Composite iron disulfide scale blocking remover as well as preparation method and application thereof

Abstract

The invention discloses a composite iron disulfide scale blocking remover as well as a preparation method and application thereof. The composite iron disulfide scale blocking remover is mainly prepared from the following raw materials in parts by weight: 15-18 parts of a sulfur dissolving agent, 15-25 parts of a chelating agent, 25-35 parts of an emulsifying agent, 10-20 parts of an organic oxidizing agent and 15-20 parts of water. The composite iron disulfide scale blocking remover is good in iron disulfide scale corrosion effect, the corrosion rate is larger than or equal to 80%, H2S poisonous gas and elemental sulfur corroding and damaging a reservoir are not generated in the corrosion process, the raw materials are wide in source and low in cost, and the composite iron disulfide scale blocking remover is a potential environment-friendly and economical iron-based sulfide blocking remover.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil reservoir development, and particularly relates to a composite ferrous disulfide scale plugging remover, a preparation method and application thereof. BACKGROUND

[0002] High hydrogen sulfide gas well bore plugging is generally caused by various iron-based sulfides. Different stoichiometric iron-based sulfide plugging materials precipitated in the formation or pipeline may cause damage to related production equipment and reduce injection capacity. For example, a thin film of iron sulfide on the surface of steel may cause fouling corrosion, and even promote hydrogen embrittlement.

[0003] Tang Mi et al. (Inner Mongolia Petrochemical Industry, 2020, 46(04): 1-3) disclosed a plugging remover for Yuanba ultra-deep high hydrogen sulfide gas well bore. The plugging material in the well bore is mainly pyrite (FeS2), barite (BaSO4), limestone (CaCO3), formation particles (SiO2), and formation asphalt. Inorganic and organic plugging removers were developed with the goal of "easy flowback, low corrosion, and high dissolution". The inorganic plugging remover formula is hydrochloric acid + corrosion inhibitor, and the organic plugging remover formula is hydrochloric acid + organic solvent + mutual solvent. The plugging remover system has a 100% dissolution rate for the plugging material in 10 minutes at room temperature. This technology mainly uses acid to dissolve the plugging material, and in the process of plugging removal, toxic gas H2S is inevitably produced.

[0004] GB2099022 A1 discloses a method for removing ferrous sulfide deposits from the surface of ferrous metals, in particular a method for removing such deposits without generating free hydrogen sulfide, comprising contacting the ferrous sulfide with an aqueous composition comprising an acid selected from maleic acid, maleic anhydride and alkali and ammonium salts of maleic acid. The plugging remover system does not produce free hydrogen sulfide, but is corrosive and requires the addition of a corrosion inhibitor.

[0005] CN111108174A1 discloses a low-corrosive composition suitable for dissolving scale on a metal, wherein the scale includes iron sulfide scale, the composition comprising: an aqueous hydrogen peroxide solution comprising hydrogen peroxide; and an acidic solution comprising at least one acid, wherein: the concentrations at which the hydrogen peroxide and the acid are present are such that the hydrogen peroxide does not decompose to form visible bubbles at room temperature, the concentrations at which the hydrogen peroxide and the acid are present are such that the iron sulfide scale is removed from the metal having the iron sulfide scale after the composition contacts the metal and the iron sulfide scale at an elevated temperature above room temperature, and the concentrations at which the hydrogen peroxide and the acid are present are such that pitting corrosion is not produced on the metal, the metal including carbon steel. The plugging remover system uses oxidation to remove iron sulfide scale, but the removal process may cause corrosion damage to elemental sulfur precipitation in the reservoir.

[0006] US11591509B2 discloses a new formula for oil and gas well pyrite scale removal and a pyrite scale removal method. The chemical formula is composed of K2B4O7-4H2O, with a concentration of about 9-20% by weight. The new formula can dissolve pyrite without producing toxic H2S, but the plug removal system can still have elemental sulfur precipitation that can corrode the reservoir.

[0007] SPE-192228-MS discloses tetrahydroxymethyl phosphonium sulfate (THPS) as a dissolving agent for controlling iron sulfide (FeS) precipitation in oilfield production systems. It is found that THPS can form a purple complex with ammonium ions, which can significantly improve the dissolution of FeS. The dissolution rate of analytical grade FeS solid and the corrosion of carbon steel at different temperatures are studied. The chemical composition of undissolved FeS solid and the structure of THPS-amine-iron complex are analyzed, the most effective dissolving agent formula is determined, and the field sampling of water injection wells and sulfur-containing gas wells is tested. However, the system has low FeS2 dissolution capacity, and the plug removal effect is poor for gas wells with high FeS2 content.

