RO122970B1 - Scale inhibitor with controlled effect and method for applying the same - Google Patents

Abstract

The invention relates to a scale inhibitor meant to be used in oil and gas industry and in the field of geothermal waters and to a method for using the same. According to the invention, the scale inhibitor consists of a liquid component comprising ammonium polyacrylate, a surface-active agent of the nonyl-phenol-ethoxylate type of an HLB value higher than 10 and a complexing agent of the citric acid type, and a solid component of the type of a zinc salt of ammonium polyacrylate, the mass ratio between the solid component and the liquid component varying in the range of 1:3...1:10. The claimed method for applying the corrosion inhibitor consists in introducing the inhibitor components into the well bore, either by gravity or by pressure, through the pipe column or through the annular space, the solid component being introduced in a first stage and the liquid component in a second stage.

Description

The invention relates to a crust inhibitor with controlled action and to a method of its application for mineralized waters of the oil and gas industry.

It is known that the transport of mineralized water through the extraction - transport - storage facilities and equipment of the oil and gas industry leads, in time, to the formation of inorganic deposits. These deposits, also called crusts, are mainly composed of salts of alkaline-earth metals (for example, calcium carbonate, calcium sulfate, barium sulfate), which are formed due to disturbance of thermodynamic conditions (temperature, pressure variations) or as a result of mixing incompatible waters (for example, sulphatic waters with chlorocalcic waters). The presence of inorganic deposits (crusts) on solid surfaces (metal, deposit rock) generates a number of difficulties, such as: reducing the flow section to blockage, pipe breaks (tubular material), excessive pressure, frequent interventions to remove the crusts (chemical or mechanical), corrosion phenomena associated with chemical dissolution, etc.

Crust inhibitors (inorganic, organic chemicals) are used to reduce these problems. These inhibitors, in concentrations in the range of 1-50 ppm, act on the crystallization germs that appear in the initial stage of crust formation, destabilizing their growth process through different mechanisms: steric hindrance, dispersion, flocculation. Crust inhibitors can be selected from a wide range of classes of molecular or macromolecular chemicals, which have various functional groups: carboxylic, sulfonic, phosphonic, sulfate, aminophosphonic, aminocarboxylic.

For production wells in the oil and gas industry, inorganic crusts become a problem when their area of occurrence is signaled near the well and on the wells in the well. In order to prevent the formation of crusts in these areas, conventional treatments are used, based on the use of a diluted inhibitor solution (about 1% by mass) for injection into the layer or for dosing it in the fluids produced with a metering pump.

The injection in the layer implies the following disadvantages: it is applied to wells that produce with more than 70% impurities, it requires a series of chronophagic tests on the compatibility of the solution polymer - fluid produced - rock, it presents a risk of blocking the well by precipitation - adsorption of the polymer, expensive for flow rates. large, high cost cost per operation.

The use of the metering pump has the following disadvantages: high cost price for equipping the probe with metering pump, the need for additional equipments (heaters), necessary for the rooms with inhibitor solutions during the cold year, not economical for the isolated probes, as well as for the extension to more wells.

A new possibility of overcoming the difficulties encountered in applying conventional methods of crust inhibition is the placement of a crust inhibitor, in solid state, upstream or downstream of the perforations area of the production well. The solid inhibitors used are based on synthetic organic monomolecular and macromolecular products which are chemically precipitated (US 5377758, 5346010, 5346009), dispersed in colloidal systems (US 6135207).

The disadvantage of solid inhibitors is that the probe closure time of up to 48 hours is required to ensure the effective concentration of inhibition of crust formation through dissolution and diffusion processes.

The technical problem that the invention solves consists in the creation of a crust inhibitor that provides a controlled action, which allows the production probe to be restarted immediately after its placement in the established location.

