A testing method and device for the effective permeability of coated sand

Abstract

The present invention belongs to the technical field of permeability testing, and specifically relates to a method and device for testing the effective permeability of coated sand. The testing method comprises the following steps: step one: heating and stirring a displacement fluid; step two: exhausting a main line; step three: exhausting a differential pressure sensor; step four: calibrating the differential pressure sensor: adjusting the differential pressure sensor so that the display value of the differential pressure sensor is 0; step five: displacement test: closing the isolation valve of the differential pressure sensor so that the differential pressure sensor forms two isolation chambers, using a delivery pump to pump the displacement fluid into a coated sand filling pipe or a coated sand artificial core for displacement, and using a metering component to meter the liquid flowing out of the coated sand filling pipe or the coated sand artificial core, collecting data of the delivery pump, the differential pressure sensor, and the metering component during the test, and calculating the permeability according to Darcy's law.

Description

Technical Field

[0001] The present invention belongs to the technical field of permeability testing, and particularly relates to an effective permeability testing device for coated sand. Background Art

[0002] When the oilfield enters the high water cut development stage, coated sand has replaced ceramic proppants due to its low cost and strong functions, reducing the cost of the fracturing process and having broad application prospects. To test the permeability of coated sand, it is necessary to make artificial simulated cores from coated sand or conduct displacement experiments by filling coated sand into a sand-filled pipe.

[0003] Most of the currently common permeability testing devices are, for example, a measuring instrument for directly measuring the oil-water relative permeability of magmatic rock disclosed in a Chinese utility model patent with the authorized announcement number CN206208711U. It includes a core holder, a liquid mixing and filling device located upstream of the core holder, and an oil-water extraction and separation machine located downstream of the core holder. The liquid mixing and filling device can mix multi-phase liquids, and the oil-water extraction and separation machine can separate the permeated oil-water mixture. A liquid flow meter is also connected to the oil-water extraction and separation machine, and the liquid flow meter can measure the amount of oil and water separated. The measuring instrument also includes an upstream detection structure for detecting the pressure upstream of the core holder (i.e., the high-pressure measurement display 1 and the low-pressure measurement display 1 in this patent), and a downstream detection structure for detecting the pressure downstream of the core holder (i.e., the low-pressure measurement display 2 and the high-pressure measurement display 2 in this patent). The pressure difference across the core holder is obtained through the numerical difference between the upstream detection structure and the downstream detection structure.

[0004] The measuring instruments of the prior art can complete the mixing of oil and water, differential pressure detection, oil-water separation and measurement, and can measure the permeability of magmatic rock. However, it is not suitable for the high permeability testing of coated sand. The reason is that the permeability of magmatic rock or other rocks is relatively low, and liquids are not easily permeated. During testing, the pressure difference across the core holder is very large. While the permeability of coated sand is relatively large and the displacement pressure is relatively low, ordinary sensors cannot collect pressure signals. Moreover, most of the differential pressure monitoring of the permeability testing devices on the market independently tests the upstream pressure and the downstream pressure with two sensors. However, the sensors are prone to electronic drift and cannot be zeroed, easily forming systematic errors, resulting in inaccurate detection results, and only new sensors can be replaced. Especially for coated sand with a relatively low displacement pressure, even if a small-range sensor is replaced, the error is still relatively large using the current differential pressure testing method.

[0005] In addition, the current method for simulating formation temperature is generally to wrap a heating tape around the outside of the core holder to heat the core. However, due to the relatively high permeability of coated sand and the relatively fast liquid flow, the low-temperature displacement fluid is likely to reduce the temperature of the core holder, resulting in the displacement temperature not conforming to the actual formation temperature. Summary of the invention

[0006] The purpose of the present invention is to provide a method for testing the effective permeability of coated sand to solve the technical problem that the permeability testing device in the prior art cannot meet the requirements of testing coated sand with high permeability; the purpose of the present invention is also to provide a device for testing the limited permeability of coated sand to solve the above-mentioned technical problem.

