EA039647B1 - Scale inhibitor - Google Patents

Abstract

The invention relates to oil and gas industry and can be used for the prevention of scaling during oil and gas production. The objective of the invention is to improve the efficiency of scale prevention in oil field equipment, pipelines and to expand the raw bases. The objective is achieved by a scale inhibitor which contains a surface-active agent (surfactant), an acid and an anionic polymer, namely pentaethylenehexamine (PEHA), orthophosphoric acid, and a 1% aqueous solution of sodium salt of carboxymethyl cellulose, at the following component ratio, wt.%: pentaethylenehexamine 11.6-23.4; orthophosphoric acid 9.8-30.6; the rest is 1% aqueous solution of sodium salt of carboxymethyl cellulose.

Description

salt precipitation rotation in oil and gas production.

A composition is known to prevent inorganic deposits containing oxyethylenediphosphonic acid (16.1-24.9%), methyl alcohol (36-44%), monoethanolamine or a mixture of monoethanolamine with ammonium hydroxide (8.1-19.9%) and water ( the rest) [1].

Known composition for the prevention of calcium deposits, including oxyethylenediphosphonic acid (4-15%), monoethanolamine (5-15%), nitrilotrimethylphosphonic acid (15-25%), a compound containing a hydroxyl group (25-30%) and water (the rest) [2].

The disadvantage of the known compositions are the lack of efficiency and the formation of sulfate and carbonate deposits.

The following composition is known to prevent inorganic salts: a phosphonic component (5.0-30.0%), a water-soluble polymer (0.1-5%), a compound containing a hydroxyl group (5.0-30.0%), an amine component (5.0 -20.0%), corrosion inhibitor (0.1-0.5%), and water (balance) [3].

The disadvantage of this composition is the low inhibitory ability.

The closest technical solution to the proposed invention is a scale inhibitor containing (wt.%) inhibited hydrochloric acid (40-60), a nitrogen-containing compound (1.5-4.2), an anionic polymer (20-25), phosphoric acid (1 -5) and water (the rest). The inhibitor contains a nitrogen-containing compound selected from the group: urea, monoethanolamine, diethanolamine, triethanolamine, diethylenetriamine, triethylenetetramine, polyethylenepolyamine. It contains carboxymethyl cellulose or polyacrylamide as an anionic polymer [4].

The use of a large amount of inhibited hydrochloric acid (40-60%), an anionic polymer (20-25%), as well as a high content (36.1-41.2) of the active component in the inhibitor are disadvantages of the prototype.

The objective of the invention is to increase the efficiency of preventing scale in oilfield equipment, pipelines and expanding the resource base.

The problem is solved by the fact that the scale inhibitor containing a surfactant (surfactant), an acid and an anionic polymer, as a surfactant contains pentaethylenehexamine (PEGA), acids - phosphoric acid, and as an anionic polymer - 1% aqueous solution of sodium salt of carboxymethyl cellulose with the following ratio of components, wt.%:

Pentaethylenehexamine 11.6-23.4

Orthophosphoric acid 9.8-30.6% solution of sodium salt of carboxymethylcellulose rest

The density of the prepared compositions at 20°C is 1050-1070 kg/m ³ , kinematic viscosity 14-20 mm ² /s, freezing point -10-15°C, pH 3-4. Appearance: colorless, transparent, flowing liquid, easily soluble in water.

The reagents used to prepare the scale inhibitor comply with the following regulatory document:

Orthophosphoric acid GOST10678-76, TU2143-002-34179766-97

PEGA TU 0254-03-53839702-2005

Sodium salt of carboxymethyl cellulose TU2231-037-26289127-01

One of the main requirements for scale inhibitors is their adsorption-desorption properties. It is known that rocks that are carriers of oil and gas have wettability and sorption capacity. To improve the adsorption-desorption properties of the scale inhibitor, it is necessary to use reagents that reduce the interfacial tension at the interface of the oil inhibitor. These reagents make it possible to expand the area of contact with a mixture of silicate and aluminosilicate, as well as carbonate components. The prepared reagents, due to their adsorption-desorption properties as a scale inhibitor, work for a long time and have high efficiency.

The technical result of the present invention is the exclusion of the use of scarce, expensive reagents, an increase in the productivity of the formation by preventing the formation of inorganic deposits during the treatment of carbonate and terrigenous productive formations, eliminating the contamination of the formation and downhole equipment with insoluble salts.

Below are examples of the preparation of scale inhibitors.

Example 1 A 1% aqueous solution of sodium carboxymethylcellulose is prepared. 78.6 g is taken from this solution and poured into a flask, then 11.6 g of pentaethylenehexamine, 9.8 g of phosphoric acid are poured into this flask and mixed until a homogeneous solution is obtained.

