A device and method for rapid determination of dynamic formation temperature of high-pressure hydrates

Abstract

This invention discloses a rapid determination device and method for the dynamic formation temperature of high-pressure hydrates, relating to the field of oil and gas extraction technology. The determination device includes: a reaction vessel system comprising a high-low temperature alternating test chamber employing nonlinear cooling and a high-pressure reaction vessel located within the test chamber; a stirring system located within the test chamber, which uses magnetic coupling to stir the experimental fluid within the high-pressure reaction vessel; a sample preparation system for preparing samples for the experiment; and an observation system for observing the experiment inside the high-pressure reaction vessel. This invention provides an accurate determination of the hydrate formation temperature of water-producing oil and gas wells and surface pipelines under different pressures, flow rates, and surface roughnesses. By fitting experimental data, an empirical formula for hydrate formation considering pressure, fluid flow rate, and surface roughness factors is obtained, providing technical support for hydrate prevention and control and ensuring oil and gas field supply during winter.

Description

Technical Field

[0001] This invention relates to the field of oil and gas extraction technology, and more specifically to a device and method for rapidly determining the dynamic formation temperature of high-pressure hydrates. Background Technology

[0002] Regarding existing hydrate temperature measurement devices and methods, there are currently four experimental methods, mainly including:

[0003] 1. Observation method: The observation method uses a visual PVT instrument to directly measure the hydrate formation temperature under different pressures through the observation window by constant pressure cooling.

[0004] 2. Graphical method: The graphical method uses a constant volume reactor. By cooling the reactor at constant volume, the temperature and pressure change curves of the hydrate formation process are measured with a pressure sensor to obtain the PT curve of the hydrate formation process. The inflection point of the PT curve can be used to obtain the hydrate formation temperature.

[0005] 3. Differential Scanning Calorimetry: Differential scanning calorimetry utilizes the thermal effect during the decomposition of hydrates using a differential scanning calorimeter. By measuring the heat flow during hydrate decomposition, the phase equilibrium conditions of the hydrate are characterized, thus obtaining the phase equilibrium curve of the hydrate.

[0006] 4. Dynamic hydrate blockage experiment: The pressure difference across the capillary tube is used to determine whether hydrates are forming. A sharp increase in the pressure difference across the capillary tube indicates that hydrates are beginning to form in large quantities. The temperature at this point is taken as the hydrate formation temperature.

[0007] The four experimental methods in the prior art mentioned above have the following problems:

[0008] (1) Observation method: The observation method can only be carried out under static conditions, which fails to allow the gas and liquid phases to fully contact each other. It is far from the actual production conditions on site and requires a long experimental time.

[0009] (2) Graphical method: The PT curve obtained by the graphical method through constant volume cooling is not under constant pressure conditions, and the hydrate production temperature under a certain pressure is not obtained. It cannot obtain the PT curve of hydrate formation temperature under arbitrary pressure.

[0010] (3) Differential scanning calorimetry: In differential scanning calorimetry, the sample is not allowed to stand for a period of time during the sample loading process, so that the gas phase is saturated with dissolution in the solution. At the same time, hydrates preferentially form at the gas-liquid interface during the experiment, which prevents the hydrates from growing further. The hydrates are in a metastable state. The temperature is increased to determine the decomposition point of the hydrates. This temperature value is not the decomposition temperature under the stable existence condition of the hydrates.

[0011] (4) Dynamic blockage experimental setup for hydrates: The hydrate formation temperature obtained by the dynamic blockage experiment is the temperature at which hydrates begin to form in large quantities, which has a certain error compared with the actual hydrate formation temperature. Summary of the Invention

[0012] To overcome the shortcomings of existing technologies, this invention discloses a rapid device and method for determining the dynamic formation temperature of high-pressure hydrates. The purpose of this invention is to solve the problems existing in the experimental methods of the prior art. Based on crystallization and phase theory, and combined with the actual working conditions of wellbore and surface pipeline flow, this invention can obtain the changes in hydrate formation temperature under different influencing factors, providing experimental data for theoretical calculations and the formulation of on-site hydrate unblocking schemes. By fitting the experimental data, a formula for the hydrate formation temperature is obtained that comprehensively considers pressure, fluid velocity, and surface roughness. This invention is applicable to the experimental determination of hydrate formation temperature in water-producing gas and oil wells and surface pipelines.

[0013] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0014] In a first aspect, the present invention provides a device for rapid determination of the dynamic formation temperature of high-pressure hydrates, comprising:

[0015] The reactor system includes a high and low temperature alternating test chamber with nonlinear cooling and a high-pressure reactor located inside the high and low temperature alternating test chamber;

[0016] A stirring system is located inside the high and low temperature alternating test chamber, and it uses magnetic coupling to stir the experimental fluid in the high pressure reactor.

