The way to prevent deposition of mineral salts and iron sulfide

 

(57) Abstract:

The invention relates to the production of oil, namely, to prevent the deposition of mineral salts and iron sulfide in wells and oilfield equipment. The technical result is the creation of a method to effectively prevent the deposition of mineral salts and iron sulfide, which is formed by the interaction found in produced water iron ions with hydrogen sulfide. In the method of preventing deposition of mineral salts and iron sulfide by treatment produced during oil extraction water phosphorus-containing reagent with additive and injection of the treated water into the reservoir, as an additive is injected aqueous solution of nitrates of alkali metals or an aqueous solution of ammonium nitrate at a ratio of phosphorus-containing reactant : Supplement 1:1 to 1:4. 13 table.

The invention relates to the production of oil, namely the prevention of deposits of mineral salts and iron sulfide in wells and oilfield equipment.

A known method of preventing deposition of sulfate and calcium carbonate by treatment with the scale inhibitor, in which the inhibitor use meritoriously remainder nitrilotriethanol acid N(CH2PO3H2)3(A. C. of the USSR №893900, 02 F 5/10, 1981). However, this connection is ineffective to prevent salt deposits that contain both sulfates, carbonates of calcium, magnesium and iron sulfide.

There is a method of preventing deposition of mineral salts and iron sulfide, providing for the use of the scale inhibitor water solution trinational salt nitrilotriethanol acid and organic amine (patent RF №2140522, E 21 In 37/00, 1999). The disadvantage of this method is the relatively low efficiency of prevention of mineral salts in the presence of iron sulfide.

Known composition to prevent deposits of inorganic salts and the method of its production on the basis of oksietilidendifosfonovaya acid (A. C. of the USSR №916442, IPC302 F 5/14, 1982). However, the known composition does not prevent the deposition of iron sulfide and does not neutralize hydrogen sulfide.

There is a method of preventing deposition of mineral salts and iron sulfide in oil production by treating produced water with an aqueous solution trinational salt nitrilotriethanol acid with the addition of maleic acid and upload obratil to the technical essence and the achieved effect. The disadvantages of this method are the relatively low efficiency of prevention sulfidogenic precipitation at high iron content in produced water.

The task of the invention is to provide a method which enables to effectively prevent the formation of deposits of mineral salts and iron sulfide, which is formed by the interaction found in produced water iron ions with hydrogen sulfide.

The problem is solved in that in the method of preventing deposition of mineral salts and iron sulfide by treatment produced during oil extraction water phosphorus-containing reagent with additive and injection of the treated water into the reservoir, as an additive is injected aqueous solution of nitrates of alkali metals or an aqueous solution of ammonium nitrate at a ratio of phosphorus-containing reactant: Supplement 1:1 to 1:4.

The ratio of the components can be adjusted depending on the content of dissolved iron in produced water (table.1).

The phosphorus-containing reagent is used nitrilo-Ametistov is or snpch-5301 and others, and as an aqueous solution of alkali metal nitrate using sodium nitrate (NaNO3) or potassium nitrate (KPO3) or ammonium nitrate (NH4NO3).

Aqueous solutions of nitrates of alkali metals or an aqueous solution of ammonium nitrate at a concentration of 17-35% is used as a neutralizer of hydrogen sulfide, thereby preventing the formation of iron sulfide.

When processing produced water containing inorganic salts, iron ions and hydrogen sulfide by the proposed method is the binding of anions and cations, including iron ions in water-soluble complexes. Simultaneously there is also the complete neutralization of hydrogen sulfide in aqueous solutions of nitrates of alkali metals or ammonium.

Of scientific-technical and patent literature known to the application of the composition to prevent deposits of inorganic salts by introducing oksietilidendifosfonovaya acid and ammonium salt (A. C. 916442, IPC 02 F 5/14, 1982). However, this technical solution the aim of the invention is to increase the degree of prevention of sulphate deposition of calcium, magnesium and barium. The claimed technical solution the aim of the invention is to prevent Obrosova scale inhibitor simultaneously with the prevention of deposition of carbonates and sulphates of calcium and magnesium binds iron ions, forming iron complexes, and also has kristallographie properties. The addition of nitrates of alkali metals or of ammonium nitrate allows you to shift the equilibrium in the direction of increasing the solubility of compounds of iron, calcium and magnesium, synergistically enhances the effect of inhibitors to prevent the formation of deposits of mineral salts, including iron sulfide, and neutralizes the hydrogen sulfide. The proposed method is more versatile, as it provides for the use of the multivariate structure, which achieves the goal of the project. Thus, the claimed technical solution meets the criterion of “inventive step”.

