Flow metering device and CO2 flooding minimum miscible pressure testing system and method

Abstract

The invention provides a flow metering device, which belongs to the CO2 drive low-permeability oil and gas reservoir development technology and comprises a metering thermotank body, a metering tube support is arranged in the metering thermotank body, and an output liquid inlet is formed in the side surface of the metering thermotank body; the first metering pipe is fixedly mounted on one side of the metering pipe bracket; the first metering pipe is communicated with the output liquid inlet through an output liquid inlet pipeline; the wet-type gas meter is fixedly arranged above the box body of the metering constant-temperature box, and the wet-type gas meter is arranged above the box body of the metering constant-temperature box; and the wet gas meter is communicated with the first metering pipe through a gas production pipeline of the first metering pipe. According to the flow metering device, output liquid enters the first metering pipe through the output liquid inlet, meanwhile, gas in the output liquid enters the wet type gas meter through the gas production pipeline of the first metering pipe, gas-liquid separation is achieved, and meanwhile gas and liquid are measured.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of CO2 flooding low-permeability oil and gas reservoir development, and particularly relates to a flow metering device, a CO2 flooding minimum miscibility pressure testing system and a method. BACKGROUND

[0002] During the displacement experiment, the fluids to be metered are the produced degassed crude oil and the produced gas (CO2 or natural gas, mixed gas of natural gas and CO2), and the produced oil volume is usually metered by means of a measuring cylinder or a balance; the application of these metering methods requires that the experimenters must be on duty during the oil production stage, and the problems in metering are manually read or manually processed; the produced gas volume is metered by the drainage gas collection method or a sealed gas metering cylinder with a scale, and these methods all require personnel on duty and manual reading, and due to the limited volume of the metering container, the container needs to be manually emptied frequently, resulting in problems such as inaccurate metering and large error of experimental data, and therefore a metering device capable of automatic reading and gas volume metering is required. SUMMARY

[0003] In view of the above problems, the application provides a flow metering device, which comprises:

[0004] a metering thermostat box body, a metering pipe support is arranged in the metering thermostat box body, and a produced liquid inlet is arranged on the side surface of the metering thermostat box body;

[0005] a first metering pipe, which is fixedly installed on one side of the metering pipe support; the first metering pipe is connected to the produced liquid inlet through a produced liquid inlet pipeline;

[0006] a wet-type gas meter, which is fixedly installed above the metering thermostat box body; the wet-type gas meter is connected to the first metering pipe through a gas pipeline of the first metering pipe.

[0007] Further, a first transparent plate is arranged on the side surface of the metering thermostat box body;

[0008] a camera support is arranged outside the first transparent plate, a camera is arranged on the camera support, and the camera faces the first metering pipe.

[0009] Further, a second transparent plate is arranged on the side surface of the metering thermostat box body, and the second transparent plate is arranged opposite to the first transparent plate;

[0010] a cold light plate is arranged outside the second transparent plate.

[0011] Further, a first metering pipe gas pipeline valve is arranged on the gas pipeline of the first metering pipe.

[0012] Further, the device further comprises:

[0013] A second metering pipe is fixedly installed on the metering pipe support, and the second metering pipe is close to one side of the produced liquid inlet, the second metering pipe is connected with the produced liquid inlet through the produced liquid inlet pipeline; the second metering pipe is communicated with the wet gas meter through the gas pipeline of the second metering pipe.

[0014] Further, the device further comprises:

[0015] A produced liquid three-way ball valve, the inlet of the produced liquid three-way ball valve is communicated with the produced liquid inlet pipeline, and the two outlets of the produced liquid three-way ball valve are communicated with the first metering pipe and the second metering pipe respectively.

[0016] Further, a second metering pipe gas pipeline valve is arranged on the gas pipeline of the second metering pipe.

[0017] A CO2 flooding minimum miscibility pressure test system, comprising:

[0018] An injection pump,

[0019] A formation oil piston container, the input end of the formation oil piston container is connected with the injection pump;

[0020] A gas piston container, the input end of the gas piston container is connected with the injection pump;

[0021] A capillary tube model, the inlet of the capillary tube model is communicated with the outlet of the formation oil piston container and the outlet of the gas piston container;

[0022] A back pressure valve, the inlet of the back pressure valve is communicated with the outlet of the capillary tube model;

[0023] And the flow metering device mentioned above, the produced liquid inlet of the flow metering device is communicated with the outlet end of the back pressure valve.