[0017] The sample preparation system includes a liquid sample preparation system and a gas sample preparation system. Both the liquid sample preparation system and the gas sample preparation system are located outside the high and low temperature alternating test chamber and are connected to the high pressure reactor through pipelines to prepare samples for the experiment.

[0018] An observation system is located inside the high and low temperature alternating test chamber and is used to observe the experiments inside the high-pressure reactor.

[0019] Preferably, the reactor system further includes a top cover, a loading and unloading hole, a sealing gasket I, a pressure-resistant transparent medium, a sealing gasket II, and a metal crystal block;

[0020] The high-pressure reactor has an opening on its side, and the top cover is screwed onto the opening in a fixed connection manner through the loading and unloading hole. The top cover is provided with a viewing window for observation by the observation system. The sealing gasket I, the pressure-resistant transparent medium, and the sealing gasket II are sequentially assembled inside the top cover. The metal crystal block is placed on the pressure-resistant transparent medium and is located inside the high-pressure reactor.

[0021] Preferably, the metal crystal block is made of oil pipe or gas pipeline material, and the metal crystal block includes several metal crystal blocks with different roughness.

[0022] Preferably, the reactor system further includes a temperature sensor, a reactor support frame, a liquid inlet shut-off valve IV, and an air inlet shut-off valve IV;

[0023] The temperature sensor is installed on the high-pressure reactor, which is mounted on the reactor support frame. The high-pressure reactor is connected to a liquid supply pipeline and a gas supply pipeline. The liquid inlet shut-off valve IV and the gas inlet shut-off valve IV are respectively installed on the liquid supply pipeline and the gas supply pipeline.

[0024] Preferably, the reactor system further includes a three-way valve, a liquid outlet shut-off valve, a back pressure controller, and a liquid collection bottle;

[0025] The liquid supply line is connected to the liquid outlet line via a T-junction. The liquid outlet shut-off valve and the back pressure controller are sequentially arranged on the liquid outlet line along the fluid flow direction. The liquid collection bottle is located at the outlet of the liquid outlet line.

[0026] Preferably, the stirring system includes a stepper motor, a strong magnetic metal block I, a soft pad, a metal-sealed bearing, a strong magnetic metal block II, and a resin rotor;

[0027] The stepper motor is mounted on the reactor support frame, and the strong magnetic metal block I is mounted on the upward rotating shaft of the stepper motor; a recess is provided at the bottom of the interior of the high-pressure reactor, the soft pad is assembled in the recess, the metal sealed bearing is assembled on the soft pad in the recess, the strong magnetic metal block II is embedded in the center hole of the metal sealed bearing, and the resin rotor is mounted on the strong magnetic metal block II.

[0028] The strong magnetic metal block I and strong magnetic metal block II are matched. The stepper motor drives the strong magnetic metal block I to rotate, and the strong magnetic metal block I drives the strong magnetic metal block II to rotate, which in turn drives the resin rotor to rotate, thus stirring the experimental fluid in the high-pressure reactor.

[0029] Preferably, the liquid preparation system includes a high-pressure displacement pump I, a pressure sensor I, an inlet shut-off valve I, an inlet shut-off valve II, an intermediate container I, and an inlet shut-off valve III;

[0030] The high-pressure displacement pump I, inlet shut-off valve I, inlet shut-off valve II, intermediate container I, and inlet shut-off valve III are connected in sequence through pipelines. The pressure sensor I is installed on the pipeline between the high-pressure displacement pump I and the inlet shut-off valve I. The inlet shut-off valve III is connected to the inlet shut-off valve IV through a pipeline.

[0031] Preferably, the gas mixing system includes a high-pressure displacement pump II, a pressure sensor II, an inlet shut-off valve I, an inlet shut-off valve II, an intermediate container II, and an inlet shut-off valve III;

[0032] The high-pressure displacement pump II, inlet shut-off valve I, inlet shut-off valve II, intermediate container II, and inlet shut-off valve III are connected in sequence through pipelines. The pressure sensor II is installed on the pipeline between the high-pressure displacement pump II and the inlet shut-off valve I. The inlet shut-off valve III is connected to the inlet shut-off valve IV through a pipeline.

[0033] Preferably, the observation system includes an industrial camera and a support frame, with the industrial camera mounted on the support frame and its camera end facing the viewing window of the top cover.

