Non-acidic scale remover for gas well borehole and preparation and application thereof

Abstract

The application discloses a non-acid scale remover for a gas well wellbore, and relates to the field of scale removers, and specifically relates to a non-acid scale remover for a gas well wellbore. The non-acid scale remover for the gas well wellbore is composed of a chelating agent, a scale inhibitor, a solubilizer, a penetrating agent and water; wherein the chelating agent accounts for 10-15% by mass percentage, the scale inhibitor accounts for 0.5-1% by mass percentage, the penetrating agent accounts for 1-2% by mass percentage, the solubilizer accounts for 1-5% by mass percentage, and the rest is water. The application further discloses preparation and application of the non-acid scale remover for the gas well wellbore. The non-acid scale remover for the gas well wellbore overcomes the shortcomings of low scale dissolving rate, insufficient environmental protection and strong corrosion of existing scale removers, has the characteristics of greenness, high efficiency and low corrosion, and has good scale removing effect on mixed scale of calcium carbonate and calcium sulfate.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of gas well wellbore non-acid scale remover and its preparation and application. BACKGROUND

[0002] With the development of gas reservoirs, gas well pressure, production gradually reduced, self liquid carrying capacity decline, widespread effusion;Output water scale ion content is high, while natural gas contains a certain amount of CO2 And H2S, there is wellbore corrosion, scaling phenomenon.Gas wellbore scaling, it can cause great harm to production, testing and maintenance, mainly performance has: (1) well encounter resistance;(2) seriously affect normal production of gas well;(3) increase the corrosion rate of pipe string.Through the composition analysis of scale in the wellbore plug of Changqing, Tarim and Southwest key gas area shows that the composition of scale is mainly calcium carbonate, calcium sulfate and a small amount of barium sulfate, etc.For gas wellbore descaling, acid descaling agent is usually used at present, but acid descaling agent can only dissolve carbonate scale, cannot remove sulfate scale, also inevitably cause serious corrosion of wellbore and gathering pipeline and other metal equipment, bring great security risks to production process.In addition, for calcium carbonate and calcium sulfate mixed scale, acid and alkali alternating treatment is often used, such as using 10% HCl to remove calcium carbonate first, then washing with clean water, and then using 20% NaOH to treat calcium sulfate scale (Liu Jie, Yuan Jianjun, Application Progress of Calcium Sulfate Scaling and Its Prevention Technology, Tianjin Chemical Industry, 2010, 24 (2), 10-13), which undoubtedly will bring more serious equipment corrosion and safety and environmental protection problems.Some gas wellbore non-acid scale removers have been developed, but the scale removal efficiency of calcium sulfate is still not high, and the scale remover also has certain pollution (Deng Hao, Wang Rongsha, Dai Xiangdong, et al. Test Evaluation of Two New Types of CaSO4 Scale Removers, Journal of Jianghan Petroleum Institute, 1995, 17 (3), 62-66; Shi Buqian, Huang Qing-song, Feng Xingwu, et al. Research on Organic Scale Remover for Removing Sulfate Scale, Progress in Fine Petroleum Chemical Industry, 2004, 5 (10), 27-30), so it is urgent to develop a non-acid, efficient, green and low-corrosion gas wellbore scale remover for calcium carbonate and calcium sulfate mixed scale, especially for the case where calcium carbonate and calcium sulfate scale coexist. SUMMARY

[0003] In order to at least partially solve the problems existing in the prior art, the embodiments of the present application provide a non-acid, efficient, green and low-corrosion gas wellbore scale remover for calcium carbonate and calcium sulfate mixed scale.

[0004] As one aspect of the present application, a kind of gas well wellbore non-acid scale remover is related, and the gas well wellbore non-acid scale remover is composed of chelating agent, scale inhibitor, solubilizer, penetrant and water;According to mass percentage, wherein chelating agent 10-15%, scale inhibitor 0.5-1%, penetrant 1-2%, solubilizer 1-5%, the rest is water.

[0005] In at least one embodiment, the chelating agent is a mixture of sodium ethylenediaminetetra(methylene phosphonate) and sodium polyamino polyether methylene phosphonate in a weight ratio of 1-2:1-2, preferably 1:1.

