EA007769B1

EA007769B1 - Dry-acidic compositions for treating terrigenous reservoirs and de-argilization of well bottom zone

Info

Publication number: EA007769B1
Application number: EA200500655A
Authority: EA
Inventors: Елена Александровна Румянцева; Кирилл Владимирович Стрижнев; Марина Владимировна Лапшина
Original assignee: Елена Александровна Румянцева; Ахмеджанов, Алиби Хакимович; Антонников, Алексей Владимирович
Priority date: 2004-10-07
Filing date: 2005-05-16
Publication date: 2006-12-29
Also published as: EA200500655A1; RU2272904C1; RU2004129513A

Abstract

The invention relates to oil and gas producing industry, in particular to acidic treatment of terrigenous reservoirs and de-argilization of formations. The acidic composition does not form sediments when mixing with stratal minerilized water and has low corrosive activity. A dry-acidic composition for treating terrigenous reservoirs and for de-argilization of well bottom zone comprises ammonium fluoride or ammonium bifluoride or ammonium bifluoride fluoride, sulfanic acid, phosphoro-containing complexon – a phosphonic acid derivative such as oxyethylidenphosphonic (OEDP) or nitriletrimethylphosphonic (NTP) acids, and ammonium chloride with the following amount thereof in aqueous solution of the dry-acidic composition, wt %:

Description

The invention relates to the oil and gas industry and can be used in acid treatments and clay bottomhole formation zones.

Known acid composition containing hydrochloric acid, ammonium bifluoride or hydrofluoric acid, aliphatic alcohol and vat residue of the production of butyl alcohols by the method of oxosynthesis [KI 2013528 C1, 03.07.1991].

The disadvantage of this composition is that as the acids are neutralized and the pH of the solution in the reservoir increases, there is a risk of the formation of gel-like precipitates of iron hydroxide. In addition, the working components of the composition are liquids, which is inconvenient during its storage and transportation to hard-to-reach wells.

Known acid composition containing ammonium bifluoride and sulfamic acid (VP Shalinov and others. Physico-chemical methods to increase the productivity of wells. Thematic scientific and technical review.- M .: VNIIENG, 1974, p. 36-37).

The disadvantage of this composition is that at a temperature of 50 ° C begins the deposition of sulphate precipitates, resulting from the hydrolysis of sulfamic acid.

Known acid composition containing ammonium fluoride, sulfamic acid in an amount of not more than equimolecular and water-soluble surfactant [KN 2101482 C1, 01/10/1998].

However, its heat resistance does not exceed 85 ° C, which limits the possibility of its use for processing high-temperature (over 90 ° C) terrigenous collectors. In addition, the disadvantage of this composition is that when mixed with formation waters containing potassium, sodium and calcium salts, solid and gel-like sediments are formed, which leads to clogging of the pore channels and decrease in the effectiveness of acid treatment.

The closest in technical essence and the achieved result is an acid composition for treating terrigenous collector, containing, wt.%: Ammonium fluoride 0.56-18.50, or ammonium bifluoride 0.43-14.25, or ammonium bifluoride-fluoride 0, 51-17.0, sulfamic acid in the amount of not more than equimolecular and lignosulfonates in the amount of 0.5-0.7 [КН 2182963 С1, 01.03.2002]. The disadvantage of this composition is also its incompatibility with formation waters, i.e. loss of solid and gel precipitation when mixed with saline waters.

The aim of the present invention is to develop a thermostable dry acid composition, when mixing an aqueous solution of which with saline stratum waters, no precipitates form.

This goal is achieved by offering a dry-acid composition for treating terrigenous reservoirs and fracturing the bottom of the well, which is found in the beginning of the first half-8 (NTF) acid, and ammonium chloride with the following amount in an aqueous solution of the dry acid composition, wt. %:

Ammonium fluoride

Ammonium bifluoride

Ammonium bifluoride-fluoride

Sulfamic acid

0.56-18.50

0.43-14.25

0.51 -17.00

In equimolecular ratio

The specified phosphorus complexone 0.01-2.0

Ammonium Chloride 0.1-3.0

Water Rest

Ammonium fluoride is a colorless crystalline substance, density at 25 ° С: 1010 kg / m ³ . Solubility in water at 20 ° С: 74 g / 100g. Available in accordance with GOST 4518-75.

