Device and method for measuring nonlinear seepage characteristics and starting pressure of high-temperature and high-pressure fluid

Abstract

The invention discloses a device and method for measuring nonlinear seepage characteristics and starting pressure of high-temperature and high-pressure fluid, and the device comprises a core holder which is internally provided with a to-be-measured core; the coarse injection system is connected with an inlet of the core holder and comprises a middle container and a first injection pump; the fine injection system comprises a first fine injection system connected with an inlet of the core holder and a second fine injection system connected with an outlet of the core holder; the liquid discharging system comprises a back-pressure valve connected with an outlet of the core holder, and a desorption meter; through the device, the nonlinear seepage characteristics and the starting pressure can be measured. According to the method, the formation fluid is truly reduced, the selected displacement medium is gas-containing oil, the viscosity, density and other high-pressure physical property parameters of the formation fluid are perfectly reduced, and the developed starting pressure gradient and nonlinear seepage characteristic research can better reflect the real condition of the reservoir.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field development, and in particular to a device and method for measuring nonlinear seepage characteristics and starting pressure of high-temperature and high-pressure fluid. Background Art

[0002] The flow of fluid in porous media is generally Darcy linear seepage. However, in special cases such as the seepage of non-Newtonian fluids such as heavy oil, the "microscale" seepage of ultra-low permeability porous media, and the dynamic interaction between high-temperature and high-pressure fluids and pore walls, the seepage characteristics deviate from the linear seepage law, and the tested seepage characteristic curve has a starting pressure gradient and a curved nonlinear segment.

[0003] According to traditional methods, the test method for nonlinear seepage is mainly the steady-state method. When studying the law of nonlinear seepage, the method of measuring pressure during the unsteady-state seepage process is usually used to determine the starting pressure gradient. The defect of the traditional experimental method is mainly that the selection of displacement fluid is not representative enough. The displacement fluids selected simulated formation fluids such as formation water, kerosene, and degassed oil, but basically no high-temperature and high-pressure gas oil was selected. For these simulated fluids, since most of them are equivalent to a certain physical property of high-temperature and high-pressure formation fluids (such as kerosene with equivalent high-temperature and high-pressure formation crude oil viscosity), the measured experimental results are difficult to reflect the dynamic fluid-solid interaction between the real formation fluid and the core pore wall, and it is difficult to characterize the real seepage characteristics of the formation fluid under high-temperature and high-pressure reservoir conditions. The starting pressure gradient obtained is not the real starting pressure gradient of the reservoir.

[0004] To this end, existing technicians have tried to test the nonlinear seepage characteristics and the starting pressure gradient at the same time, such as the "capillary balance method", which uses the principle of communicating vessels to connect capillaries at the inlet and outlet of the core when measuring the starting pressure gradient. The effect of gravity will cause the fluid at the inlet to flow through the core to the outlet. After the liquid levels at both ends are fully balanced, a height difference will eventually be maintained, which is the minimum starting pressure value of the sample. Since the test device usually uses a glass tube, it cannot withstand high temperature and pressure. Therefore, the measurement conditions of this method are all low pressure or even normal pressure, which cannot truly characterize the seepage characteristics of the fluid under high temperature and high pressure conditions of the formation.

[0005] Chinese patent CN107676083A discloses an experimental method for determining the starting pressure gradient under low permeability reservoir formation conditions, which includes: step 1, preparing a low permeability rock sample; step 2, conducting a dynamic high temperature and high pressure water-rock simulation test under the temperature and pressure conditions of the low permeability sample formation fluid, and recording the fluid pressure and seepage velocity under different pressures; step 3, determining the starting pressure of the low permeability rock sample according to multiple groups of fluid pressure and seepage velocity values ​​of the low permeability rock sample, and obtaining the starting pressure of the low permeability reservoir section according to the starting pressure of multiple cores. After analysis, although the experimental conditions for testing the starting pressure gradient in this method are formation temperature and pressure conditions, the fluid used is formation water, and the test is not based on real formation gas-bearing crude oil.