[0034] Secondly, this invention provides a method for rapid determination of the dynamic formation temperature of high-pressure hydrates, comprising the following steps:

[0035] S1: Cleaning the high-pressure reactor: Clean the entire high-pressure reactor with organic solvent and then dry it;

[0036] S2: Prepare the experimental samples: Fill intermediate container I with formation water, fill intermediate container II with the experimental natural gas sample, and pressurize it to the experimental pressure P. i And maintain constant pressure;

[0037] S3: Evacuate the reactor system and connect it to the sample preparation system;

[0038] S4: Pressure Holding and Sample Transfer: Open the liquid inlet shut-off valve and use high-pressure displacement pump I to inject the formation water from intermediate container I into the high-pressure reactor until half of the metal crystal block is submerged. Then close the liquid inlet shut-off valve, open the gas inlet shut-off valve, and use high-pressure displacement pump II to inject the natural gas from intermediate container II into the high-pressure reactor and pressurize it until the value of pressure sensor II equals P. i High-pressure displacement pump II stops pumping and maintains constant pressure, then closes the intake shut-off valve;

[0039] S5: The back pressure controller applies back pressure, causing the back pressure P to... h equal to the pressure P in the high-pressure reactor i ;

[0040] S6: Start the high and low temperature alternating test chamber to raise the temperature of the high-pressure reactor to the formation temperature T. max And keep the temperature constant;

[0041] S7: Start the stirring system. The stirring system rotates at a certain speed v to simulate the flow state of a well or surface pipeline.

[0042] S8: Cooling: Cooling is achieved using a high and low temperature alternating test chamber in a non-linear cooling manner;

[0043] S9: Observation: Start the industrial camera and record the real-time temperature T;

[0044] S10: Formation Temperature Verification: Review the footage recorded by the industrial camera to find the temperature T at which the hydrate just began to form. i ;

[0045] S11: Turn off the stirring system and the high and low temperature alternating test chamber, and use the back pressure controller to reduce the back pressure P. h This was adjusted to be slightly lower than the experimental test pressure P. i Open the inlet shut-off valve IV and the outlet shut-off valve to release all the experimental fluid in the high-pressure reactor into the collection bottle. Then close the outlet shut-off valve and use the back pressure controller to increase the back pressure P. h To a pressure Pi slightly higher than that in the high-pressure reactor;

[0046] S12: Disassemble the reactor system and sample preparation system; clean the high-pressure reactor and change the experimental pressure P. i Repeat S2 to S12;

[0047] S13: Plot the generation temperature T i With pressure P i The curve showing the change.

[0048] Preferred options also include:

[0049] S14: Change the stepper motor speed v, repeat S2~S13, different speeds v i Below, the generation temperature T i With pressure P i The curve showing the change.

[0050] Preferred options also include:

[0051] S15: Change the roughness μ of the metal crystal block, repeat S2~S13, different roughness μ i Below, the generation temperature T i With pressure P i The curve showing the change.

[0052] Preferred options also include:

[0053] S16: Fit the experimental data to obtain an empirical formula for the hydrate formation temperature that takes into account factors such as pressure, fluid velocity, and surface roughness.

[0054] Preferably, the empirical formula for temperature is:

[0055] T i =A(P i ) D ×B(v i ) E×C(μ i ) F

[0056] In the formula, T i v is the temperature at which hydrates form, in °C. i Rotational speed, r / min; μ i Let A be the surface roughness, which is dimensionless; A, B, C, D, E, and F are all constants.

[0057] The main innovative points of this invention include the following four points:

[0058] (1) Consider the influence of hydrate formation temperature as much as possible.

[0059] The reactor and reactor system can be used to account for the effects of pressure and surface roughness on the hydrate formation temperature. The stirring system can be used to account for the effects of fluid flow rate on the hydrate formation temperature.

[0060] (2) Create dynamic experimental conditions and solve the sealing problem.

[0061] This invention employs the principle of magnetic coupling, utilizing an external stepper motor to drive the rotation of a strong magnetic metal block. This allows the resin rotor to rotate almost without resistance along with a metal-sealed bearing, thereby shearing and stirring the experimental fluid to simulate the flow of fluids in wells or surface pipe networks. The stepper motor is located outside the reactor, using the rotation of the strong magnet to rotate the resin rotor. Traditional high-pressure stirring devices use a method of drilling holes in the reactor, allowing the motor rotor to pass through the holes, and placing a sealing ring inside to achieve dynamic simulation and sealing. However, this method leads to wear of the sealing ring, causing seal failure. The stirring system used in this invention enables dynamic experiments while avoiding seal failure.

[0062] (3) Create conditions for rapid generation

[0063] Metal crystal blocks made from oil or gas pipeline materials have rough surfaces, which can provide nuclei for hydrate formation, enabling hydrate crystals to grow rapidly and shortening experimental time.

[0064] (4) Nonlinear cooling

[0065] By employing a high-low temperature alternating test chamber with non-linear cooling, the phenomenon of hydrate formation occurring despite reaching the hydrate formation temperature during continuous cooling can be effectively avoided. This achieves the goal of accurately determining the hydrate formation temperature.

