A device and method for evaluating the solubility and viscosity of a CO2 thickener

Abstract

The application discloses a CO2 thickening agent solubility and viscosity increasing experiment evaluation device and method, belongs to the technical field of CO2 thickening agent experiments, and comprises a mixing cavity, a booster system is arranged on the top of the mixing cavity, and a stirrer is arranged on the bottom of the mixing cavity; the mixing cavity is connected with a CO2 thickening agent system and a CO2 booster system through an injection pipeline; the bottom of the mixing cavity is respectively connected with an online monitoring system and a gas-liquid separator through pipelines; the gas-liquid separator is respectively connected with a sample collector and a buffer tank through pipelines; the buffer tank is connected with a CO2 booster pump through a pipeline; and a visual window is arranged on the mixing cavity. The CO2 thickening agent solubility and viscosity increasing experiment evaluation device and method can meet the research on the influence of different pressures on experiments, realize online and accurate determination of the viscosity of a CO2 and CO2 thickening agent mixed system, realize recycling of CO2, protect the environment, save experimental costs, realize highly automatic control and intelligent adjustment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of CO2 thickener experiment, in particular to a CO2 thickener solubility and viscosity increasing experiment evaluation device and method. BACKGROUND

[0002] Unconventional oil and gas, represented by shale oil and gas and low-permeability tight oil and gas, is an important replacement resource. Due to poor reservoir properties, it is difficult to effectively exploit. At present, reservoir reconstruction is mainly carried out through horizontal well volume fracturing technology, but there are still problems such as water resource waste, large reservoir damage and general stimulation effect. Supercritical / liquid CO2 has the characteristics of low viscosity, high density and high diffusivity, and can quickly enter the micro-pore and micro-fracture of the reservoir. CO2 fracturing can effectively reduce the fracture pressure, form a complex fracture network, increase the formation energy, improve the flowback rate, reduce the reservoir damage and achieve single well stimulation, and is suitable for efficient and green exploitation of unconventional oil and gas resources.

[0003] Due to the low viscosity (0.02-0.04 mPa·s) of pure CO2 fracturing fluid, the CO2 fracturing fluid has problems such as viscous fingering, gravity separation, large filtration loss, high friction and poor sand carrying performance, which seriously affects the reservoir fracturing reconstruction effect. The most effective method to solve this problem is to add a thickening agent to pure CO2 to increase the viscosity of the fracturing fluid, so as to improve the reservoir reconstruction effect. Therefore, the evaluation of the solubility and viscosity increasing of the CO2 thickening agent is particularly important. The existing device cannot realize the dynamic change of the volume and pressure of the CO2 and thickening agent mixing cavity, and cannot realize the online testing of the viscosity of the system after the CO2 and CO2 thickening agent are fully dissolved. After the experiment of the existing device is completed, the CO2 gas is directly vented, the recycling of the CO2 gas is not realized, and the environmental protection is poor. Based on this, the present application provides a CO2 thickening agent solubility and viscosity increasing experiment evaluation device and method. SUMMARY

[0004] The purpose of the present application is to provide a CO2 thickening agent solubility and viscosity increasing experiment evaluation device and method to solve the above-mentioned problems.

[0005] To solve the above technical problems, the present application adopts the following technical scheme:

[0006] The CO2 thickening agent solubility and viscosity increasing experiment evaluation device of the present application comprises a mixing cavity, a booster system is arranged at the top position in the mixing cavity, and a stirrer is arranged at the bottom position; the mixing cavity is connected with a CO2 thickening agent system and a CO2 booster system through an injection pipeline; the bottom of the mixing cavity is respectively connected with an online monitoring system and a gas-liquid separator through a pipeline; the gas-liquid separator is respectively connected with a sample collector and a buffer tank through a pipeline, and the buffer tank is connected with a CO2 booster pump through a pipeline; and a visual window is arranged on the mixing cavity.

[0007] Further, the pressurization system comprises a piston rod inside the mixing cavity, the bottom of the piston rod is provided with a piston head in sliding connection with the inner sidewall of the mixing cavity, and the top of the piston rod is connected with an electric elevator after penetrating out of the mixing cavity.

[0008] Further, the stirrer comprises a stirring blade inside the mixing cavity, the stirring blades are circumferentially distributed on the upper end of a stirring shaft, and the lower end of the stirring shaft is connected with a stirring motor after penetrating out of the mixing cavity.

[0009] Further, the CO2 thickening agent system comprises an intermediate container, the intermediate container is connected with a convection pump through a pipeline, the other end of the convection pump is connected with a water source; the liquid in the intermediate container is divided into two layers, the upper layer is a CO2 thickening agent, and the lower layer is water.

[0010] Further, the CO2 pressurization system comprises a CO2 gas cylinder, and the pipeline between the CO2 gas cylinder and the mixing cavity is provided with the CO2 pressurization pump.