[0024] Further, the system further comprises a workstation, and the workstation is electrically connected with the camera of the flow metering device.

[0025] Further, the system further comprises a high-pressure observation window,

[0026] The high-pressure observation window is installed between the capillary tube model and the back pressure valve.

[0027] Further, the system further comprises a second valve, and the valve is installed between the capillary tube model and the high-pressure observation window.

[0028] A CO2 flooding minimum miscibility pressure test method, using the above-mentioned system, comprising the following steps:

[0029] After testing the air permeability of the tubular model, the tubular model is connected to the flow process, the tubular model is cleaned, and the pore volume of the tubular model is tested; the formation oil is injected into the formation oil piston container; the CO2 is injected into the gas piston container;

[0030] The formation oil is injected into the tubular model by driving the formation oil piston container of the injection pump to complete the oil saturation;

[0031] After the oil saturation of the tubular model is completed, the first metering pipe is cleaned, a preset amount of dark indicating liquid is added to the initial liquid level scale in the first metering pipe, and the camera is aimed at the initial liquid level in the first metering pipe; the wet gas flow meter reading is cleared;

[0032] The CO2 is injected into the tubular model by driving the gas piston container of the injection pump, and the produced fluid passes through the high-pressure observation window and the back pressure valve and enters the first metering pipe, while the wet gas meter measures the gas, and the change of the liquid level height is measured by the camera to calculate the produced fluid volume; the oil and gas production is recorded once for every injection of a preset pore volume of CO2.

[0033] Further, the oil saturation of the tubular model includes the following steps:

[0034] The tubular model is cleaned;

[0035] The injection pump drives the formation oil piston container to inject the formation oil into the tubular model to complete the oil saturation process;

[0036] The data of the wet gas meter and the workstation are collected and calculated, the gas-oil ratio of the produced fluid is consistent with the formation gas-oil ratio, the displacement is stopped, and the oil saturation process is completed.

[0037] The present application has the following advantages:

[0038] 1. The flow metering device of the present application allows the produced fluid to enter the first metering pipe through the produced fluid inlet, and the gas in the produced fluid enters the wet gas meter through the gas pipeline of the first metering pipe, realizing gas-liquid separation and measurement.

[0039] 2. The flow metering device of the present application can track the change of the liquid level of the first metering pipe by setting a camera, and calculate the produced fluid volume by the liquid level height; realizing automatic measurement of the produced fluid volume.

[0040] 3. The test system of the present application realizes automatic measurement of the produced gas volume and liquid volume by the flow metering device, realizes automatic measurement, and improves the work efficiency.

[0041] Additional features and advantages of the present application will be set forth in the description that follows, and in part will be apparent from the description, or can be learned by practice of the application. The objectives and other advantages of the present application will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without any creative effort.

[0043] Figure 1 A structural schematic diagram of a flow metering device in an embodiment of the present application is shown;

[0044] Figure 2 A partial structural enlarged schematic diagram in Figure 1

[0045] Figure 3 A front view of a flow metering device in an embodiment of the present application is shown;

[0046] Figure 4 A side view of a flow metering device in an embodiment of the present application is shown;

[0047] Figure 5 A schematic diagram of a CO2 flooding minimum miscibility pressure test system in an embodiment of the present application is shown.

[0048] In the figure, 10 is a flow metering device;

[0049] 101 is a metering thermostat support, 102 is a metering thermostat box, 103 is a camera, 104 is a camera support, 105 is a wet gas meter, 106 is a first metering pipe, 107 is a gas production pipeline of the first metering pipe, 108 is a produced liquid three-way ball valve, 109 is a third metering pipe, 110 is a metering pipe support, 111 is a second metering pipe, 112 is a cool light plate, 113 is a produced liquid inlet, 114 is a produced liquid inlet pipeline, 115 is a gas production pipeline of the second metering pipe, 116 is a first metering pipe gas production pipeline valve, 117 is a second metering pipe gas production pipeline valve, 118 is a three-way joint, 119 is a first transparent plate, and 120 is a second transparent plate.

