Effect evaluation device and method for hydrate low-dosage additive

Abstract

The invention discloses an effect evaluation device and method for a hydrate low-dose additive. The device is used for evaluating the effects of a hydrate kinetic inhibitor and a polymerization inhibitor at the same time, and comprises a reaction kettle which is transversely arranged and does periodic reciprocating rectilinear motion in the test process, a steel ball capable of freely moving is arranged in the reaction kettle, and a window for observing the hydrate generation process is arranged on the wall surface of the reaction kettle; the liquid inlet unit is connected with the reaction kettle and is used for providing an oil-water emulsion and a hydrate kinetic inhibitor and / or a polymerization inhibitor for the test; the control unit is used for controlling the liquid temperature and the gas pressure in the reaction kettle; and the data acquisition and processing unit is used for acquiring occurrence time data of the hydrate in the reaction kettle and movement retarding degree data of the steel ball in a certain temperature and pressure environment, and calculating safe operation time when the multiphase environment reaches the hydrate condition. According to the invention, the disturbance state in a field pipeline can be better simulated; and the effects of the hydrate kinetic inhibitor and the polymerization inhibitor can be effectively evaluated in the same test.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrate safety control in oil and gas transportation process, and in particular to a device and method for evaluating the effect of a low-dose hydrate additive. Background Art

[0002] Under low temperature, high pressure and flowing environment, water phase and low molecular weight gas (such as methane, ethane and carbon dioxide) under equilibrium conditions can form hydrates, in which water molecules form pore structures to bind gas molecules, thus forming stable ice-like substances.

[0003] In the process of offshore crude oil extraction, multiple components such as crude oil, natural gas and produced water coexist in the pipeline. The presence of natural surfactants such as colloids and asphaltene in crude oil makes the oil-water system mostly exist in the form of oil-in-water emulsion. The low temperature, high pressure and flowing environment inside the pipeline are very likely to cause hydrate formation. Hydrate particles transformed from water droplets will aggregate under the action of capillary liquid bridge force to form large-size aggregates, reduce the pipeline flow radius, increase energy consumption during transportation, and may even block the pipeline, resulting in huge economic losses and safety accidents.

[0004] In order to ensure the safe operation of pipelines, hydrate formation inhibitors and polymerization inhibitors are widely used in hydrate management. In the prior art, low-dose additives (LDHI) are applied to engineering sites. Low-dose additives are mainly hydrate kinetic inhibitors (KHI) and polymerization inhibitors (AA), and the amount added is generally not more than 5wt% of the total mass of the liquid. Generally speaking, low-dose inhibitors can show interfacial activity and adsorb on the oil-water interface, thereby coating water droplets and forming a diffusion barrier, weakening gas mass transfer and hydrate particle surface contact effects. Specifically, hydrate kinetic inhibitors can prolong the formation time of hydrates under equilibrium conditions; the main function of polymerization inhibitors is to hinder the formation of large-size aggregates of generated hydrate particles, enhance the dispersibility and fluidity of hydrate particles, and thus avoid the problem of pipeline blockage caused by hydrates. At present, due to the complex composition of wellhead produced fluids in engineering sites, new and efficient inhibitors are still being developed and evaluated for their effects.

[0005] There are also technical solutions for evaluating devices and methods of additives in the prior art. For example, Chinese patent application CN112546982A discloses a device and method for dynamically and long-term evaluating the effect of additives on hydrates, including a temperature control system composed of a low-temperature circulating bath and a temperature sensor, a gas circulation system composed of a gas source, a return storage tank, a servo booster pump, a first buffer tank, a second buffer tank, a precision flow meter, a pressure regulating valve, and a tank flushing drying pipe, a hydrate generation system composed of a reactor, upper and lower end covers, and a stirring rotor, and a data recording and monitoring system composed of a camera, a computer, a temperature sensor, and a pressure sensor. This solution can monitor hydrate formation over a long time span and realize real-time monitoring of the hydrate formation rate. However, this type of device generally uses a high-pressure stirred reactor and a hydrate flow loop for evaluation. The high-pressure stirred reactor generally simulates the pipeline flow environment through a stirring paddle, and records the hydrate generation time through a sensor to evaluate the hydrate kinetic inhibitor. The liquid disturbance of the stirred reactor is far from the actual flow state of the pipeline, and it is difficult to evaluate the effect of the inhibitor. Hydrate flow loops can ideally simulate the flow state of crude oil pipelines on site and evaluate the inhibitor effect. However, the construction cost of such devices is high, and it is difficult to accurately control the temperature of large-volume loops, which makes the repeatability of hydrate formation experiments poor.

[0006] Therefore, there is an urgent need for a visual reactor that is closer to the liquid disturbance in the on-site pipeline, and a device and method that can simultaneously evaluate the effects of inhibitors and polymerization inhibitors in low-dose additives.

[0007] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0008] The object of the present invention is to provide a device and method for evaluating the effect of a low-dose hydrate additive. Liquid disturbance is provided by a moving steel ball in a reactor, so that the disturbance state in a field pipeline can be better simulated; the effects of a hydrate kinetic inhibitor and an inhibitor can be evaluated in the same test through the displacement change of the moving steel ball.