[0008] The above-mentioned iron-based sulfide plug dissolving system has strong acid corrosion and produces toxic H2S gas, and the oxidation produces elemental sulfur plugging, and the chelating agent has strong specificity. Therefore, a plug removal agent system is needed, which can have a certain dissolution effect on the most difficult to dissolve FeS2 in iron-based sulfides, can effectively inhibit the precipitation of sulfur and the generation of toxic H2S gas, has low corrosion and certain economy. SUMMARY

[0009] In view of the deficiencies of the prior art, the present application provides a composite ferrous disulfide scale remover and its preparation method and application. The composite ferrous disulfide scale remover has good ferrous disulfide scale dissolving effect, with a dissolution rate of ≥80%, and does not produce H2S toxic gas and corrosive elemental sulfur during the dissolution process. The raw materials are widely available and low in cost, making it a potential environmentally friendly and economical iron-based sulfide plug remover.

[0010] In a first aspect of the application, a composite ferrous disulfide scale remover is provided, which is mainly made of the following raw materials: 15-18 parts by weight of a sulfur dissolving agent, 15-25 parts by weight of a chelating agent, 25-35 parts by weight of an emulsifier, 10-20 parts by weight of an organic oxidizing agent, and 15-20 parts by weight of water.

[0011] According to the specific embodiments of the present application, the organic oxidizing agent is at least one of organic peroxide, preferably tert-butyl hydroperoxide, dimethyl ketone peroxide, and peroxoacetic acid.

[0012] According to the specific embodiments of the present application, the sulfur dissolving agent is selected from at least one of substituted or unsubstituted aromatic hydrocarbons, naphthenes, and petroleum distillates, preferably at least one of toluene, xylene, and heavy aromatic oil.

[0013] According to the specific embodiment of the present application, the chelating agent is selected from organic phosphoric acid and / or amino polycarboxylic acid.

[0014] According to the specific embodiment of the present application, the organic phosphoric acid is hydroxyethylidene diphosphonic acid.

[0015] According to the specific embodiment of the present application, the amino polycarboxylic acid is sodium ethylenediaminetetraacetate.

[0016] According to the specific embodiment of the present application, the emulsifier is a fatty alcohol polyoxyethylene ether, preferably having a molecular formula of C m H 2m+1 O(CH2CH2O) n H, and m is an integer of 13-15, and n is an integer of 3-10.

[0017] In the second aspect of the present application, a preparation method of the aforementioned composite ferrous disulfide scale remover is provided, comprising: mixing the chelating agent, the emulsifier and water, and stirring to obtain an aqueous phase; mixing the sulfur dissolving agent and the organic oxidizing agent, and stirring to obtain an oil phase; adding the oil phase into the aqueous phase, and stirring to obtain the composite ferrous disulfide scale remover.

[0018] In the third aspect of the present application, the aforementioned composite ferrous disulfide scale remover is provided for use in dissolving ferrous disulfide.

[0019] In the fourth aspect of the present application, the aforementioned composite ferrous disulfide scale remover is provided for use in plugging removal of the wellbore plugging of the oil and gas well.

[0020] The present application has the following beneficial effects:

[0021] 1. The plugging remover provided by the present application is prepared by using organic oxidizing agent, chelating agent and sulfur dissolving agent as main raw materials. The organic oxidizing agent solves the problems of inorganic oxidizing agent, such as easy decomposition in high-temperature aqueous solution, low oxidation efficiency, slow release and high-efficiency oxidation of ferrous disulfide scale to generate elemental sulfur and iron ions. The chelating agent reduces the oxidation potential of ferrous disulfide scale and has strong complexing ability to iron ions, so that the iron ions generated by oxidation can be combined to avoid secondary precipitation of iron ions. The sulfur dissolving agent is used to dissolve the elemental sulfur. The plugging remover can effectively dissolve ferrous disulfide scale, has high dissolution rate, does not generate toxic H2S gas and corrosive elemental sulfur during the dissolution process, has a wide source of raw materials and low cost, and is a potential environmentally friendly and economical iron sulfide plugging remover.