[0050] 201 is an injection pump, 202 is a formation oil piston container, 203 is a gas piston container, 204 is a thin tube model, 205 is a high-pressure observation window, 206 is a back pressure valve, 207 is a main thermostat, 208 is a workstation, 209 is a first valve, and 210 is a second valve. ​DETAILED DESCRIPTION

[0051] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0052] Embodiment 1,

[0053] As Figures 1-2 shown, Figure 1 The structure of the flow metering device 10 in the embodiment of the present application is shown in the schematic view; Figure 2 The partial structure of the flow metering device 10 in the embodiment of the present application is shown in the enlarged schematic view; and Figure 1 Reference Figure 1 and Figure 2 The output metering device comprises a metering thermostat box body 102, a metering pipe support 110 arranged in the metering thermostat box body 102, and an output liquid inlet 113 arranged on the side of the metering thermostat box body 102. The temperature control precision of the metering thermostat box body 102 is 0.1℃, the temperature control range is from room temperature to 150℃, and the metering thermostat box body 102 is a large thermostat box. Transparent glass flat plates, i.e., a first transparent plate 119 and a second transparent plate 120, are inlaid on the left and right sides of the metering thermostat box body 102, and a metering thermostat support 101 is installed below the metering thermostat box body 102 to facilitate moving the metering thermostat box body 102.

[0054] The first metering pipe 106 is fixedly installed on one side of the metering pipe support 110. The first metering pipe 106 is connected to the output liquid inlet 113 through an output liquid inlet pipeline 114. The first metering pipe 106 is mainly used to meter the output oil quantity in the CO2 driving process. A rubber plug is arranged at the outlet of the first metering pipe 106, the rubber plug is used to block the first metering pipe 106, two 3cm through holes are arranged on the rubber plug, the through holes are connected to the output liquid inlet pipeline 114, the output liquid inlet pipeline 114 is about 5cm deep, and a gas pipeline 107 of the first metering pipe is inserted into the other through hole by about 1cm.

[0055] The wet gas meter 105 is fixedly installed above the metering thermostat box body 102. The wet gas meter 105 is connected to the first metering pipe 106 through the gas pipeline 107 of the first metering pipe.

[0056] In the embodiment, the output liquid enters the first metering pipe 106 through the output liquid inlet 113, and the gas in the output liquid enters the wet gas meter 105 through the gas pipeline 107 of the first metering pipe to be measured.

[0057] In this invention, a first transparent plate 119 is provided on the side of the metering constant temperature chamber 102; a camera bracket 104 is provided on the outside of the first transparent plate 119, and a camera 103 is provided on the camera bracket 104. A telescopic mechanism in the camera bracket 104 can drive the camera 103 to move, and the camera 103 is directly facing the first metering tube 106; specifically, the camera 103 can track the change of the liquid level in the first metering tube 106 and calculate the liquid production by the liquid level height; by setting the software to record data once after injecting 0.1 times the pore volume of CO2, i.e., recording the oil production and gas production, and then calculating the gas-oil ratio and recovery degree, etc. The camera bracket 104 can ensure the flexible up and down movement of the camera 103; the camera 103 is fixed on the camera bracket 104 and can achieve automatic and accurate metering under the control of the software as the liquid level in the first metering tube 106 moves.

[0058] In accordance with this embodiment of the invention, a second transparent plate 120 is provided on the side of the metering constant temperature chamber 102, and the second transparent plate 120 is disposed opposite to the first transparent plate 119; a cold light plate 112 is provided on the outside of the second transparent plate 120. The cold light plate 112 is used to provide a light source to facilitate the camera 103 to accurately identify the liquid level of the first metering tube 106.

[0059] Preferably, a first metering tube gas production line valve 116 is provided on the gas production line 107 of the first metering tube; the first metering tube gas production line valve 116 is used to switch the gas production line 107 of the first metering tube on and off.