[0009] To achieve the above-mentioned purpose, according to the first aspect of the present invention, there is provided a device for evaluating the effect of a low-dose hydrate additive, which is used to simultaneously evaluate the effects of a hydrate kinetic inhibitor and an inhibitor, and comprises: a reactor, which is arranged horizontally and performs periodic reciprocating linear motion during the test, a freely movable steel ball is arranged in the reactor, and a window for observing the hydrate formation process is arranged on the wall of the reactor; a liquid inlet unit, which is connected to the reactor and is used to provide an oil-water emulsion and a hydrate kinetic inhibitor and / or an inhibitor for use in the test; a control unit, which is used to control the liquid temperature and gas pressure in the reactor; a data acquisition and processing unit, which is used to collect the appearance time data of hydrates in the reactor under a certain temperature and pressure environment, the movement slowdown degree data of the steel ball, and calculate the safe operation time when the multiphase environment reaches the hydrate condition.

[0010] Furthermore, in the above technical solution, the appearance time data of hydrates can be determined by the time point when the temperature and pressure mutations occur in the reactor, and used to evaluate the effect of the inhibitor.

[0011] Furthermore, in the above technical solution, the data on the degree of slowing down of the movement of the steel ball can be determined by the displacement data of the steel ball, the time when the steel ball stops moving, or the test stop time, and is used to evaluate the effect of the inhibitor.

[0012] Furthermore, in the above technical solution, the reactor can be a stainless steel chamber sealed by flanges at both ends; a steel ball displacement sensor is provided on the outer wall of the stainless steel chamber.

[0013] Furthermore, in the above technical solution, the reactor can drive the rotating wheel through the motor, thereby driving the three-bar linkage to achieve periodic reciprocating motion.

[0014] Furthermore, in the above technical solution, the reactor can be supported by a support frame and a bottom plate with pulleys and can slide freely in the horizontal direction.

[0015] Furthermore, in the above technical solution, the liquid inlet unit may include: an oil-water emulsion inlet sub-unit, which is used to pump the oil-water emulsion in the storage tank into the reactor, and a liquid flow meter is provided on the pumping pipeline; a reagent addition valve, which is arranged on the pumping pipeline and is used to add hydrate kinetic inhibitors and / or polymerization inhibitors.

[0016] Furthermore, in the above technical solution, the control unit may include: a temperature control subunit, which performs constant temperature control through a programmable constant temperature water bath and a water jacket wrapped around the outer wall of the reactor, and monitors the temperature of the fluid in the reactor through a temperature sensor; a pressure control subunit, which provides the gas required for hydrate formation into the reactor through a gas cylinder and a valve assembly and pressurizes it to a required pressure, and a gas flow meter is provided on the gas supply pipeline.

[0017] Furthermore, in the above technical solution, the data acquisition and processing unit can record the collected temperature, pressure data and liquid and gas flow data of the reactor, and calculate the safe operation time of the multiphase environment under hydrate conditions through the collected hydrate appearance time data, steel ball stop movement time or test stop time data and fluid flow rate in the reactor.

[0018] Furthermore, in the above technical solution, the evaluation device may also include: a liquid discharge unit, which includes a liquid discharge valve and a waste liquid tank, and is used to discharge the waste liquid into the waste liquid tank through the waste liquid pipeline for storage after the test is completed.

[0019] According to the second aspect of the present invention, the present invention provides a method for evaluating the effect of a low-dose hydrate additive, comprising the following steps: A, injecting an oil-water emulsion and a low-dose additive into a reactor in sequence and extracting residual gas in the reactor; B, driving the reactor to perform reciprocating linear motion, and controlling the temperature in the reactor to reach a set temperature and maintain stability; during the reciprocating motion of the reactor, a steel ball applies disturbance to the fluid in the reactor; C, charging the reactor with reaction gas and pressurizing it to the pressure required for the hydrate reaction; lowering the set temperature to the temperature required for the hydrate reaction; D, recording the collected temperature, pressure data, and flow data of the liquid and gas inlet of the reactor, and observing the fluid morphology in the reactor through a window; collecting time data of a sudden increase in temperature and a sudden drop in pressure when hydrates appear, as well as steel ball displacement data; E, calculating the safe operation time under hydrate conditions in a multiphase environment through the collected hydrate appearance time data, steel ball stop movement time or test stop time data, and fluid flow rate in the reactor.

[0020] Furthermore, in the above technical solution, the calculation of the safe operation time when the multiphase environment reaches the hydrate condition can be carried out in the following manner:

[0021]

[0022] Among them, t sf is the safe operation time for the multiphase environment to reach hydrate conditions; t f is the time of hydrate appearance in the reactor; t c The multiphase environment satisfies the hydrate formation time, which is obtained through the three-phase equilibrium curve of hydrate formation; t e v is the time when the steel ball stops moving or the test stops; a is the actual fluid velocity in the pipeline; v b is the fluid flow rate in the reactor, v b It can be determined by the lateral dimension of the reactor chamber and the reciprocating motion period.

[0023] Furthermore, in the above technical solution, the low-dose additive in step A may include a hydrate kinetic inhibitor and / or a polymerization inhibitor; and the vacuum degree after extracting the residual gas in the kettle may be controlled to be 0.1 Kpa.

