A device for evaluating the microscopic effect of hydrate inhibitors and a method for using the same

Abstract

The present invention discloses a device for evaluating the microscopic effect of a hydrate inhibitor and a method for using the device, which relates to the technical field of the oil and gas industry. The device comprises an autoclave, an aluminum cup, a nanodisplacer, a movable cantilever and a fixed cantilever. The autoclave cavity is provided with an aluminum cup and a nanodisplacer, one end of the movable cantilever is mounted on the nanodisplacer, and the other end extends into the aluminum cup. One end of the fixed cantilever is fixed on the inner wall of the autoclave, and the other end extends into the aluminum cup. A water bath coil is wound on the outer wall of the aluminum cup. The device also comprises a controller, and the nanodisplacer is electrically connected to the controller. The device of the present invention can accurately measure the shell strength of micron-sized hydrate particles in different liquid phase environments (such as formation water and alkanes) and the force between the particles and the pipeline surface, and intuitively reflects the microscopic effect of different hydrate inhibitors on the hydrate particles.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas industry, and in particular to a device for evaluating the microscopic effect of a hydrate inhibitor and a method for using the device. Background Art

[0002] In the process of hydrate resource exploitation and oil and gas transportation, the components of the fluid include natural gas and water. Under this flow state, due to the low temperature and high pressure conditions in the pipeline, tiny bubbles in the liquid phase and condensed water droplets in the gas phase may form hydrate particles. Hydrate particles will aggregate and may adhere to the pipe wall during the flow of the fluid, eventually blocking the pipeline, causing local pressure increase, reduced mining efficiency and potential safety problems. Therefore, studying the effects of hydrate inhibitors on hydrate particle growth and surface morphology, especially the adhesion and shell strength of hydrate particles to the pipeline surface, is very important for exploring the mechanism of action of hydrate inhibitors and reducing the phenomenon of hydrate blocking pipelines. The adhesion between hydrate particles and the pipeline surface can quantitatively measure the difficulty of hydrate particles to adhere to the pipe wall; the properties of the hydrate particle shell also have an important influence on the aggregation and deposition of hydrate clusters in the pipeline. There is water in the hydrate particles that has not been converted into hydrate. If the shell of the hydrate particles is broken due to compression or shearing, the broken shell will provide many additional nucleation sites, and the water contained in the particles will also be released, which will lead to the rapid formation of hydrates and generate greater adhesion between the particles, promoting the occurrence of hydrate blockage.

[0003] Existing hydrate inhibitor performance evaluation technologies generally observe the changes in the hydrate formation process in the presence of hydrate inhibitors from a macroscopic level in large pipelines or high-pressure reactors, but it is difficult to measure the changes in the physical and chemical properties of hydrates during this process, which is not accurate enough to judge the effectiveness of hydrate inhibitors. Summary of the invention

[0004] To this end, the present invention provides a device for evaluating the microscopic effect of a hydrate inhibitor and a method for using the same, in order to solve the problem that the existing hydrate inhibitor performance evaluation technology generally observes the changes in the hydrate formation process in the presence of the hydrate inhibitor from a macroscopic level in a large pipeline or a high-pressure reactor, but it is difficult to measure the changes in the physical and chemical properties of the hydrate in this process, which is not accurate enough to judge the effect of the hydrate inhibitor.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] According to a first aspect of the present invention, a device for evaluating the microscopic effect of a hydrate inhibitor comprises a high-pressure reactor, an aluminum cup, a nanodisplacer, a movable cantilever and a fixed cantilever, wherein the aluminum cup and the nanodisplacer are arranged in a cavity of the high-pressure reactor, one end of the movable cantilever is mounted on the nanodisplacer, and the other end extends into the aluminum cup, one end of the fixed cantilever is fixed to the inner wall of the high-pressure reactor, and the other end extends into the aluminum cup; a water bath coil is wound on the outer wall of the aluminum cup; the device further comprises a controller, and the nanodisplacer is electrically connected to the controller.

[0007] Furthermore, a pressure sensor is provided at the bottom of the aluminum cup; the pressure sensor is electrically connected to the controller.

[0008] Furthermore, the device also includes a constant temperature water bath, which is arranged outside the high-pressure reactor and connected to the water bath coil through a circulation pipeline; the temperature control accuracy of the constant temperature water bath is ±0.1°C, and the lowest temperature can reach -10°C.

