Chemical blocking remover for gas well and preparation method thereof

Abstract

The invention discloses a chemical blocking remover for a gas well. The chemical blocking remover comprises the following components in percentage by mass: 8-12% of an acid liquid system, 5-7% of a scale inhibitor, 1-3% of a penetrant, 0.5-1% of a water blocking remover, 0.1-0.3% of a defoaming agent and the balance of water. The invention also discloses a preparation method of the chemical blocking remover for the gas well, which comprises the following steps: sequentially taking the required acid liquor system, the scale inhibitor, the penetrant, the water blocking remover, the defoaming agent and the water according to the mass percentage, then putting into a reaction kettle, stirring and heating to 50-60 DEG C, and finally adjusting the pH value of the solution to 5-6 to obtain the chemical blocking remover for the gas well. The chemical blocking remover for the gas well can be used for efficiently dissolving scales of barium sulfate.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas field development, and specifically relates to a chemical plugging removal agent for gas wells, and also relates to a preparation method of a chemical plugging removal agent for gas wells. Background Art

[0002] During the gas field exploitation process, the salinity of the produced water is high, and there are plugging problems such as corrosion, inorganic scaling, and organic scaling to varying degrees in some gas well strings, perforation sections, and near-well zones, resulting in the inability of gas wells to produce normally, and even forced well shut-in, seriously affecting the effective exertion of the single-well productivity. At the same time, it also affects the opening rate, utilization rate, and ultimate recovery rate of gas wells. Currently, there are many chemical agents used for plugging removal in gas wells, which are mainly divided into the following categories: The first category: mainly low-cost inorganic acids, which are mainly used for inorganic scales in gas wells and have good effects on carbonate scales, but there are problems such as too fast reaction rate and small effective action radius in the near-well zone; The second category: mainly EDTA, DTPA, HEDTA, etc., for barium strontium sulfate scales in the gas well borehole, with the highest scale dissolution capacity of 10.2 g / L, but the scale dissolution effect on composite scales such as iron sulfide, ferric oxide, and silicon dioxide is poor; The third category: for plugging removal of organic substances in gas wells, mainly used for wax, asphaltene, etc.

[0003] Chinese Patent CN102746838 discloses a plugging removal agent for a gas well borehole; by weight percentage: alcohol ether compound 5 - 25%, dispersant 0.5 - 10%, cleaning agent 1 - 10%, chelating agent 0.5 - 5%, and the rest is a nitrogen-containing polar solvent. Among them, the surfactant is a conventional surfactant, which has a good effect on reducing the interfacial tension between kerosene and water; the chelating agents are citric acid and EDTA, and both have good anti-scaling effects on calcium carbonate, but have poor anti-scaling and scale dissolution effects on barium sulfate, and are used for plugging removal in gas well boreholes within 120°C.

[0004] Chinese Patent CN113025295A discloses a preparation method and use of a low-temperature plugging removal agent for oil and gas wells, which is made of the following raw materials by mass fraction: main agent DTPA 5 - 20%, auxiliary agent EDTA 1 - 3%, suspending agent 1 - 2%, anionic emulsifier 1 - 3%, lubricant 0.5 - 1%, and the balance is water; this patent can have a relatively high corrosion rate for barium sulfate at a low temperature of 45°C, but is only applicable to the scale dissolution of low-content barium sulfate, has a poor deposition effect on composite scales, and is not applicable to plugging removal in reservoirs with low porosity and low permeability at the same time. Summary of the Invention

[0005] The first object of the present invention is to provide a chemical plugging removal agent for gas wells, which solves the problem that existing plugging removal agents for oil and gas wells are difficult to dissolve barium sulfate scale.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: A chemical plugging removal agent for gas wells, comprising by mass percentage: 8%-12% of an acid liquor system, 5%-7% of a scale inhibitor, 1%-3% of a penetrant, 0.5%-1% of a water block remover, 0.1%-0.3% of an antifoaming agent, and the balance being water.

[0007] As a preferred technical solution of the present invention, the acid liquor system is prepared from calcium maleate, oxalic acid, poly-2-hydroxypropyl-N,N-dimethylammonium chloride, and cinnamaldehyde in a mass ratio of 5:1:1:2.

[0008] As a preferred technical solution of the present invention, the scale inhibitor is prepared from pentasodium diethylenetriaminepentaacetate and bisphosphate open-chain crown ether in a mass ratio of 7:3.

[0009] As a preferred technical solution of the present invention, the penetrant is hexyl 2-cyano-3-amino-3-phenylacrylate.

[0010] As a preferred technical solution of the present invention, the water block remover is prepared from RfSM fluorocarbon surfactant, polyether polyol SYP-1, and diammonium EDTA in a mass ratio of 5:1:2.