[0022] 2. The preparation method of the plugging remover provided by the present application mixes the organic oxidizing agent, the sulfur dissolving agent and the chelating agent to prepare a thermodynamically stable, clear and transparent microemulsion. The microemulsion has strong stability and nano structure, can realize slow release of the organic oxidizing agent and rapid dissolution of the precipitated sulfur, continuously moves the dissolution equilibrium, and effectively solves the problem of reservoir damage caused by the release of the organic oxidizing agent in the aqueous phase and the precipitation of elemental sulfur. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the unclogging mechanism of the composite iron disulfide scale unclogging agent, where HL is a chelating agent; [O] is an oxidizing agent; [FeL] is a chelating agent that has chelated iron ions; and [R] is a reducing agent. It is a nanoscale oil phase;

[0024] Figure 2 The particle size distribution of the composite iron disulfide scale unblocking agent in Example 1 is shown. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1

[0027] Add 18g of hydroxyethylidene diphosphonic acid and 20g of water to a 100ml plastic beaker, heat to 50℃ in a 50℃ water bath, and add 26g of tridecanol polyoxyethylene ether-6 surfactant while stirring, so that it is fully dissolved into a homogeneous aqueous solution; add 16g of xylene and 20g of tert-butyl hydrogen peroxide to a 100ml glass beaker, stir at room temperature for 1 hour to obtain a homogeneous organic solution; mix the organic solution and aqueous solution thoroughly in a glass flask to obtain a homogeneous transparent microemulsion, which is the composite iron disulfide scale unblocking agent.

[0028] Example 2

[0029] Add 15g of sodium ethylenediaminetetraacetate and 21g of water to a 100ml plastic beaker, heat to 50℃ in a 50℃ water bath, and add 25g of tridecanol polyoxyethylene ether-9 surfactant while stirring to fully dissolve it into a homogeneous aqueous solution; add 18g of heavy aromatic oil and 21g of peracetic acid to a 100ml glass beaker, stir at room temperature for 1 hour to obtain a homogeneous organic solution; mix the organic solution and aqueous solution thoroughly in a glass beaker to obtain a homogeneous transparent microemulsion, which is the composite iron disulfide scale unblocking agent.

[0030] Experimental Example 3

[0031] Into a 100ml plastic beaker, 25g hydroxyethylidene diphosphonic acid and 15g water were added, heated to 50℃ in a 50℃ water bath, and 35g tridecyl alcohol polyoxyethylene ether-6 surfactant was added while stirring to form a homogeneous aqueous solution. Into a 100ml glass beaker, 15g dimethylbenzene and 10g tert-butyl hydroperoxide were added, stirred at room temperature for 1h to form a homogeneous organic solution. The organic solution and the aqueous solution were stirred in a glass beaker to form a homogeneous transparent microemulsion, which was the composite iron disulfide scale remover.

[0032] Comparative Example 1

[0033] Into a 100ml plastic beaker, 25g hydroxyethylidene diphosphonic acid, 10g hydrogen peroxide and 15g water were added, and stirred to form a homogeneous solution in a 20℃ water bath. 35g tridecyl alcohol polyoxyethylene ether-6 surfactant was added while stirring to form a homogeneous aqueous solution. Into a 100ml glass beaker, 15g dimethylbenzene was added, stirred at room temperature for 1h to form a homogeneous organic solution. The organic solution and the aqueous solution were stirred in a glass beaker to form a homogeneous transparent microemulsion, which was the inorganic oxidant iron disulfide scale remover.

[0034] Test Example 1

[0035] Iron disulfide scale dissolution capacity test: The experiment used analytical pure pyrite, which was crushed into powder less than 40 mesh. The above examples and comparative examples were used for iron disulfide scale dissolution experiments, with hydrochloric acid and peracetic acid as control experiments. The experimental conditions were a 60℃ water bath, reaction for 4h, and after reaction, the reaction mixture was filtered, dried for 24h, and weighed to measure the mass after reaction to obtain the dissolution rate of iron disulfide scale. The reaction amount and dissolution rate were calculated by weighing before and after reaction.