[0066] Key improvements of this invention:

[0067] This invention comprehensively considers the factors influencing hydrate formation and establishes a dynamic hydrate formation temperature experimental determination device that simultaneously considers pressure, surface roughness, and fluid flow velocity. It overcomes the shortcomings of existing experimental devices, such as incomplete consideration of factors and inconsistencies with the actual conditions of wellbores and surface pipelines. It achieves the goal of dynamic hydrate formation temperature testing under pressurized conditions. The stirring system designed based on the principle of magnetic coupling in this invention can generate a flow state while avoiding the sealing problems of traditional stirrers. The metal crystal block designed based on crystallization theory in this invention can provide crystal nuclei for hydrate formation and simulate the material of wellbores and surface pipelines, achieving rapid hydrate formation and shortening experimental time. The use of nonlinear cooling avoids the phenomenon of hydrate formation temperature being reached but not yet formed, which is common with previous continuous cooling methods, thus achieving accurate determination of the hydrate formation temperature.

[0068] The beneficial effects of this invention are:

[0069] (1) The present invention provides a method to accurately determine the hydrate formation temperature of water-producing oil and gas wells and surface pipelines under different pressures, flow rates and surface roughnesses. By fitting the experimental data, an empirical formula for hydrate formation that comprehensively considers the factors of pressure, fluid flow rate and surface roughness is obtained, which is more effective in guiding on-site production.

[0070] (2) The stirring system designed by the present invention based on the principle of magnetic coupling can conduct dynamic experiments and also avoids the occurrence of sealing failure.

[0071] (3) The metal crystal block of the present invention can provide crystal nuclei for hydrate formation and simulate the material of well barrels and ground pipelines to achieve rapid hydrate formation and shorten the experimental time.

[0072] (4) The present invention adopts a non-linear cooling method to avoid the phenomenon that the hydrate formation temperature has been reached but no hydrate has formed due to continuous cooling in the past, thus achieving the purpose of accurately measuring the hydrate formation temperature. Attached Figure Description

[0073] Figure 1 This is a schematic diagram of the device for rapid determination of dynamic formation temperature of high-pressure hydrates according to the present invention.

[0074] Figure 2 This is a front view of the top cover of the present invention;

[0075] Figure 3 This is a top view of the top cover of the present invention;

[0076] Figure 4 This is a schematic diagram of the pressure-resistant transparent medium and metal crystal block of the present invention;

[0077] Figure 5 This is a graph showing the hydrate formation temperature of an embodiment of the present invention;

[0078] Figure label:

[0079] 1. Temperature sensor; 2. High and low temperature alternating test chamber; 3. High pressure reactor; 4. Top cover; 5. Loading and unloading hole; 6. Industrial camera; 7. Support frame; 8. Sealing gasket I; 9. Pressure-resistant transparent medium; 10. Metal crystal block; 11. Reactor support frame; 12. Strong magnetic metal block I; 13. Stepper motor; 14. Liquid collecting bottle; 15. Back pressure controller; 16. Liquid outlet shut-off valve; 17. T-junction; 18. Liquid inlet shut-off valve III; 19. Intermediate container I; 20. 21. Liquid inlet shut-off valve II; 22. Liquid inlet shut-off valve I; 23. Pressure sensor I; 24. High-pressure displacement pump I; 25. Air inlet shut-off valve I; 26. High-pressure displacement pump II; 27. Pressure sensor II; 28. Air inlet shut-off valve II; 29. ​​Intermediate container II; 30. Air inlet shut-off valve III; 31. Liquid inlet shut-off valve IV; 32. Metal-sealed bearing; 33. Strong magnetic metal block II; 34. Air inlet shut-off valve IV; 35. Resin rotor; 36. Soft pad; 37. Sealing gasket II. Detailed Implementation

[0080] The following will provide a clear and complete description of the concept, specific structure, and technical effects of the present invention in conjunction with the embodiments and accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention.

[0081] Example 1

[0082] A device for rapid determination of the dynamic formation temperature of high-pressure hydrates, such as Figure 1 As shown, it includes:

[0083] The reactor system includes a high and low temperature alternating test chamber 2 with nonlinear cooling and a high-pressure reactor 3 located inside the high and low temperature alternating test chamber 2;

[0084] The stirring system is located inside the high and low temperature alternating test chamber 2. It uses magnetic coupling to stir the experimental fluid in the high pressure reactor 3.

[0085] The sample preparation system includes a liquid sample preparation system and a gas sample preparation system. Both the liquid sample preparation system and the gas sample preparation system are located outside the high and low temperature alternating test chamber 2 and are connected to the high pressure reactor 3 through pipelines to prepare samples for the experiment.

[0086] The observation system is located inside the high and low temperature alternating test chamber 2 and is used to observe the experiments inside the high pressure reactor 3.

[0087] In this embodiment, the high and low temperature alternating test chamber adopts a nonlinear cooling method, which can effectively avoid the phenomenon that the hydrate formation temperature has been reached but hydrates have not formed due to continuous cooling. The stirring system uses magnetic coupling to stir the experimental fluid in the high-pressure reactor 3, avoiding the occurrence of sealing failure.