[0024] Furthermore, in the above technical solution, a cleaning step of the device before use and a gas tightness detection step of the device may be included before step A. In the cleaning step, petroleum ether and pure water may be used to clean the liquid inlet unit and the chamber of the reactor, and the cleaning process may be repeated three times.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1) The present invention can better simulate the flow state of an actual pipeline by performing a reciprocating linear motion of the reactor and the disturbance of the steel ball in the reactor; in addition, the two low-dose additives, hydrate kinetic inhibitor and polymerization inhibitor, can be simultaneously evaluated by monitoring the reciprocating motion of the reactor and the displacement of the moving steel ball. Under the same environmental conditions, when evaluating the effect of the hydrate kinetic inhibitor, the longer the time required for hydrate formation, the better the effect of the kinetic inhibitor; when evaluating the effect of the polymerization inhibitor, the smaller the degree of slowing down of the moving steel ball, the better the effect of the polymerization inhibitor;

[0027] 2) The present invention can calculate the safe operation time when the multiphase environment reaches the hydrate condition by collecting the appearance time data of the hydrate in the reactor and the movement slowdown degree data of the steel ball. After testing and calculation, and by comparing with the results of the loop test method, the evaluation device of the present invention is closer to the safe operation data in the actual pipeline on site than the test data of the existing high-pressure stirring reactor, and the evaluation of the effect of the inhibitor and the polymerization inhibitor is more objective; the experimental study shows that the safe operation time (i.e., the time when the steel ball does not stop moving) obtained by calculating through the collected relevant parameter indicators and the calculation formula of the present invention is slightly different from the operation time of the loop safety detection, which can better simulate the operation of the actual pipeline;

[0028] 3) The present invention realizes visualization of the hydrate formation process by introducing a pressure-resistant sapphire window, and can observe the existence state of the oil-water two phases before hydrate formation, determine whether hydrate is formed, and observe the morphology of hydrate particle aggregates through the window, so as to further reflect the effect of low-dose additives;

[0029] 4) The present invention realizes the linear reciprocating motion of the reactor by introducing a mechanical structure, and enhances the shear strength of the fluid by the disturbance of the moving steel ball, thereby increasing the contact strength of the gas-liquid two-phase, strengthening the gas mass transfer and heat transfer, and adjusting the reciprocating motion cycle of the reactor by adjusting the speed of the motor according to the test needs;

[0030] 5) The reciprocating reactor and the steel ball design in the evaluation device of the present invention are simple to operate, low in construction cost, and require less raw materials than the loop detection method. The liquid flow state is closer to the actual pipeline than the paddle-type reactor, which is convenient for evaluating the effect of low-dose additives in the laboratory.

[0031] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, and to make the above and other purposes, technical features and advantages of the present invention easier to understand, one or more preferred embodiments are listed below and described in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the structure of the effect evaluation device of the low-dose hydrate additive of the present invention.

[0033] Figure 2 It is the temperature change curve of the hydrate formation process in the system with the addition of hydrate kinetic inhibitor and the system without hydrate inhibitor in Example 1 of the present invention.

[0034] Description of main reference numerals:

[0035] 1-rotating wheel; 2-electric motor; 3-first connecting rod; 4-second connecting rod; 5-third connecting rod; 6-liquid storage tank; 7-liquid pump; 8-liquid flow meter; 9-liquid inlet valve; 10-reagent addition valve; 11-pressure sensor; 12-displacement sensor; 13-water jacket; 14-high-pressure visual reactor; 15-steel ball; 16-sapphire window; 17-exhaust valve; 18-vacuum valve; 19-safety valve; 20-vacuum pump; 21-drain valve; 22-inlet valve; 23-gas flow meter; 24-check valve; 25-pressure regulating valve; 26-gas cylinder; 27-waste liquid tank; 28-bottom plate with pulley; 29-reactor support frame; 30-programmed constant temperature water bath; 31-temperature sensor; 32-data acquisition and processing unit. DETAILED DESCRIPTION

[0036] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation modes.

[0037] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0038] In this document, for the convenience of description, spatial relative terms such as "below", "below", "down", "above", "above", "upper", etc. may be used to describe the relationship between one element or feature and another element or feature in the accompanying drawings. It should be understood that the spatial relative terms are intended to include different orientations of the object in use or operation in addition to the orientation depicted in the figure. For example, if the object in the figure is turned over, the element described as being "below" or "below" other elements or features will be oriented "above" the element or feature. Therefore, the exemplary term "below" can include both below and above. Objects may also have other orientations (rotated 90 degrees or other orientations) and the spatial relative terms used in this document should be interpreted accordingly.

[0039] In this document, the terms "first", "second", etc. are used to distinguish two different elements or parts, and are not used to limit a specific position or relative relationship. In other words, in some embodiments, the terms "first", "second", etc. can also be interchangeable.