[0006] Chinese patent CN117607005B discloses an experimental method for determining the starting pressure gradient of rock, and the steps mainly include: step 1, pressurizing the rock sample to be tested for a period of time after being filled with a first test fluid; step 2, connecting an intermediate container filled with the first test fluid and with a certain pressure to a core holder, recording the pressure difference at both ends of the rock sample to be tested, and when the change value of the pressure difference is less than a set threshold value of 0.001MPa, calculating the starting pressure gradient of the first test fluid according to the pressure difference; step 3, when the volume of the first test fluid collected in the measuring cylinder no longer changes, connecting the intermediate container filled with the second test fluid and with a certain pressure to the core holder, and obtaining the starting pressure gradients of each phase fluid under different saturation conditions. Through analysis, it can be seen that compared with the method of CN107676083A which only selects single-phase formation water as the test medium, this method further considers the starting pressure gradient of oil-water two-phase fluid under different water saturation conditions. However, according to its description, the fluid selected is still ground degassed crude oil, and the test is not based on real formation gas-containing crude oil. The experimental temperature is also room temperature, and the description of judging whether the displacement state has reached stability by real-time acquisition of the pressure difference change at the core inlet and outlet is not detailed. Summary of the invention

[0007] In order to solve at least one of the above problems, the present invention proposes a device and method for measuring the nonlinear seepage characteristics and starting pressure of high-temperature and high-pressure fluid.

[0008] The technical solution of the present invention is: a device for measuring nonlinear seepage characteristics and starting pressure of high-temperature and high-pressure fluid, comprising:

[0009] A core holder, wherein the core to be tested is arranged in the core holder;

[0010] a coarse injection system connected to the inlet of the core holder, comprising an intermediate container and a first injection pump;

[0011] A fine injection system, comprising a first fine injection system connected to the inlet of the core holder and a second fine injection system connected to the outlet of the core holder; the first fine injection system comprises a first transparent pressure-resistant injection pipe and a second injection pump connected in sequence to the core holder, a piston being provided in the first transparent pressure-resistant injection pipe; the second fine injection system comprises a second transparent pressure-resistant injection pipe and a third injection pump connected in sequence to the core holder, a piston being provided in the second transparent pressure-resistant injection pipe; the inner diameters of the first transparent pressure-resistant injection pipe and the second transparent pressure-resistant injection pipe are both not greater than 10 mm;

[0012] A drainage system, including a back pressure valve connected to the core holder outlet and a desorption meter;

[0013] An oven is used to heat the core holder, the intermediate container and the fine injection system.

[0014] One embodiment of the present invention is that a sample preparer is further provided, the sample preparer is used to prepare crude oil with dissolved gas, and the first transparent pressure-resistant injection pipe and the second transparent pressure-resistant injection pipe are both connected to the sample preparer.

[0015] One embodiment of the present invention is that the shapes of the first transparent pressure-resistant injection tube and the second transparent pressure-resistant injection tube are one of a plane spiral, a bow shape, and a three-dimensional spiral shape, and the first transparent pressure-resistant injection tube and the second transparent pressure-resistant injection tube are provided with scales.

[0016] One embodiment of the present invention is that it also includes a metering system, which includes a camera, and the camera is used to take pictures of the first transparent pressure-resistant injection tube and the second transparent pressure-resistant injection tube. The camera is electrically connected to an image recognition system, and the image is used to identify the picture transmitted by the camera, thereby obtaining the position of the piston and further obtaining the injection amount.

[0017] Another object of the present invention is to disclose a method for measuring the nonlinear seepage characteristics and starting pressure of a high-temperature and high-pressure fluid. The method is based on any of the above-mentioned devices and comprises the following steps:

[0018] Connect the device, inject degassed oil into the intermediate container, and inject gas-containing oil into the first transparent pressure-resistant injection pipe and the second transparent pressure-resistant injection pipe;

[0019] The temperature is raised to the reservoir temperature, and then the degassed oil is injected into the core through the first injection pump to saturate it;