[0011] As a preferred technical solution of the present invention, the antifoaming agent is a mixture of polyacrylic acid and alkoxylated polyalkylene glycol esters.

[0012] The second object of the present invention is to provide a preparation method of a chemical plugging removal agent for gas wells, which solves the problem that the existing plugging removal agents for oil and gas wells are difficult to dissolve barium sulfate scale.

[0013] To achieve the above object, the technical solution adopted by the present invention is as follows: A preparation method of a chemical plugging removal agent for gas wells, first take the required acid liquor system, scale inhibitor, penetrant, water block remover, antifoaming agent and water in sequence according to mass percentage, then place them in a reaction kettle, stir and heat up to 50°C - 60°C, and finally adjust the pH of the solution to 5 - 6 to obtain the chemical plugging removal agent for gas wells.

[0014] The beneficial effects of the present invention are as follows: (1) A chemical plugging removal agent for gas wells of the present invention can efficiently remove the plugged sediments in the gas well string, perforation section, and near-well zone, especially has a good scale dissolution effect on high-content barium sulfate and strontium scale. Among them, in the environment of 45°C to 80°C, it has a good scale dissolution effect on composite scales such as calcium carbonate, barium strontium sulfate, iron sulfide, ferric oxide, and silicon dioxide; (2) A chemical plugging removal agent for gas wells of the present invention has a certain dispersing effect on corrosion inhibitors and foam displacement organic blockages in the near-well zone of gas wells; (3) A chemical plugging removal agent for gas wells of the present invention is applicable to low-permeability and tight reservoir gas wells with small reservoir pores and low permeability, avoiding problems such as water lock caused by the chemical agent system, resulting in a decrease in permeability. Specific embodiments

[0015] A chemical plugging removal agent for gas wells of the present invention includes, by mass percentage: 8%-12% of an acid solution system, 5%-7% of a scale inhibitor, 1%-3% of a penetrant, 0.5%-1% of a water blockage remover, 0.1%-0.3% of an antifoaming agent, and the rest is water.

[0016] The acid solution system is prepared from calcium maleate, oxalic acid, poly-2-hydroxypropyl-N,N-dimethylammonium chloride, and cinnamaldehyde according to a mass ratio of 5:1:1:2. This acid solution system delays the acid reaction rate, expands the effective radius of the acid solution in the near-well zone, and has a good dissolution effect on calcium carbonate inorganic scale, corrosion inhibitors, and residual organic matter of foam displacement.

[0017] The scale inhibitor is prepared from pentasodium diethylenetriaminepentaacetate and diphosphonate open-chain crown ether according to a mass ratio of 7:3. Selecting this scale inhibitor can achieve a dissolution amount of 16 g / L of barium sulfate (strontium) scale in 2 hours at 45°C to 80°C. At the same time, in a high-content carbon dioxide gas environment, it selectively forms stable and highly soluble chelates with metal ions.

[0018] The penetrant is 2-cyano-3-amino-3-phenylacrylic acid hexyl ester.

[0019] The water blockage remover is prepared from RfSM fluorocarbon surfactant, polyether polyol SYP-1, and diammonium EDTA according to a mass ratio of 5:1:2. This selection of the water blockage remover can reduce the interfacial tension, avoid particle migration and formation damage, and for damaged reservoirs, the permeability increase rate is 30%.

[0020] The antifoaming agent is a mixture of polyacrylic acid and alkoxy polyalkylene glycol esters. This antifoaming agent can especially reduce the formation damage of gas wells with a permeability lower than.

[0021] The present invention also discloses a preparation method of a chemical plugging removal agent for gas wells. Specifically: first, take the required acid solution system, scale inhibitor, penetrant, water block remover, defoamer and water in sequence according to mass percentage, then place them in a reaction kettle, stir and heat up to 50°C - 60°C, and finally adjust the pH of the solution to 5 - 6 to obtain the chemical plugging removal agent for gas wells.

[0022] The chemical plugging removal agent for gas wells prepared by the present invention has the following advantages:

[0023] (1) The plugging removal agent of the present invention chelates metal ions, selectively forms stable chelates with good solubility with metal ions, especially the chelating ability for barium and strontium ions is 800 mg / L, and no secondary precipitation will occur.

[0024] (2) The plugging removal agent of the present invention has good compatibility with the injected water, the scale dissolution rate for composite scale reaches 80%, and it has a certain dispersing effect on corrosion inhibitors and residual organic substances in foam displacement agents.

[0025] Table 1 Composition of composite scale samples

[0026]

[0027] (3) The plugging removal agent prepared by the present invention has no corrosion on the gas well string, and the corrosion rate is 1.92 g / (m ·h).

