Natural gas hydrate inhibitor for high-sulfur-content gas well and preparation method of natural gas hydrate inhibitor

Abstract

The invention discloses a natural gas hydrate inhibitor for a high-sulfur-content gas well and a preparation method of the natural gas hydrate inhibitor. The natural gas hydrate inhibitor comprises the following components in parts by weight: 40-45 parts of a kinetic inhibitor, 1-3 parts of a synergist, 5-10 parts of polymeric alcohol, 10-20 parts of inorganic salt and 500-600 parts of water. According to the hydrate inhibitor, the kinetic inhibitor is used as a main material, after the kinetic inhibitor is compounded with the thermodynamic inhibitor, the polymeric alcohol and the synergist, the inhibition performance of the kinetic inhibitor is greatly improved, the kinetic hydrate inhibition effect can be remarkably improved, and the hydrate inhibitor is suitable for sulfur-containing natural gas with the H2S content being 5%-15%.

Description

Technical Field

[0001] The invention relates to the technical field of natural gas hydrates, and in particular to a natural gas hydrate inhibitor for high-sulfur gas wells and a preparation method thereof. Background Art

[0002] Gas hydrates are cage-shaped structures formed by water molecules connected by hydrogen bonds. Small gas molecules are enclosed in the cage-shaped structure by van der Waals forces to form ice-like compounds. Certain components in natural gas (methane, ethane, propane, isobutane, etc.) are enclosed in it to form a crystalline solid substance, which is called natural gas hydrate.

[0003] Natural gas hydrate is an ice-like substance formed by water and natural gas components under low temperature and high pressure. Once this hydrate is formed, it will cause serious blockage of wellbore and gas pipelines, causing shutdown and production, which has a very adverse impact on natural gas production. Some natural gas fields in my country have a high H2S content, especially in Sichuan and Chongqing. Since natural gas containing H2S is more likely to form hydrates than ordinary methane and ethane, and the hydrate formation temperature is higher, it is more likely to encounter hydrate blockage problems during the extraction and collection of high-sulfur natural gas.

[0004] A large amount of practical experience abroad shows that the injection of high-efficiency, low-dose, and environmentally friendly hydrate kinetic inhibitors is one of the key technologies to prevent the exploitation of sour natural gas fields and the blockage of gathering and transportation pipelines. The injection of hydrate inhibitors is the most promising hydrate prevention and control technology for widespread industrial application. The injection of inhibitors to prevent hydrates is more adaptable to the environment and the process is more controllable. In the existing technology, methanol and ethylene glycol are the most commonly used thermodynamic inhibitors. However, the amount of thermodynamic inhibitors added is large, and the huge injection amount requires huge costs. According to conservative estimates, the injection of methanol thermodynamic inhibitors costs oil companies about US$500 million per year. Especially in oil and gas fields with high water production rates, they are faced with multiple cost pressures of adding and recovering.

[0005] In view of this, this patent application is filed. Summary of the invention

[0006] The purpose of the present invention is to provide a natural gas hydrate inhibitor for high-sulfur gas wells, and also provide a method for preparing the natural gas hydrate inhibitor, which is suitable for sour natural gas with an H2S content of 5% to 15%. Compared with existing hydrate inhibitors, the natural gas hydrate inhibitor can be better applied to high-sulfur gas reservoirs and maintain good inhibition performance.

[0007] The first object of the present invention is to provide a natural gas hydrate inhibitor for high-sulfur gas wells, which adopts the following technical scheme:

[0008] A natural gas hydrate inhibitor for high-sulfur gas wells comprises the following components in parts by weight: 40 to 45 parts of a kinetic inhibitor, 1 to 3 parts of a synergist, 5 to 10 parts of a polymeric alcohol, 10 to 20 parts of an inorganic salt, and 500 to 600 parts of water.