[0007] To achieve the above object, the technical solution of the effective permeability test method of coated sand provided by the present invention is: a method for testing the effective permeability of coated sand, comprising the following steps:

[0008] Step 1: Heating and stirring: Stir the displacement fluid to make the temperature of the displacement fluid reach the design requirement;

[0009] Step 2: Mainline exhaust: connect the manufactured coated sand filling pipe or coated sand artificial core to the process, close the upstream valve and downstream valve of the differential pressure sensor, the downstream valve of the mainline and the mainline vent valve, and use the displacement fluid to pressure-displace. After displacement, open the mainline vent valve to release the pressure;

[0010] Step 3: Exhaust the differential pressure sensor: Close the downstream valve and the vent valve of the trunk line, open the upstream valve, downstream valve and isolation valve of the differential pressure sensor, and open the trunk vent valve to release the pressure after displacing the differential pressure sensor with displacement fluid;

[0011] Step 4: Differential pressure sensor calibration: adjust the differential pressure sensor so that the displayed value of the differential pressure sensor is 0;

[0012] Step 5: Displacement test: Close the isolation valve of the differential pressure sensor to form two isolation chambers. Use a delivery pump to pump the displacement fluid into the coated sand filling pipe or coated sand artificial core for displacement. Use a metering component to measure the liquid flowing out of the coated sand filling pipe or coated sand artificial core. During the test, data from the delivery pump, differential pressure sensor, and metering component are collected and the permeability is calculated according to Darcy's law.

[0013] Beneficial effects: The present invention belongs to an innovative invention. In the method for testing the permeability of coated sand of the present invention, steps such as heating the displacement fluid, stirring and mixing, system exhaust, and pressure calibration are provided, meeting the testing method for high permeability and low pressure difference of coated sand, and realizing the normal displacement and parameter monitoring of the permeability test of coated sand. In the present invention, the displacement fluid meets the temperature requirements when it is input from the transfer pump. Compared with the prior art method of setting a heating belt at the core holder for heating, the temperature of the coated sand filling tube or the artificial core of coated sand is maintained at the formation simulation temperature, which is closer to the actual environment. The differential pressure sensor can be zeroed and the main line exhaust and differential pressure sensor exhaust are carried out before starting to work, with higher monitoring accuracy and being suitable for the use environment with lower displacement pressure. In the present invention, when the downstream valve of the main line is opened, the coated sand can be normally displaced. When the downstream valve of the main line is closed, the displacement fluid can be retained in the coated sand filling tube or the artificial core of coated sand at a certain pressure, enabling the coated sand to fully react with the displacement fluid. After reacting for a period of time, the downstream valve of the main line is opened to carry out normal displacement, and the permeability during the displacement process of the coated sand can be obtained, and the permeability of the coated sand can be accurately obtained. By comparing the change in permeability before and after displacement of the same coated sand filling tube or artificial core, the degree of realization of the loading function of the coated sand can be judged. For example, whether the coated sand has the function of oil permeability and water resistance, and whether the coated sand is resistant to erosion after consolidation, etc.

[0014] Preferably, the main line exhaust and differential pressure sensor exhaust are repeated multiple times to improve the exhaust effect. Through multiple operations, it can be ensured that the gas at the main line and differential pressure sensor is completely emptied, avoiding affecting the test results due to the presence of gas.

[0015] Preferably, when collecting data, data collection and calculation start when the readings of the metering component are consistent with those of the transfer pump. This can reduce the amount of data and discard useless data.

[0016] Preferably, the metering component includes an oil-water separator and two metering structures for respectively measuring oil and water. During the test, the data of the two metering structures are collected.

