Environment-friendly hydrate compound inhibitor as well as preparation method and application thereof

Abstract

The invention discloses an environment-friendly hydrate compound inhibitor as well as a preparation method and application thereof, and relates to the technical field of hydrates. The compound inhibitor is prepared from potassium acetate serving as a main inhibitor, glycine serving as an auxiliary agent and water, can synergistically achieve the inhibition effect on hydrate generation in the two aspects of thermodynamics and dynamics, and has a good inhibition effect on hydrate formation and blocking. Meanwhile, the compound inhibitor has the characteristics of low use cost, no toxicity, no corrosion and environmental friendliness, has wide application prospects in the field of oil and gas transportation, and is easy to popularize and use.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrates, and in particular to an environmentally friendly hydrate compound inhibitor and a preparation method and application thereof. Background Art

[0002] Natural gas hydrate is a solid with an appearance similar to ice and a cage-like microstructure. Water molecules serve as the main molecules of the hydrate cage, and the guest molecules are usually alkane gas molecules with smaller molecular diameters, such as methane, ethane, propane, etc. The formation of natural gas hydrates is one of the main challenges currently faced by the oil and gas transportation industry. It costs about millions of dollars each year to inhibit the formation of natural gas hydrates in pipelines. The formation of natural gas hydrates in pipelines for the production and transportation of natural gas can cause many problems such as pipeline blockage, blowout preventer blockage, and endangerment of deep-water platforms. In severe cases, explosions may occur, which will not only cause huge losses to the economy and the environment, but may even cause casualties. The formation of natural gas hydrates mainly depends on the environment and thermodynamic state conditions of the hydrates. Therefore, controlling the thermodynamic conditions for hydrate formation is the main means to inhibit hydrate formation.

[0003] In response to the problem of hydrates in pipelines, the oil and gas industry has tried a variety of prevention and control methods. At present, the main methods to prevent hydrate formation include pipeline insulation, natural gas dehydration, and the addition of chemical inhibitors. Although pipeline insulation and natural gas dehydration can effectively slow down the formation of hydrates, these methods are often costly and difficult to be widely used in large-scale commercial operations. Therefore, adding hydrate inhibitors to the fluid has become the most economical and technically feasible option. At present, hydrate inhibitors are mainly divided into three categories: kinetic hydrate inhibitors (KHIs), thermodynamic hydrate inhibitors (THIs) and anti-agglomerants (AAs). If KHIs are used alone, the fluid stays in the pipeline for too long and the inhibition effect will decrease. If THIs are used alone, a large amount is required and the cost is high. The use of AAs has great limitations, and the water content of the fluid is required to be high. When the water content exceeds 50%, the function of the anti-agglomerant will fail. At present, there are no efficient, environmentally friendly and low-cost hydrate inhibitors that are widely used in the field of inhibiting hydrate formation. Finding new, low-cost, environmentally friendly inhibitors that are suitable for large-scale applications has very important practical value and significance for solving the hydrate blockage problem and ensuring the safe and efficient flow of natural gas resources. Summary of the invention

[0004] The present invention provides an environmentally friendly composite hydrate inhibitor and a preparation method and application thereof, which overcomes the problems of high cost, poor inhibition effect and environmental pollution in the prior art of inhibiting hydrate formation.

[0005] According to one aspect of the present invention, an environmentally friendly hydrate composite inhibitor is provided, comprising a main inhibitor, an auxiliary agent and a solvent, wherein the main inhibitor is potassium acetate, CAS No. 127-08-2, chemical formula CH3COOK, and structural formula: ; The auxiliary agent is glycine, CAS No. 56-40-6, chemical formula C2H5NO2, and structural formula: ; The solvent is deionized water.

[0006] Furthermore, the ratio of each component in the environmentally friendly hydrate composite inhibitor is in the range of: main inhibitor: auxiliary agent: solvent = (5~17wt%): (0~3wt%): (83~95wt%), where wt% represents weight percentage.

[0007] According to another aspect of the present invention, there is also provided a method for preparing the above-mentioned environmentally friendly composite hydrate inhibitor, comprising: weighing a required mass of a main inhibitor and placing it into a sample preparation container according to the total amount of the composite inhibitor to be prepared and the proportion of each component; weighing a required mass of an auxiliary agent and placing it into the sample preparation container; measuring a required volume of a solvent and adding it to the sample preparation container for stirring, so that the main inhibitor and the auxiliary agent are fully dissolved in the solvent, to prepare the composite hydrate inhibitor, wherein the main inhibitor is potassium acetate, the auxiliary agent is glycine, and the solvent is deionized water.

[0008] According to another aspect of the present invention, there is also provided a use of the above-mentioned environmentally friendly hydrate compound inhibitor in an oil and gas transportation pipeline.

