl alcohol production by oxosynthesis, the ether-aldehyde fraction is a by-product of ethyl alcohol rectification; C1-C3 dihydric alcohol, low molecular weight polyethylene glycol and polyglycol Glycoil-1; polyhydric alcohol: glycerin or its containing product - polyglycerol, in a volume ratio of 1: 4-1, in the following ratio of components, wt. %: Surfactant or surfactant mixture 0.1-3.0, the specified polymer 0.02-3.0, the specified scale inhibitor 0.1-3.0, the specified mixture 5.0 30.0, the rest of the saline water

The disadvantage of these compositions is the low efficiency of inhibition of salt deposits, significant corrosiveness and instability of the mixture over time, accompanied by the precipitation of finely dispersed sediments from the solution.

A known composition for the prevention of inorganic scaling according to the patent of the Russian Federation No. 2417954, C02F 5/14, op. 05/10/2011, including hydroxyethylidene diphosphonic acid, methyl alcohol, monoethanolamine or a mixture of monoethanolamine and ammonium hydroxide and water in the following ratio, wt. %: hydroxyethylidene diphosphonic acid - 16.1-24.9; methyl alcohol - 36-44; monoethanolamine or a mixture of monoethanolamine and ammonium hydroxide - 8.1-19.9; water is the rest.

The disadvantage of the composition is the insufficiently high efficiency of inhibition of sulfate deposits of calcium and barium, high corrosion activity.

Closest to the claimed combination of essential features and the achieved result, the composition for preventing calcium deposits according to the patent of the Russian Federation No. 2179625, ЕВВ 37/00, C02F 5/10, publ. 02/20/2002, with the following ratio of components, wt. %: hydroxyethylidene diphosphonic acid - 4-15; monoethanolamine - 5-15; nitrilotrimethylphosphonic acid - 15-25; hydroxyl-containing compound - 25-30; water - the rest (prototype).

The disadvantage of the composition of the prototype is the insufficiently high efficiency of inhibition of sulfate deposits of calcium and barium, high corrosion activity.

The problem and the technical result of the claimed invention are to create a composition with a high inhibitory ability against inorganic salt deposits of both calcium and barium; and reduced corrosiveness.

The specified technical result is achieved due to the fact that the components of the proposed composition are adsorbed (deposited) on the surface of the embryonic salt crystals and thereby prevent the building up of the cells of the crystal lattice adjacent to the growth steps. Due to this, the growth of salt crystals is impossible. If, as a result of the blocking of the motion of the growth steps, the growth process of the crystal nucleus stops before the nucleus enlarges to the sizes ensuring its stability, the nucleus remains unstable and collapses. Introduction to water of the components of the proposed composition leads to inhibition of scaling.

The problem is solved in that a composition is proposed for preventing the loss of water-insoluble calcium carbonate, calcium and barium sulfates, including hydroxyethylidene diphosphonic, nitrilotrimethylphosphonic acid, monoethanolamine, methanol and water, characterized in that it additionally contains hydrolyzed polyacrylonitrile in the form of a solution with a density of 1 , 1 to 1.3 g / cm ³ in the following ratio of components, wt. %:

Oxyethylidene diphosphonic acid - 8.0-12.0

Nitrilotrimethylphosphonic acid - 2.0-3.0

Monoethanolamine - 10.0-12.0

Hydrolyzed polyacrylonitrile in the form of the specified solution with a density of from 1.1 to 1.3 g / cm ³ (dry) - 0.38-0.63

Methanol - 36.0-44.0

Water is the rest.

Hydrolyzed polyacrylonitrile (gipan, geopan - trade names for hydrolyzed polyacrylonitrile) is an industrial product, it is a homogeneous liquid from light yellow to light brown in color, the mass fraction of dry matter in an aqueous solution is from 18% to 21%. The density of 1.1-1.3 g / cm ³ at 20 °. Chemical formula:

It has high adsorption ability on the nuclei of the formed salt crystals, acting as a substrate for the adsorption of phosphonic acids, preventing the growth of crystals. The resulting crystals remain in finely divided form, thereby inhibiting the formation of large crystals.

The following reagents are also used to prepare the claimed composition.