[0009] The hydrate inhibitor of the present invention is mainly a kinetic inhibitor. After compounding with a thermodynamic inhibitor polyol and a synergist, the inhibitory performance of the kinetic inhibitor is greatly improved by the synergist in the nucleation stage. In the hydrate growth stage, the compounded synergist can effectively prevent the kinetic inhibitor from failing at high cooling, improve the durable supercooling of the main agent, reduce the influence of supercooling on the kinetic inhibitor, inhibit the preferential growth direction of natural gas hydrate crystals and the directional stability of hydrate crystals, and significantly improve the kinetic hydrate inhibition effect.

[0010] At the same time, under the condition of the coexistence of compounded alcohols and salts, the activity of water is very low, the hydrate phase equilibrium curve shifts to the left, and the inhibitor effect is significantly improved, which can not only reduce the amount of hydrate generated, but also improve the effect of kinetic inhibitors, and has a wider range of applications, which can better prevent and solve the problem of hydrate blockage in high-sulfur gas wells and transmission pipelines. By compounding a small amount of thermodynamic inhibitor polyol, a good inhibition effect can be achieved, which can be used for the exploitation and gathering of high-sulfur natural gas.

[0011] In an optional embodiment, the following components are included in parts by weight: 42 to 45 parts of a kinetic inhibitor, 1 to 3 parts of a synergist, 6 to 9 parts of a polymeric alcohol, 13 to 20 parts of an inorganic salt, and 550 to 590 parts of water.

[0012] In an optional embodiment, the kinetic inhibitor is CT5-54, purchased from Chengdu Nengte Technology Development Co., Ltd. CT5-54 inhibits the formation and growth rate of hydrate nuclei, prevents the aggregation of hydrate crystals, and prevents hydrates from growing too fast and causing blockage within a certain fluid retention time. A small amount is used, and the inhibitory effect on hydrate formation is good.

[0013] In an optional embodiment, the synergist is one or more of glycine, alanine, and leucine. Glycine, alanine, and leucine are all small molecule amino acids that disturb the orderly arrangement of water molecules, thereby enhancing the effect of the kinetic inhibitor in inhibiting hydrate nucleation. In the hydrate growth stage, amino acids represented by glycine easily cover spaces that are difficult for polymers to reach, thereby improving the performance of the kinetic inhibitor in inhibiting the growth of hydrate nuclei.

[0014] In an optional embodiment, the polymer alcohol is one or more of polyethylene glycol and polypropylene glycol.

[0015] In an optional embodiment, the inorganic salt is one or more of sodium chloride, potassium chloride, and sodium formate.

[0016] In an optional embodiment, the water is deionized water.

[0017] In an optional embodiment, the following components are included in parts by weight: 44 parts of CT5-54, 1 part of glycine, 1 part of alanine, 1 part of leucine, 8 parts of polyethylene glycol, 15 parts of sodium chloride, and 550 parts of deionized water.

[0018] The second object of the present invention is to provide a method for preparing the natural gas hydrate inhibitor described in any one of the above, using the following technical scheme:

[0019] The preparation method comprises the following steps:

[0020] S1: according to the amount of each component, the kinetic inhibitor, the synergist and the deionized water are mixed to obtain the first solution system;

[0021] S2: adding polymeric alcohols and inorganic salts to the first group of solution systems and mixing them to obtain the hydrate inhibitor.

[0022] The third object of the present invention is to provide an application of the above-mentioned natural gas hydrate inhibitor for inhibiting the formation of natural gas hydrates during the production and transportation of natural gas with a hydrogen sulfide content of 5% to 15%.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] First, the present invention mainly uses a kinetic inhibitor, which is compounded with a thermodynamic inhibitor and a synergist, and the inhibitory performance of the kinetic inhibitor CT5-54 is greatly improved by the synergist in the nucleation stage.

[0025] Second, during the hydrate growth stage, the compound enhancer can effectively prevent the kinetic inhibitor from failing under high cooling conditions, improve the durable supercooling of the main agent, reduce the effect of supercooling on the kinetic inhibitor, inhibit the preferential growth direction of natural gas hydrate crystals and the directional stability of hydrate crystals, and significantly improve the kinetic hydrate inhibition effect.