[0017] The technical solution of the effective permeability test device for coated sand of the present invention is as follows: An effective permeability test device for coated sand includes a sample physical model assembly. The sample physical model assembly is a sand filling tube or a core holder. The sand filling tube is used to fill coated sand, and the core holder is used to hold a core made of coated sand. The test device also includes differential pressure monitoring pipelines connected to the upstream and downstream of the sample physical model assembly. A differential pressure sensor for monitoring the pressure difference between the upstream and downstream of the sample physical model assembly is provided on the differential pressure monitoring pipeline. An upstream valve is provided upstream of the differential pressure sensor on the differential pressure monitoring pipeline, and a downstream valve is provided downstream of the differential pressure sensor. The test device also includes a heating and stirring structure and a delivery pump located upstream of the sample physical model assembly. The heating and stirring structure is used to heat and stir the displacement fluid, and the delivery pump is used to pump the displacement fluid in the heating and stirring structure into the sample physical model assembly. A pressure gauge for calibrating with the differential pressure sensor is also provided between the delivery pump and the sample physical model assembly. The test device also includes a main line vent valve located upstream of the sample physical model assembly and a main line downstream valve located downstream of the differential pressure sensor. The test device also includes a metering assembly for measuring the liquid flowing out of the coated sand filling tube or the artificial coated sand core.

[0018] Beneficial effects: The present invention belongs to an exploratory invention. In the coated sand permeability test device of the present invention, steps such as heating, stirring and mixing of the displacement fluid, system exhaust and pressure calibration are provided, which meet the test method for high permeability and low pressure difference of coated sand, and realize the normal displacement and parameter monitoring of the coated sand permeability test. In the present invention, the displacement fluid meets the temperature requirements when it is input from the delivery pump. Compared with the method of setting a heating belt at the core holder in the prior art, the temperature of the coated sand filling tube or the artificial coated sand core remains at the formation simulation temperature, which is closer to the actual environment. The differential pressure sensor can be zero-adjusted and the main line and the differential pressure sensor are exhausted before starting to work, with higher monitoring accuracy and suitable for the use environment with lower displacement pressure. In the present invention, when the main line downstream valve is opened, normal displacement of the coated sand can be carried out. When the main line downstream valve is closed, the displacement fluid can be retained in the coated sand filling tube or the artificial coated sand core at a certain pressure, so that the coated sand and the displacement fluid can fully react. After reacting for a period of time, the main line downstream valve is opened to carry out normal displacement, and the permeability during the displacement of the coated sand can be obtained, and the permeation performance of the coated sand can be accurately obtained. By comparing the change in permeability before and after displacement of the same coated sand filling tube or artificial core, the realization degree of the loading function of the coated sand can be judged. For example, whether the coated sand has the function of oil penetration and water resistance, and whether the coated sand is resistant to scouring after consolidation.

[0019] Preferably, the testing device further includes an upstream valve on the main line between the transfer pump and the sample physical model assembly. The upstream valve on the main line is used to open during displacement to allow liquid to enter the sample physical model assembly, and is also used to close during pressure maintenance of the sample physical model assembly to prevent the liquid in the sample physical model assembly from flowing back and impacting the transfer pump. Although the sample physical model assembly can be maintained under pressure by closing the transfer pump, closing the upstream valve on the main line during pressure maintenance can prevent the liquid in the sample physical model assembly from flowing back to the transfer pump due to the closing of the downstream valve on the main line, thereby avoiding impact damage to the transfer pump.

[0020] Preferably, the heating and stirring structure is a magnetic stirrer. The magnetic stirrer can ensure uniform mixing of the liquid. Moreover, the magnetic rotor rotating at the bottom of the magnetic stirrer will not affect the pipelines extending into the magnetic stirrer.

[0021] Preferably, the metering assembly includes an oil-water separation structure and a metering structure. The oil-water separation structure is used to separate the oil-water mixture flowing out of the sample physical model assembly, and the metering structure is used to measure the separated oil and water.

[0022] Preferably, the oil-water separation structure is a glass oil-water separator. The glass oil-water separator includes a main pipe and a branch pipe connected to the main pipe. A valve for controlling the opening degree of the branch pipe is provided on the main pipe. By adjusting the opening degree of the valve, the oil top surface is located at the intersection position of the main pipe and the branch pipe. The glass oil-water separator is a manual structure with simple structure, reliable use and low cost.