[0060] like Figure 3 and Figure 4 As shown, Figure 3 A front view of the flow metering device 10 in an embodiment of the present invention is shown; Figure 4 A side view of the flow metering device 10 in an embodiment of the present invention is shown; Reference Figure 3 and 4 The device also includes,

[0061] The second metering tube 111 is fixedly installed on the metering tube bracket 110, and the second metering tube 111 is located on the side near the produced liquid inlet 113. The second metering tube 111 is connected to the produced liquid inlet 113 through the produced liquid inlet pipe 114. The second metering tube 111 is connected to the wet gas metering gauge 105 through the gas production pipe 115 of the second metering tube. The second metering tube 111 is mainly used in the process of saturating formation oil in the fine tube model 204 and washing oil in the fine tube model 204. The second metering tube 111 is used to store the washing waste liquid. A rubber stopper is provided at the outlet of the second metering tube 111. The rubber stopper is used to seal the second metering tube 111. There are two 3cm through holes on the rubber stopper. The produced liquid inlet pipe 114 is installed and connected to the through holes. The connection of the produced liquid inlet pipe 114 is about 5cm deep. The gas production pipe 115 of the second metering tube is inserted into the through hole about 1cm.

[0062] In the above embodiment, optionally another embodiment is that the device further comprises,

[0063] The production fluid three-way ball valve 108, the production fluid three-way ball valve 108 inlet communicates with the production fluid inlet pipeline 114, and the two outlets of the production fluid three-way ball valve 108 respectively communicate with the first metering pipe 106 and the second metering pipe 111. The first metering pipe 106 and the second metering pipe 111 are combined together through the production fluid three-way ball valve 108; the three-way joint 118 two inlets are respectively connected with the gas production pipeline 107 of the first metering pipe and the gas production pipeline 115 of the second metering pipe, and the three-way joint 118 outlet is connected with the wet gas meter 105 inlet.

[0064] Preferably, the second metering pipe gas production pipeline 115 is provided with a second metering pipe gas production pipeline valve 117; the second metering pipe gas production pipeline valve 117 is used to open and close the second metering pipe gas production pipeline 115.

[0065] The third metering pipe 109 is fixedly installed on the metering pipe support 110, and the third metering pipe 109 is located away from the production fluid inlet 113 end. For standby pipe, and then realize other situation needs to replace the pipeline, for replacement.

[0066] Working principle,

[0067] In the experimental preparation stage, the metering pipe support 110 is put into the metering constant temperature box body 102, and the metering pipe support 110 can fix three metering pipes, wherein the second metering pipe 111 is used in the saturated oil and washing oil process, the first metering pipe 106 is used to measure the oil production in the CO2 drive process, and the third metering pipe 109 is a standby pipe;

[0068] The first metering pipe 106 bottom pours about 20ml black dyed water or black oil, and the interface of the black liquid is used as the initial liquid level of the camera 103 calibration; 3 metering pipes are respectively installed on the metering pipe support 110 in the metering constant temperature box body 102, the bottle mouth of the first metering pipe 106 and the second metering pipe 111 is blocked with a rubber bottle plug, and the bottle plug has two 3mm diameter pipeline inlets.

[0069] Then the outlet pipe 114 is connected to the outlet three-way ball valve 108, the high temperature hose is connected to the first metering pipe 106 and the second metering pipe 111 respectively, and the high temperature hose is inserted into the rubber plug about 5 cm away from the inlet of the metering pipe; the second outlet of the bottle plug of the first metering pipe 106 and the second metering pipe 111 is inserted and connected with the gas production pipe 107 of the first metering pipe and the gas production pipe 115 of the second metering pipe with a diameter of 3 mm, and the insertion depth is about 1 cm, that is, the gas production pipe 115 of the second metering pipe and the gas production pipe 107 of the first metering pipe are connected with the second metering pipe gas production pipe valve 117 and the first metering pipe gas production pipe valve 116 respectively, and then the gas production pipe 115 of the second metering pipe and the gas production pipe 107 of the first metering pipe are connected with the three-way joint 118 through the outlet, and finally connected to the wet gas meter 105 for measuring the gas flow.