[0006] In at least one embodiment, the scale inhibitor is a mixture of sodium polyepoxysuccinate and sodium polyaspartate in a weight ratio of 1-3:1-3, preferably 2:1.

[0007] In at least one embodiment, the penetrating agent is a temperature-resistant penetrating agent, which is a mixture of alpha-olefin sulfonate and residual oil sulfonate in a weight ratio of 1-2:1-2, preferably 1:2.

[0008] In at least one embodiment, the solubilizing agent is a mixture of glycerol laurate polyoxyethylene ether and diethanol laurate in a weight ratio of 1-2:1-2, preferably 2:1.

[0009] As another aspect of the present application, a method for preparing the above-mentioned non-acid gas well borehole scale remover is provided, which comprises: adding distilled water into a reaction kettle, heating to 45-50°C, and adding the chelating agent, scale inhibitor, penetrating agent and solubilizing agent into the reaction kettle. In a specific embodiment, after the addition is completed, the system is stirred for 30 min until it is uniform, thereby obtaining the non-acid gas well borehole scale remover.

[0010] As still another aspect of the present application, the above-mentioned non-acid gas well borehole scale remover is used for removing scale in a gas well borehole.

[0011] The chelating agent sodium ethylenediaminetetra(methylene phosphonate) and sodium polyamino polyether methylene phosphonate are produced by Shandong Taihe Water Treatment Technology Co., Ltd.

[0012] Sodium ethylenediaminetetra(methylene phosphonate) is a nitrogen-containing organic polyphosphonate salt, which can chelate with multiple metal ions to form a large molecular network complex with multiple monomer structures, so that the normal crystallization of calcium scale is destroyed. It has good scale dissolving and dispersing effect on calcium sulfate scale and the like, is water-miscible, non-toxic and non-polluting, has good chemical stability and temperature resistance, and still has good scale dissolving and inhibiting effect at 200°C. Moreover, it has good corrosion inhibition performance. Sodium polyamino polyether methylene phosphonate has high chelating and dispersing performance, high calcium tolerance and excellent scale inhibition performance, and is particularly suitable for high-hardness, high-alkalinity and high-pH oilfield water treatment, and has excellent scale inhibition performance on calcium carbonate, calcium phosphate and calcium sulfate.

[0013] The scale inhibitor sodium polyepoxysuccinate and sodium polyaspartate are produced by Shandong Taihe Water Treatment Technology Co., Ltd.

[0014] Sodium polyepoxysuccinate is a kind of phosphorus-free green environment-friendly water-soluble polymer, which has good scale inhibition and dispersion performance for calcium carbonate, calcium sulfate, barium sulfate, strontium sulfate, calcium fluoride and other scales in water. It has good biodegradability, wide application range, and is especially suitable for water systems under high alkalinity, high hardness and high pH conditions. Sodium polyaspartate is a kind of water-soluble polymer, which is a new type of green water treatment agent, and has the characteristics of non-phosphorus, non-toxic, non-pollution and complete biodegradability. It has strong chelating ability for ions, and has the dual effects of corrosion inhibition and scale inhibition. It has good scale inhibition effect on calcium carbonate, calcium sulfate, barium sulfate, calcium phosphate and other scale-forming salts, and can effectively prevent the corrosion of metal equipment.

[0015] The penetrating agent alpha-olefin sulfonate is produced by Xi'an Nanfeng Chemical Group, and the residual oil sulfonate is produced by Daqing Zaichuang Technology Co., Ltd. The main function of the penetrating agent is to make the scale remover components quickly penetrate into the inside of the solid scale, make the scale wet and fluffy, increase the reaction area of the scale and chelating agent, and also has the effect of dissolving a small amount of organic matter such as wax and oil stains.

[0016] The solubilizing agent lauryl glycerin polyoxyethylene ether and diethanol laurate are commercially available chemical raw materials. The main function of the solubilizing agent is to increase the solubility of each component in the scale remover system, thereby improving the scale removal performance.

[0017] The gas well shaft non-acid scale remover of the present application overcomes the shortcomings of low scale dissolution rate, insufficient environmental protection and strong corrosion of the existing scale remover, has the characteristics of green, high efficiency and low corrosion, and has good scale removal effect on calcium carbonate and calcium sulfate mixed scale.