[0026] Third, under the condition of the co-existence of compound alcohols and salts, the activity of water is very low, the hydrate phase equilibrium curve shifts to the left, and the inhibitor effect is significantly improved. It can not only reduce the amount of hydrate formation, but also improve the effect of kinetic inhibitors. The scope of application is wider, and it can better prevent and solve the problem of hydrate blockage in high-sulfur gas wells and transmission pipelines.

[0027] Fourthly, the hydrate inhibitor of the present invention has a wide range of applications, and is applicable to sour natural gas with an H2S content of 5% to 15%. There are no strict requirements for use conditions. At the same time, compared with existing hydrate inhibitors, it can be better applied to high-sulfur gas reservoirs and maintain good inhibition performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0029] Figure 1 It is an evaluation device used in the present invention to evaluate the performance of hydrate inhibitors;

[0030] Figure 2 is a curve diagram showing the relationship between pressure and time of natural gas hydrate formation in the blank group (without inhibitor) of the present invention;

[0031] Figure 3 It is a curve diagram of the relationship between pressure and time of natural gas hydrate formation in Example 1 of the present invention.

[0032] The components and marks in the accompanying drawings are:

[0033] 1-gas source A, 2-gas source B, 3-pressurizing device, 4-stirring device, 5-temperature control system, 6-high pressure visual reactor, 7-liquid inlet device, 8-data acquisition system. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. The illustrative embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0035] Example 1

[0036] A hydrate inhibitor suitable for high-sulfur gas wells, comprising: 44 parts of CT5-54, 1 part of glycine, 1 part of alanine, 1 part of leucine, 8 parts of polyethylene glycol, 15 parts of sodium chloride, and 550 parts of deionized water.

[0037] A preparation method for a hydrate inhibitor suitable for a high-sulfur gas well comprises the following steps: S1, mixing a kinetic inhibitor CT5-54, glycine, alanine, leucine, and deionized water to obtain a first solution system; S2, adding polyethylene glycol and sodium chloride to the first solution system to obtain the hydrate inhibitor.

[0038] Example 2

[0039] A hydrate inhibitor suitable for high-sulfur gas wells, comprising: 43 parts of CT5-54, 1 part of glycine, 7 parts of polyethylene glycol, 20 parts of sodium chloride, and 560 parts of deionized water.

[0040] A preparation method for a hydrate inhibitor suitable for a high-sulfur gas well comprises the following steps: S1, mixing a kinetic inhibitor CT5-54, glycine, and deionized water to obtain a first solution system; S2, adding polyethylene glycol and sodium chloride to the first solution system to obtain the hydrate inhibitor.

[0041] Example 3

[0042] A hydrate inhibitor suitable for high-sulfur gas wells, comprising: 42 parts of CT5-54, 1 part of glycine, 1 part of alanine, 9 parts of polyethylene glycol, 17 parts of sodium chloride, and 590 parts of deionized water.

[0043] A preparation method for a hydrate inhibitor suitable for a high-sulfur gas well comprises the following steps: S1, mixing a kinetic inhibitor CT5-54, glycine, alanine, and deionized water to obtain a first solution system; S2, adding polyethylene glycol and sodium chloride to the first solution system to obtain the hydrate inhibitor.

[0044] Example 4

[0045] A hydrate inhibitor suitable for high-sulfur gas wells, comprising: 45 parts of CT5-54, 1 part of glycine, 1.5 parts of leucine, 6 parts of polyglycerol, 16 parts of sodium chloride, and 570 parts of deionized water.

[0046] A preparation method for a hydrate inhibitor suitable for a high-sulfur gas well comprises the following steps: S1, mixing a kinetic inhibitor CT5-54, glycine, leucine and deionized water to obtain a first solution system; S2, adding polyglycerol and sodium chloride to the first solution system to obtain the hydrate inhibitor.