[0070] The second metering pipe 111 is mainly used to store waste liquid when cleaning the fine tube model 204. Before or after the experiment, the fine tube model 204 needs to be cleaned with petroleum ether, and the waste liquid generated at this time enters the second metering pipe 111. Before cleaning, the outlet three-way ball valve 108 is connected to the second metering pipe 111, the second metering pipe gas production pipe valve 117 is opened, and after cleaning the CO2 flooding minimum miscibility pressure test system, the cleaning liquid enters the second metering pipe 111 through the outlet inlet 113 to complete the cleaning, and after cleaning, the cleaning of the second metering pipe 111 is completed by replacing or cleaning the second metering pipe 111.

[0071] Example 2,

[0072] As Figure 5 shown, Figure 5 The CO2 flooding minimum miscibility pressure test system in the embodiment of the application is shown, and the CO2 flooding minimum miscibility pressure test system is shown in Figure 5 The CO2 flooding minimum miscibility pressure test system comprises,

[0073] The formation oil piston container 202 is connected with the injection pump 201 at an input end; the gas piston container 203 is connected with the injection pump 201 at an input end; the capillary tube model 204 is connected with the formation oil piston container 202 at an outlet and connected with the gas piston container 203 at an outlet; the back pressure valve 206 is connected with the capillary tube model 204 at an outlet; the outlet of the flow metering device 10 is connected with the back pressure valve 206 at an outlet end. The workstation 208 is electrically connected with the camera 103 of the flow metering device 10. The liquid level recognized by the camera 103 is processed by the workstation 208, and the volume of the liquid is calculated; meanwhile, the workstation 208 is electrically connected with the wet gas meter 105, and the data of the wet gas meter 105 and the data recognized by the camera 103 are combined to determine whether the saturated oil is realized, and the injection pump 201 is driven to record the data, i.e. the oil production, the gas production, the gas-oil ratio and the recovery degree, etc. after 0.1 times of the pore volume of CO2 is injected.

[0074] In the embodiment, the high-pressure observation window 205 is installed between the capillary tube model 204 and the back pressure valve 206. The high-pressure observation window 205 is used to observe the oil outlet of the capillary tube model 204.

[0075] In the above embodiment, optionally, another embodiment is that the second valve 210 is installed between the capillary tube model 204 and the high-pressure observation window 205; specifically, the first valve 209 is further included, and the first valve 209 has four, which are respectively installed at the inlet end and the outlet end of the formation oil piston container 202 and the gas piston container 203.

[0076] Specifically, the system further includes the main constant temperature box 207, and the formation oil piston container 202, the gas piston container 203, the capillary tube model 204, the second valve 210, the high-pressure observation window 205 and the back pressure valve 206 are installed in the main constant temperature box 207. The main constant temperature box 207 is used to keep the temperature of the formation oil piston container 202, the gas piston container 203, the capillary tube model 204, the high-pressure observation window 205 and the back pressure valve 206 constant, thereby improving the accuracy of the experiment.

[0077] Embodiment 3,

[0078] A CO2 flooding minimum miscibility pressure testing method, comprising the following steps,

[0079] Before the experiment, the air permeability of the capillary tube model 204 is tested, then the capillary tube model 204 is connected to the flow process, the capillary tube model 204 is cleaned, and the pore volume of the capillary tube model 204 is tested; the formation oil is injected into the formation oil piston container 202; the CO2 is injected into the gas piston container 203;

[0080] Saturation of the core 204, after cleaning the core 204, open the first metering tube gas pipeline valve 116, open the injection pump 201, the injection pump 201 by driving the formation of oil piston container 202 to the formation of oil injection core 204 to complete the saturation of oil; the usual way is to clean the core 204, inject nitrogen or aviation kerosene, and keep the experimental temperature and pressure. The back pressure is set to the experimental pressure value (should be higher than the saturation pressure value of the formation of crude oil). The formation of crude oil sample is kept at experimental temperature for more than 4h, and the sample is pressurized to the experimental pressure by the injection pump 201, and fully stirred to become a single phase. At the experimental pressure and experimental temperature, slowly open the first valve 209 at the outlet of the formation of oil piston container 202 and the second valve 210 at the inlet of the core 204, and displace the nitrogen or aviation kerosene in the core 204 with the formation of crude oil sample. The displacement speed is 1-1.5ml / min; when the displacement is 2 times the pore volume, every 0.1-0.2 times the pore volume, the oil and gas volume at the outlet end of the core 204 is measured (according to the requirements of GB / T26981), and the oil and gas sample is analyzed for its composition. If the composition of the output sample and the gas oil ratio are consistent with the formation of crude oil sample, stop displacement. The displacement experiment needs to be carried out within 2h after the core saturation is completed, so as to prevent oil and gas separation in the core.