[0018] (1) The gas well shaft non-acid scale remover of the present application has high scale dissolution rate. On the one hand, the synergistic effect of different chelating agents is used to chelate scale-forming ions to form stable metal ion chelates, thereby improving the scale dissolution efficiency of the chelating agent. On the other hand, the scale inhibition effect of different scale inhibitors is used to further destroy the crystallization of inorganic scale, thereby preventing the scale-forming ions in the solution from forming secondary precipitation.

[0019] (2) The gas well shaft non-acid scale remover of the present application, wherein the chelating agents ethylenediamine tetramethylene phosphonic acid sodium and polyamino polyether-based sodium methylene phosphonic acid both have the characteristics of good water solubility, non-toxicity, non-pollution and good chemical stability; the scale inhibitors polyepoxysuccinic acid sodium and polyaspartic acid sodium both have the characteristics of non-phosphorus, non-toxicity, green and good biodegradability.

[0020] (3) The gas well shaft non-acid scale remover of the present application, wherein the chelating agents ethylenediamine tetramethylene phosphonic acid sodium and polyamino polyether-based sodium methylene phosphonic acid and the scale inhibitors polyepoxysuccinic acid sodium and polyaspartic acid sodium all have good corrosion inhibition performance. At the same time, the gas well shaft non-acid scale remover does not add any acid component, so the corrosion effect of the gas well shaft non-acid scale remover on the equipment is very small.

[0021] (4) On the basis of the action of chelating agent, scale inhibitor, the introduction of penetrating agent can promote the rapid penetration of scale remover to the inside of solid scale, increase the reaction area of solid scale and chelating agent, scale inhibitor, the introduction of solubilizer can improve the solubility of each component, and thus greatly improve the scale removal effect of scale remover. DETAILED DESCRIPTION

[0022] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present application, the technical solutions of the present application will be described in detail as follows, but it cannot be understood as limiting the scope of implementation of the present application.

[0023] In order to obtain excellent scale removal effect of non-acid scale remover, a large number of indoor optimization experiments show that the chelating agent, scale inhibitor, penetrating agent and solubilizer in the scale remover formula need to be mixed by two components in a certain proportion. As long as the two components are within the appropriate proportion range, better scale removal effect can be obtained, and the scale removal rate and corrosion rate of the scale remover can meet the field requirements. On this basis, the best proportion of the two components is further optimized, and under this proportion, the scale removal effect of the scale remover is optimal. Among them:

[0024] (1) The chelating agent is compounded by two components of ethylenediamine tetramethylene phosphonic acid sodium and polyamino polyether methyl phosphonic acid sodium, and better scale removal effect can be obtained by compounding them in a weight ratio of 1-2:1-2. On this basis, the proportion of the two components is further optimized, and when they are compounded in a weight ratio of 1:1, the scale removal effect of the scale remover is optimal.

[0025] (2) The scale inhibitor is compounded by two components of polyepoxysuccinic acid sodium and polyaspartic acid sodium, and better scale removal effect can be obtained by compounding them in a weight ratio of 1-3:1-3. On this basis, the proportion of the two components is further optimized, and when they are compounded in a weight ratio of 2:1, the scale removal effect of the scale remover is optimal.

[0026] (3) The penetrating agent is compounded by two components of alpha-olefin sulfonate and residual oil sulfonate, and better scale removal effect can be obtained by compounding them in a weight ratio of 1-2:1-2. On this basis, the proportion of the two components is further optimized, and when they are compounded in a weight ratio of 1:2, the scale removal effect of the scale remover is optimal.

[0027] (4) The solubilizer is compounded by two components of lauric acid glycerol polyoxyethylene ether and diethanol laurate, and better scale removal effect can be obtained by compounding them in a weight ratio of 1-2:1-2. On this basis, the proportion of the two components is further optimized, and when they are compounded in a weight ratio of 2:1, the scale removal effect of the scale remover is optimal.

[0028] (5) The two components of chelating agent, scale inhibitor, penetrating agent and solubilizer in the following examples are compounded according to the optimal proportion in (1)-(4) above.

[0029] Example 1

[0030] The present example provides a preparation method of a non-acid scale remover for gas well borehole, which comprises the following steps: adding distilled water into a reaction kettle according to a designed formula amount, and heating to 45℃, then adding 10% chelating agent, 1% scale inhibitor, 1.5% penetrating agent, and 2.5% solubilizer into the reaction kettle, and stirring for 30 min after the completion of feeding until the system is uniform, thereby obtaining the non-acid scale remover for gas well borehole.