[0009] The beneficial effects of the present invention are: Excellent effect: The composite inhibitor of the present invention has strong inhibitory activity, and can synergistically improve the thermodynamic inhibition performance and kinetic inhibition performance of hydrates after adding glycine, and has a significant inhibitory effect on hydrate formation.

[0010] More environmentally friendly: The composite inhibitor of the present invention uses easily degradable potassium acetate and glycine as main components. These two components are easily decomposed in nature and will not cause long-term pollution to the environment. Therefore, compared with traditional hydrate inhibitors, the inhibitor of the present invention is less polluting and more in line with environmental protection requirements.

[0011] Low cost: The main inhibitor potassium acetate is often used as an environmentally friendly snow-melting agent. It is simple to prepare and has low cost. Glycine is used as a kinetic aid at a concentration of no more than 3wt%, which further reduces the overall cost of the compound inhibitor, making the inhibitor more economical and affordable in practical applications.

[0012] Non-corrosive: The environmentally friendly hydrate compound inhibitor of the present invention does not contain chloride ions that are harmful to metals and concrete, and has extremely low corrosion performance on equipment and pipelines. This feature enables the inhibitor to maintain the integrity and stability of the equipment during long-term use, extend its service life, and reduce maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 The structural formula of potassium acetate, the main inhibitor in the environmentally friendly hydrate composite inhibitor of the present invention; Figure 2 An experimental device for evaluating the performance of the environmentally friendly hydrate composite inhibitor of the present invention; Figure 3 The pressure-time variation curves of each group of experiments of the embodiments of the present invention and the comparative examples are shown in FIG. DETAILED DESCRIPTION

[0014] The present invention is further described below in conjunction with specific implementation methods and the accompanying drawings. The following examples are further detailed descriptions of the present invention, but are not intended to limit the present invention.

[0015] Unless otherwise specified, the equipment, reagents and methods used in the present invention are conventional equipment, reagents and methods in the art, and the materials used are commercially available.

[0016] In practical applications, improvements and adjustments made by technicians based on the present invention still fall within the protection scope of the present invention.

[0017] The present invention provides an environmentally friendly hydrate compound inhibitor, which is composed of a main inhibitor, an auxiliary agent and a solvent, wherein: The main inhibitor is potassium acetate, the chemical formula is CH3COOK, CAS No. 127-08-2, and the structural formula is: ; The auxiliary agent is glycine, the chemical formula is C2H5NO2, CAS number 56-40-6, and the structural formula is: ; The solvent is deionized water.

[0018] The core of the composite hydrate inhibitor of the present invention is to achieve effective inhibition of hydrate formation by compounding a main inhibitor (potassium acetate) and an auxiliary agent (glycine).

[0019] Potassium acetate is used as the main inhibitor, which slows down or prevents the formation of hydrates by interfering with the formation of hydrogen bonds between water molecules, and plays a key role in inhibiting the formation of hydrates. Glycine is used as an auxiliary agent, which synergizes with the main inhibitor potassium acetate to enhance the inhibitory effect. Deionized water is used as a solvent to dissolve the main inhibitor and the auxiliary agent to form a uniform solution. The present invention achieves a synergistic inhibitory effect by compounding THIs and KHIs, realizes the purpose of inhibiting the formation of hydrates, and has the characteristics of high efficiency and environmental protection.

[0020] When preparing the composite hydrate inhibitor of the present invention, a suitable preparation ratio can be selected according to the specific application scenario and the desired inhibitory effect. Among them, the component ratio range is: main inhibitor (potassium acetate): auxiliary agent (glycine): solvent (deionized water) = (5~17wt%): (0~3wt%): (83~95wt%), wt% means weight percentage.

[0021] The present invention also provides a method for preparing an environmentally friendly hydrate composite inhibitor, comprising the following steps: Determine the total amount of the environmentally friendly hydrate compound inhibitor to be prepared and the appropriate component ratio according to the needs; According to the total amount and component ratio required, weigh the required mass of the main inhibitor (potassium acetate, chemical formula CH3COOK, structural formula Figure 1 As shown), put it into the sample preparation container; Weigh the required amount of auxiliary agent (glycine, chemical formula C2H5NO2) and add it to the same sample preparation container; Add solvent (deionized water) into the sample preparation container according to the required concentration of the compound inhibitor, stir, so that the main inhibitor and the auxiliary agent are fully dissolved in the solvent, and prepare the required environmentally friendly hydrate compound inhibitor.

[0022] The environmentally friendly composite hydrate inhibitor of the present invention can be used in oil and gas transportation pipelines.

[0023] Furthermore, when the environmentally friendly hydrate composite inhibitor is used, the applicable pressure range is 1~20 MPa and the applicable temperature range is -20~20℃.