Hydroxyethylidene diphosphonic acid (HEDP) is a well-known industrial product produced in the form of crystals. The solid compound is a white powder with a slight beige or grayish tint. The chemical formula is C ₂ H ₈ O ₇ P ₂ . HEDP is highly soluble in acids, alkalis, ethanol, methanol and water. The crystalline form can be made, for example, according to TU 2439-363-05763441-2002.

Nitrilotrimethylphosphonic acid (NTP) is an industrial product produced in powder form. Colorless or slightly greenish crystalline free-flowing powder. Chemical formula: C3H12N09P3. NTP is well soluble in fresh water, acids, alkalis, methanol. The crystalline form can be made, for example, according to TU 2439-347-05763441-2001.

Monoethanolamine (MEA) is an industrial product manufactured, for example, according to TU 2423-065-05807977-2004. MEA is a viscous colorless oily liquid, miscible with water in all respects, with a density of 1.01-1.13 g / cm ³ at 20 ° C. The chemical formula is C ₂ H ₇ NO. MEA is the acidity regulator in the composition of the scale inhibitor, as it enters into a neutralization reaction with phosphonic acids and their acid salts.

Methyl alcohol (methanol) is an industrial product produced, for example, according to GOST 2222-95. The chemical formula is CH ₃ OH. Methanol is a poisonous, colorless mobile liquid, miscible with water in any resp. The density of methanol is 0.79 g / cm at 20 ° C. Methanol is used in the composition of the scale inhibitor to lower the pour point and lower the viscosity of the inhibitor.

The inventive composition is prepared by mixing the components. For example, 10 g of HEDP, 2 g of NTF, 12 g of MEA, 40 g of methanol and 3 g of geopan are added successively to 33 g of water with stirring. During the preparation of the composition, the process of neutralizing the MEA phosphonic acid solution is carried out with cooling, not allowing the temperature to rise above 40 ° C. Each of the components is added to the mixture only after complete dissolution of the previous one.

In the course of laboratory studies, the effectiveness of the proposed composition for the inhibition of deposits of calcium carbonate ^{1 was} determined ( ¹ V.E. Kashchavtsev, I.T. Mishchenko Salt formation in oil production. - M.: Orbit Publishing House - M, 2004. - 432 p.) at a test temperature of 80 ° C in the following sequence.

A scale inhibitor solution is prepared by dissolving 100 mg of the reagent in a small amount of distilled water, followed by bringing the solution volume to 100 ml in a volumetric flask so that 1 mg of the scale inhibitor is contained in 1 ml of the resulting solution.

In a series of flasks with a capacity of 250 ml, the corresponding amount of a solution of chloride salts was placed, the required amount of scaling inhibitor was added, then the corresponding amount of sodium hydrogen carbonate solution was added to the flask to create a model solution.

Samples with and without an inhibitor — a “blank” sample — were thermostated at a temperature of 80 ° C for 4 hours. After cooling the samples, the precipitate formed was filtered off. The residual content of calcium cations in the solution was determined by trilonometric titration.

The efficiency of inhibition (E,%) was calculated by the formula:

E = (Cp-Cx) ⋅100 / (C ₀ -Cx),%

where Cp is the content of calcium ions in the sample with a scale inhibitor after temperature control, mg / l;

Cx - the content of calcium ions in the "blank" sample, mg / l;

With ₀ - the content of calcium ions in the initial solution, mg / L.

Two parallel determinations of the effectiveness of the corresponding scaling inhibitor were carried out at each dosage. The arithmetic average of the results of parallel measurements was calculated.

Sedimentation stability of aqueous disperse systems:

CaSO ₄ - scale inhibitor was studied at 80 ° C;

BaSO ₄ - Scale Inhibitor - at 25 ° C

on the Turbiscan Tower instrumentation complex for measuring the dispersion stability (Formulaction SA).

Turbiscan technology is based on multiple optical scanning of a vial with a sample in height with registration of two profiles: transmission and backscattering of infrared radiation. The obtained profiles of signal changes along the height of the sample and in time were used to quantitatively interpret the changes taking place in the test sample. An indicator of the stability of a dispersed system is the Turbiscan Stability Index (TSI), the higher the value (TSI), the less stable this sample.

The effectiveness of inhibiting the formation of salts can be determined by the equation:

where TSI ₀ is the stability index in the absence of an inhibitor;

TSI _ing - stability index in the presence of an inhibitor.