[0009] Furthermore, the fixed cantilever is in a "Z" shape.

[0010] Furthermore, a carbon steel surface simulating the wall of an oil and gas pipeline is installed at the front end of the movable cantilever.

[0011] Furthermore, the cavity of the high-pressure reactor is cylindrical, with an internal size of φ328mm×148mm, made of 316L material, and a pressure resistance of 10Mpa.

[0012] Furthermore, the top of the high-pressure reactor is provided with an air inlet interface, a temperature measurement interface, a pressure measurement interface and a plurality of high-pressure through interfaces, and the bottom is provided with a circulation pipeline inlet and outlet interface.

[0013] Furthermore, the device also includes a pressurizing system, which consists of a vacuum pump, a high-pressure gas cylinder and an air intake pipe. The vacuum pump is connected to the high-pressure reactor, and the high-pressure gas cylinder is connected to the high-pressure reactor through the air intake pipe.

[0014] Furthermore, a temperature and pressure gauge is installed on the high-pressure reactor.

[0015] According to a second aspect of the present invention, a method for using the above-mentioned device comprises the following steps:

[0016] The constant temperature water bath of the device is turned on to pre-cool the aluminum cup; ice particles are fixed on the fixed cantilever, and the nano-displacer is controlled by the controller to make the carbon steel surface at the front end of the movable cantilever close to the ice particles;

[0017] Injecting the required liquid into the aluminum cup, and adding an appropriate amount of hydrate inhibitor;

[0018] Starting the vacuum pump in the pressurization system of the device to exhaust the air in the high-pressure reactor; turning off the vacuum pump and opening the air inlet valve; adjusting the temperature of the constant temperature water bath to a temperature 1-2°C higher than the stable existence temperature of the hydrate, and maintaining it for 25-35 minutes to melt the ice particles into water, and then lowering the temperature to allow the water and gas to react to form hydrate particles;

[0019] The controller controls the nanodisplacer to gradually approach the hydrate particles until the carbon steel surface just contacts the hydrate particles; the movable cantilever is slowly moved upward to record the adhesion force when the carbon steel surface and the hydrate particles are out of contact; the movable cantilever is slowly moved downward until the shell of the hydrate particles is crushed by the carbon steel surface, and the strength of the shell of the hydrate particles is recorded.

[0020] The present invention has the following advantages:

[0021] A device for evaluating the microscopic effect of a hydrate inhibitor of the present invention introduces a water bath coil in a high-pressure reactor, thereby improving the problem of low refrigeration efficiency caused by immersing the entire high-pressure reactor in a water bath in a traditional design, and being able to more accurately control the temperature of a test area; a nano-displacer is used to control a movable cantilever, which gradually approaches hydrate particles with a nanometer-level tiny step, so that the entire test process is in a quasi-static process, thereby ensuring the accuracy of microscopic measurements; a carbon steel surface is used to simulate an oil and gas pipeline wall, and the pressure change generated in the process of the carbon steel surface approaching the hydrate particles and finally crushing them is used as the shell strength of the hydrate particles, thereby realizing accurate measurement of the shell strength of the hydrate particles from a microscopic perspective.

[0022] The device for evaluating the microscopic effect of a hydrate inhibitor of the present invention can accurately measure the adhesion between micron-sized hydrate particles and the surface of a carbon steel pipe and the anti-breakage strength of the hydrate particle shell in different liquid environments (such as formation water and alkanes) under the condition of adding a hydrate inhibitor, intuitively reflects the microscopic effects of different hydrate inhibitors on hydrate particles, and uses the reduction in the force and the change in the strength of the hydrate shell as quantitative indicators for judging the effect of the hydrate inhibitor, thereby conducting a multi-angle evaluation of the surface and interface. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0024] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0025] Figure 1 This is a schematic diagram of the structure of a device for evaluating the microscopic effect of a hydrate inhibitor provided by the present invention 1. DETAILED DESCRIPTION