[0011] Further, the online monitoring system comprises a temperature sensor, a pressure sensor and an online capillary viscometer, and the temperature sensor, the pressure sensor and the online capillary viscometer are electrically connected with a central control system; the online capillary viscometer is connected with a vacuum pump, and the pipeline between the online capillary viscometer and the mixing cavity is provided with a viscometer inlet valve.

[0012] Further, the sample collector is connected with a thickening agent analysis system.

[0013] Further, an electric heating jacket is sleeved on the outer periphery of the mixing cavity.

[0014] Further, a gas-liquid separator inlet valve is arranged on the pipeline between the gas-liquid separator and the mixing cavity.

[0015] A CO2 thickening agent solubility and viscosity evaluation method, characterized by comprising the following steps:

[0016] Step one, start the convection pump, increase the amount of water in the bottom layer of the intermediate container, and push the CO2 thickening agent in the upper layer into the mixing cavity;

[0017] Step two, open the CO2 gas cylinder, start the CO2 pressurization pump, and inject CO2 into the mixing cavity;

[0018] Step three, start the electric heating jacket, and heat the mixing cavity to the designed temperature;

[0019] Step four, start the stirrer, and stir the CO2 thickener and injected CO2 gas in the mixing chamber;

[0020] Step five, observe the dissolution of the CO2 thickener through the visual window, if it is not fully dissolved, start the piston rod to move down, pressurize the mixing chamber, until the CO2 thickener is fully dissolved in the CO2 gas;

[0021] Step six, after the CO2 thickener is dissolved stably, start the vacuum pump to vacuum the online capillary viscometer, and simultaneously start the electric heating system on the online capillary viscometer to heat the entire online capillary viscometer to the design temperature (consistent with the temperature in the mixing chamber), then open the viscometer inlet valve, and send the mixed system after dissolution into the online capillary viscometer to measure its viscosity;

[0022] Step seven, after the viscosity coefficient measurement of step six is completed, open the gas-liquid separator inlet valve, and the material in the mixing chamber enters the gas-liquid separator, the entering material is separated from the CO2 thickener and CO2 gas due to the decrease in temperature and pressure after entering the gas-liquid separator and under the action of gravity, wherein the CO2 gas enters the buffer tank for use in the next experiment after the CO2 booster pump is started again; and the CO2 thickener is collected by the sample collector for subsequent characterization analysis of the thickener analysis system.

[0023] Compared with the prior art, the beneficial technical effects of the present application are:

[0024] The CO2 thickener solubility and viscosity increasing experimental evaluation device and method of the present application realizes dynamic adjustment of the cavity volume and pressure through the design of the piston rod, meets the research of the influence of different pressures on the experiment, is equipped with an online capillary viscometer to realize accurate online measurement of the viscosity of the CO2 and CO2 thickener mixed system, designs a gas-liquid separator, and after the experiment is completed, the mixed gas enters the gas-liquid separator, the separated CO2 is pressurized by the CO2 booster pump to realize the recycling of CO2, protect the environment, and save experimental cost; and all devices in the device are connected to the central control system to realize highly automatic control and intelligent adjustment. BRIEF DESCRIPTION OF DRAWINGS

[0025] The present application will be further described below in conjunction with the drawings.

[0026] Figure 1 The structure diagram of the CO2 thickener solubility and viscosity increasing experimental evaluation device of the present application is shown in the figure;

[0027] Explanation of the accompanying symbols: 1. Horizontal flow pump; 2. Intermediate container; 3. CO2 booster pump; 4. Injection pipeline; 5. Mixing chamber; 6. Visualization window; 7. Piston rod; 8. Agitator; 9. Temperature sensor; 10. Pressure sensor; 11. Online capillary viscometer; 12. Vacuum pump; 13. Gas-liquid separator; 14. Sample collector; 15. Thickener analysis system; 16. Central control system; 17. Viscometer inlet valve; 18. Gas-liquid separator inlet valve; 19. Electric heating jacket. DETAILED DESCRIPTION

[0028] like Figure 1 As shown, a CO2 thickener solubility and viscosity-increasing experimental evaluation device includes a mixing chamber 5, with a pressurizing system installed at the top and an agitator 8 installed at the bottom. The mixing chamber 5 is connected to the CO2 thickener system and the CO2 pressurizing system via an injection line 4, through which the CO2 thickener and CO2 gas enter the mixing chamber 5. The bottom of the mixing chamber 5 is connected to an online monitoring system and a gas-liquid separator 13 via pipelines. The gas-liquid separator 13 is connected to a sample collector 14 and a buffer tank via pipelines, and the buffer tank is connected to a CO2 booster pump 3 via pipelines. A visualization window 6 is installed on the mixing chamber 5 to facilitate observation of the dissolution status.