[0023] Preferably, the metering structure includes a balance. The balance is used to receive the separated oil and water and conduct weighing and metering. Using a balance to weigh the oil quantity and water quantity, the balance is a structure that is regularly sent for inspection according to the management regulations of measuring instruments, which can ensure the accuracy and effectiveness of the measurement results; compared with an electromagnetic flowmeter, the data of the electromagnetic flowmeter is prone to drift due to voltage fluctuations, with large errors, and it is difficult to calibrate, and the effectiveness of the data lacks evidence. Description of the Drawings

[0024] Figure 1 It is the test flow chart in the effective permeability testing device for coated sand provided by the present invention;

[0025] Figure 2 It is a schematic diagram of the effective permeability testing device for coated sand provided by the present invention;

[0026] Description of the Reference Numerals

[0027] 1. Magnetic stirrer; 2. Peristaltic pump; 3. Upstream valve on the main line; 4. First vent valve; 5. Tee; 6. First pressure gauge; 7. Upstream valve; 8. Differential pressure monitoring pipeline; 9. Differential pressure sensor; 10. Data collector; 11. Downstream valve; 12. Balance; 13. Glass oil-water separator; 14. Downstream valve on the main line; 15. Core holder; 16. Second pressure gauge; 17. Pressure maintaining valve; 18. Second vent valve; 19. Annular pressure pump. Detailed implementation manners

[0028] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention, that is, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Usually, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0029] Therefore, the detailed description of the embodiments of the present invention provided in the drawings below is not intended to limit the scope of the claimed present invention, but only represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the present invention.

[0030] It should be noted that relational terms such as "first" and "second" that may appear are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, terms such as "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent in such process, method, article or device. Without further limitation, the elements defined by the statement "including one..." do not exclude other elements included in the process, method.

[0031] In the description of the present invention, unless otherwise clearly defined and limited, the terms "installation", "connection" and "connection" that may appear should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through an intermediate medium, or it may be the internal communication of two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances.

[0032] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the term "provided with" that may appear should be understood in a broad sense. For example, the object of "provided with" can be a part of the main body, or can be arranged separately from the main body and connected to the main body, and this connection can be a detachable connection or a non-detachable connection. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0033] The present invention will be further described in detail below in conjunction with embodiments.

[0034] Specific embodiments of the effective permeability testing device for coated sand provided by the present invention:

[0035] The testing principle of the effective permeability testing device for coated sand (hereinafter referred to as the testing device for short) is as follows: The coated sand is filled into the sand-filled pipe, or after the consolidated coated sand is made into an artificial simulated core, it is installed in the core holder. Oil and water are simultaneously injected into the sand-filled pipe or the core holder at a certain flow rate, and a differential pressure is generated at both ends of the sand-filled pipe or the core holder. When the oil and water flow rates are constant, the oil and water saturation in the coated sand no longer changes. According to Darcy's law, the permeability at a certain saturation is calculated.

[0036] As Figure 2 shown, the testing device includes a sample physical model assembly. The sample physical model assembly in this embodiment includes a core holder 15. The specification of the core holder 15 here is ￠25×38mm, with a pressure resistance of 50 MPa and a temperature resistance of 300 °C, and its connection is a ￠4 quick connector. Since a confining pressure needs to be provided when the core holder 15 is in use, the testing device further includes a confining pressure pump 19 connected to the core holder 15. A pressure maintaining valve 17 is connected between the confining pressure pump 19 and the core holder 15. Three-way joints 5 are connected between the pressure maintaining valve 17 and the confining pressure pump 19 and between the pressure maintaining valve 17 and the core holder 15 respectively. A second vent valve 18 is connected to the three-way joint 5 between the pressure maintaining valve 17 and the confining pressure pump 19, and a second pressure gauge 16 is connected to the three-way joint 5 between the pressure maintaining valve 17 and the core holder 15. The second vent valve 18 is used for pressure relief, and the second pressure gauge 16 detects the confining pressure.