[0040] like Figure 1 As shown, the effect evaluation device of the low-dose hydrate additive of the present invention can better simulate the flow environment of the on-site pipeline compared with the existing reactor using high-pressure stirring paddle type, and can be used to simultaneously evaluate the effects of the hydrate kinetic inhibitor and the polymerization inhibitor in the low-dose additive. The device at least includes a reactor (i.e., a high-pressure visual reactor 14), a liquid inlet unit, a control unit, and a data acquisition and processing unit 32. Among them, the reactor 14 is arranged horizontally and performs periodic reciprocating linear motion during the test. A freely movable steel ball 15 is arranged in the reactor 14, and a window (i.e., a sapphire window 16) for observing the hydrate formation process is arranged on the wall of the reactor 14. The liquid inlet unit is connected to the reactor 14 to provide the oil-water emulsion and the hydrate kinetic inhibitor and / or the polymerization inhibitor used in the test. The control unit is used to control the liquid temperature and gas pressure in the reactor 14. The data acquisition and processing unit 32 is used to collect the appearance time data of the hydrate in the reactor under a certain temperature and pressure environment, the movement slowdown degree data of the steel ball, and calculate the safe operation time when the multiphase environment reaches the hydrate condition. Preferably, but not limiting, the hydrate appearance time data can be determined by the time point when the temperature and pressure mutations occur in the reactor (refer to Figure 2 ), which is used to evaluate the effect of the inhibitor. The data on the degree of slowing down of the movement of the steel ball can be determined by the displacement data of the steel ball, the time when the steel ball stops moving, or the test stop time, and is used to evaluate the effect of the inhibitor.

[0041] The present invention can better simulate the flow state of the actual pipeline by performing reciprocating linear motion of the reactor and the disturbance of the steel ball in the reactor; in addition, the two low-dose additives of hydrate kinetic inhibitor and polymerization inhibitor can be evaluated simultaneously by monitoring the reciprocating motion of the reactor and the displacement of the moving steel ball. Under the same environmental conditions, when evaluating the effect of the hydrate kinetic inhibitor, the longer the time required for hydrate generation, the better the effect of the kinetic inhibitor; when evaluating the effect of the polymerization inhibitor, the smaller the degree of slowing down of the moving steel ball, the better the effect of the polymerization inhibitor. Furthermore, the present invention can calculate the safe operation time when the multiphase environment reaches the hydrate condition by collecting the appearance time data of the hydrate in the reactor and the degree of slowing down of the steel ball. After testing and calculation, and by comparing with the results of the loop test method, the evaluation device of the present invention is closer to the safe operation data in the actual pipeline on site than the existing test data using a high-pressure stirring reactor, and the evaluation of the effect of the inhibitor and the polymerization inhibitor is more objective.

[0042] Further Figure 1 As shown, the high-pressure visualization reactor 14 of the present invention includes a stainless steel chamber, which is sealed at both ends by flanges. Preferably, but not restrictively, the inner diameter of the stainless steel chamber is 100mm, the outer diameter is 120mm, and the length is 300mm. It can work stably at a pressure of 0.1-15MPa and a temperature of -20-80°C, and the diameter of the moving steel ball is 95mm. The fluid flow rate in the reactor 14 can be controlled between 0 and 0.4m / s. The reactor 14 is provided with a sapphire window 16, which can observe the fluid movement state in the reactor in real time and realize the visualization of the emulsion and hydrate slurry during the hydrate formation process. The steel ball 15 in the reactor can exert disturbance on the fluid in the reactor as the reactor reciprocates. At the same time, the movement state of the steel ball can be used to react the effect of the polymerization inhibitor. Two displacement sensors 12 are installed on the outer wall of the reactor to record the reciprocating motion time of the moving steel ball.

[0043] Further Figure 1 As shown, the reactor 14 of the present invention drives the rotating wheel 1 through the motor 2, thereby driving the three-bar mechanism to realize periodic reciprocating motion. Specifically, the rotating wheel 1 rotates through the rotation of the motor 2, and the period of the reciprocating motion of the reactor 14 can be adjusted by adjusting the speed of the motor. The rotating wheel 1 and the first connecting rod 3 are fixedly connected, and the first connecting rod 3, the second connecting rod 4 and the third connecting rod 5 are hinged. The third connecting rod 5 and the end cover of the reactor 14 are fixedly connected. The reactor 14 is supported by a support frame 29 and a bottom plate 28 with a pulley and slides freely in the horizontal direction. Specifically, the reactor support frame 29 is used to support the reactor 14 and fixedly connect the reactor 14 and the bottom plate 28 with a pulley. The bottom plate 28 with a pulley can reciprocate with the movement of the reactor 14.

[0044] Further Figure 1 As shown, the liquid inlet unit of the present invention may include an oil-water emulsion liquid inlet subunit and a reagent addition valve 10. Among them, the oil-water emulsion liquid inlet subunit is used to pump the oil-water emulsion in the liquid storage tank 6 into the reactor 14, and a liquid flowmeter 8 is provided on the pumping pipeline. The reagent addition valve 10 is arranged on the pumping pipeline, and is used to add hydrate kinetic inhibitors and / or polymerization inhibitors. The liquid storage tank 6 is used to store the oil-water emulsion for the test. The fluid in the liquid storage tank 6 can enter the reactor 14 under the drive of the liquid pump 7, and the liquid flowmeter 8 is used to record the liquid flow rate of the pumping process. The present invention also includes a liquid discharge unit, which includes a liquid discharge valve 21 and a waste liquid tank 27. After the liquid discharge valve 21 is opened, the waste liquid flows into the waste liquid tank 27 through the waste liquid pipeline for storage.