[0026] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Example 1

[0028] like Figure 1 A device for evaluating the microscopic effect of a hydrate inhibitor shown in the figure comprises a high-pressure reactor 1, an aluminum cup 2, a nanodisplacer 3, a movable cantilever 4 and a "Z"-shaped fixed cantilever 5, wherein the aluminum cup 2 and the nanodisplacer 3 are arranged in the cavity of the high-pressure reactor 1, one end of the movable cantilever 4 is mounted on the nanodisplacer 3, and the other end extends into the aluminum cup 2, one end of the fixed cantilever 5 is fixed on the inner wall of the high-pressure reactor 1, and the other end extends into the aluminum cup 2; the cavity of the high-pressure reactor 1 is cylindrical, with an internal size of φ328mm×148mm, 316L material, and a pressure resistance of 10Mpa; the top of the high-pressure reactor 1 is provided with an air inlet interface, a temperature measurement interface, a pressure measurement interface and a plurality of high-pressure through interfaces, and the bottom is provided with a circulation pipeline inlet and outlet interface. A water bath coil 6 is wound on the outer wall of the aluminum cup 2; a pressure sensor 7 is arranged at the bottom of the aluminum cup 2; the device also includes a controller, and the nanodisplacer 3 and the pressure sensor 7 are electrically connected to the controller; a high-pressure through-connector 12 is installed on the high-pressure through-connector interface, which is used to transmit data of the nanodisplacer 3, pressure sensor 7 and other equipment in the high-pressure reactor 1 to the controller through the high-pressure through-connector 12; the front end of the movable cantilever 4 is installed with a carbon steel surface 40 simulating the wall of an oil and gas pipeline.

[0029] The testing system of the device of the present invention is composed of an aluminum cup 2 wound by a water bath coil 6, a nano-displacer 3, a fixed cantilever 5 and a movable cantilever 4 connected to the nano-displacer 3. When evaluating the microscopic effect of the hydrate inhibitor, the aluminum cup 2 contains a liquid with the hydrate inhibitor added and a force measuring module equipped with a pressure sensor 7. The water bath coil 6 surrounding the aluminum cup is used to cool down and maintain the temperature required for the stable existence of the hydrate. The fixed cantilever 5 fixes the hydrate particles on the force measuring module in the aluminum cup 2. The front end of the movable cantilever 4 is equipped with a carbon steel surface 40 simulating the wall of the oil and gas pipeline. The movable cantilever 4 is controlled by the nano displacement device 3 so that the carbon steel surface 40 gradually approaches the hydrate particles in nanometer steps. When it just touches the hydrate particles, it can be lifted up or continued to press down and finally crush the hydrate shell, and the adhesion between the hydrate particles and the carbon steel surface and the shell strength of the hydrate particles are measured respectively. The pressure sensor 7 will respectively record the pressure changes in the above two processes, and use the pressure decrease value and the pressure increase value as the adhesion between the hydrate particles and the carbon steel surface and the shell strength of the hydrate particles respectively.

[0030] The device further comprises a constant temperature water bath 8, which is arranged outside the autoclave 1 and connected to the water bath coil 6 via a circulation pipe 9; the temperature control accuracy of the constant temperature water bath 8 is ±0.1°C, and the lowest temperature can reach -10°C. The circulation pipe 9 provides coldness to the cavity of the autoclave 1 to maintain the low temperature conditions required for the stable existence of hydrates.

[0031] The device also includes a pressurizing system, which is composed of a vacuum pump, a high-pressure gas cylinder and an air inlet pipe. The vacuum pump is connected to the high-pressure reactor, and the high-pressure gas cylinder is connected to the high-pressure reactor 1 through the air inlet pipe. At the beginning of the experiment, the air in the high-pressure reactor 1 is first discharged by the vacuum pump, and then the natural gas in the high-pressure gas cylinder is introduced until the high-pressure condition required for the stable existence of hydrates is reached.

[0032] The high-pressure reactor 1 is also provided with a temperature and pressure gauge 10. The temperature and pressure of the high-pressure reactor 1 are constantly monitored by the temperature and pressure gauge 10.