[0037] The test device also includes a pressure monitoring component. Here, the pressure monitoring component is a differential pressure sensor 9. The output range of the differential pressure sensor 9 is 0 - 100 KPa, and the working voltage is 24 Vdc. It can provide a current signal of 4 - 20 mA differential pressure signal for an electronic digital meter or a computer interface, meeting the monitoring requirement of differential pressure less than 100 Kpa in the coated sand displacement experiment. The pressure monitoring component also includes an electronic digital meter. The external voltage of the electronic digital meter is AC90 - 265 / 50HZ, and after conversion, it provides a working voltage of 24 Vdc for the differential pressure sensor 9 with an accuracy of 5%. The electronic digital meter is used to receive the 4 - 20 mA differential pressure signal output by the differential pressure sensor 9 and calculate and display the real-time differential pressure according to the range of 0 - 10 Kpa. The pressure monitoring component also includes a first pressure gauge 6 located upstream of the core holder 15. The first pressure gauge 6 is a mechanical gauge with a range of 100 KPa. Its main function is to compare with the value of the differential pressure sensor 9 to ensure that the values of the electronic digital meter and the first pressure gauge 6 are consistent. Among them, the first pressure gauge 6 is connected to the inlet of the core holder 15 through a tee 5.

[0038] As Figure 1 shown, the test device includes a differential pressure monitoring pipeline 8. The differential pressure monitoring pipeline 8 is connected to both ends of the core holder 15. The differential pressure sensor 9 is installed on the differential pressure monitoring pipeline 8. Upstream valve 7 and downstream valve 11 are respectively installed on both sides of the differential pressure sensor 9. The two valves can connect and disconnect the differential pressure sensor 9. When the differential pressure sensor 9 is not needed for monitoring, close the upstream valve 7 and the downstream valve 11 to avoid pressure affecting the differential pressure sensor 9 and protect the differential pressure sensor 9. Among them, the differential pressure monitoring pipeline 8 is installed between the first pressure gauge 6 and the core holder 15.

[0039] The test device also includes a stirring component. Here, the stirring component includes a magnetic stirrer 1. The magnetic stirrer is installed upstream of the peristaltic pump 2. The magnetic stirrer 1 is an existing device on the market. The working voltage of the magnetic stirrer 1 is AC90 - 265 / 50HZ, the rotation speed is 0 - 60 revolutions / min, and the maximum heating temperature is 300 °C. The magnetic stirrer 1 can fully mix the oil and water. The stirring component also includes a measuring cylinder and a stopwatch. The measuring cylinder and the stopwatch are used as equipment accessories to sample the liquid in the stirring container to verify whether the stirred oil-water mixture is evenly mixed and whether it meets the concentration requirements of the displacement mixture. The capacity of the measuring cylinder is 10 ml, the sampling interval is set to 5 min, the sampling time is 3 min, the sample settles for 5 min, and the water content of the sample is calculated. When in use, sample continuously 3 times and calculate that the water content deviation is less than 5% for even stirring. Usually, sampling is carried out after stirring for 30 min. When simulating the formation temperature, according to the experimental temperature requirements, set to heat and stir at the same time.

[0040] The test device further includes an oil-water metering assembly. The oil-water metering assembly here includes a glass oil-water separator 13. The glass oil-water separator 13 here has a common structure on the market and separates oil and water by using the density difference between oil and water and the gravity difference of droplet sizes. The glass oil-water separator 13 includes a main pipe and branch pipes. There is an adjusting valve on the main pipe. The capacity of the glass oil-water separator 13 is 150 ml, the length is 250 mm, the diameter of the main pipe is 28 mm, and it has a glass core valve. When the oil-water mixer enters from the top opening and fills the glass oil-water separator 13, by adjusting the glass core valve, since the density of oil is lower than that of water, the oil-water interface is above the glass core valve, and the top of the oil volume is just at the intersection position of the main pipe and the branch pipes. When the glass oil-water separator 13 enters the oil-water mixture, water flows out from below the main pipe, and oil flows out from the branch pipes. The outflow ratio of water and oil is related to the opening degree of the glass core valve. The larger the opening degree, the more water flows out; the smaller the opening degree, the more oil flows out.