[0045] Further Figure 1 As shown, the control unit of the present invention may include a temperature control subunit and a pressure control subunit. Among them, the temperature control subunit can be thermostatically controlled through a programmable constant temperature water bath 30 (temperature range is -15 to 80 ° C) and a water jacket 13 wrapped around the outer wall of the reactor, and monitor the temperature of the fluid in the reactor 14 through a temperature sensor 31 (accuracy is 0.1 ° C). Specifically, the programmable constant temperature water bath 30 can heat up and cool down at a fixed rate by setting a program, and the coolant in the programmable constant temperature water bath 30 can fill the water jacket 13 and circulate to control the temperature of the fluid in the reactor 14. The pressure control subunit can provide the reaction gas required for hydrate formation to the reactor 14 through a gas cylinder 26 and a valve assembly and pressurize it to the required pressure, and a gas flowmeter 23 is provided on the gas supply pipeline. Specifically, the pressure control unit of the present invention includes a gas cylinder 26, a pressure regulating valve 25, a check valve 24, a gas flow meter 23, an intake valve 22, a vacuum valve 18, a safety valve 19, a vacuum pump 20, an exhaust valve 17 and a pressure sensor 11 (with an accuracy of 0.01 MPa). During the test, the gas enters the reactor 14 from the gas cylinder 26 through the pressure regulating valve 25, the check valve 24, the gas flow meter 23 and the intake valve 22 in sequence to pressurize the system. The vacuum pump 20 is used to discharge the residual air in the reactor 14, the exhaust valve 17 is used to relieve the pressure of the reactor 14, and the gas flow meter 23 can record the unit time flow rate and the total flow rate of the gas injected into the reactor from the gas cylinder.

[0046] Further Figure 1As shown, the data acquisition processing unit 32 of the present invention can record the collected temperature and pressure data of the reactor and the flow data of the liquid and gas inlet, and calculate the safe operation time of the multiphase environment under the hydrate condition through the collected hydrate appearance time data (i.e., the time point when the temperature suddenly increases and the pressure suddenly drops), the steel ball stop movement time or the test stop time data (the steel ball keeps moving during the test and uses this data when it does not stop) and the fluid flow rate in the reactor 14. The calculated "safe operation time of the multiphase environment under the hydrate condition" can more intuitively evaluate the safe operation time before the occurrence of blockage and other accidents in the actual pipeline when using a certain inhibitor and / or polymerization inhibitor.

[0047] The present invention also provides a method for evaluating the effect of a low-dose hydrate additive, which uses the aforementioned evaluation device and may include the following steps:

[0048] Step S101, cleaning of the device before use: connecting each unit in the aforementioned evaluation device to the visual high-pressure reactor 14, turning on the main power supply and the liquid inlet unit, and using petroleum ether and pure water to clean the liquid inlet unit and the chamber of the reactor 14 in turn, and passing the waste liquid into the waste liquid tank 27 through the liquid discharge unit for storage, and repeating the cleaning process three times;

[0049] Step S102, check the air tightness of the device: close the liquid inlet valve 9 and the liquid discharge valve 21, connect the pressure control subunit, close the exhaust valve 17, open the gas cylinder 26 and the air inlet valve 22, and adjust the gas flow through the pressure regulating valve 25, and then close the air inlet valve 22 after introducing a certain pressure gas into the reactor 14 and maintain it for 30 minutes, and observe whether the pressure decreases. If the pressure indication does not change, it proves that the air tightness of the device is good, and then open the exhaust valve 17 to release the pressure;

[0050] Step S103, injecting the liquid phase and replacing the gas (i.e., injecting the oil-water emulsion and the low-dose additive into the reactor in sequence and extracting the residual gas in the reactor): specifically, opening the liquid inlet valve 9, and injecting the oil-water emulsion and the low-dose additive into the cavity of the visualized high-pressure reactor 14 in sequence through the liquid inlet unit, closing the liquid inlet unit and the exhaust valve 17 after the liquid phase is added, opening the vacuum valve 18 and the vacuum pump 20 to extract the residual gas in the reactor, and when the vacuum degree is stabilized at 0.1 KPa, closing the vacuum pump 20 and the vacuum valve 18;

[0051] Step S104, start the device: turn on the motor and set the speed to drive the reactor to do reciprocating linear motion, start the data acquisition processing unit 32 to record relevant parameters (i.e. Figure 1 The parameters of the acquisition equipment are shown by the dashed line in the figure), and the program-controlled constant temperature water bath is adjusted to the set temperature and maintained stable. During the reciprocating motion of the reactor, the steel ball can disturb the fluid in the reactor to better simulate the fluid state in the actual pipeline;

[0052] Step S105, pressurizing the system: i.e., charging the reaction gas (i.e., methane, ethane, and carbon dioxide, etc.) into the reactor 14 and pressurizing it to the pressure required for the hydrate reaction. Specifically, open the air inlet valve 22, adjust the pressure regulating valve 25 to allow the reaction gas to enter the reactor 14 from the gas cylinder 26 at a constant rate, and pressurize the system while replenishing the reaction gas. After the pressure in the reactor 14 reaches the test pressure value (i.e., the pressure required for the hydrate reaction), close the air inlet valve 22;