[0088] like Figure 1 , 2 As shown in Figures 3 and 4, the reactor system also includes a top cover 4, a loading and unloading hole 5, a sealing gasket I 8, a pressure-resistant transparent medium 9, a sealing gasket II 36, and a metal crystal block 10;

[0089] The high-pressure reactor 3 has an opening on its side. The top cover 4 is screwed onto the opening by means of a fixed connection through the loading and unloading hole 5. The top cover 4 is provided with a viewing window for observation by the observation system. The sealing gasket I 8, the pressure-resistant transparent medium 9, and the sealing gasket II 36 are sequentially assembled inside the top cover 4. The metal crystal block 10 is placed on the pressure-resistant transparent medium 9 and is located inside the high-pressure reactor 3.

[0090] In this embodiment, the metal crystal block 10 is made of oil pipe or gas pipeline material, and the metal crystal block 10 includes several metal crystal blocks with different roughnesses. The metal crystal block 10 made of oil pipe or gas pipeline material has a rough surface, which can provide crystal nuclei for the formation of hydrates, enabling hydrate crystals to grow rapidly and shortening the experimental time.

[0091] like Figure 1 As shown, the reactor system also includes a temperature sensor 1, a reactor support frame 11, a liquid inlet shut-off valve IV 30, and an air inlet shut-off valve IV 33;

[0092] Temperature sensor 1 is installed on high-pressure reactor 3 to measure the internal temperature of high-pressure reactor 3. High-pressure reactor 3 is mounted on reactor support frame 11. High-pressure reactor 3 is connected to liquid supply pipeline and gas supply pipeline. Liquid inlet shut-off valve IV30 and gas inlet shut-off valve IV33 are respectively installed on liquid supply pipeline and gas supply pipeline.

[0093] like Figure 1 As shown, the reactor system also includes a three-way valve 17, a liquid outlet shut-off valve 16, a back pressure controller 15, and a collection bottle 14. The liquid supply line is connected to the liquid outlet line via the three-way valve 17. The liquid outlet shut-off valve 16 and the back pressure controller 15 are sequentially arranged on the liquid outlet line along the fluid flow direction, and the collection bottle 14 is located at the outlet of the liquid outlet line. By setting up the above structure, it is possible to facilitate the drainage of the high-pressure reactor 3 and the control of back pressure.

[0094] like Figure 1 As shown, the stirring system includes a stepper motor 13, a strong magnetic metal block I 12, a soft pad 35, a metal sealed bearing 31, a strong magnetic metal block II 32, and a resin rotor 34;

[0095] A stepper motor 13 is mounted on the reactor support frame 11, and a strong magnetic metal block I 12 is mounted on the upward rotating shaft of the stepper motor 13; a recess is provided at the bottom of the high-pressure reactor 3, a soft pad 35 is assembled in the recess, a metal sealed bearing 31 is assembled on the soft pad 35 in the recess, a strong magnetic metal block II 32 is embedded in the center hole of the metal sealed bearing 31, and a resin rotor 34 is mounted on the strong magnetic metal block II 32.

[0096] Strong magnetic metal block I12 and strong magnetic metal block II32 are matched. Stepper motor 13 drives strong magnetic metal block I12 to rotate, which in turn drives strong magnetic metal block II32 to rotate, thereby driving resin rotor 34 to rotate and stirring the experimental fluid in high-pressure reactor 3. Utilizing the principle of magnetic coupling, an external stepper motor drives the rotation of the strong magnetic metal blocks, allowing the resin rotor to rotate almost without resistance together with the metal sealed bearing, thus shearing and stirring the experimental fluid to simulate the flow of fluid in a well or surface pipe network.

[0097] like Figure 1 As shown, the liquid preparation system includes a high-pressure displacement pump I23, a pressure sensor I22, an inlet shut-off valve I21, an inlet shut-off valve II20, an intermediate container I19, and an inlet shut-off valve III18;

[0098] High-pressure displacement pump I23, inlet shut-off valve I21, inlet shut-off valve II20, intermediate container I19, and inlet shut-off valve III18 are connected sequentially via pipelines. Pressure sensor I22 is installed on the pipeline between high-pressure displacement pump I23 and inlet shut-off valve I21. Inlet shut-off valve III18 is connected to inlet shut-off valve IV30 via a pipeline. This structure facilitates liquid sample preparation in the high-pressure reactor 3.

[0099] like Figure 1 As shown, the gas mixing system includes a high-pressure displacement pump II 25, a pressure sensor II 26, an inlet shut-off valve I 24, an inlet shut-off valve II 27, an intermediate container II 28, and an inlet shut-off valve III 29.

[0100] High-pressure displacement pump II 25, inlet shut-off valve I 24, inlet shut-off valve II 27, intermediate container II 28, and inlet shut-off valve III 29 are connected sequentially via pipelines. Pressure sensor II 26 is installed on the pipeline between high-pressure displacement pump II 25 and inlet shut-off valve I 24. Inlet shut-off valve III 29 is connected to inlet shut-off valve IV 33 via a pipeline. This structure facilitates gas sampling in the high-pressure reactor 3.