[0036]

[0037] In the formula, R is the dissolution rate, dimensionless; m1 and m2 are the masses of iron disulfide scale before and after reaction (both were dried at 105℃ for 24h before weighing), g;

[0038] Table 1 Results of mixed scale dissolution experiments with 6 dissolution solutions

[0039]

[0040] From Table 1, the maximum dissolution amount of the six kinds of dissolving solutions on the iron disulfide scale within 4h is compared, wherein the dissolution amount of hydrochloric acid is the lowest, and a small amount of H2S is released, which is consistent with the report that hydrochloric acid cannot corrode iron disulfide. In the case of adding only the oxidizing agent peracetic acid, the corrosion efficiency is negative, which is due to the low acidity of the acid solution, resulting in secondary precipitation of iron salt and precipitation of elemental sulfur. The three example samples can effectively dissolve the iron disulfide, and the corrosion rate is more than 80%, wherein the corrosion rate of Example 2 is more than 85%. It is found from Comparative Example 1 that if the oxidizing agent in Experimental Example 3 is replaced by water-soluble hydrogen peroxide instead of organic oxidizing agent, the corrosion rate is greatly reduced, only about 10%. After disassembling the device, it is found that a large amount of gas is generated, which is judged by smell to be oxygen, not H2S. It is indicated that the inorganic oxidizing agent is easy to release oxygen quickly under the catalysis of iron ions, which reduces the oxidation efficiency. The solution after dissolution of all test examples is homogeneous or oil-water two-phase state, and no H2S is released.

[0041] Test Example 2

[0042] Particle size distribution test: It is generally believed that the particle size range of microemulsion is between 10-100nm, in order to confirm that the plug removal agent system is microemulsion, laser nanoparticle size instrument is used for particle size distribution test.

[0043] Table 2 particle size test result table

[0044]

[0045] The composite iron disulfide plug removal agent has uniform particle size distribution in the initial state, is a nano-level microemulsion state, and is a thermodynamic stable system. The particle size of the oil phase and the water phase of the system is small, the specific surface area is large, the solid phase material can be fully contacted, and the plug removal efficiency is high.

[0046] In summary, the fluid has the characteristics of thermodynamic stability, clarity and transparency, can not produce toxic H2S gas and precipitate sulfur single element when dissolving iron disulfide, and can achieve a high corrosion rate, which is a potential environmentally friendly and economic iron sulfide plug removal agent system.

[0047] The preferred embodiments of the application are described in detail above, but the application is not limited to the specific details in the above-described embodiments, and various simple modifications can be made to the technical solutions of the application within the technical concept of the application, and these simple modifications all belong to the protection scope of the application.

Claims

1. A composite iron disulfide scale remover, characterized in that, The composite iron disulfide scale breaker is mainly made of the following raw materials: 15-18 parts by weight of a sulfur dissolver, 15-25 parts by weight of a chelating agent, 25-35 parts by weight of an emulsifier, 10-20 parts by weight of an organic oxidizing agent, and 15-20 parts by weight of water.

2. The composite ferrous sulfide scale remover according to claim 1, wherein, The organic oxidizing agent is at least one of organic peroxides, preferably at least one of tert-butyl hydroperoxide, dimethyl ketone peroxide, and peroxyacetic acid.

3. The composite ferrous sulfide scale remover according to claim 1, wherein the composite ferrous sulfide scale remover is characterized by, The sulfur dissolver is at least one of substituted or unsubstituted aromatic hydrocarbons, cycloalkanes, and petroleum distillates, preferably at least one of toluene, xylene, and heavy aromatic oil.

4. The composite ferrous sulfide scale remover according to claim 1, wherein the composite ferrous sulfide scale remover is characterized by, The chelating agent is selected from organic phosphoric acid and / or amino polycarboxylic acid.

5. The composite iron disulfide scale breaker according to claim 4, characterized in that, The organic phosphoric acid is hydroxyethylidene diphosphonic acid.

6. The composite iron disulfide scale breaker according to claim 4, characterized in that, The amino polycarboxylic acid is sodium ethylenediaminetetraacetate.

7. The composite iron disulfide scale remover according to claim 1, wherein the composite iron disulfide scale remover is characterized by, The emulsifier is a fatty alcohol polyoxyethylene ether, preferably of the formula C m H 2m+1 O(CH2CH2O) n H, and m is an integer from 13 to 15 and n is an integer from 3 to 10.

8. A method for preparing the composite iron disulfide scale remover according to any one of claims 1 to 7, characterized in that, The preparation method comprises: mixing the chelating agent, the emulsifier, and water, and stirring to obtain an aqueous phase; mixing the sulfur dissolver and the organic oxidizing agent, and stirring to obtain an oil phase; adding the oil phase into the aqueous phase, and stirring to obtain the composite iron disulfide scale breaker.

9. Use of the composite iron disulfide scale breaker according to any one of claims 1-7 in dissolving iron disulfide.

10. Use of the composite iron disulfide scale breaker according to any one of claims 1-7 in plugging removal of oil and gas well bore.

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