[0047] Example 5

[0048] A hydrate inhibitor suitable for high-sulfur gas wells, comprising: 43 parts of CT5-54, 1 part of glycine, 1 part of alanine, 9 parts of polyethylene glycol, 13 parts of sodium chloride, and 560 parts of deionized water.

[0049] A preparation method for a hydrate inhibitor suitable for a high-sulfur gas well comprises the following steps: S1, mixing a kinetic inhibitor CT5-54, glycine, alanine, and deionized water to obtain a first solution system; S2, adding polyethylene glycol and sodium chloride to the first solution system to obtain the hydrate inhibitor.

[0050] Comparative Example 1

[0051] A hydrate inhibitor suitable for high-sulfur gas wells, which is different from Example 1 in that the kinetic inhibitor is the natural gas hydrate kinetic inhibitor Luvicap.

[0052] A preparation method for a hydrate inhibitor suitable for a high-sulfur gas well comprises the following steps: S1, mixing a hydrate kinetic inhibitor Luvicap, glycine, alanine, leucine, and deionized water to obtain a first solution system; S2, adding polyethylene glycol and sodium chloride to the first solution system to obtain the hydrate inhibitor.

[0053] Comparative Example 2

[0054] A hydrate inhibitor suitable for high-sulfur gas wells, which is different from Example 4 in that it does not contain polymeric alcohols and inorganic salts, and the amount of kinetic inhibitor CT5-54 used is 67 parts.

[0055] A preparation method for a hydrate inhibitor suitable for a high-sulfur gas well comprises mixing a kinetic inhibitor CT5-54, a synergist and deionized water to obtain the hydrate inhibitor.

[0056] Comparative Example 3

[0057] A hydrate inhibitor suitable for high-sulfur gas wells, which is different from Example 3 in that CT5-54 is not included, the amount of polyethylene glycol used is 39 parts, and the amount of sodium chloride used is 29 parts.

[0058] A preparation method for a hydrate inhibitor suitable for a high-sulfur gas well comprises mixing a synergist, polyethylene glycol, sodium chloride and deionized water to obtain the hydrate inhibitor.

[0059] The above-mentioned embodiment uses a hydrate inhibitor performance evaluation device to evaluate the performance of the product of the present invention, and the evaluation device used is a high-pressure reactor system.

[0060] The structure of the high pressure reactor system used is as follows: Figure 1 The device shown includes gas source A 1, gas source B 2, pressurizing device 3, stirring device 4, temperature control system 5, high pressure visual reactor 6, liquid inlet device 7, and data acquisition system 8. The maximum working volume of the evaluation device is 500 ml, the working pressure range is 0 to 50 MPa, and the working temperature range is -50°C to 200°C.

[0061] The experimental liquid was deionized water, and the dosage of the hydrate inhibitor used was 3%.

[0062] The gas-liquid volume ratio in the reactor was 60:40 (liquid volume 200 mL), and the simulated stirring speed was 500 rad / min.

[0063] The evaluation test gas used was natural gas with high H2S content simulating the site, and the gas composition is shown in Table 1;

[0064] Table 1 Simulated natural gas components used in hydrate inhibitor evaluation experiments

[0065]

[0066] In the experiment, the pressurizing device 3 and the temperature control system 5 are used to simulate the formation conditions of hydrates, and the stirring device 4 is used to simulate the gas flow. Under room temperature conditions, the prepared reaction solution containing the hydrate inhibitor is added to the reactor 6 through the liquid inlet device 7, and a certain amount of prepared natural gas is added to the reactor 6 containing the reaction liquid, and it is kept under the set temperature and pressure conditions.

[0067] Since the hydrate formation conditions are met, the quality of natural gas in the reactor 6 is constant. Once hydrates begin to form in the reactor 6, the gas pressure in the reactor 6 will drop. At the beginning, due to the decrease in temperature, the pressure will have a process of decrease, which conforms to the gas state equation. When the pressure drops sharply, it indicates that hydrates begin to form. The formation speed and amount of hydrates can be judged by observing the pressure change and the observation window of the visual reactor 6. In this experiment, the performance effect of the hydrate inhibitor is evaluated by observing the time when a large amount of hydrates are generated in the reactor 6. The performance evaluation results of the hydrate inhibitor are shown in Table 2.