[0101] like Figure 1 As shown, the observation system includes an industrial camera 6 and a support frame 7. The industrial camera 6 is mounted on the support frame 7, and the camera end of the industrial camera 6 faces the viewing window of the top cover 4 to capture the experimental conditions inside the high-pressure reactor 3.

[0102] Example 2

[0103] A rapid method for determining the dynamic formation temperature of high-pressure hydrates includes the following steps:

[0104] S1: Cleaning the high-pressure reactor 3: Clean the entire high-pressure reactor 3 with an organic solvent and then dry it;

[0105] S2: Prepare the experimental samples: Fill intermediate container I19 with formation water, and fill intermediate container II28 with the experimental natural gas sample, and pressurize it to the experimental pressure P. i And maintain constant pressure;

[0106] S3: Evacuate the reactor system and connect it to the sample preparation system;

[0107] S4: Pressure Holding and Sample Transfer: Open the liquid inlet shut-off valve and use high-pressure displacement pump I23 to inject the formation water from intermediate container I19 into high-pressure reactor 3 until half of the metal crystal block 10 is submerged. Then close the liquid inlet shut-off valve, open the gas inlet shut-off valve, and use high-pressure displacement pump II25 to inject the natural gas from intermediate container II28 into high-pressure reactor 3 and pressurize it until the value of pressure sensor II26 equals P. i The high-pressure displacement pump II25 stops pumping and maintains constant pressure, then the intake shut-off valve is closed.

[0108] S5: Back pressure controller 15 applies back pressure, causing back pressure P h equal to the pressure P in high-pressure reactor 3 i ;

[0109] S6: Start the high and low temperature alternating test chamber 2 to raise the temperature of the high pressure reactor 3 to the formation temperature T. max And keep the temperature constant;

[0110] S7: Start the stirring system. The stirring system rotates at a certain speed v to simulate the flow state of a well or surface pipeline.

[0111] S8: Cooling: Cooling is achieved using the high and low temperature alternating test chamber 2 in a non-linear cooling manner;

[0112] S9: Observation: Start industrial camera 6 and record real-time temperature T;

[0113] S10: Formation Temperature Verification: Review the images recorded by industrial camera 6 to find the temperature T at which the hydrate just began to form. i ;

[0114] S11: Turn off the stirring system and the high and low temperature alternating test chamber 2, and use the back pressure controller 15 to reduce the back pressure P. h This was adjusted to be slightly lower than the experimental test pressure P. iOpen the inlet shut-off valve IV30 and the outlet shut-off valve 16 to release all the experimental fluid in the high-pressure reactor 3 into the collection bottle 14. Then close the outlet shut-off valve 16 and use the back pressure controller 15 to increase the back pressure P. h The pressure Pi is slightly higher than that in the high-pressure reactor 3;

[0115] S12: Disassemble the reactor system and sample preparation system; clean the high-pressure reactor 3, and change the experimental pressure P. i Repeat S2 to S12;

[0116] S13: Plot the generation temperature T i With pressure P i The curve showing the change.

[0117] S14: Change the speed v of the stepper motor 13, repeat S2~S13, different speeds v i Below, the generation temperature T i With pressure P i The curve showing the change.

[0118] S15: Change the roughness μ of the metal crystal block 10, and repeat S2 to S13. Different roughness μ i Below, the generation temperature T i With pressure P i The curve showing the change.

[0119] S16: Fit the experimental data to obtain an empirical formula for the hydrate formation temperature that takes into account factors such as pressure, fluid velocity, and surface roughness.

[0120] The empirical formula for temperature is:

[0121] T i =A(P i ) D ×B(v i ) E ×C(μ i ) F

[0122] In the formula, T i v is the temperature at which hydrates form, in °C. i Rotational speed, r / min; μ i Let A be the surface roughness, which is dimensionless; A, B, C, D, E, and F are all constants.

[0123] Taking a water-gas well in a block in Northwest China as an example, this well is characterized by low temperature, high pressure, and high production. According to a rapid method for determining the dynamic formation temperature of high-pressure hydrates, firstly, experimental formation water and natural gas are injected into the reaction vessel system using a sample mixing system. The stirring system and high-low temperature alternating test chamber are then started, and the experiment is conducted at the experimental pressure and rotation speed. Nonlinear cooling is then performed. After a period of reaction, whether hydrates form is observed, and the formation temperature is recorded. By changing the test pressure and rotation speed, the hydrate formation temperatures under different pressures and rotation speeds are obtained.