[0028] (4) The plugging removal agent prepared by the present invention is also applicable to low-permeability tight gas wells and is also used for gas wells in high-temperature reservoirs, with a temperature resistance of 150 - 170°C. The process parameters of the chemical plugging removal agent for gas fields of the present invention are shown in Table 2.

[0029] Table 2 Process parameters of a chemical plugging removal agent for gas fields

[0030]

[0031] Example 1

[0032] A chemical plugging removal agent for gas wells of the present invention, by mass percentage, includes: 8% of acid solution system, 5% of scale inhibitor, 1% of penetrant, 0.5% of water block remover, 0.1% of defoamer, and the rest is water.

[0033] Example 2

[0034] A chemical plugging removal agent for gas wells of the present invention, by mass percentage, includes: 10% of acid solution system, 6% of scale inhibitor, 2% of penetrant, 0.7% of water block remover, 0.2% of defoamer, and the rest is water.

[0035] Example 3

[0036] A chemical plug removal agent for gas wells of the present invention comprises, by mass percentage: 12% acid solution system, 7% scale inhibitor, 3% penetrant, 1% water block remover, 0.3% defoamer, and the balance is water.

[0037] Example 4

[0038] The present invention also discloses a preparation method of a chemical plug removal agent for gas wells. Specifically: first, take the required acid solution system, scale inhibitor, penetrant, water block remover, defoamer and water in sequence according to mass percentage, which comprises, by mass percentage: 8% acid solution system, 5% scale inhibitor, 1% penetrant, 0.5% water block remover, 0.1% defoamer, and the balance is water; then place them in a reaction kettle, stir and heat up to 50 °C, and finally adjust the pH of the solution to 5 to obtain the chemical plug removal agent for gas wells.

[0039] Example 5

[0040] The present invention also discloses a preparation method of a chemical plug removal agent for gas wells. Specifically: first, take the required acid solution system, scale inhibitor, penetrant, water block remover, defoamer and water in sequence according to mass percentage, which comprises, by mass percentage: 10% acid solution system, 6% scale inhibitor, 2% penetrant, 0.7% water block remover, 0.2% defoamer, and the balance is water; then place them in a reaction kettle, stir and heat up to 55 °C, and finally adjust the pH of the solution to 6 to obtain the chemical plug removal agent for gas wells.

[0041] Example 6

[0042] The present invention also discloses a preparation method of a chemical plug removal agent for gas wells. Specifically: first, take the required acid solution system, scale inhibitor, penetrant, water block remover, defoamer and water in sequence according to mass percentage, which comprises, by mass percentage: 12% acid solution system, 7% scale inhibitor, 3% penetrant, 1% water block remover, 0.3% defoamer, and the balance is water; then place them in a reaction kettle, stir and heat up to 60 °C, and finally adjust the pH of the solution to 6 to obtain the chemical plug removal agent for gas wells.

Claims

1. A chemical plugging remover for gas wells, characterized in that: The composition comprises, by mass percentage, 8%-12% of an acid solution system, 5%-7% of a scale inhibitor, 1%-3% of a penetrant, 0.5%-1% of a water-locking agent, 0.1%-0.3% of a defoaming agent, and the remainder is water.

2. The chemical plugging remover for gas wells according to claim 1, characterized in that: The acid solution system is prepared from calcium maleate, oxalic acid, poly-2-hydroxypropyl-N,N-dimethylammonium chloride and cinnamaldehyde in a mass ratio of 5:1:1:

2.

3. The chemical plugging remover for gas wells according to claim 1, characterized in that: The scale inhibitor is prepared from pentasodium diethylenetriamine pentaacetate and bisphosphate type open-chain crown ether in a mass ratio of 7:

3.

4. The chemical plugging remover for gas wells according to claim 1, characterized in that: The penetrant is 2-cyano-3-amino-3-phenyl acrylate.

5. The chemical plugging remover for gas wells according to claim 1, characterized in that: The water-locking agent is prepared from RfSM fluorocarbon surfactant, polyether polyol SYP-1 and EDTA diammonium in a mass ratio of 5:1:

2.

6. The chemical plugging remover for gas wells according to claim 1, characterized in that: The defoamer is a mixture of polyacrylic acid and alkoxy polyalkylene glycol ester.

7. The method for preparing a chemical plugging remover for gas wells according to any one of claims 1 to 6, characterized in that: First, take the required acid system, scale inhibitor, penetrant, water-locking agent, defoaming agent and water in order according to mass percentage, then put them in a reactor, stir and heat them to 50°C to 60°C, and finally adjust the pH of the solution to 5 to 6 to obtain a chemical plugging remover for gas wells.

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