RO 122970 Β1

The controlled action crust inhibitor according to the invention is bicomponent, with 1 a liquid component of density 1.1 ... 1.25 g / cm ³ , preferably 1.15 g / cm ³ , containing an anionic macromolecular compound, ammonium polyacrylate type, in a mass concentration of 3 10 ... 30%, preferably 20%, a surfactant with HLB> 10, nonylphenolethoxylate type, by mass 10% to 25%, preferably 17.5%, a complexing agent, citric acid type, in concentration 3 ... 8%, preferably 5.5% and a solid component, density 1,2 ... 1,8 g / cm ³ , preferably 1 , 45 g / cm ³ , of the zinc salt type of ammonium polyacrylate, with a controlled rate of 7 dissolution in mineralized waters, 2 ... 10 g / m ³ water, preferably 5 g / m ³ water, in a temperature range between 30 and 120 ° C. 9

The method of applying the inhibitor defined above, to prevent the formation of crusts on solid surfaces in the probe, by periodic treatment, which ensures the dose of 1 to 11 10 ppm inhibitor, according to the invention, is that the introduction of the inhibitor components into the probe gravitationally or under pressure, by means of tubing or through the annular space 13, in the first phase introducing the solid component, and in the second phase, the liquid component, the solids utilization ratio being 1/3 ... 1/10, de preference 1/6. 15

The crust inhibitor according to the invention consists of a liquid component and a solid component, of which, the liquid component consists of a synergy mixture, 17 viscous structure, which comprises an anionic macromolecular compound or anionic macromolecular compound mixture, such as sodium or ammonium polyacrylate 10-19

40%, polyaminophosphonic-co-carboxylic acid, polyacrylamide-co-acrylate of ammonium, etc.), polybase, organic complexing agent (eg ethylenediaminetetraacetic acid, citric acid, 21 tartaric acid, nitrilotriacetic acid), as a simple or in mixture, a surfactant hydrophilic with HLB> 10, nonionic (for example, alkylphenolietoxylates, ethoxylated fatty alcohols) or anionic (for example 23, sulphated alkylphenolietoxylates, alkylphenols sulphonates) or a mixture of surfactants, respectively the solid component which is obtained by a chemical precipitation from a macromolecular compound or mixture of macromolecular compounds having ionizable functional groups (eg, carboxylic, sulfonic, phosphonylated) (for example, polyacrylates (acrylate-co-acrylamide)), water-soluble salts of polyvalent metal ions ( for example, CaCl ₂ , CuCl ₂ , ZnCl ₂ , ZnSO ₄ , cadmium acetate, zinc acetate 29 etc.), complexing agents or polybase hooks (for example, ethylenediaminetetraacetic acid, citric acid, tartaric acid, nitrilotriacetic acid). 31

The two-component crust inhibitor, according to the invention, acts as a growth inhibiting agent of crystallization nuclei formed in mineralized waters, thermodynamically disturbed 33 in the process of producing the well, ensuring an efficient concentration of inhibition when the well in the production is restored, through the liquid component, up to when establishing the chemical equilibrium of dissolution - diffusion between the solid component and the water produced.

By applying the invention, the following advantages are obtained: 37

- simplification of the treatment technology (gravitational placement through tubing or through the annular space), 39

- reducing the operating costs of production wells by reducing the number of interventions at the well;

- restarting the probe immediately after the completion of the placement of the two-component crust inhibitor in the established location;

- thermal (120-130 ° C) and chemical stability;

- reducing the ecological impact; 45

- prevention of technical accidents due to crusts;

- controlled dissolution rate.47

RO 122970 Β1

The following is an example of an embodiment of the two-component crust inhibitor according to the invention, in conjunction with Tables 1-4, which respectively represent:

- table 1 - the physico-chemical characteristics of the reservoir waters;

- Table 2 - efficiency (E%) of liquid and solid inhibitors in mineralized waters;

- table 3 - technical data on the candidate probes;

- Table 4 - the results of the application of the product on site, according to the invention MZAC ₃₀

According to the invention, the liquid component is prepared, comprising ammonium polyacrylate, commercially called MEDAMON 30B, citric acid and oxyethylated nonylphenol, called NF-10. Prepare an aqueous solution of citric acid, in a percentage between 3.5 and 7%, preferably 5.5%, which, used in the mass ratio of 15-25%, preferably 21%, is mixed with a solution of ammonium polyacrylate (MEDAMON 30B), with a mass concentration of 10-30%, preferably 20%, used in a mass ratio of 50 to 70%, preferably 60%. Nonylphenolpolyethoxylate (NF-10) is added by mass percentage of 15 to 25%, preferably 17.5%. The working temperature is between 20 and 45 ° C, preferably 30 ° C.