[0031] The testing method of the scale removal rate of the non-acid scale remover for gas well borehole is as follows: according to the recommended method of the Technical Requirements for Chemical Scale Remover of Oilfield Gathering System of China Petroleum Natural Gas Group Company, the testing temperature is 90℃, the testing time is 12 h, the scale sample used is simulated CaCO3 scale, CaSO4 scale, and gas well borehole scale sample obtained from an oilfield, and the main components are CaCO3 and CaSO4. The scale removal rate test results are 93.36%, 89.62%, and 93.02%, respectively.

[0032] The testing method of the corrosion rate of the non-acid scale remover for gas well borehole is as follows: referring to the Water Corrosion Test Method of Petroleum and Natural Gas Industry Standard SY / T0026-1999, using the hanging piece weight loss method, the hanging piece material is N80 steel piece, the testing temperature is 90℃, the testing time is 12 h, and the corrosion rate test result is 0.062 mm / a, which is significantly lower than the industry standard 0.076 mm / a, indicating that the non-acid scale remover for gas well borehole has weak corrosivity.

[0033] Table 1 Testing results of scale removal performance and corrosion performance of the scale remover formula system of Example 1

[0034]

[0035] Example 2

[0036] The present example provides a preparation method of a non-acid scale remover for gas well borehole, which comprises the following steps: adding distilled water into a reaction kettle according to a designed formula amount, and heating to 50℃, then adding 15% chelating agent, 0.5% scale inhibitor, 1.0% penetrating agent, and 3.0% solubilizer into the reaction kettle, and stirring for 30 min after the completion of feeding until the system is uniform, thereby obtaining the non-acid scale remover for gas well borehole.

[0037] The gas well borehole non-acid scale remover dissolving scale rate test: according to the method recommended by the China Petroleum Natural Gas Group Company Enterprise Standard Q / SY148-2007 "Oilfield gathering system chemical scale remover technical requirements", the test temperature is 90℃, the test time is 12h, the scale sample used is simulated CaCO3 scale, CaSO4 scale and the gas well borehole scale sample obtained from the oilfield, the main components are CaCO3 and CaSO4. The scale dissolving rate test results are 92.20%, 88.34% and 92.08% respectively.

[0038] The gas well borehole non-acid scale remover corrosion rate test: according to the oil and gas industry standard SY / T0026-1999 "Water corrosion test method", the hanging piece weight loss method is used, the hanging piece material is N80 steel piece, the test temperature is 90℃, the test time is 12h, the corrosion rate test result is 0.057mm / a, which is significantly lower than the industry standard 0.076mm / a, indicating that the gas well borehole non-acid scale remover has weak corrosion.

[0039] Table 2 scale remover formula system dissolving performance and corrosion performance test results of example 2

[0040]

[0041] Example 3:

[0042] The embodiment provides a gas well borehole non-acid scale remover preparation method, which comprises the following steps: according to the designed formula amount, distilled water is added to a reaction kettle, and the temperature is raised to 45℃, then 13% chelating agent, 1.0% scale inhibitor, 2.0% penetrating agent and 5.0% solubilizer are added to the reaction kettle, and after the feeding is completed, the system is stirred for 30min to be uniform, thereby obtaining the gas well borehole non-acid scale remover.

[0043] The gas well borehole non-acid scale remover dissolving scale rate test: according to the method recommended by the China Petroleum Natural Gas Group Company Enterprise Standard Q / SY148-2007 "Oilfield gathering system chemical scale remover technical requirements", the test temperature is 90℃, the test time is 12h, the scale sample used is simulated CaCO3 scale, CaSO4 scale and the gas well borehole scale sample obtained from the oilfield, the main components are CaCO3 and CaSO4. The scale dissolving rate test results are 92.20%, 88.34% and 92.08% respectively.

[0044] The gas well borehole non-acid scale remover corrosion rate test: according to the oil and gas industry standard SY / T0026-1999 "Water corrosion test method", the hanging piece weight loss method is used, the hanging piece material is N80 steel piece, the test temperature is 90℃, the test time is 12h, the corrosion rate test result is 0.057mm / a, which is significantly lower than the industry standard 0.076mm / a, indicating that the gas well borehole non-acid scale remover has weak corrosion.