For implementing the method have been used reagents with the following physico-chemical properties.

Nitrilotriacetate acid (NTF) is produced according to TU 6-09-5283-86. Purpose scale inhibitor forms stable complexes with a number of cations.

The aggregate state is a crystalline powder

Color - white

Temperature

ignition of aerospace,With +370

Samovol the

1 Oksietilidendifosfonovaya acid (OEDPK) produced according to TU 6-02-1215-81. Purpose scale inhibitor forms strong complexes with many cations, including alkali-earth and transition metals.

The aggregate state is a crystalline powder

Color - white

Temperature

ignition of aerospace,C above +340

C aerogel,With +221

Solubility - well in water, acids, alcohols, alkalis, methanol and ethanol.

INCREA-1, composite reagent, active beginning which are nitrilotriacetate acid, methyliminodiacetic acid, produced according to TU 6-09-5363-87. Purpose scale inhibitor has a complexing and kristallographie properties.

Physical state - liquid

Density, kg/m3- 1300 1400...

Color - green

The smell is weak, specific

pH 1,5...2,0

Freezing point,With below -40

Solubility in water (fresh and reservoir) good, ladet the properties of strong acid, not flammable, not explosive.

Snpch-5311, composite phosphorus-containing reagent, produced according to TU 39-05765670 OP-233-97, with var. No. 1, 2. Purpose scale inhibitor has a complexing and kristallographie properties.

Snpch-5312, composite phosphorus-containing reagent, produced according to TU 2458-261-05765670-99. Purpose scale inhibitor has a complexing and kristallographie properties.

Physical state - liquid

Density, kg/m3- 1072

Color is light to dark yellow

The smell is essential

pH 1,0 1,8...

Freezing point,With below -40

Solubility in water

Snpch-5312 - the substance is moderately hazardous, according to the degree of impact on the human body belongs to the 3rd class of hazard, combustible and explosive at elevated temperatures.

Snpch-5313, composite phosphorus-containing reagent, produced according to TU 2458-265-05765670-99. Purpose scale inhibitor has a complexing and kristallographie properties.

Snpch-5314, composite phosphorus-containing reagent, produced according to TU 2458-262-05765670-99 with ISM. No. 1.ASS="ptx2">

Sodium nitrate NaNO3(sodium nitrate) is produced according to GOST 828-54 in the form of a crystalline powder and may contain a composition of not less than 16.1% nitrogen, 0.5% chloride, 0,03 0,04...% oxidizable substances, insoluble residue of 0.15% and 1.5... 2% water. Known field of application: agriculture fertilizer. In the proposed method enhances the validity of the scale inhibitor to prevent the formation of deposits of inorganic salts, including iron sulfide, and neutralizes the hydrogen sulfide.

The aggregate state of dry substance

Density, kg/m3- 1250 1300...

Color - white with a yellowish sheen

The melting point With + 169,6... 170,4

Solubility in water and other solvents

Potassium nitrate KNO3(potassium nitrate) is produced according to GOST 1949-65 in the form of a crystalline powder and may contain a composition of not less than 98% KNO3, 0.1% chloride, 0,03 0,04...% carbonate, insoluble residue of 0.03% and 0.2...2% water. Known field of application: agriculture fertilizer. In the proposed method enhances the validity of the scale inhibitor to prevent the formation of deposits is standing - dry matter

Density, kg/m3- 1280 1490...

Color - white

Melting point, °C +169,6... 170,4

Solubility in water and other solvents

Ammonium nitrate NH4NO3(ammonium nitrate) is produced according to GOST 2-65 grade B in granular form and may contain a composition of not less than 34.2% of nitrogen, 0.5 to 1.2% phosphate (in terms of P2O5), 0,3... 0,6% of the nitrates of calcium and magnesium (in terms of Cao) and not more than 0.2% substances insoluble in 10% nitric acid. Known field of application: agriculture fertilizer. In the proposed method enhances the validity of the scale inhibitor to prevent the formation of deposits of inorganic salts, including iron sulfide, and neutralizes the hydrogen sulfide.