[0029] The boosting system includes a piston rod 7 located within the mixing chamber 5. A piston head is mounted at the bottom of the piston rod 7, which is slidably connected to the inner wall of the mixing chamber 5. The top of the piston rod 7, after passing through the mixing chamber 5, is connected to an electric lift. The electric lift drives the piston rod 7 up and down, thereby adjusting the size of the mixing chamber 5 to meet the boosting requirements.

[0030] The agitator 8 includes stirring blades located within the mixing chamber 5. The stirring blades are circumferentially distributed at the upper end of the stirring shaft. The lower end of the stirring shaft extends through the mixing chamber 5 and is connected to a stirring motor. When the stirring motor is activated, the stirring shaft drives the stirring blades to rotate, stirring the CO2 thickener and CO2 gas within the mixing chamber 5 to promote their complete dissolution.

[0031] The CO2 thickener system includes an intermediate container 2, which is connected to a horizontal flow pump 1 via a pipeline. The other end of the horizontal flow pump 1 is connected to a water source. The liquid in the intermediate container 2 is divided into two layers: the upper layer contains the CO2 thickener, and the lower layer contains water. When the horizontal flow pump 1 is activated, water enters the intermediate container 2, increasing the water volume in the lower layer and occupying a larger volume. The CO2 thickener in the upper layer then flows through the pipeline into the mixing chamber 5.

[0032] The CO2 pressurization system comprises a CO2 gas cylinder, and the CO2 pressurization pump 3 is installed on the pipeline between the CO2 gas cylinder and the mixing cavity 5.

[0033] The online monitoring system comprises a temperature sensor 9, a pressure sensor 10 and an online capillary viscometer 11, all of which are electrically connected to the central control system 16, and the parameters such as temperature, pressure and viscosity are displayed on the display screen of the central control system 16. The online capillary viscometer 11 is connected to a vacuum pump 12, and a viscometer inlet valve 17 is installed on the pipeline between the online capillary viscometer 11 and the mixing cavity 5. In addition, in this embodiment, the central control system 16 is also electrically connected to the convection pump 1, the CO2 pressurization pump 3, the stirrer 8 and the electric elevator (the electric elevator is used to realize the lifting of the piston rod 7), so as to intelligently control the running state and condition of each device, and realize highly automatic control and intelligent adjustment of the entire experimental process.

[0034] The sample collector 14 is connected to the thickening agent analysis system 15 for characterization and analysis of the CO2 thickening agent after the experiment.

[0035] An electric heating jacket 19 is installed around the mixing cavity 5 in a sleeved manner, which is used to heat the mixing cavity 5 and is required for the internal CO2 thickening agent to dissolve and heat up.

[0036] A gas-liquid separator inlet valve 18 is installed on the pipeline between the gas-liquid separator 13 and the mixing cavity 5.

[0037] A CO2 thickening agent solubility and viscosity increasing experimental evaluation method, comprising the following steps:

[0038] Step one, start the convection pump 1, increase the amount of water at the bottom layer in the intermediate container 2, and push the CO2 thickening agent at the upper layer into the mixing cavity 5;

[0039] Step two, open the CO2 gas cylinder, start the CO2 pressurization pump 3, and inject CO2 into the mixing cavity 5;

[0040] Step three, start the electric heating jacket 19, and heat the mixing cavity 5 to the designed temperature;

[0041] Step four, start the stirrer 8, and stir the CO2 thickening agent and the injected CO2 gas in the mixing cavity 5 to make them fully dissolve;

[0042] Step five, observe the dissolution of the CO2 thickening agent through the visual window 6, if it is not fully dissolved, start the piston rod 7 to move downward to pressurize the mixing cavity 5, until the CO2 thickening agent is fully dissolved in the CO2 gas;

[0043] Step six, after the CO2 thickener is dissolved and stable, the vacuum pump 12 is started to vacuum the online capillary viscometer 11, and the electric heating system on the online capillary viscometer 11 is started at the same time to heat the entire online capillary viscometer 11 to the design temperature (consistent with the temperature in the mixing chamber), then the viscometer inlet valve 17 is opened, and the mixed system after dissolution is sent into the online capillary viscometer 11 to measure its viscosity;

[0044] Step seven, after the viscosity coefficient measurement of step six is completed, the gas-liquid separator inlet valve 18 is opened, and the material in the mixing chamber 5 enters the gas-liquid separator 13. The entering material is separated from the CO2 thickener and CO2 gas due to the decrease in temperature and pressure after entering the gas-liquid separator 13 and under the action of gravity. The CO2 gas enters the buffer tank for use in the next experiment after the CO2 booster pump 3 is started again. The CO2 thickener is collected by the sample collector 14 for subsequent characterization analysis by the thickener analysis system 15.