[0081] Cleaning and resetting the metering device, after the core 204 saturation of oil is completed, the first metering tube 106 of the flow metering device 10 is cleaned and reinstalled in the flow metering device 10, and the camera 103 is aligned with the initial liquid level in the first metering tube 106; the wet gas meter 105 reading is cleared.

[0082] CO2 displacement of the core 204, at the experimental temperature and experimental pressure, constant injection speed, displace the formation of crude oil in the core 204 with the injection gas (CO2). The displacement speed is generally 0.1-0.25ml / min. During the displacement process, the displacement pressure difference between the injection pressure of the core 204 and the experimental pressure set by the back pressure regulator should be less than 0.5MPa. If the displacement pressure difference is too high, the injection speed should be reduced.

[0083] Record data, inject CO2 into the core 204 by driving the gas piston container 203 by the injection pump 201, and the output fluid enters the first metering tube 106, while the wet gas meter 105 measures the gas, and the camera 103 calculates the liquid production by the liquid level;

[0084] During displacement, the volume of oil and gas produced is measured every 0.1 PV injected, the pump reading, injection pressure and back pressure are recorded, and the composition and properties of the produced oil and gas can be determined, and the phase and color of the fluid in the high-pressure observation window 205 can be observed. After gas breakthrough, the data collection density is increased as much as possible. When the cumulative pump exceeds 1.20 PV or no more oil is produced, the displacement is stopped.

[0085] Generally, the experiment is first carried out at the original formation pressure, and according to whether it is miscible or not and the degree of miscibility, the method of successive approximation to the minimum miscibility pressure is used to determine other displacement experiment pressures. There should be at least three or more experiment pressure points in the miscible and non-miscible sections. The relationship between oil displacement efficiency and displacement pressure when injecting 1.20 PV in the tube experiment is plotted, and the pressure corresponding to the intersection of the non-miscible section and the miscible curve is the minimum miscibility pressure (MMP).

[0086] Preferably, the completion of the saturation of the oil in the tube model 204 includes the following steps,

[0087] After cleaning the tube model 204, before the experiment of saturating oil in the tube model 204, the produced fluid three-way ball valve 108 is connected to the first metering tube 106, and the second metering tube gas pipeline valve 117 is closed,

[0088] The first metering tube gas pipeline valve 116 is opened, and the injection pump 201 is opened, which drives the formation oil piston container 202 to inject formation oil into the tube model 204, and the saturation of oil process begins.

[0089] After the formation oil displacement of 2 PV, every 0.1-0.2 PV, through the data collection and calculation of the wet gas meter 105 and the workstation 208, the gas-oil ratio of the produced fluid is consistent with the gas-oil ratio of the formation oil, and the displacement is stopped, and the saturation of oil process is completed. Specifically, the minimum miscibility pressure test method of CO2 flooding adopts the following steps,

[0090] Step 1, during the preparation stage of the experiment, the metering tube support 110 is placed into the metering thermostat box body 102, and three metering tubes can be fixed on the support, of which the second metering tube 111 is used in the saturation of oil and oil washing process, and the first metering tube 106 is used to meter the oil produced in the CO2 flooding process.

[0091] Step 2, pour about 20 ml of black dyed water or black oil into the bottom of the first metering tube 106, and the interface of the black liquid is used as the initial liquid level calibration of the camera 103; install the three metering tubes on the metering tube support 110 in the metering thermostat box body 102, plug the bottle mouths of the first metering tube 106 and the second metering tube 111 with rubber bottle plugs, and there are two pipeline inlets with a diameter of 3 mm on the bottle plugs.