[0068] Table 2 Hydrate inhibitor performance evaluation results

[0069]

[0070] It can be seen from the performance evaluation results of hydrate inhibitors in Table 2 that under the experimental conditions of an experimental pressure of 12 MPa and an experimental temperature of 5°C, the time for the blank group to generate a large amount of hydrates is 406 minutes. The hydrate inhibitor provided in the embodiment of the present invention greatly prolongs the time for the generation of a large amount of hydrates under the condition of an added concentration of 3%. The use of the hydrate inhibitor provided by the present invention inhibits the preferential growth direction of natural gas hydrate crystals and the directional stability of hydrate crystals, and is more conducive to adsorption on the surface of natural gas hydrates, thereby preventing the growth of hydrate crystals; under the condition of the co-existence of synergists, alcohols and salts, the activity of water is very low, and the hydrate phase equilibrium curve shifts to the left (see Figure 2 and Figure 3As shown in the figure, the inhibitor effect is significantly improved, the time for the large-scale formation of hydrates is greatly extended, and sufficient hydrate inhibition time is provided for gas well production and transportation. The hydrate inhibitor provided by the present invention has a good hydrate prevention and control effect for the production and gathering of sulfur-containing or even high-sulfur gas wells, and can ensure the safe production conditions of high-sulfur gas wells.

[0071] The above specific implementation methods further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A natural gas hydrate inhibitor for high-sulfur gas wells, characterized in that: The invention comprises the following components in parts by weight: 40 to 45 parts of a kinetic inhibitor, 1 to 3 parts of a synergist, 5 to 10 parts of a polymeric alcohol, 10 to 20 parts of an inorganic salt, and 500 to 600 parts of water.

2. The natural gas hydrate inhibitor for high-sulfur gas wells according to claim 1, characterized in that: The invention comprises the following components in parts by weight: 42 to 45 parts of a kinetic inhibitor, 1 to 3 parts of a synergist, 6 to 9 parts of a polymeric alcohol, 13 to 20 parts of an inorganic salt and 550 to 590 parts of water.

3. A natural gas hydrate inhibitor for high-sulfur gas wells according to claim 1 or 2, characterized in that: The kinetic inhibitor is CT5-54.

4. A natural gas hydrate inhibitor for high-sulfur gas wells according to claim 1 or 2, characterized in that: The synergist is one or more of glycine, alanine and leucine.

5. The natural gas hydrate inhibitor for high-sulfur gas wells according to claim 1, characterized in that: The polymer alcohol is one or more of polyethylene glycol and polypropylene glycol.

6. The natural gas hydrate inhibitor for high-sulfur gas wells according to claim 1, characterized in that: The inorganic salt is one or more of sodium chloride, potassium chloride and sodium formate.

7. The natural gas hydrate inhibitor for high-sulfur gas wells according to claim 1, characterized in that: The water is deionized water.

8. The natural gas hydrate inhibitor for high-sulfur gas wells according to claim 1, characterized in that: The invention comprises the following components in parts by weight: 44 parts of CT5-54, 1 part of glycine, 1 part of alanine, 1 part of leucine, 8 parts of polyethylene glycol, 15 parts of sodium chloride and 550 parts of deionized water.

9. The method for preparing a natural gas hydrate inhibitor for a high-sulfur gas well according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1: according to the amount of each component, the kinetic inhibitor, the synergist and the deionized water are mixed to obtain the first solution system; S2: adding polymeric alcohols and inorganic salts to the first group of solution systems and mixing them to obtain the hydrate inhibitor.

10. Use of the inhibitor according to any one of claims 1 to 8 or the inhibitor prepared by the preparation method according to claim 9 in a high-sulfur gas well, characterized in that: Inhibit the formation of natural gas hydrates during the production and transportation of natural gas with a hydrogen sulfide content of 5% to 15%.

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