[0124] This invention tested the hydrate formation temperature of the well under different pressures and rotational speeds. The results are attached. Figure 5 As shown, the hydrate formation temperatures were obtained at rotational speeds of 5 r / s and 10 r / s, and pressures of 42 MPa, 35 MPa, 27 MPa, 18 MPa, 10 MPa, and 5 MPa, respectively. At the same rotational speed, higher pressure resulted in a higher hydrate formation temperature; conversely, at the same pressure, higher rotational speed resulted in a higher hydrate formation temperature. These results demonstrate that the present invention can accurately measure the hydrate formation temperature under high-pressure conditions.

[0125] The alternative approach of this invention is to use a gas-liquid-solid three-phase model and calculate the hydrate formation temperature under different pressures through programming.

[0126] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalents or substitutions are all included within the scope defined by the claims of the present invention.

Claims

1. A device for rapid determination of the dynamic formation temperature of high-pressure hydrates, characterized in that, include: The reactor system includes a high and low temperature alternating test chamber (2) with nonlinear cooling and a high pressure reactor (3) located inside the high and low temperature alternating test chamber (2). The stirring system is located inside the high and low temperature alternating test chamber (2), and it uses magnetic coupling to stir the experimental fluid in the high pressure reactor (3); The sample preparation system includes a liquid sample preparation system and a gas sample preparation system. Both the liquid sample preparation system and the gas sample preparation system are located outside the high and low temperature alternating test chamber (2) and are connected to the high pressure reactor (3) through pipelines to prepare samples for the experiment. The observation system is located inside the high and low temperature alternating test chamber (2) and is used to observe the experiments inside the high pressure reactor (3); The reactor system also includes a top cover (4), a loading and unloading hole (5), a sealing gasket I (8), a pressure-resistant transparent medium (9), a sealing gasket II (36), and a metal crystal block (10). The high-pressure reactor (3) has an opening on its side. The top cover (4) is screwed onto the opening in a fixed connection manner through the loading and unloading hole (5). The top cover (4) has a viewing window for observation by the observation system. The sealing gasket I (8), the pressure-resistant transparent medium (9), and the sealing gasket II (36) are sequentially assembled inside the top cover (4). The metal crystal block (10) is placed on the pressure-resistant transparent medium (9) and located inside the high-pressure reactor (3).

2. The measuring device as described in claim 1, characterized in that, The metal crystal block (10) is made of oil pipe or gas pipeline material, and the metal crystal block (10) includes several metal crystal blocks with different roughness.

3. The measuring device as described in claim 1, characterized in that, The reactor system also includes a temperature sensor (1), a reactor support frame (11), a liquid inlet shut-off valve IV (30), and an air inlet shut-off valve IV (33). The temperature sensor (1) is installed on the high-pressure reactor (3), the high-pressure reactor (3) is mounted on the reactor support frame (11), the high-pressure reactor (3) is connected to a liquid supply pipeline and a gas supply pipeline, and the liquid inlet shut-off valve IV (30) and the gas inlet shut-off valve IV (33) are respectively installed on the liquid supply pipeline and the gas supply pipeline.

4. The measuring device as described in claim 3, characterized in that, The reactor system also includes a three-way valve (17), a liquid outlet shut-off valve (16), a back pressure controller (15), and a liquid collection bottle (14). The liquid supply pipeline is connected to the liquid outlet pipeline via a tee (17). The liquid outlet shut-off valve (16) and back pressure controller (15) are sequentially arranged on the liquid outlet pipeline along the fluid flow direction. The liquid collection bottle (14) is located at the outlet of the liquid outlet pipeline.

5. The measuring device as described in claim 4, characterized in that, The stirring system includes a stepper motor (13), a strong magnetic metal block I (12), a soft pad (35), a metal sealed bearing (31), a strong magnetic metal block II (32), and a resin rotor (34). The stepper motor (13) is mounted on the reactor support frame (11) and located below the high-pressure reactor (3). The strong magnetic metal block I (12) is mounted on the upward rotating shaft of the stepper motor (13). A recess is provided at the bottom of the interior of the high-pressure reactor (3). The soft pad (35) is assembled in the recess. The metal sealed bearing (31) is assembled on the soft pad (35) of the recess. The strong magnetic metal block II (32) is embedded in the center hole of the metal sealed bearing (31). The resin rotor (34) is mounted on the strong magnetic metal block II (32). The strong magnetic metal block I (12) and strong magnetic metal block II (32) are matched. The stepper motor (13) drives the strong magnetic metal block I (12) to rotate. The strong magnetic metal block I (12) drives the strong magnetic metal block II (32) to rotate, which in turn drives the resin rotor (34) to rotate, thus stirring the experimental fluid in the high-pressure reactor (3).

6. The measuring device as described in claim 5, characterized in that, The liquid preparation system includes a high-pressure displacement pump I (23), a pressure sensor I (22), an inlet shut-off valve I (21), an inlet shut-off valve II (20), an intermediate container I (19), and an inlet shut-off valve III (18). The high-pressure displacement pump I (23), inlet shut-off valve I (21), inlet shut-off valve II (20), intermediate container I (19) and inlet shut-off valve III (18) are connected in sequence through pipelines. The pressure sensor I (22) is installed on the pipeline between the high-pressure displacement pump I (23) and inlet shut-off valve I (21). The inlet shut-off valve III (18) is connected to the inlet shut-off valve IV (30) through a pipeline.