Ammonium bifluoride is a colorless crystalline substance, density at 2525 ° С: 1010 kg / m ³ . Solubility in water at 20 ° С: 39.8 g / 100g. Available in accordance with GOST 954675.

Ammonium bifluoride-fluoride is a mixture of ammonium bifluoride double salt and ammonium fluoride.

Sulfamic acid is a colorless crystalline substance, refers to strong acids (dissociation constant at 25 ° C: 1.01-10 ^-1 ). Solubility of sulfamic acid in water at 20 ° С: 14.7 g / 100g. Produced according to TU 2121-400-05763441-2002.

Ammonium chloride is a white crystalline powder. Solubility in water at 20 ° С: 29.4 g / 100g. Available in accordance with GOST 3773-72.

Hydroxyethylene diphosphonic acid (HEDP) is a powder from white to gray color, well soluble in water, is used according to TU 2121-400-05763441-2002.

The main working component of the composition, dissolving quartz, silicate material and terrigenous collector kaolin hydrofluoric acid, is obtained as a result of the reaction between the components when dissolved in water according to the following reaction equations:

- 1 007769

ΝΗ ₄ Ρ + ΝΗ28Ο3Η = ΝΗ28Ο3ΝΗ4 + NOT (1)

ΝΗ ₄ Ρ * ΗΡ + ΝΗ ₂ 8Ο ₃ Η = ΝΗ ₂ 8Ο ₃ ΝΗ ₄ + 2ΗΡ (2)

Upon contact of hydrofluoric acid with reservoir waters containing sodium and potassium ions, insoluble salts are formed: sodium hexafluoro silicate Να ₂ 8ΐΡ ₆ and potassium Κ ₂ 8ΐΡ ₆ in the form of gel precipitates. When interacting with water containing calcium ions, partially soluble calcium fluorosilicate CA81P _{6 is formed} . A terrigenous reservoir may contain a small amount of carbonate rock (up to 10%), when interacting with hydrofluoric acid, a solid precipitate of calcium fluoride - CaP _{2 is formed} .

During the operation of wells, a large amount of iron ions with injected water is additionally introduced into the formation and during hydrochloric acid treatments. The increased iron content in the reservoir and in the saline reservoir waters during acid treatment leads to the formation of bulk gel-like precipitates of iron hydroxide already at a sufficiently low pH value (Table 1).

Table 1

No Hydroxide PH value Start of precipitation at initial concentration of precipitated ion Total precipitation 1M 0.01M one Re (OH) ₃ 1.5 2.3 4.1 2 Gay (OH) ₂ 6.5 7.5 9.7

Precipitates formed by mixing a solution of hydrofluoric acid with saline waters of the reservoir and its interaction with calcite rocks clog the microchannels of the pore space of the rock, reducing the filtration characteristics of the reservoir or completely blocking the treated zone, which significantly impairs the efficiency of acid treatment.

In order to prevent the formation of precipitates, phosphorus-containing complexones and ammonium chloride are introduced into the acid composition in an amount of 0.01-2.0 wt.% And 0.1-3.0 wt.%, Respectively.

Phosphorus-containing complexones, phosphonic acid derivatives - hydroxyethylidene diphosphonic acid (HEDP) and nitrile trimethylphosphonic acid (NTF) exhibit high specificity of interaction with a number of important metal cations. So HEDP contains two, and NTF contains four phosphonic groups capable of complexing in a strongly acidic medium. It is important that such substances bind iron ions into durable soluble complexes, which prevents the formation of gel-like precipitates of iron hydroxide. In addition, phosphorus-containing complexones prevent nucleation in supersaturated solutions and can effectively inhibit the process of scaling.

The introduction of ammonium chloride in an acidic solution prevents the precipitation of fluorosilicates by binding metal ions in solution. In addition, ammonium chloride reacts with calcium carbonate by the reaction

CaCO3 + 2ΝΗ ₄ Са = CaC1 ₂ + (ΝΗ ₄ ) ₂ σθ ₃ (3)

The dissolution of calcite rock with ammonium chloride prevents the formation of calcium fluorides and increases the filtration channels, which increases the overall effect of acid exposure.

The amount of added additives - ammonium chloride and HEDP is determined experimentally, depending on the type and composition of the formation waters of a particular field.