[0020] Injecting fluid into the core through a second injection pump until the oil-gas ratio of the fluid at the core holder outlet is the same as the oil-gas ratio of the gas-containing oil, and recording the amount of gas-containing oil in the first transparent pressure-resistant injection pipe;

[0021] The first fine injection system, the core holder and the second fine injection system are connected. When the gas and oil content in the first transparent pressure-resistant injection pipe and the second transparent pressure-resistant injection pipe remains unchanged, the outlet pressure difference between the second displacement pump and the third displacement pump is the starting pressure. The starting pressure gradient is obtained based on the starting pressure and the core length. At the same time, the outlet pressure P1 of the second displacement pump and the outlet pressure P2 of the third displacement pump are recorded.

[0022] Maintain the outlet pressure of the third displacement pump at P2, increase the outlet pressure of the second displacement pump to the first pressure, until the gas-oil content in the first transparent pressure-resistant injection pipe and the second transparent pressure-resistant injection pipe change at the same speed, record the change of the gas-oil content in the first transparent pressure-resistant injection pipe per unit time at this time; then change the magnitude of the first pressure to obtain the change of the gas-oil content in the first transparent pressure-resistant injection pipe per unit time under multiple pressure difference conditions, and draw a forward nonlinear seepage curve based on the above changes.

[0023] Furthermore, the following steps are included: maintaining the outlet pressure of the second displacement pump at P1, increasing the outlet pressure of the third displacement pump to the second pressure, until the gas-oil content in the second transparent pressure-resistant injection pipe and the first transparent pressure-resistant injection pipe change at the same rate, and recording the change in the gas-oil content in the second transparent pressure-resistant injection pipe per unit time at this time; then changing the second pressure to obtain the change in the gas-oil content in the second transparent pressure-resistant injection pipe per unit time under multiple pressure difference conditions, and drawing a reverse nonlinear seepage curve based on the aforementioned change.

[0024] Beneficial effects: The present invention truly restores the formation fluid. The displacement medium selected by the present invention is gas-containing oil, which perfectly restores the high-pressure physical parameters such as viscosity and density of the formation fluid. The research on the start-up pressure gradient and nonlinear seepage characteristics can better reflect the real situation of the reservoir. At the same time, the test of the present invention can be carried out under high pressure conditions, can restore the real formation environment, and the measured results are more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the device of Example 1;

[0026] Figure 2 It is a schematic diagram of the structure of the first transparent pressure-resistant injection tube and the second transparent pressure-resistant injection tube.

[0027] In the figure, 1 is a core holder, 2 is an intermediate container, 3 is a first injection pump, 4 is a back pressure valve, 5 is a desorption meter, 6 is a first transparent pressure-resistant injection pipe, 7 is a second injection pump, 8 is a third injection pump, 9 is a camera, 10 is a sample dispenser, 11 is a second transparent pressure-resistant injection pipe, 12 is a gas tank, 13 is a crude oil tank, 14 is a pressurizing device, and 15 is an oven. DETAILED DESCRIPTION

[0028] The specific implementation modes of the present invention will be described clearly and completely below with reference to examples and drawings. Obviously, the described examples are only some embodiments of the present invention, rather than all embodiments.

[0029] Example 1

[0030] like Figures 1-2 As shown, a device for measuring nonlinear seepage characteristics and starting pressure of high-temperature and high-pressure fluids comprises:

[0031] A core holder 1, wherein the core holder 1 is provided with a core to be tested;

[0032] As for the core clamp 1, it is a conventional core clamp 1 in the art, for example, it is provided with components such as a plug, a shell, a confining pressure chamber and a rubber cylinder.