[0045] The above-described embodiments are only descriptions of the preferred modes of the present application and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those of ordinary skill in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A CO2 thickener solubility and viscosity evaluation test device, characterized by: The invention comprises a mixing chamber (5), wherein a pressurizing system is provided at the top position of the mixing chamber (5), and an agitator (8) is provided at the bottom position; the mixing chamber (5) is connected to a CO2 thickener system and a CO2 pressurizing system via a thickener / CO2 injection pipeline (4); the bottom of the mixing chamber (5) is connected to an online monitoring system and a gas-liquid separator (13) via pipelines; the gas-liquid separator (13) is connected to a sample collector (14) and a buffer tank via pipelines, and the buffer tank is connected to a CO2 booster pump (3) via pipelines; a visualization window (6) is provided on the mixing chamber (5); The CO2 thickener system comprises an intermediate container (2), the intermediate container (2) being connected to a horizontal flow pump (1) via a pipeline, and the other end of the horizontal flow pump (1) being connected to a water source; the liquid in the intermediate container (2) is divided into two layers, the upper layer being the CO2 thickener and the lower layer being water; The online monitoring system includes a temperature sensor (9), a pressure sensor (10) and an online capillary viscometer (11), wherein the temperature sensor (9), the pressure sensor (10) and the online capillary viscometer (11) are all electrically connected to a central control system (16); the online capillary viscometer (11) is connected to a vacuum pump (12), an electric heating system is provided on the online capillary viscometer (11), and a viscometer inlet valve (17) is provided on the pipeline between the online capillary viscometer (11) and the mixing chamber (5).

2. The CO2 thickener solubility and viscosity increasing test evaluation device according to claim 1, characterized in that: The boosting system includes a piston rod (7) located inside the mixing chamber (5), a piston head slidably connected to the inner wall of the mixing chamber (5) is provided at the bottom of the piston rod (7), and the top of the piston rod (7) passes through the mixing chamber (5) and is connected to an electric lift.

3. The CO2 thickener solubility and viscosity increasing test evaluation device according to claim 1, characterized in that: The stirrer (8) includes stirring blades located inside the mixing cavity (5), the stirring blades are circumferentially distributed at the upper end of the stirring shaft, and the lower end of the stirring shaft passes through the mixing cavity (5) and is connected to a stirring motor.

4. The CO2 thickener solubility and viscosity increasing test evaluation device according to claim 1, characterized in that: The CO2 boosting system comprises a CO2 gas cylinder, and the CO2 boosting pump (3) is provided on the pipeline between the CO2 gas cylinder and the mixing chamber (5).

5. The CO2 thickener solubility and viscosity increasing test evaluation device according to claim 2, characterized in that: The sample collector (14) is connected to a thickener analysis system (15).

6. The CO2 thickener solubility and viscosity increasing test evaluation device according to claim 1, characterized in that: The outer periphery of the mixing cavity (5) is covered with an electric heating jacket (19).

7. The CO2 thickener solubility and viscosity-increasing test and evaluation device according to claim 5, characterized in that: A gas-liquid separator inlet valve (18) is provided on the pipeline between the gas-liquid separator (13) and the mixing chamber (5).

8. A method for evaluating the solubility and viscosity of a CO2 thickener, using the CO2 thickener solubility and viscosity evaluation device of claim 7, characterized in that: The following steps are involved: Step 1: Start the horizontal flow pump, the water volume at the bottom layer of the intermediate container increases, pushing the CO2 thickener at the upper layer into the mixing chamber; Step 2: Open the CO2 cylinder, start the CO2 booster pump, and inject CO2 into the mixing chamber; Step 3: Start the electric heating jacket to heat the mixing chamber to the designed temperature; Step 4: Start the stirrer to stir the CO2 thickener and the injected CO2 gas in the mixing chamber; Step 5: Observe the dissolution of the CO2 thickener through the visual window. If it is not fully dissolved, start the piston rod to move downward to increase the pressure in the mixing chamber until the CO2 thickener is fully dissolved in the CO2 gas. Step 6: After the CO2 thickener is dissolved and stabilized, start the vacuum pump to evacuate the online capillary viscometer, and simultaneously start the electric heating system on the online capillary viscometer to heat the entire online capillary viscometer to the designed temperature (consistent with the temperature in the mixing chamber). Then, open the viscometer inlet valve and send the dissolved mixed system into the online capillary viscometer to measure its viscosity. Step seven, after the viscosity coefficient is determined in step six, the gas-liquid separator inlet valve is opened, and the material in the mixing chamber enters the gas-liquid separator. The temperature and pressure of the material entering the gas-liquid separator decrease after entering the gas-liquid separator, and the CO2 thickener and CO2 gas are separated under the action of gravity. The CO2 gas enters the buffer tank and is used for the next experiment after the CO2 booster pump is started; the CO2 thickener is collected by the sample collector for subsequent characterization analysis of the thickener analysis system.

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