[0053] Step S106, cooling the system (i.e., reducing the set temperature in step S104 to the temperature required for the hydrate reaction): specifically, the program-controlled circulating water bath 30 is cooled to the test value at a fixed rate and maintained constant. During this process, cold water flows through the water jacket 13 to take away the heat of the fluid in the reactor 14, so that the temperature of the fluid in the reactor is gradually reduced to the temperature required for the hydrate reaction for the test;

[0054] Step S107, record the collected temperature, pressure data and flow data of liquid and gas in the reactor 14, observe the fluid morphology in the reactor through the window; collect the time data of the sudden increase in temperature and the sudden decrease in pressure when hydrates appear, and the displacement data of the steel ball. When hydrates appear, the temperature increases suddenly, the pressure drops suddenly, the movement of the steel ball slows down, and turbidity can be observed in the reactor through the window 16;

[0055] Step S108, calculate the safe operation time of the multiphase environment under the hydrate condition by using the collected hydrate appearance time data, the steel ball stop movement time or the test stop time data and the fluid flow rate in the reactor. Specifically, the safe operation time of the multiphase environment under the hydrate condition can be calculated in the following manner:

[0056]

[0057] Among them, t sf is the safe operation time for the multiphase environment to reach hydrate conditions; t f is the time of hydrate appearance in the reactor; t c The multiphase environment satisfies the hydrate formation time, which is obtained through the three-phase equilibrium curve of hydrate formation; t e v is the time when the steel ball stops moving or the test stops; a is the actual fluid velocity in the pipeline; v b is the fluid flow rate in the reactor, v b It can be determined by the lateral dimension of the reactor chamber and the reciprocating motion period.

[0058] It should be noted that when the inhibitor has a good effect, the steel ball is always in motion during the entire test and does not stop. eThe value of is the test stop time. Experimental research shows that the safe operation time (i.e. the time when the steel ball does not stop moving) obtained by collecting the above parameter indicators and calculating in the above way is slightly different from the operation time of the ring channel safety detection, which can better simulate the operation of the actual pipeline;

[0059] Step S109, after the test is finished, the reciprocating motion of the reactor is stopped, the temperature control subunit and the gas cylinder 26 are turned off, the exhaust valve 17 is opened to reduce the pressure in the reactor to normal pressure, and after the hydrate phase in the system is decomposed, the drain valve 21 is opened to allow the liquid in the reactor to enter the waste liquid tank 27 for storage, the reactor is cleaned with pure water and petroleum ether, and finally the data acquisition processing unit 32 and the main power supply are turned off.

[0060] Example 1

[0061] This example focuses on the effect of the device of the present invention on the evaluation of hydrate kinetic inhibitors. The specific steps of this example are:

[0062] (1) Use petroleum ether and deionized water to clean the test device in turn, and clean the high-pressure visual reactor chamber and the liquid inlet pipeline.

[0063] (2) Check the air tightness of the device, connect the air inlet unit, close the exhaust valve, open the gas cylinder and the air inlet valve, and adjust the gas flow through the pressure regulating valve. Introduce gas into the reactor until the pressure reaches 0.2MPa, then close the air inlet valve and maintain it for 30 minutes. Observe that the pressure display does not change, which proves that the air tightness of the device is good.

[0064] (3) 1.2 L of oil-water emulsion with a water content of 40% was injected into the visualized high-pressure reactor chamber through the liquid inlet unit, and then the reagent addition valve was opened to inject the hydrate kinetic inhibitor PVP into the reactor. The inhibitor accounted for 1 wt% of the total mass fraction of the liquid. After the liquid phase was added, the liquid inlet unit and the exhaust valve were closed, and the residual gas was exhausted by vacuum operation.

[0065] (4) Turn on the motor to set the liquid flow rate to 0.2 m / s, drive the reactor to perform reciprocating linear motion, turn on the data acquisition and processing unit to record the temperature, pressure, flow rate, and steel ball displacement parameters, set one point to be collected every 1 minute, and adjust the programmable constant temperature water bath to 20°C and maintain stability.

[0066] (5) Open the air inlet valve and adjust the pressure regulating valve to allow gas to enter the reactor from the gas cylinder. During the process of replenishing the reaction gas, the system is pressurized. After the pressure in the reactor reaches 2.4 MPa, close the air inlet valve.

[0067] (6) The temperature of the programmed circulating water bath is gradually lowered to 2°C and maintained constant. Cold water flows through the water jacket to remove the heat of the fluid in the reactor, causing the temperature of the system in the reactor to gradually decrease.

[0068] (7) Maintaining a constant water bath temperature until hydrates are generated, when the steel ball is blocked and stops running or the ball can still move 1 hour after the hydrates appear, the test is terminated and the evaluation device of the present invention is turned off.