[0092] Step 3, connect the high temperature resistant hose with 3mm diameter to the outlet of back pressure valve 206, and then to the inlet 113 of the first measuring cylinder 106 on the left side of the constant temperature oven 102. Then connect the outlet pipe 114 of the first measuring cylinder 106 to the three-way valve 108, and then connect the outlet pipe 114 of the first measuring cylinder 106 to the three-way valve 108 with high temperature resistant hose. The other end of the high temperature resistant hose is inserted into the rubber plug of the first measuring cylinder 106 about 5 cm from the inlet of the first measuring cylinder 106. The second outlet of the rubber plug of the first measuring cylinder 106 is connected to the second measuring cylinder 111 with a 3mm diameter hose, and the insertion depth is about 1cm. The gas outlet pipe 115 of the second measuring cylinder 111 and the gas outlet pipe 107 of the first measuring cylinder 106 are respectively connected to the first measuring cylinder gas outlet pipe valve 116 and the second measuring cylinder gas outlet pipe valve 117, and then connected to the three-way joint 118 through the hose, and finally connected to the wet gas meter 105 for measuring the gas flow.

[0093] Step 4, the second measuring cylinder 111 is mainly used to store waste liquid when cleaning the capillary model 204. Before or after the experiment, the capillary model 204 needs to be cleaned with petroleum ether, etc. At this time, the waste liquid generated is entered into the second measuring cylinder 111. Before cleaning, rotate the outlet three-way valve 108 to connect the second measuring cylinder 111, open the second measuring cylinder gas outlet pipe valve 117, and prepare to clean the capillary model 204.

[0094] Step 5, after cleaning the capillary model 204, before the experiment of saturating the capillary model 204 with oil, rotate the outlet three-way valve 108 to connect the first measuring cylinder 106, close the second measuring cylinder gas outlet pipe valve 117, and open the first measuring cylinder gas outlet pipe valve 116. Prepare to measure the amount of oil and gas produced during the saturation of oil. After starting saturation, compare the composition, gas-oil ratio of the produced sample with the original oil sample of the formation. If the values are the same, the saturation of oil is complete.

[0095] Step 6, after saturating the capillary model 204 with oil, remove the first measuring cylinder 106, pour the residual oil in the first measuring cylinder 106 into the waste liquid bucket, and then wash the first measuring cylinder 106 and place it back on the constant temperature oven support 101. Seal the first measuring cylinder 106 with a rubber plug and prepare for oil and gas measurement during CO2 flooding.

[0096] Step 7, through the workstation 208 control software, align the camera 103 with the initial liquid level in the first measuring cylinder 106; and reset the reading of the wet gas meter 105 to zero.

[0097] Step 8, after the start of CO2 flooding, with the increase of CO2 injection, the produced fluid begins to enter the first metering pipe 106, due to the low injection rate, the oil droplets are directly dropped into the first metering pipe 106, in the process of the produced liquid droplet, the gas separated out enters the wet gas meter 105 through the gas pipeline 107 of the first metering pipe, and the gas production is directly metered; the camera 103 can track the change of the liquid level, and the liquid production is calculated through the liquid level; through the software setting, after injecting 0.1 times of the pore volume of CO2, the data is recorded once, that is, the oil production, gas production, and then the gas-oil ratio and the recovery degree are calculated.

[0098] Step 9, since the minimum number of capillary tube experiments is 6 displacement experiments, after each experiment, steps 1 to 8 are repeated.

[0099] Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A flow metering device, characterized by The device comprises: a metering thermostat box (102) in which a metering tube support (110) is arranged, and an outlet liquid inlet (113) is arranged on the side of the metering thermostat box (102); a first metering tube (106) fixedly installed on one side of the metering tube support (110); the first metering tube (106) is connected with the outlet liquid inlet (113) through an outlet liquid inlet pipeline (114); a wet gas meter (105) fixedly installed above the metering thermostat box (102); the wet gas meter (105) is connected with the first metering tube (106) through a first metering tube gas production pipeline (107).

2. A flow metering device according to claim 1, characterised in that A first transparent plate (119) is arranged on the side of the metering thermostat box (102); A camera support (104) is arranged outside the first transparent plate (119), and a camera (103) is arranged on the camera support (104) and faces the first metering tube (106).