[0033] A rough injection system connected to the inlet of the core holder 1, comprising an intermediate container 2 and a first injection pump 3;

[0034] A fine injection system, comprising a first fine injection system connected to the inlet of the core holder 1 and a second fine injection system connected to the outlet of the core holder 1; the first fine injection system comprises a first transparent pressure-resistant injection pipe 6 and a second injection pump 7 sequentially connected to the core holder 1, and a piston is provided in the first transparent pressure-resistant injection pipe 6; the second fine injection system comprises a second transparent pressure-resistant injection pipe 11 and a third injection pump 8 sequentially connected to the core holder 1, and a piston is provided in the second transparent pressure-resistant injection pipe 11; the inner diameters of the first transparent pressure-resistant injection pipe 7 and the second transparent pressure-resistant injection pipe 11 are both not greater than 10 mm;

[0035] The rough injection system is mainly used to inject the corresponding degassed oil into the core in the early stage of the experiment. For crude oil, when it is produced to the ground, due to the reduction of pressure, a large amount of dissolved gas in the crude oil is desorbed to form degassed oil, and the properties of degassed oil are quite different from those of gas-containing oil before desorption. For example, the viscosity of gas-containing oil flooded with carbon dioxide is significantly lower than that of degassed oil; the natural gas in crude oil can also reduce its viscosity to a certain extent.

[0036] At the same time, for gas oil, if it is directly injected into the core, due to the low initial pressure in the core, the gas oil is easily desorbed in the core and other parts, resulting in a mixture of degassed oil and gas actually injected into the core. The final result is still not the true result in the reservoir.

[0037] To this end, in this embodiment, a coarse injection system and a fine injection system are used to inject degassed oil and gas-containing oil respectively. The coarse injection system uses a relatively conventional injection device, such as an intermediate container 2 and a first injection pump 3. The intermediate container 2 is filled with degassed oil. One end of the intermediate container 2 is connected to the first injection pump 3, and the other end is connected to the inlet end of the core holder 1, so as to inject degassed oil into the core holder 1.

[0038] As for the fine injection system, since the device of this embodiment needs to study the nonlinear seepage characteristics and the starting pressure, considering the research characteristics of the starting pressure and the forward and reverse displacement of the nonlinear seepage characteristics, a first fine injection system and a second fine injection system are provided, and the structures of the two fine injection systems are exactly the same, except that one end of the first fine injection system is connected to the inlet end of the core holder 1, and one end of the second fine injection system is connected to the outlet end of the core holder 1. The cooperation of the first fine injection system and the second fine injection system not only enables the device to study the starting pressure, but also can study both the forward and reverse nonlinear seepage characteristics, which greatly broadens the scope of use of the device.

[0039] The first fine injection system includes a first transparent pressure-resistant injection pipe 6 and a second injection pump 7 connected in sequence to the core holder 1. A piston is provided in the first transparent pressure-resistant injection pipe 6. The piston separates the first transparent pressure-resistant injection pipe 6. When the second injection pump 7 works, the gas-containing oil at the bottom of the piston can be injected into the core of the core holder 1 through the piston. At the same time, in the subsequent nonlinear seepage characteristic test and the start-up pressure test, it is necessary to record the flow change in the process, and the flow change in the process is low, usually a few milliliters or a few tenths of a milliliter. If the size of the first transparent pressure-resistant injection pipe 6 is too large, the error is large and the credibility of the final result is low. For this reason, in this embodiment, the inner diameter of the first transparent pressure-resistant injection pipe 6 is limited to no more than 10 mm, and can usually be set to 3.5-8 mm. For the first transparent pressure-resistant injection pipe 6, its material can be selected from existing high-strength transparent pressure-resistant materials, such as common pressure-resistant sapphire glass materials, and those skilled in the art can also select other materials suitable for this embodiment.

[0040] The second fine injection system includes a second transparent pressure-resistant injection pipe 11 and a third injection pump 8 connected in sequence to the core clamp 1. A piston is provided in the second transparent pressure-resistant injection pipe 11. The specific component arrangement is the same as that of the first fine injection system and will not be described in detail in this embodiment.