The aggregate state of dry substance

Density, kg/m3- 1690...1725

Color - white with a yellowish sheen

Temperature

melting With +169,6... 170,4

Solubility in water and other solvents

As a concrete example of the use of the proposed method was preparing a composition consisting of phosphorus-containing Leah or ammonium nitrate) in aqueous solution in the mixing ratio 1:1...1:4.

Next, on the basis of this composition was prepared 1% aqueous solution, which was tested on the effectiveness of inhibition.

Preparation of a 1% aqueous solution of the composition

In volumetric flask add 1 g of mixture and bring distilled water volume up to the mark.

The effectiveness of the recommended method of inhibiting scale deposition and scavenging of hydrogen sulfide was estimated using the same methodology adopted in Bashneft, based on the ability of the reagent to hold cations CA2+in the amount of artificially prepared mineral water carbonate and sulfate types with added iron ions and hydrogen sulphide, modeling produced water oil fields of Bashkortostan. Synthetic water was prepared as follows:

Carbonate water

The first solution, g/DM3:

NaHCO32,3

The second solution, g/DM3:

Caso32,92

MgCl6N2About 4.26 deaths

NaCl 40,4

Sulfate water

The first solution, g/DM3:

Na2SO4 13,0

NaCl 18,8

MgCl6H2O 1,24

In a flask with a capacity of 100 ml was made by pipette specified amount of 1% solution of the test composition of reagents. Then there was added 50 ml of a 1 artificially prepared carbonate or sulfate water, the products were mixed, then adding a solution of 2 carbonate or sulfate water in a 50 ml flask was added a given amount of solution Fl3. The sample was saturated with hydrogen sulfide concentrations up to 100 mg/DM3. After thorough mixing, the sample was kept at 80C for 6 hours. At the same time put a control sample without the addition of the reagent. The sample was filtered hot and the filtrate trigonometricheskom method was determined by the content of calcium ions and iron, and the effect of neutralization of hydrogen sulfide was determined by iodometric method. Each experiment was carried out in the twofold repetition.

Protective effect of inhibition of inorganic salts was determined by the formula:

E=(Cx-Cabout)/(Cand-Cabout),

where e, % - protective effect;

WITHx(mg/DM3- the content of sedimentation ions in solution in the presence of inhibitory composition, after a certain experience;

Withis after a certain experience;

WITHand(mg/DM3- the content of sedimentation ions in the original solution, determined by prior experience.

Protective effect on the neutralization of hydrogen sulfide was determined by the formula:

E=(Cx-Cabout)/(Cand-Cabout),

where e, % - protective effect;

WITHx(mg/DM3the content of hydrogen sulfide in solution in the presence of inhibitory composition, after a certain experience;

WITHomg/DM3the content of hydrogen sulfide in solution, not containing inhibitory composition, after a certain experience;

WITHand(mg/DM3the hydrogen sulfide concentration in the original solution, determined by prior experience.

The results of the tests are presented in table. 2-11.

From the experimental data it follows that the proposed method effectively prevents the formation of mineral salts and iron sulfide, and neutralizes the hydrogen sulfide.

The results of industrial tests of the effectiveness of treatment of wells conducted in the quotarlanneft “ANK “Bashneft” on the proposed method, a composition Increta:NH4NO3shown in the table. 12, and the composition snpch-5312:NaNO3- in table.13.

1... 1:3)

Technical and economic advantage of the proposed method is higher compared to the prototype, the efficiency of inhibition of scale deposition of inorganic salts with iron sulfide, as well as complete neutralization of hydrogen sulfide in crude production, reducing the consumption of expensive scaling inhibitors and increase the duration of the protective effect 1.3... 1.5 times.

Composition of reagents have universal scope, as inhibit the deposition of a whole series of salts (carbonates, sulfates and complex by processing produced in oil-water phosphorus-containing reagent with additive and injection of the treated water into the reservoir, characterized in that the additive is injected aqueous solution of nitrates of alkali metals or an aqueous solution of ammonium nitrate at a ratio of phosphorus-containing reactant : Supplement 1:1 to 1:4.

 

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