[0045] Table 3 Test results of the scale removal performance and corrosion performance of the scale remover formulation system of Example 3

[0046]

[0047] Example 4:

[0048] The present example provides a preparation method of a non-acid scale remover for a gas well wellbore, which comprises the following steps: adding distilled water into a reaction kettle according to the designed formulation amount, and heating to 50℃, then adding 12% chelating agent, 0.8% scale inhibitor, 1.5% penetrating agent, and 1.0% solubilizer into the reaction kettle, and stirring for 30 min after the feeding is completed until the system is uniform, thereby obtaining the non-acid scale remover for a gas well wellbore.

[0049] The test of the scale removal rate of the non-acid scale remover for a gas well wellbore: according to the recommended method of the Technical Requirements for Oilfield Gathering System Chemical Scale Remover of China Petroleum Natural Gas Group Corporation, the test temperature is 90℃, the test time is 12h, the scale sample used is a simulated CaCO3 scale, CaSO4 scale, and a gas well wellbore scale sample obtained from an oilfield, and the main components are CaCO3 and CaSO4. The scale removal rate test results are 90.73%, 88.33%, and 90.58%, respectively.

[0050] The test of the corrosion rate of the non-acid scale remover for a gas well wellbore: according to the Water Corrosion Test Method of the Petroleum and Natural Gas Industry Standard SY / T0026-1999, the weight loss method is used, the hanging piece material is N80 steel sheet, the test temperature is 90℃, the test time is 12h, and the corrosion rate test result is 0.059mm / a, which is significantly lower than the industry standard of 0.076mm / a, indicating that the non-acid scale remover for a gas well wellbore has weak corrosion.

[0051] Table 4 Test results of the scale removal performance and corrosion performance of the scale remover formulation system of Example 4

[0052]

Claims

1. A non-acidic descaling agent for gas well shafts, characterized in that, This non-acidic descaling agent for gas wellbore consists of chelating agent, scale inhibitor, solubilizer, penetrant, and water; by mass percentage, it comprises 10-15% chelating agent, 0.5-1% scale inhibitor, 1-2% penetrant, 1-5% solubilizer, and the balance being water. The penetrant is a heat-resistant penetrant, which is a mixture of α-olefin sulfonate and residue sulfonate in a weight ratio of 1-2:1-2; The chelating agent is composed of sodium ethylenediaminetetramethylenephosphonate and sodium polyaminopolyethermethylenephosphonate in a weight ratio of 1-2:1-2; The scale inhibitor is composed of sodium polyepoxysuccinate and sodium polyaspartate in a weight ratio of 1-3:1-3. The solubilizer is composed of glyceryl laurate polyoxyethylene ether and diethanol laurate in a weight ratio of 1-2:1-2.

2. The non-acidic descaling agent for gas wellbore as described in claim 1, characterized in that, The chelating agent is a mixture of sodium ethylenediaminetetramethylenephosphonate and sodium polyaminopolyethermethylenephosphonate in a weight ratio of 1:

1.

3. The non-acidic descaling agent for gas wellbore as described in claim 1, characterized in that, The scale inhibitor is composed of sodium polyepoxysuccinate and sodium polyaspartate in a weight ratio of 2:

1.

4. The non-acidic descaling agent for gas wellbore as described in claim 1, characterized in that, The penetrant is a temperature-resistant penetrant, which is a mixture of α-olefin sulfonate and residue sulfonate in a weight ratio of 1:

2.

5. The non-acidic descaling agent for gas wellbore as described in claim 1, characterized in that, The solubilizer is composed of glyceryl laurate polyoxyethylene ether and diethanol laurate in a weight ratio of 2:

1.

6. A method for preparing the non-acidic descaling agent for gas wellbore according to any one of claims 1-5, comprising: Add distilled water to the reactor and heat it to 45-50°C. Add the chelating agent, scale inhibitor, penetrant, and solubilizer to the reactor. After the addition is complete, stir for 30 minutes until the system is homogeneous to obtain the non-acidic descaling agent for gas well shafts.

7. The application of the non-acidic descaling agent for gas well shafts according to any one of claims 1-5 in the descaling of gas well shafts.

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