The compatibility of the acid composition with saline waters was assessed visually by the qualitative study of sedimentation by mixing the composition with saline waters. A sign of the incompatibility of the composition with salt water is the formation of precipitation. Precipitation was observed 24 hours after mixing the composition with formation waters. In studying the compatibility of the composition with saline waters, model waters containing calcium and sodium ions according to Table 2 were used. 2

table 2

No Salt Water salinity, g / l 15 40 60 by 260 one ΝαΟ 12.3 30.7 45 90 90 2 CaC1 ₂ 2.7 9.3 15 20 170

- 2 007769

The research results are presented in Table. 3

Table 3

No Content in aqueous solution,% mass Content NOT in water Mineral water analysis, g / l Sediment formation Bfa F Sc HA OEDF solution by reaction,% one 2 3 four five 6 7 eight 9 ten one prototype 0.5 1,3 0.3 15 Sediment obp. '' R 2 prototype 0.5 1,3 0.3 110 Sediment arr 3 prototype 1.0 1.7 0.7 15 Sediment arr four prototype 1.0 1.7 0.7 110 Sediment arr five prototype 3.0 5.1 2.1 15 Sediment arr 6 prototype 3.0 5.1 2.1 60 Sediment arr 7 prototype 3.0 5.1 2.1 110 Sediment arr eight prototype 3.0 5.1 2.1 260 Sediment arr 9 declare 3.0 5.1 3.0 0.01 2.1 15 The precipitate is not arr. ten declare 3.0 5.1 0.5 0.5 2.1 60 The precipitate is not arr. AND declare 3.0 5.1 0.5 1.0 2.1 110 The precipitate is not arr. 12 declare 3.0 5.1 0.5 2.0 2.1 260 The precipitate is not arr.

BPA - ammonium bifluoride,

FA - ammonium fluoride,

SC - sulfamic acid,

XA - ammonium chloride,

HEDP - hydroxyethylidene diphosphonic acid.

As can be seen from the table. 3, the proposed composition (9-21) does not form precipitation upon contact with saline waters, while the composition of the prototype (1-8), when mixed with saline waters, forms gel-like precipitates: fluorosilicates and fluorides. In the case of highly mineralized waters (260 g / l), it is necessary to introduce into the dry acid composition a large amount of complexone (compositions 11, 12, 14, 19 tab. 3).

The precipitation of iron (III) ions in the form of its hydroxide was studied visually. Marble cubes were placed in a heat-resistant fluoroplastic vessel, poured 100 ml of a mixture of salt (model) water containing 80-300 mg / l of ferric ions, and an aqueous solution of dry acid composition in a 1: 1 ratio. The reaction vessel was placed in a water bath (temperature - 60 ° C) for 1 h. The stability of the solution to the precipitation of ferrous sediments was evaluated after the extraction of marble cubes. On the precipitation of iron ions on the surface of the cube shows a reddish solid coating. The results of the experiments are given in table. four.

Table 4

No The number of the composition of the table №3 The content of iron ions in solution, mg / l The formation of iron hydroxide precipitate one 1 (prototype) 80 Sediment arr. 2 5 (prototype) 80 Sediment arr. 3 5 (prototype) 300 Sediment arr. four 9 (declared) 80 The precipitate is not arr. five 11 (claimed) 300 The precipitate is not arr.

From tab. 4 shows that the proposed composition is stable to precipitation of iron hydroxide compared with the prototype, which does not contain complexing agents. With a high content of io

- 3 007769 new iron in the solution, it is necessary to introduce a larger amount of complexone (compositions 11, 12, 14, 16, 17, according to Table 3).

The content of complexones varies depending on the properties of the formation waters of specific fields. For example, for Kharampursky field (Western Siberia) with water mineralization - g / l, composition 10 was selected (Table 3). For Iskrinskoye deposit (Tatarstan) with water mineralization 190 g / l, composition 12 was selected (Table 3).

The effectiveness of the proposed composition is confirmed by laboratory studies performed on filtration plants using bulk linear core models.

Bulk models are metal tubes with a length of 5-10 cm and a diameter of 3.0 cm. When modeling a production well, the core was filled with a mixture of quartz sand fraction <200 μm, bentonite clay and carbonate in the ratio 45:45:10. The prepared core was saturated under vacuum with kerosene to measure the initial permeability, then the water with a salinity of 40 g / l was pumped in the forward direction. At steady state flow, the core permeability after swelling of the clay was determined. Permeability was determined by the formula (4) · ΔΡ ^μ 'where k is the permeability, μm ² , μ is the viscosity of kerosene, cP, and k is the core length, cm,

C) - the specified flow, cm ³ / s

- core area, cm ² ,

LR - pressure drop, atm.