[0069] The temperature variation curve in this embodiment is as follows: Figure 2 As shown. Figure 2 It can be seen that the temperature of the fluid in the reactor is continuously reduced to a constant temperature due to the cooling of the water bath within about 100 minutes, and a sudden change occurs at 223 minutes. This is because the formation of hydrates is an exothermic reaction, and the heat released by the hydrates cannot be taken away by the water bath in a short time, causing the temperature of the system to rise rapidly in a short time. At the same time, it can be seen from the pressure indication that the system pressure is reduced, and solid phase particles are found through the sapphire window. Although the speed of the steel ball slows down within 60 minutes after the hydrate is generated, the reciprocating motion is never stopped, indicating that the reagent can inhibit the aggregation of hydrates and block the pipeline. At the same time, the hydrate formation process is carried out under the same temperature, pressure and flow rate conditions with the same composition liquid through the hydrate loop, and the safe and stable operation time of the loop is recorded. The experiment is stopped when the pipeline is blocked or the hydrate is generated and stably runs for 1 hour. The test results of the reciprocating high-pressure visual evaluation device and the loop operation in this embodiment are shown in Table 1.

[0070] Example 2

[0071] The experimental conditions and experimental steps are the same as those in Example 1, except that no kinetic inhibitor is added in step (3). Figure 2 It can be seen that hydrates were generated at 115 minutes into the test. At this time, it was found from the viewing window that hydrates formed large-size aggregates. The displacement sensor showed that the movement of the steel ball began to slow down, and within 10 minutes after the hydrates were generated, it was wrapped by the hydrates and stopped moving, and the reactor was blocked. At the same time, the hydrate generation process was carried out through the hydrate loop with the same liquid under the same temperature, pressure and flow rate conditions, and the safe operation time of the loop was recorded. The test results of the reciprocating high-pressure visual evaluation device and the loop operation in this embodiment are shown in Table 1.

[0072] Example 3

[0073] The test conditions and test steps are the same as those in Example 1, except that the injection amount of the hydrate kinetic inhibitor PVP in step (3) is 0.1wt% of the total mass fraction of the liquid, and the liquid flow rate in step (4) is 0.1m / s. The results show that hydrates are generated in 132min, and the steel ball stops moving 13min after the hydrates are generated, indicating that this content of PVP has a certain inhibitory effect on the formation and aggregation of hydrates. At the same time, the hydrate formation process was carried out through the hydrate loop with the same liquid under the same temperature, pressure and 0.2m / s conditions, and the safe operation time of the loop was recorded. The results of the reciprocating high-pressure visual evaluation device experiment and the loop operation in the embodiment are shown in Table 1.

[0074] Example 4

[0075] The test conditions and test steps are the same as those in Example 1, except that the injection amount of the hydrate kinetic inhibitor PVP in step (3) is 0.2wt% of the total mass fraction of the liquid, and the liquid flow rate in step (4) is 0.3m / s. The results show that hydrates are generated in 147min, and the steel ball stops moving 21min after generation, indicating that this content of PVP has a certain inhibitory effect on the generation and aggregation of hydrates. At the same time, the hydrate generation process was carried out through the hydrate loop with the same liquid under the same temperature, pressure and 0.2m / s conditions, and the safe operation time of the loop was recorded. The test results of the reciprocating high-pressure visual evaluation device and the loop operation in this embodiment are shown in Table 1.

[0076] Example 5

[0077] The test conditions and test steps are the same as those in Example 1, except that in step (3), the hydrate kinetic inhibitor PVP is not added but the polymerization inhibitor Span80, and the injection amount is 2wt% of the total mass fraction of the liquid. The results show that hydrates are generated in 153 minutes, and the steel ball does not stop reciprocating within 60 minutes after generation. At the same time, the hydrate generation process is carried out through the hydrate loop with the same liquid under the same temperature, pressure and flow rate conditions, and the safe operation time of the loop is recorded. The test results of the reciprocating high-pressure visual evaluation device and the loop operation in this embodiment are shown in Table 1.

[0078] Table 1 Reciprocating high pressure visual evaluation device and loop operation results

[0079]

[0080]

[0081] The above test results show that the evaluation device of the present invention can evaluate the effects of hydrate kinetic inhibitors and polymerization inhibitors in a simple, convenient, fast and efficient manner through one test, judge the hydrate formation time by temperature and pressure parameters and observe the fluid state, and evaluate the effects of hydrate kinetic inhibitors or polymerization inhibitors by the formation time. At the same time, the evaluation device and evaluation method of the present invention can be used to evaluate the safe operation time when a multiphase system reaches the hydrate formation conditions. The loop result verification shows that this method can evaluate the safe operation time of pipelines under different chemical additive conditions within the acceptable error range (deviation is less than 20 minutes), and can determine the safe operation time of pipelines and the amount of chemical reagents added.

[0082] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. Any simple modifications, equivalent changes and modifications made to the above exemplary embodiments should fall within the scope of protection of the present invention.

Claims

1. A device for evaluating the effect of a low-dose hydrate additive, characterized in that: Used to simultaneously evaluate the effects of hydrate kinetic inhibitors and polymerization inhibitors, including: A reactor is arranged horizontally and performs periodic reciprocating linear motion during the test. A freely movable steel ball is arranged in the reactor, and a window for observing the hydrate formation process is arranged on the wall of the reactor; A liquid inlet unit, connected to the reactor, for providing the oil-water emulsion used in the test and the hydrate kinetic inhibitor and / or polymerization inhibitor; A control unit, which is used to control the liquid temperature and gas pressure in the reactor; The data acquisition and processing unit is used to collect the appearance time data of hydrates in the reactor under a certain temperature and pressure environment, the movement slowdown degree data of the steel ball, and calculate the safe operation time when the multiphase environment reaches the hydrate condition.