[0024] Reference Figure 2 , Figure 2 The experimental device for evaluating the performance of the environmentally friendly hydrate compound inhibitor of the present invention is as follows: Figure 2 As shown in the figure, the experimental device mainly includes a high-pressure reactor, a methane (CH4) gas cylinder, a vacuum pump, a gas-liquid separator, a buffer tank, a hand pump, a data acquisition device, a temperature sensor, a pressure sensor, a constant temperature water bath, etc.

[0025] The liquid in the constant temperature water bath is a 30% ethylene glycol solution, the temperature adjustment range is -30℃-100℃, and the temperature fluctuation range is ±0.05℃. The high-pressure reactor is made of 316L stainless steel, with an effective volume of 226 mL and a designed pressure of 20 MPa. The data acquisition system consists of a temperature sensor, a pressure sensor, and a data acquisition device. The temperature sensor and the pressure sensor are both connected to the inside of the reactor, with measurement errors of ±0.1℃ and ±25 kPa, respectively, which are used to monitor the temperature and pressure changes in the reactor in real time. A computer is used for data acquisition and recording, and the data is recorded every 10 seconds.

[0026] The specific implementation process of the experiment includes: (1) Before the experiment begins, check the air tightness of the device. If the pressure change within 24 hours after the reactor is filled with 5 MPa nitrogen is less than ±0.001 MPa, the device is considered to be airtight.

[0027] (2) Adjust the temperature of the constant temperature water bath to the required experimental temperature.

[0028] (3) Use deionized water to clean the reactor cavity and upper cover, dry them and set them aside for later use.

[0029] (4) After weighing the liquid of the required concentration, put it into the reactor and seal it. Place the sealed reactor in a cold bath thermostatic bath.

[0030] (5) When the temperature reaches the preset temperature, use a vacuum pump to evacuate for 10 minutes to remove any free gas in the reactor and pipelines.

[0031] (6) Open the air inlet valve, slowly turn the pressure regulating valve, and slowly introduce CH4 gas into the reactor to reduce the influence of the Joule-Thomson effect on the experimental temperature.

[0032] (7) When the pressure reaches 7 MPa, stop gas injection.

[0033] (8) Observe the changes in temperature and pressure in the reactor, and compare the inhibitory effects on hydrate formation under different compound inhibitor conditions.

[0034] The mass concentration of the main inhibitor and the mass concentration of the auxiliary agent in the present invention are relative to the entire solution.

[0035] The evaluation index of the inhibition effect is determined by the final hydrate saturation. A low saturation indicates a good inhibition effect. The calculation method is shown in Formulas 1 to 3: Formula 1: ; In the formula, is the gas consumption, unit is mol; P is the gas pressure, unit is kPa;V is the gas volume, unit is mL; Z is the compression factor, obtained from the Peng-Robinson equation; R is the ideal gas constant 8.314, unit J / (mol·K); T is the temperature, unit K; the subscript 0 indicates the initial time, the subscript t Indicates a moment of reaction; Formula 2: ; In the formula, is the volume of hydrate, in mL; is the volume of the reactor, in mL; is the porosity, unit: % is the initial gas saturation, in mL / mL; is the atmospheric pressure, in kPa; Formula 3: .

[0036] In the formula, is the hydrate saturation, in cm 3 / cm 3 .

[0037] Embodiment 1 of the present invention Take 11.3g of potassium acetate and put it into the sample dispenser, then add 1.26g of glycine into the sample dispenser, and then add 113g of deionized water into the sample dispenser, and stir thoroughly until the main inhibitor and the auxiliary agent are completely dissolved.

[0038] The prepared inhibitor was added into the reaction vessel, which was sealed and placed in a constant temperature cold bath.

[0039] The temperature of the constant temperature water area was adjusted to 1°C, and after the temperature stabilized, CH4 gas was charged into the reactor to 7MPa. The hydrate formation reaction proceeded, and the pressure decreased. The experiment was stopped when the pressure no longer decreased.

[0040] The results showed that the final pressure in the reactor was 6.44 MPa and the final hydrate saturation was 3.415%, indicating that the amount of hydrate generated was small.

[0041] Embodiment 2 of the present invention Take 11.43g of potassium acetate and put it into the sample dispenser, then add 2.54g of glycine into the sample dispenser, and then add 113g of deionized water into the sample dispenser, and stir thoroughly until the main inhibitor and the auxiliary agent are completely dissolved.

[0042] The inhibitory effect experiment was performed according to the above experimental steps.

[0043] The results showed that the final pressure in the reactor was 6.53 MPa and the final hydrate saturation was 2.866%, indicating that the amount of hydrate generated was further reduced.