[0033] Example 2

[0034] The method for using the device described in Example 1 comprises the following steps:

[0035] The constant temperature water bath 8 is turned on, and the low temperature water in the constant temperature water bath 8 circulates in the water bath coil 6 through the circulation pipe 9 to pre-cool the aluminum cup 2; ice particles are fixed on the fixed cantilever 5, and the nano displacement device 3 is controlled by the controller to make the carbon steel surface 40 at the front end of the movable cantilever 4 close to the ice particles;

[0036] Inject the required liquid into the aluminum cup 2, and add an appropriate amount of hydrate inhibitor;

[0037] Start the vacuum pump to exhaust the air in the autoclave 1; turn off the vacuum pump, open the air inlet valve, and introduce the natural gas in the high-pressure gas cylinder into the autoclave 1 through the air inlet pipe until the high-pressure condition required for the stable existence of hydrates is reached; in order to reduce the induction time of hydrate formation, first adjust the temperature of the constant temperature water bath to a temperature 1-2°C higher than the stable existence temperature of hydrates, and keep it for 30 minutes to melt the ice particles into water, and then lower the temperature to react with water and gas to form hydrate particles;

[0038] The controller controls the nanodisplacer 3 to gradually move the movable cantilever 4 close to the hydrate particle 11 until the carbon steel surface just contacts the hydrate particle 11; the movable cantilever is slowly moved upward to record the adhesion force when the carbon steel surface and the hydrate particle 11 are out of contact; the movable cantilever 4 is slowly moved downward until the hydrate particle shell is crushed by the carbon steel surface, and the strength of the hydrate particle shell is recorded.

[0039] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A device for evaluating the microscopic effect of a hydrate inhibitor, characterized in that: The device comprises a high-pressure reactor, an aluminum cup, a nanodisplacer, a movable cantilever and a fixed cantilever. The aluminum cup and the nanodisplacer are arranged in the cavity of the high-pressure reactor. One end of the movable cantilever is mounted on the nanodisplacer and the other end extends into the aluminum cup. One end of the fixed cantilever is fixed on the inner wall of the high-pressure reactor and the other end extends into the aluminum cup. A water bath coil is wound on the outer wall of the aluminum cup. The device also comprises a controller, and the nanodisplacer is electrically connected to the controller. A pressure sensor is provided at the bottom of the aluminum cup; the pressure sensor is electrically connected to the controller; The device also includes a constant temperature water bath, which is arranged outside the high pressure reactor and connected to the water bath coil through a circulation pipeline; the temperature control accuracy of the constant temperature water bath is ±0.1°C, and the lowest temperature can reach -10°C; The device also includes a pressurizing system, which is composed of a vacuum pump, a high-pressure gas cylinder and an air intake pipeline. The vacuum pump is connected to the high-pressure reactor, and the high-pressure gas cylinder is connected to the high-pressure reactor through the air intake pipeline; The method for using the device comprises the following steps: The constant temperature water bath of the device is turned on to pre-cool the aluminum cup; ice particles are fixed on the fixed cantilever, and the nano-displacer is controlled by the controller to make the carbon steel surface at the front end of the movable cantilever close to the ice particles; Injecting the required liquid into the aluminum cup and adding an appropriate amount of hydrate inhibitor until the liquid phase temperature drops to a temperature required for hydrate formation; Starting the vacuum pump in the pressurization system of the device to exhaust the air in the high-pressure reactor; closing the vacuum pump and opening the air inlet valve until the pressure in the reactor reaches the pressure required for hydrate formation; adjusting the temperature of the constant temperature water bath to a temperature 1-2°C higher than the stable existence temperature of the hydrate, and maintaining it for 25-35 minutes to melt the ice particles into water, and then lowering the temperature to allow the water and gas to react to form hydrate particles; The controller controls the nanodisplacer to gradually approach the hydrate particles until the carbon steel surface just contacts the hydrate particles; the movable cantilever is slowly moved upward to record the adhesion force when the carbon steel surface and the hydrate particles are out of contact; the movable cantilever is slowly moved downward until the shell of the hydrate particles is crushed by the carbon steel surface, and the strength of the shell of the hydrate particles is recorded.

2. The device according to claim 1, characterized in that The fixed cantilever is in a "Z" shape.

3. The device according to claim 1, characterized in that A carbon steel surface simulating the wall of an oil and gas pipeline is installed at the front end of the movable cantilever.

4. The device according to claim 1, characterized in that The cavity of the high-pressure reactor is cylindrical, with an internal size of φ328mm×148mm, made of 316L material, and a pressure resistance of 10Mpa.

5. The device according to claim 1, characterized in that The top of the high-pressure reactor is provided with an air inlet interface, a temperature measuring interface, a pressure measuring interface and a plurality of high-pressure through interfaces, and the bottom is provided with a circulation pipeline inlet and outlet interface.

6. The device according to claim 1, characterized in that The high-pressure reactor is also equipped with a temperature and pressure gauge.

Images