The solid component of the crust inhibitor is prepared, comprising ammonium polyacrylate (MEDAMON 30B), citric acid and zinc acetate. An aqueous solution is prepared, which contains citric acid in a mass concentration of between 1 and 7%, preferably 3.3%, and zinc acetate in a mass concentration of between 5 and 20%, preferably 6.6%. This aqueous solution of citric acid and zinc acetate is mixed in mass percentages between 30 and 80%, preferably 56%, with a solution of ammonium polyacrylate (MEDAMON 30B), with the mass concentration of macromolecular compound between 10 and 40 %, preferably 20%, by mass mixing ratio between 0.9 and 1.6, preferably 1.33.

The working temperature is between 30 and 750 ° C, preferably 60 ° C. It works with agitation. The product obtained after precipitation and filtration is processed in different forms (sticks, granules), after which it is dried at a temperature between 20 and 60C, preferably 40 ° C, for 1-5 days, preferably 3 days. A hard solid product with a density between 1.2 and 1.8 g / cm ³ is obtained, preferably 1.5 g / cm ³ .

The efficiency of the liquid product, respectively solid, realized according to the presented example, named MZAC ₃₀ , is tested in terms of the ability to reduce calcium carbonate deposits, as a crust inhibitor, according to the internal methodology, which is to maintain for 24-72 h, at elevated temperatures, 40-100 ° C (closed systems), of water samples treated in 5-25 ppm doses, and the formed deposits are filtered, acidified, the Ca ²⁺ ions passed in solution being quantitatively determined by complexometric method (STAS 3662/90). '

The tests are performed on samples of reservoir water from the Turnu structure, belonging to the Arad Oil Scale, taken according to STAS SRIISO 5667-70, which due to the physico-chemical characteristics (mineralization 18-25 g / l, hardness 20-70 g °, contained in bicarbonic ions of 3-6 g / l) has a high potential for depositing calcium carbonate-type crusts, under the conditions of changing the thermodynamic parameters (table 1).

Table 1

The physico-chemical characteristics of the reservoir waters

The provenance of the water sample The type of water Group Subgroup Hardness (g ') Content of HCO ₃ 'ions (mg / l) The deposit (mg / l CaCO ₃ ) formed at 70'C Probe A NaHCO ₃ BUT N / A 24 6039 205.3 Probe B NaHCO ₃ BUT N / A 62.8 4087 285.6

RO 122970 Β1

The efficiency of the liquid product, respectively solid, realized according to the example presented, is presented (table 2) compared to the conventional inhibitors used in S.N.P. PETROM SA, such as acrylic acid copolymers (eg FRC 12), acrylamide-sodium acrylate copolymers (eg AS 3, AS 4), polyacrylates (eg MEDAMON 30 B) etc. at their doses optimal for the prevention of crusts.

The test results highlight the effect of increasing the efficiency in preventing the deposition by 40-50% of the precipitated inhibitors, realized according to the presented example, in the concentration range studied, indicating a maximum efficiency at 7 ppm, over 90%.

Table 2

Efficiency (%) of liquid and solid inhibitors in mineralized waters

The provenance of the water sample inhibitor Inhibitor dose (PPm) Deposition (mg / l CaCO ₃ ) of the waters treated with: Liquid inhibitor E (%) Precipitated inhibitor E (%) Probe A FRC12 0 180.36 - 180.36 - 7 125.35 30.5 34.27 81 10 120.66 33.1 21.64 88 MEDAMON 30B 0 180.36 - 180.36 - 7 92.7 48.6 12.63 93 10 107.3 40.5 18.04 90 AS-4 0 180.36 - 180.36 - 7 133.1 26.2 63.13 65 10 126.25 30 57.72 68 Probe B FCR12 0 147.79 - 147.79 - 7 102.7 30.5 22.17 85 10 92.68 37.5 14.78 90 MEDAMON 30B 0 147.79 - 147.79 - 7 65.76 55.5 8.87 94 10 75.96 48.6 26.60 82 AS-3 0 147.79 - 147.79 - 7 118.08 20.1 76.11 48.5 10 143.65 2.8 67.54 54.3

The fields of application of the liquid product, respectively solid, realized according to the example 47 presented, named MZAC ₃₀ , are the wells of production in pump / gas-lift, with bag, whose produced fluids have a high percentage of impurities generating crusts, waters of 49 injection, the geothermal waters, the product being usable in solid-liquid form in the ratio 1/3 ... 1/10, preferably 1/6. 51