Example 2. 69 g of a 1% solution of sodium salt of carboxymethyl cellulose is poured into a flask. Then 12.5 g of PEGA and 18.5 g of phosphoric acid are added to it, mixed until a homogeneous solution is obtained.

Example 3. 69.5 g of a 1% solution of sodium salt of carboxymethyl cellulose is poured into a flask. Then 15.5 g of PEGA and 20 g of phosphoric acid are added thereto and mixed until a homogeneous solution is obtained.

Formulations 4-10 are prepared in a similar manner. The results are shown in table. one.

Table 1

Example No. The content of the components that make up the inhibitor, in mass percent Na-CMC PEGA o-H ₃ RO ₄ one 78.6 11.6 9.8 2 69 12.5 18.5 3 54.5 15.5 20.0 4 59.2 17.3 23.5 5 54.8 19.5 25.7 6 50.2 21.3 28.5 7 46.0 23.4 30.6 eight 65.0 13.8 21.2 nine 71.5 10.5 18.0 ten 75.5 8.5 16.0

As can be seen from Table. 1 the amount of Na-CMC (1% aqueous solution) varies within 46.0-78.6%, orthophosphoric acid 9.8-30.6%, PEGA-a 8.5-23.4%. The prepared compositions are homogeneous, readily soluble in water. The density of the compositions at 20°C is 1030-1050 kg/m ³ , the kinematic viscosity is 10.2513.345 mm ² /s, the pH value is 5.0-7.5.

The effectiveness of scale inhibitors was tested in model formation waters to prevent the precipitation of calcium sulfates and carbonates. Preparation of model formation waters that precipitate CaSO ₄ H CaCO ₃ have the following compositions:

For the precipitation of CaSO ₄

First part

NaSO ₄ 13.0g/l

NaCl 18.8g/l

MgCl ₂ *6H ₂ O 1.24g/l

Second part

CaCl ₂ 13.6g/l

To precipitate CaCO ₃

First part

NaHCO ₃ 2.4g/l

Second part

CaCl ₂ 2.92 g/l

NaCl 40.4g/l

MgCl ₂ 6H ₂ O 4.26 g / l

The effectiveness of inhibition to scale of the prepared samples was carried out in model formation waters [5]. Laboratory tests were carried out at 80°C for 5 hours. The inhibition efficiency (E) was calculated using the following formula:

E \u003d (C _R -C _X ) 100 / (C ₀ -C _x )

Here, C _p is the number of Ca ^{2+ ions} in a thermostated and inhibited medium, mg/l; Cx - the number of Ca ^{2+ ions} in the medium without inhibitor; Co - the amount of Ca ^{2+ ions} in the initial solution, mg/l. The results of the prepared scale inhibitors are shown in table. 2.

-2039647

table 2

Example No. Reagent consumption, g/t Effect against scaling,% _CaSO4 CaCO3 one ten 80 40 20 100 65 thirty 100 90 2 ten 85 72 20 100 90 thirty 100 100 3 ten 70 80 20 90 92 thirty 100 100 4 ten 73 90 20 90 100 thirty 100 100 5 ten 100 75 20 100 90 thirty 100 100 6 ten 100 85 20 100 100 thirty 100 100 7 ten 85 70 20 100 90 thirty 100 100 eight ten 75 100 20 100 100 thirty 100 100 nine ten 100 100 20 100 100 thirty 100 100 ten ten 100 100 20 100 100 thirty 100 100

As can be seen from the table, the prepared samples at a flow rate of 10-30 g/t exhibit an inhibitory effect to prevent the precipitation of calcium sulfate and carbonate.

Literature

1. RU 2417954, C02F 5/14, 2009.

2. RU 2179625, E21B 37/00, C02F 5/14, 2002.

3. RU 2447197, C23F 11/10, С09К 8/54, 2010.

4. A 2012 0004, E21B 43/27, C09K 8/528, Bulletin No. 3, 06/30/2015.

5. Bikchanteva N.V., Monakhova N.V., Aleshkina I.V. Study of the properties of a new scale inhibitor SNPKh-5312 (grades C and T)//Oil industry. 11, 2000, p. 39-40.

CLAIM

Claims (1)

CLAIM Scale inhibitor containing a surfactant (surfactant), an acid and an anionic polymer, which contains pentaethylenehexamine (PETA) as a surfactant, orthophosphoric acid as an acid, and 1% aqueous solution of carboxymethyl cellulose sodium salt as an anionic polymer at the following ratio of components, wt.%: pentaethylenehexamine - 11.6-23.4; phosphoric acid - 9.8-30.6;