2. The effect evaluation device of low-dose hydrate additive according to claim 1, characterized in that: The hydrate appearance time data is determined by the time point when the temperature and pressure sudden changes occur in the reactor, and is used to evaluate the effect of the inhibitor.

3. The effect evaluation device of low-dose hydrate additive according to claim 1, characterized in that: The data on the degree of slowing down of the movement of the steel ball is determined by the displacement data of the steel ball, the stopping time of the steel ball or the test stopping time, and is used to evaluate the effect of the inhibitor.

4. The effect evaluation device of low-dose hydrate additive according to claim 1, characterized in that: The reactor is a stainless steel chamber sealed with flanges at both ends; a steel ball displacement sensor is arranged on the outer wall of the stainless steel chamber.

5. The effect evaluation device of low-dose hydrate additive according to claim 4, characterized in that: The reactor drives the rotating wheel through the motor, thereby driving the three-link mechanism to realize periodic reciprocating motion.

6. The effect evaluation device of low-dose hydrate additive according to claim 5, characterized in that: The reactor is supported by a support frame and a bottom plate with pulleys and can slide freely in a horizontal direction.

7. The effect evaluation device of low-dose hydrate additive according to claim 1, characterized in that: The liquid inlet unit comprises: The oil-water emulsion inlet subunit is used to pump the oil-water emulsion in the liquid storage tank into the reactor, and a liquid flow meter is provided on the pumping pipeline; A reagent adding valve is arranged on the pumping pipeline and is used for adding a hydrate kinetic inhibitor and / or an inhibitor.

8. The effect evaluation device of low-dose hydrate additive according to claim 1, characterized in that: The control unit comprises: The temperature control subunit is used to control the temperature through a programmable constant temperature water bath and a water jacket wrapped around the outer wall of the reactor, and monitors the temperature of the fluid in the reactor through a temperature sensor; The pressure control subunit supplies the gas required for hydrate formation to the reactor through a gas cylinder and a valve assembly and pressurizes the gas to the required pressure. A gas flow meter is provided on the gas supply pipeline.

9. The effect evaluation device of low-dose hydrate additive according to claim 1, characterized in that: The data acquisition and processing unit records the collected temperature and pressure data of the reactor and the flow data of the liquid and gas inlet, and calculates the safe operation time of the multiphase environment under the hydrate condition through the collected hydrate appearance time data, the steel ball stopping time or the test stopping time data and the fluid flow rate in the reactor.

10. The effect evaluation device of low-dose hydrate additive according to claim 1, characterized in that: The evaluation device also includes: The liquid discharge unit comprises a liquid discharge valve and a waste liquid tank, and is used to discharge the waste liquid into the waste liquid tank through the waste liquid pipeline for storage after the test is completed.

11. A method for evaluating the effect of a low-dose hydrate additive, characterized in that: The steps include: A. Inject the oil-water emulsion and low-dose additives into the reactor in sequence and extract the residual gas in the reactor; B. driving the reactor to perform reciprocating linear motion, and controlling the temperature in the reactor to reach a set temperature and maintain stability; during the reciprocating motion of the reactor, the steel ball exerts disturbance on the fluid in the reactor; C. Filling the reactor with reaction gas and pressurizing it to the pressure required for the hydrate reaction; lowering the set temperature to the temperature required for the hydrate reaction; D. Record the collected temperature and pressure data of the reactor and the flow data of the liquid and gas inlet, and observe the fluid morphology in the reactor through the window; Collect the time data of sudden temperature increase and pressure drop as well as the displacement data of the steel ball when hydrate appears; E. Calculate the safe operation time of the multiphase environment under hydrate conditions by using the collected hydrate appearance time data, steel ball stop movement time or test stop time data and the fluid flow rate in the reactor.

12. The method for evaluating the effect of a low-dose hydrate additive according to claim 11, characterized in that: The safe operation time when the multiphase environment reaches the hydrate condition is calculated as follows: Among them, t sf is the safe operation time for the multiphase environment to reach hydrate conditions; t f is the time of hydrate appearance in the reactor; t c The multiphase environment satisfies the hydrate formation time, which is obtained through the three-phase equilibrium curve of hydrate formation; t e v is the time when the steel ball stops moving or the test stops; a is the actual fluid velocity in the pipeline; v b is the flow rate of the fluid in the reactor.

13. The method for evaluating the effect of a low-dose hydrate additive according to claim 11, characterized in that: The low-dose additive in step A includes a hydrate kinetic inhibitor and / or a polymerization inhibitor; the vacuum degree after the residual gas in the kettle is extracted is 0.1 Kpa.

14. The method for evaluating the effect of a low-dose hydrate additive according to claim 11, characterized in that: The step A also includes a cleaning step of the device before use and a gas tightness testing step of the device.

15. The method for evaluating the effect of a low-dose hydrate additive according to claim 14, characterized in that: The cleaning step uses petroleum ether and pure water to clean the liquid inlet unit and the chamber of the reactor, and the cleaning process is repeated three times.

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