[0041] The first transparent pressure-resistant injection tube 6 and the second transparent pressure-resistant injection tube 11 can be set to a plurality of different shapes, such as a common straight tube, a curved tube, etc. However, since the first transparent pressure-resistant injection tube 6 and the second transparent pressure-resistant injection tube 11 have a small diameter, if they are prepared as common straight tubes and curved tubes, their length will be too long, which is not conducive to monitoring the changes in the amount of gas and oil in the tube, and it will also take up a large space. For this reason, the shape of the first transparent pressure-resistant injection tube 6 and the second transparent pressure-resistant injection tube 11 can be set to a plane spiral shape (such as Figure 2 a), bow shape (as shown in Figure 2 b) and a three-dimensional spiral shape (not shown in the figure). In this case, the normal operation of the first transparent pressure-resistant injection pipe 6 and the second transparent pressure-resistant injection pipe 11 will not be affected, and the space occupied by them will be reduced. At the same time, it is also beneficial to monitor the changes in the gas and oil content in the pipe.

[0042] A liquid discharge system, including a back pressure valve 4 connected to the outlet of the core holder 1 and a desorption meter 5;

[0043] The drainage system is connected to the outlet of the core holder 1, and is mainly used to discharge the excess liquid in the core holder 1. At the same time, as shown above, gas-containing oil is injected into the device, and it is difficult to check whether the core is completely filled with gas-containing oil by conventional methods. For this reason, in this embodiment, the produced liquid discharged from the core holder 1 is separated and tested by the desorption meter 5 provided until the oil-gas ratio of the produced liquid is substantially the same as the oil-gas ratio of the gas-containing oil, indicating that the gas-containing oil has completely replaced the degassed oil in the core. The desorption meter used is a common device in the art for detecting the desorbed gas content, and its structure is not described in detail here. As for the back pressure valve 4, it belongs to a conventional device in the art, such as being provided with a back pressure pump, etc., so its specific structure is not described in detail here.

[0044] The oven 15 is used to heat the core holder 1, the intermediate container 2 and the fine injection system. The oven 15 is mainly used to maintain a high temperature environment of the device.

[0045] In some cases, it is difficult to obtain gas-containing oil directly from the formation. In order to solve this problem, the inventor configures the corresponding gas-containing oil by setting a sample dispenser 10. The sample dispenser 10 is connected to the crude oil storage tank 13 and the gas tank 12. At the same time, a booster 14 is also provided on the gas tank 12. The booster 14 can pressurize the crude oil and gas inside the sample dispenser 10. Under the action of a long time, the gas will dissolve into the crude oil to form gas-containing oil. Of course, those skilled in the art can also accelerate the preparation of gas-containing oil by setting an agitator inside the sample dispenser 10. These belong to conventional settings in this field, and their specific structures are not described here. The sample dispenser 10 is also connected to the first transparent pressure-resistant injection pipe 6 and the second transparent pressure-resistant injection pipe 11. After the oil-containing gas is configured, the oil-containing gas is injected into the first transparent pressure-resistant injection pipe 6 and the second transparent pressure-resistant injection pipe 11.

[0046] This embodiment also includes a metering system, which includes a camera 9. The camera 9 is used to take pictures of the first transparent pressure-resistant injection tube 6 and the second transparent pressure-resistant injection tube 11. The camera 9 is electrically connected to an image recognition system. The image is used to recognize the picture transmitted by the camera 9, thereby obtaining the position of the piston and further obtaining the injection amount.

[0047] Conventionally, the changes in the oil content of the first transparent pressure-resistant injection tube 9 and the second transparent pressure-resistant injection tube 11 can be monitored by the human eye, but human eye monitoring not only wastes manpower, but also has relatively poor results. To this end, this embodiment provides an automatic metering system. The system takes pictures through a camera 9, and then uses an image recognition system to perform image recognition on the taken pictures to obtain the specific oil content in the first transparent pressure-resistant injection tube 6 and the second transparent pressure-resistant injection tube 11 at this time. By comparing multiple consecutive pictures, the change in oil content can be obtained. For the image recognition used in this process, conventional means in the field can be used. For example, for the taken pictures, the scale points where the edge of the piston is located are read through a deep learning image segmentation algorithm to achieve automatic scale recognition, thereby calculating the injection amount.