To study the protective effect of scale inhibitors, water models of the following composition were used:

- in relation to the inhibition of calcium carbonate, mg / l: Ca ²⁺ - 250; Mg ²⁺ - 85; Na ⁺ - 3048; Cl ^- - 4425; NSO ₃ ^- - 1658;

- in relation to gypsum inhibition, mg / l: Ca ²⁺ - 4912.4; Mg ²⁺ - 74.5; Na ⁺ - 2863.0; Cl ^{- -} 11758,7; SO ₄ ^2- - 5245.1;

- in relation to the inhibition of barium sulfate, mg / l: Ba ²⁺ - 157.2; Na ⁺ - 5966.3; Cl ^- - 9180.4; SO ₄ ^2- - 135.1 mg / L.

Simultaneously with the proposed composition of the scale inhibitor, the effectiveness of the composition of the scale inhibitor was studied according to the prototype (RF No. 2179625), as well as one of the analogues, which has, like the claimed one, hypane (RF No. 2504571) (hypane, geopan - trade names for hydrolyzed polyacrylonitrile) .

Preparation of the prototype composition: 15 g of NTF are added to 4 g of HEDP, acids are dissolved in 51 g of water, 5 g of MEA are neutralized and 25 g of methanol are added. The mixture is stirred until a homogeneous product.

Preparation of an analogue composition. To 70.0 wt. % formation water with a salinity of 250 g / l is added with constant stirring

2.0 wt. % fluorine surfactant brand Polizam - 05;

2.0 wt. % sodium hexametaphosphate;

1.0 wt. % hypana

and stirred until the polymer is dissolved.

Then, 25 wt. % mixture of urea-formaldehyde concentrate in isopropyl alcohol (IPA) in a volume ratio of 3: 1. All added components are thoroughly mixed for 15 minutes. until smooth.

The inventive compositions and their effectiveness in relation to the inhibition of precipitation of the corresponding sparingly soluble salts are presented in tables 1-3.

The effectiveness of inhibiting the deposition of calcium carbonate of the claimed composition in a dosage range of 10-50 mg / l exceeds the effectiveness of the composition of the prototype and analogue (table 2).

The effectiveness of inhibition of precipitation of calcium sulfate and barite of the claimed composition in the dosage range of 10-100 mg / l exceeds the effectiveness of the composition of the prototype and analogue (table 3).

The dependence of the corrosiveness of the claimed compounds on the content of the MEA are presented in table 4. The data on the corrosiveness of the composition of the analogue and prototype are also given there.

When added to the claimed compounds 10-12 wt. % MEA, depending on the content of phosphorus-containing reagents, its corrosiveness is at the level of a slightly corrosive liquid (RD 39-0147103-362-86. Guidelines for the use of anti-corrosion measures in the preparation of projects for the arrangement and reconstruction of oil field facilities. - Ufa: VNIISPTneft , 1987 p. 9). The decrease in the content of MEA in the composition below 10 wt. % is undesirable, because its corrosiveness increases. The increase in the content of MEA above 12 wt. % increases the alkalinity of the composition and reduces its inhibitory activity (table 4).

Data on the pour point of the compositions at different methanol contents are presented in table 5. The data on the pour point of the analogue and prototype compositions are also given there.

It is not recommended to reduce the methanol content in the claimed compositions below 36 wt. % due to an increase in the pour point of the composition above minus 40 ° C.

Thus, the developed composition has a high inhibitory activity with respect to the precipitation of both calcium carbonate and calcium and barium sulfates, surpassing the prototype and the analogue composition in terms of effectiveness. The developed composition also has a reduced corrosiveness and is frost-resistant.

Claims (2)

Composition for preventing the precipitation of water-insoluble calcium carbonate, calcium and barium sulfates, including hydroxyethylidene diphosphonic, nitrilotrimethylphosphonic acid, monoethanolamine, methanol and water, characterized in that it further comprises hydrolyzed polyacrylonitrile in the form of a solution with a density of from 1.1 to 1.3 g / cm ³ in the following ratio of components, wt.%: Hydroxyethylidene diphosphonic acid 8.0-12.0 Nitrilotrimethylphosphonic acid 2.0-3.0 Monoethanolamine 10.0-12.0 Hydrolyzed Polyacrylonitrile in the form of a specified solution with a density from 1.1 to 1.3 g / cm ³ (dry) 0.38-0.63 Methanol 36.0-44.0 Water Rest