RO 122970 Β1

The efficiency of the MZAC ₃₀ product has also been tested under construction conditions. Two candidate wells, A and B, are selected from the Turnu structure, taking into account the following criteria: the frequency of interventions at the wells, caused by the formation of calcium carbonate deposits, the areas with deposits indicated on the path of the fluid flow extracted, from the level of impurities and the size of the probe bag (table 3),

Table 3

Technical data on candidate wells

Probe H (M) T CC) You. Bag" (I) Average flow (m ³ water / day) Impurities (%) ' Location of crusts Frequency of interventions caused by the formation of crusts A 931 70 66 19 90 - tubing - pump - mix line - acidification (1 / 3-5 weeks) - treatment with FRC 12 * liquid inhibitor (1 / 4-6 weeks) B 949 70 613 16 89 - tubing - pump - mix line - acidification (1 / 2-4 weeks) - treatment with FRC 12 * liquid (1 / 2-4 weeks)

* In a treatment with FRC 12 liquid crust inhibitor, use 10 m ³ diluted solution (3-10%), which has antifoam effect 2-5 weeks

For the treatment of the two probes, in calculating the quantities of MZAC _3D product (liquid and solid), necessary to obtain an anti-deposition effect for a minimum of 4 months, the average water flow of the wells and the dissolution rate of the solid component at 70 ° C, which is 3-6 g / m ³ water, preferably 5 g / m ³ water, in water having the characteristics presented in table 1.

The densities of the liquid and solid components of the MZAC ₃₀ product, realized according to the presented example, allow their gravitational placement in the probe bag, either by tubing or through the annular space.

The results of the site experimentation are shown in table 4.

The experimental data confirm the efficiency of the precipitated crust inhibitor MZAC ₃₀ , according to the invention, in the sense of preventing 100% for 6 months of carbonate deposits in both the wells and the associated mixing lines and reducing the costs caused by deposits by 85%.

RO 122970 Β1

Table 4

The results of the application on site of the treatment with the product MZAC ₃₀ , according to the invention

Probe Quantities MZAC ₃₀ used MZACjq product introduction mode in the probe Location of control samples The crust formed (mg CaCO ^{3/100 m3} of water E (%) Observations during treatment Comp. A (l) Comp. B (kg) before treatment within 6 months of treatment A 100 17 gravity through tubing in the probe 5840 0 100 there were no interventions due to carbonates in-line mix (at the well) 300 0 100 in line mix (at the park) <100 0 100 B 100 16 gravitational through the column in the probe 7538 0 100 there were no interventions due to carbonates in-line mix (at the well) 443 0 100 in line mix (at the park) <100 0 100

Claims (2)

1.1 ... 1.25 g / cm ³ , preferably 1.15 g / cm ³ , containing an anionic macromolecular compound, ammonium polyacrylate type, in a mass concentration of 10 ... 30%, preferably 20%, a surfactant with HLB > 10, nonylphenolethoxylate type, by mass 10% to 25%, preferably 17.5%, a complexing agent, citric acid type, in a concentration of 3 ... 8%, preferably 5.5% and a component solid, density 1,2 ... 1,8 g / cm ³ , preferably 1,45 g / cm ³ , of the zinc salt type of ammonium polyacrylate with controlled dissolution rate in mineralized waters, 2 .. .10 g / m ³ water, preferably 5 g / m ³ water, in a temperature range between 30 and 120 ° C. 1. Crust inhibitor with controlled action, for mineralized waters from the oil and gas industry, and for geothermal waters, with synergistic action of washing the solid contact surfaces and preventing the formation on them of inorganic deposits, carbonate type, characterized by that is two-component, with a liquid density component 2. Method of applying the inhibitor defined in claim 1, to prevent the formation of crusts on solid surfaces in the well, by periodic treatment, providing the dose of 1 to 10 ppm inhibitor, characterized in that the insertion of the inhibitor components in the well can be done. gravitational or pressure, through tubing or through the annular space, in the first phase introducing the solid component, and in the second phase, the liquid component, the solid use ratio: liquid being 1/3 ... 1/10, de preference 1/6.