[0048] Example 2

[0049] A method for measuring nonlinear seepage characteristics and starting pressure of high-temperature and high-pressure fluid, based on the device of embodiment 1, comprises the following steps:

[0050] Connect the device, inject degassed oil into the intermediate container, and inject gas-containing oil into the first transparent pressure-resistant injection pipe and the second transparent pressure-resistant injection pipe;

[0051] In this step, in order to avoid differences between different oil products, the base oil used in the gas oil preparation process is the aforementioned degassed oil.

[0052] The gas-bearing oil in this step can be the configured gas-bearing oil or the gas-bearing oil extracted from the formation, but considering the cost, it is relatively better to use the configured gas-bearing oil. Meanwhile, for the gas in the gas-bearing oil, natural gas, carbon dioxide, etc. commonly used in the oil displacement process can be selected.

[0053] The temperature is raised to the reservoir temperature, and then the degassed oil is injected into the core through the first injection pump to saturate it;

[0054] In this step, the purpose of first injecting degassed oil is to maintain the pressure in the core to avoid rapid desorption of the subsequent gas-containing oil after it is injected into the core.

[0055] Injecting fluid into the core through a second injection pump until the oil-gas ratio of the fluid at the core holder outlet is the same as the oil-gas ratio of the gas-containing oil, and recording the amount of gas-containing oil in the first transparent pressure-resistant injection pipe;

[0056] In this step, the injection of gas-bearing oil is used to simulate the actual situation of underground crude oil, so that the final measured result is more accurate. In order to verify whether the gas-bearing oil is saturated in the core, the oil-gas ratio of the core outlet oil after desorption is determined: if the oil-gas ratio of the outlet oil is less than the oil-gas ratio of the gas-bearing oil, it means that the core still contains a certain amount of degassed oil and needs to continue to inject gas-bearing oil; if the oil-gas ratio of the outlet oil is basically the same as the oil-gas ratio of the gas-bearing oil, it means that the core is saturated with gas-bearing oil.

[0057] The first fine injection system, the core holder and the second fine injection system are connected. When the gas and oil content in the first transparent pressure-resistant injection pipe and the second transparent pressure-resistant injection pipe remains unchanged, the outlet pressure difference between the second displacement pump and the third displacement pump is the starting pressure. The starting pressure gradient is obtained based on the starting pressure and the core length. At the same time, the outlet pressure P1 of the second displacement pump and the outlet pressure P2 of the third displacement pump are recorded.

[0058] As described in Example 1, in this example, P1 and P2 can be observed by human eyes or calculated and analyzed by an automatic metering system. The starting pressure gradient is calculated using the following formula: starting pressure gradient = starting pressure / core length.

[0059] Maintain the outlet pressure of the third displacement pump at P2, increase the outlet pressure of the second displacement pump to the first pressure, until the gas-oil content in the first transparent pressure-resistant injection pipe and the second transparent pressure-resistant injection pipe change at the same speed, record the change of the gas-oil content in the first transparent pressure-resistant injection pipe per unit time at this time; then change the magnitude of the first pressure to obtain the change of the gas-oil content in the first transparent pressure-resistant injection pipe per unit time under multiple pressure difference conditions, and draw a forward nonlinear seepage curve based on the above changes.

[0060] After the forward nonlinear seepage curve is calculated by the above process, the reverse nonlinear seepage curve can also be calculated by the following steps: maintain the outlet pressure of the second displacement pump at P1, increase the outlet pressure of the third displacement pump to the second pressure, until the gas-oil content in the second transparent pressure-resistant injection pipe and the first transparent pressure-resistant injection pipe change at the same rate, and record the change in the gas-oil content in the second transparent pressure-resistant injection pipe per unit time at this time; then change the magnitude of the second pressure to obtain the change in the gas-oil content in the second transparent pressure-resistant injection pipe per unit time under multiple pressure difference conditions, and draw the reverse nonlinear seepage curve based on the above changes.