After determining the permeability through the core in the direction opposite to saturation, a solution of dry acid composition was pumped. Displacement of working fluids was carried out with kerosene.

At steady state, the permeability was again determined by the formula (4). Based on the calculated permeabilities, the magnitude of the intensification was determined by the formula (5)

where K ₁ is the mobility of the porous medium before treatment, μm ² ;

K2 - the mobility of the porous medium after treatment, μm ² .

The tests were carried out at a temperature of 90 ° C.

The results of filtration experiments are presented in table. five.

Table 5

No The number of the composition of the table №3 The initial permeability of the core, K1, Permeability of the core after clogging before treatment with the composition, K2 The permeability of the core after treatment with the composition, short-circuit Intensification factor, KZ / K2, times one 1 (prototype) 0.28 0.05 0.06 1.2 2 5 (prototype) 0.28 0.05 0.09 1.8 3 9 (declared) 0.28 0.05 0.17 3.4 four Yu (declared) 0.28 0.05 0.21 4.2

When modeling the injection well, water permeability with a salinity of 40 g / l was determined, the tests were carried out at a temperature of 60 ° C. Calculation of changes in permeability was carried out according to formulas (4,5), as described above. The results of filtration experiments are given in table. 6

Table 6

No The number of the composition of the table №3 Initial core permeability, Κ1 Permeability of the core after clogging before treatment with the composition, K2 The permeability of the core after treatment with the composition, short-circuit Intensification factor, KZ / K2, times one 5 (prototype) 0.27 0.036 0.04 1.1 2 10 (claimed by th) 0.28 0.025 0.07 2.8

From the results of experiments to determine the factor of intensification, are given in table. 5 and 6, it is clear

- 4 007769 that the introduction of complexing additives leads to a slight increase in the coefficient of core permeability recovery, which can be explained by the partial dissolution of the silicate rock with hydroxyethylidene diphosphonic acid and carbonate with ammonium chloride.

Additionally, studies have been conducted corrosion activity of the compositions. The corrosion activity of the compositions was checked by the standard method on metal plates (steel 3) at a temperature of 60 ° C and atmospheric pressure. The research results are presented in Table. 7

Table 7

No The number of the composition of the table №3 Corrosion activity, g / m ² * h one 5 (prototype) 35.45 2 10 (declared) 35.31

Analysis table. 7 allows us to conclude that the introduction of additives does not increase the corrosivity of the composition compared to the prototype.

Thus, the results of laboratory studies allow us to recommend the developed dry-acid composition for treating terrigenous reservoirs and outgrowing the well bottom zone. The composition does not form precipitation when mixed with formation waters, has low corrosiveness and high intensifying ability.

Information sources:

1. The patent of the Russian Federation 2013528, cl. E21 B 43/27, publ. 1994.

2. RF patent 2101482, cl. E21 B 43/27, publ. 1998

3. RF patent 2182963, cl. E21 B 43/27, publ. 2002

4. V.P. Shalinov et al. Physico-chemical methods for increasing well productivity. Thematic scientific and technical review.- M .: VNIIOENG, 1974, p. 36-37.

5. W.W. Razhetdinov et al. Use of ammonium bifluoride-fluoride for well treatment. J. Oil Industry, No. 4, 1984, p. 19-21.

Claims

CLAIM

A dry acid composition for treating terrigenous reservoirs and mudding wells, containing ammonium fluoride, or ammonium bifluoride, or ammonium bifluoride, sulfamic acid, a phosphorus-containing complexon - a derivative of phosphonic acid, such as hydroxyethylidene diphosphonic (nitriethylphosphonate (nitrile EDF) ammonium chloride in the following quantity in an aqueous solution of a dry acid composition, wt.%:

Ammonium Fluoride Ammonium Bifluoride Ammonium Bifluoride Ammonium Fluoride Sulfamic Acid 0.56-18.50 0.43-14.25 0.51-17.00 In equimolecular ratio The specified phosphorus-containing complexone Ammonium chloride Water 0.01-2.0 0.1-3.0 Else

Eurasian Patent Organization, EAPO