[0044] Embodiment 3 of the present invention Take 11.56g of potassium acetate and put it into the sample dispenser, then add 3.85g of glycine into the sample dispenser, and then add 113g of deionized water into the sample dispenser, and stir thoroughly until the main inhibitor and the auxiliary agent are completely dissolved.

[0045] The inhibitory effect experiment was performed according to the above experimental steps.

[0046] The results show that the final pressure in the reactor is 6.79 MPa, and the final hydrate saturation is 1.28%. Compared with Examples 1 and 2, the amount of hydrate generated in Example 3 is the least.

[0047] In addition, in order to more comprehensively verify the inhibitory effect of the environmentally friendly composite hydrate inhibitor in the present invention, the present invention also designs comparative examples 1 and 2 as control groups. These two control groups use different formulations or conditions from the present invention so as to be compared with the composite inhibitor of the present invention, thereby more intuitively illustrating the superiority of the present invention.

[0048] Comparative Example 1: Control group without inhibitor 113 g of deionized water was added to the reaction kettle, which was sealed and placed in a constant temperature cold bath.

[0049] The inhibitory effect experiment was performed according to the above experimental steps.

[0050] The results showed that the final pressure in the reactor was 3.01 MPa and the final hydrate saturation was 24.33%, indicating that the amount of hydrate generated was very large in the absence of inhibitors.

[0051] Comparative Example 2: Single Main Inhibitor Control Group Take 11.18g of potassium acetate and put it into the sample dispenser, then add 113g of deionized water into the sample dispenser and stir thoroughly until the potassium acetate is completely dissolved.

[0052] The inhibitory effect experiment was performed according to the above experimental steps.

[0053] The results showed that the final pressure in the reactor was 5.51 MPa and the final hydrate saturation was 9.09%, indicating that when only the main inhibitor potassium acetate existed, although there was a certain inhibitory effect on the formation of hydrates, the effect was not significant, indicating that the inhibitory effect of a single main inhibitor was limited.

[0054] Reference Figure 3 , Figure 3The pressure-time variation curves of each group of experiments in the embodiments of the present invention and the comparative examples are shown in FIG. Figure 3 As shown, in the absence of an inhibitor (Comparative Example 1), the pressure drops rapidly and a large amount of hydrate is generated. Under the condition of using only the main inhibitor potassium acetate (Comparative Example 2), the pressure drop is slowed down, but there is still a large drop, and the amount of hydrate generated is relatively small. Under the condition of using the environmentally friendly hydrate composite inhibitor of the present invention (Examples 1, 2, and 3), the pressure drop is significantly reduced, the amount of hydrate generated is small, and the inhibition effect is the best. Therefore, the environmentally friendly hydrate composite inhibitor of the present invention has good inhibitory performance for the formation of hydrates. Compared with no inhibitor and a single main inhibitor, the inhibitory effect of the composite inhibitor is more significant, and it can effectively prevent hydrates from causing blockage in oil and gas transportation pipelines.

[0055] The above describes in detail the preferred embodiments of the present invention, which is not intended to limit the embodiments of the present invention. For those skilled in the art, other forms of changes or modifications can be made based on the above description. It is impossible to list all the embodiments here. Any modification, combination and replacement within the spirit and principle of the present invention shall fall within the scope of protection of the claims of the present invention.

Claims

1. An environmentally friendly hydrate compound inhibitor, characterized in that: It includes a main inhibitor, an auxiliary agent and a solvent, wherein the main inhibitor is potassium acetate, CAS No. 127-08-2, chemical formula CH3COOK, and structural formula: ； The auxiliary agent is glycine, CAS No. 56-40-6, chemical formula C2H5NO2, and structural formula: ； The solvent is deionized water.

2. The environmentally friendly hydrate composite inhibitor according to claim 1, characterized in that: The ratio of each component in the environmentally friendly hydrate composite inhibitor is in the range of: main inhibitor: auxiliary agent: solvent = (5-17wt%): (0-3wt%): (83-95wt%), where wt% represents weight percentage.

3. A method for preparing the environmentally friendly composite hydrate inhibitor according to claim 1 or 2, characterized in that: include: According to the total amount of the composite inhibitor to be prepared and the proportion of each component, weigh the required mass of the main inhibitor and put it into the sample preparation container; Weigh the required amount of auxiliary agent and put it into the sample preparation container; The required volume of solvent is measured and added into the sample preparation container for stirring, so that the main inhibitor and the auxiliary agent are fully dissolved in the solvent to prepare a hydrate composite inhibitor, wherein the main inhibitor is potassium acetate, the auxiliary agent is glycine, and the solvent is deionized water.

4. Use of the environmentally friendly composite hydrate inhibitor according to claim 1 or 2 in oil and gas transportation pipelines.

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