[0061] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A device for measuring nonlinear seepage characteristics and starting pressure of high temperature and high pressure fluid, characterized in that: include: A core holder, wherein the core to be tested is arranged in the core holder; a coarse injection system connected to the inlet of the core holder, comprising an intermediate container and a first injection pump; A fine injection system, comprising a first fine injection system connected to the inlet of the core holder and a second fine injection system connected to the outlet of the core holder; the first fine injection system comprises a first transparent pressure-resistant injection pipe and a second injection pump connected in sequence to the core holder, a piston being provided in the first transparent pressure-resistant injection pipe; the second fine injection system comprises a second transparent pressure-resistant injection pipe and a third injection pump connected in sequence to the core holder, a piston being provided in the second transparent pressure-resistant injection pipe; the inner diameters of the first transparent pressure-resistant injection pipe and the second transparent pressure-resistant injection pipe are both not greater than 10 mm; A drainage system, including a back pressure valve connected to the core holder outlet and a desorption meter; An oven is used to heat the core holder, the intermediate container and the fine injection system.

2. The device according to claim 1, characterized in that A sample preparer is also provided, and the sample preparer is used to prepare crude oil with dissolved gas, and the first transparent pressure-resistant injection pipe and the second transparent pressure-resistant injection pipe are both connected to the sample preparer.

3. The device according to claim 1, characterized in that The shapes of the first transparent pressure-resistant injection tube and the second transparent pressure-resistant injection tube are one of a plane spiral, a bow shape, and a three-dimensional spiral shape, and the first transparent pressure-resistant injection tube and the second transparent pressure-resistant injection tube are provided with scales.

4. The device according to claim 1, characterized in that It also includes a metering system, which includes a camera. The camera is used to take pictures of the first transparent pressure-resistant injection tube and the second transparent pressure-resistant injection tube. The camera is electrically connected to an image recognition system. The image is used to recognize the picture transmitted by the camera, thereby obtaining the position of the piston and further obtaining the injection volume.

5. A method for measuring nonlinear seepage characteristics and starting pressure of high temperature and high pressure fluid, characterized in that: The method is based on the device according to any one of claims 1 to 4, and comprises the following steps: Connect the device, inject degassed oil into the intermediate container, and inject gas-containing oil into the first transparent pressure-resistant injection pipe and the second transparent pressure-resistant injection pipe; The temperature is raised to the reservoir temperature, and then the degassed oil is injected into the core through the first injection pump to saturate it; Injecting fluid into the core through a second injection pump until the oil-gas ratio of the fluid at the core holder outlet is the same as the oil-gas ratio of the gas-containing oil, and recording the amount of gas-containing oil in the first transparent pressure-resistant injection pipe; The first fine injection system, the core holder and the second fine injection system are connected. When the gas and oil content in the first transparent pressure-resistant injection pipe and the second transparent pressure-resistant injection pipe remains unchanged, the outlet pressure difference between the second displacement pump and the third displacement pump is the starting pressure. The starting pressure gradient is obtained based on the starting pressure and the core length. At the same time, the outlet pressure P1 of the second displacement pump and the outlet pressure P2 of the third displacement pump are recorded. Maintain the outlet pressure of the third displacement pump at P2, increase the outlet pressure of the second displacement pump to the first pressure, until the gas-oil content in the first transparent pressure-resistant injection pipe and the second transparent pressure-resistant injection pipe change at the same speed, record the change of the gas-oil content in the first transparent pressure-resistant injection pipe per unit time at this time; then change the magnitude of the first pressure to obtain the change of the gas-oil content in the first transparent pressure-resistant injection pipe per unit time under multiple pressure difference conditions, and draw a forward nonlinear seepage curve based on the above changes.

6. The method according to claim 5, characterized in that The following steps are also included: Maintain the outlet pressure of the second displacement pump at P1, increase the outlet pressure of the third displacement pump to the second pressure, until the gas-oil content in the second transparent pressure-resistant injection pipe changes at the same rate as that in the first transparent pressure-resistant injection pipe, and record the change in the gas-oil content in the second transparent pressure-resistant injection pipe per unit time at this time; then change the magnitude of the second pressure to obtain the change in the gas-oil content in the second transparent pressure-resistant injection pipe per unit time under multiple pressure difference conditions, and draw a reverse nonlinear seepage curve based on the aforementioned changes.

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