7. The measuring device as described in claim 6, characterized in that, The gas mixing system includes a high-pressure displacement pump II (25), a pressure sensor II (26), an inlet shut-off valve I (24), an inlet shut-off valve II (27), an intermediate container II (28), and an inlet shut-off valve III (29). The high-pressure displacement pump II (25), inlet shut-off valve I (24), inlet shut-off valve II (27), intermediate container II (28) and inlet shut-off valve III (29) are connected in sequence through pipelines. The pressure sensor II (26) is installed on the pipeline between the high-pressure displacement pump II (25) and inlet shut-off valve I (24). The inlet shut-off valve III (29) is connected to the inlet shut-off valve IV (33) through a pipeline.

8. The measuring apparatus as described in claim 7, characterized in that, The observation system includes an industrial camera (6) and a support frame (7). The industrial camera (6) is mounted on the support frame (7), and the camera end of the industrial camera (6) faces the viewing window of the top cover (4).

9. A rapid method for determining the dynamic formation temperature of high-pressure hydrates based on the measuring device of claim 8, characterized in that, Includes the following steps: S1: Cleaning the high-pressure reactor (3): Clean the entire high-pressure reactor (3) with organic solvent and dry it; S2: Prepare the experimental sample: Fill intermediate container I (19) with formation water, fill intermediate container II (28) with the experimental natural gas sample, and pressurize it to the experimental pressure P. i And maintain constant pressure; S3: Evacuate the reactor system and connect it to the sample preparation system; S4: Pressure Holding and Sample Transfer: Open the liquid inlet shut-off valve and use the high-pressure displacement pump I (23) to inject the formation water from intermediate container I (19) into the high-pressure reactor (3) until half of the metal crystal block (10) is submerged. Then close the liquid inlet shut-off valve, open the gas inlet shut-off valve, and use the high-pressure displacement pump II (25) to inject the natural gas from intermediate container II (28) into the high-pressure reactor (3) and pressurize it until the value of pressure sensor II (26) equals P. i , the high pressure displacement pump II (25) stops pumping and maintains constant pressure, and then closes the air inlet shut-off valve; S5: Back pressure controller (15) loads back pressure, making back pressure P h Equal to the pressure P in the high-pressure reactor (3) i ; S6: Start the high and low temperature alternating test chamber (2) to raise the temperature of the high pressure reactor (3) to the formation temperature T. max And keep the temperature constant; S7: Start the stirring system; the stirring system will operate at a certain speed. v Rotation simulates the flow state of wellbores or surface pipelines; S8: Cooling: Cooling is achieved by using a high and low temperature alternating test chamber (2) in a non-linear cooling manner; S9: Observation: Start the industrial camera (6) and record the real-time temperature T; S10: Formation temperature verification: Review the images recorded by the industrial camera (6) to find the temperature T at which the hydrate just began to form. i ; S11: Turn off the stirring system and the high and low temperature alternating test chamber (2), and use the back pressure controller (15) to reduce the back pressure P. h To make it lower than the experimental test pressure P i Open the inlet shut-off valve IV (30) and the outlet shut-off valve (16) to release all the experimental fluid in the high-pressure reactor (3) into the collection bottle (14). Then close the outlet shut-off valve (16) and use the back pressure controller (15) to raise the back pressure P. h The pressure Pi is higher than that in the high-pressure reactor (3); S12: Disassemble the reactor system and sample preparation system; clean the high-pressure reactor (3), and change the experimental pressure P. i Repeat S2~S12; S13: Plot the generation temperature T i With pressure P i The curve showing the change.

10. The determination method as described in claim 9, characterized in that, Also includes: S14: Change the speed of the stepper motor (13) v Repeat steps S2 to S13 at different speeds. v i Below, the generation temperature T i With pressure P i The curve showing the change.

11. The determination method as described in claim 10, characterized in that, Also includes: S15: Change the roughness of the metal crystal block (10) μ Repeat steps S2 to S13 with different roughnesses. μ i Down ， Generation temperature T i With pressure P i The curve showing the change.

12. The determination method as described in claim 11, characterized in that, Also includes: S16: Fit the experimental data to obtain an empirical formula for the hydrate formation temperature that takes into account factors such as pressure, fluid velocity, and surface roughness.

13. The determination method as described in claim 12, characterized in that, The empirical formula for temperature is: ； In the formula, T i The temperature at which the hydrate forms, in °C; v i Rotational speed, in r / min; μ i Let A be the surface roughness, which is dimensionless; A, B, C, D, E, and F are all constants.

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