3. A flow metering device according to claim 2, wherein A second transparent plate (120) is arranged on the side of the metering thermostat box (102) and opposite to the first transparent plate (119); A cold light plate (112) is arranged outside the second transparent plate (120).

4. A flow metering device according to claim 1, wherein A first metering tube gas production pipeline valve (116) is arranged on the first metering tube gas production pipeline (107).

5. A flow metering device according to any one of claims 1-4, characterised in that The device further comprises: a second metering tube (111) fixedly installed on the metering tube support (110) and close to one side of the outlet liquid inlet (113); the second metering tube (111) is connected with the outlet liquid inlet (113) through the outlet liquid inlet pipeline (114); the second metering tube (111) is connected with the wet gas meter (105) through a second metering tube gas production pipeline (115).

6. A flow metering device according to any one of claim 5, characterised in that The device further comprises: an outlet liquid three-way ball valve (108) having an inlet connected with the outlet liquid inlet pipeline (114) and two outlets connected with the first metering tube (106) and the second metering tube (111) respectively.

7. A flow metering device according to claim 5, wherein A second metering tube gas production pipeline valve (117) is arranged on the second metering tube gas production pipeline (115).

8. A CO2 flood minimum miscibility pressure test system characterized by, The device comprises: an injection pump (201), a formation oil piston container (202) having an input end connected with the injection pump (201); a gas piston container (203) having an input end connected with the injection pump (201); a capillary tube model (204) having an inlet connected with outlets of the formation oil piston container (202) and the gas piston container (203); a back pressure valve (206) having an inlet connected with an outlet of the capillary tube model (204); The flow metering device (10) of any one of claims 1-7, wherein the outlet of the back pressure valve (206) is connected to the outlet of the flow metering device (10).

9. The CO2 flood minimum miscibility pressure test system of claim 8, wherein, The system further comprises a workstation (208) electrically connected to the camera (103) of the flow metering device (10).

10. The CO2 flood minimum miscibility pressure testing system of claim 8, wherein, The system further comprises a high pressure observation window (205), The high pressure observation window (205) is installed between the fine tube model (204) and the back pressure valve (206).

11. The CO2 flood minimum miscibility pressure test system of claim 10, wherein, The system further comprises a second valve (210) installed between the fine tube model (204) and the high pressure observation window (205).

12. A method of testing for the minimum miscibility pressure of CO2 flooding, characterized by, The system of any one of claims 8-11, comprising the following steps: Injecting formation oil into the formation oil piston container (202); connecting the fine tube model (204) to the flow path after testing the air permeability of the fine tube model (204), cleaning the fine tube model (204), and testing the pore volume of the fine tube model (204); injecting formation oil into the formation oil piston container (202); injecting CO2 into the gas piston container (203); Injecting formation oil into the fine tube model (204) by driving the formation oil piston container (202) with the injection pump (201) to complete the oil saturation; After the oil saturation of the fine tube model (204) is completed, cleaning the first metering tube (106), adding a preset amount of dark indicating liquid to the initial liquid level scale in the first metering tube (106), and aligning the camera (103) with the initial liquid level in the first metering tube (106); zeroing the reading of the wet gas flow meter (105); Injecting CO2 into the fine tube model (204) by driving the gas piston container (203) with the injection pump (201), and the output fluid enters the first metering tube (106) through the high pressure observation window (205) and the back pressure valve (206), while the wet gas meter (105) measures the gas, and the liquid level height change is calculated by the camera (103) to calculate the liquid production; recording the oil and gas production once every preset amount of CO2 is injected.

13. The method of testing for the minimum miscibility pressure of CO2 flooding according to claim 12, wherein, The oil saturation of the fine tube model (204) comprises the following steps: Cleaning the fine tube model (204); Injecting formation oil into the fine tube model (204) by driving the formation oil piston container (202) with the injection pump (201) to complete the oil saturation process; Through the data collection and calculation of the wet gas meter (105) and the workstation (208), the gas-oil ratio of the output fluid is consistent with the gas-oil ratio of the formation oil, the displacement is stopped, and the oil saturation process is completed.

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