[0041] The oil-water metering assembly further includes two weighing scales 12. When the two weighing scales 12 are in use, they respectively receive the water and oil separated by the glass oil-water separator 13, and measure the water volume and oil volume respectively. The graduation of the weighing scale 12 is 0.0001 g, and the maximum weighing capacity is 1200 g. It has an RS232 interface for convenient computer communication and real-time collection of the weighing scale readings. The average value can be taken as the flow value at the outlet of the core holder 15 within a certain metering time.

[0042] In this embodiment, the test device further includes a data collector 10. The data collector 10 collects the values of the weighing scale 12, the differential pressure sensor 9, and the peristaltic pump 2, and calculates the permeability through an internal formula. By using computer software to collect the values of the differential pressure sensor 9, the weighing scale 12, and the displacement time at a set time, the oil-phase permeability, water-phase permeability, and relative permeability can be calculated.

[0043] As Figure 1 shown, the test device further includes an upstream valve 3 and a first vent valve 4 on the main line connected between the peristaltic pump 2 and the first pressure gauge 6. Among them, the first vent valve 4 is connected between the peristaltic pump 2 and the first pressure gauge 6 through a tee 5. The test device further includes a downstream valve 14 on the main line connected between the differential pressure monitoring line 8 and the glass oil-water separator 13.

[0044] The process of testing the permeability of the coated sand artificial core in the present invention is as Figure 1 shown:

[0045] (1) Apply confining pressure

[0046] First, place the core made of coated sand into the core holder 15. (Of course, in actual use, if the length of the core holder 15 is insufficient, a special core spacer can be added.) Connect the core holder 15 to the process through a quick connector. Close the second vent valve 18, open the pressure-holding valve 17, start the annular pressure pump 19, and apply pressure until the second pressure gauge 16 shows 2 MPa. Then, close the annular pressure pump 19, close the pressure-holding valve 17, and open the second vent valve 18. After the above operations, the annular pressure is applied to the core holder 15 to ensure that the displacement fluid flows out from the middle of the core. In actual use, the minimum annular pressure is 2 - 3 MPa.

[0047] (2) Heat and stir the displacement fluid

[0048] Add water to the magnetic stirrer 1, place the beaker containing the displacement fluid (300 ml of kerosene and 700 ml of distilled water) into the stirring container, and put the magnetic stirring rod into the beaker. Set the stirring speed to 40 revolutions per minute and start stirring. Insert the temperature sensor into the magnetic stirrer, turn on the heating switch, set the heating temperature to 40 °C, and start heating. Usually, after stirring for 30 minutes, sampling is carried out. Use a measuring cylinder with a capacity of 10 ml for sampling, set the sampling interval to 5 minutes, let the sample settle for 5 minutes, and calculate the water content of the sample. In actual use, the water content calculated by continuously sampling 3 times is 69.6%.

[0049] (3) Exhaust the main line

[0050] First, close the upstream valve 7, downstream valve 11, first vent valve 4, and downstream main line valve 14. Open the upstream main line valve 3, set the displacement flow rate of the peristaltic pump 2 to 4 ml / min. Stop the pump when the reading of the first pressure gauge 6 reaches 80 kPa, open the first vent valve 4 to release the pressure until the pressure gauge reading is 0. This needs to be repeated 3 - 5 times.

[0051] (4) Exhaust the differential pressure sensor

[0052] First, open the upstream valve 7, downstream valve 11, and the isolation valve of the differential pressure sensor 9 itself. Close the first vent valve 4 and the downstream main line valve 14. Open the upstream main line valve 3, set the displacement flow rate of the peristaltic pump 2 to 4 ml / min. Stop the pump when the reading of the first pressure gauge 6 reaches 80 kPa, open the first vent valve 4 to release the pressure until the pressure gauge reading is 0. This needs to be repeated 3 - 5 times.

[0053] (5) Calibrate the differential pressure sensor

[0054] Adjust the display value of the differential pressure sensor 9 through the electronic digital display instruction so that its display value and the reading of the first pressure gauge 6 are both kept at 0. Close the isolation valve of the differential pressure sensor 9 itself to form two isolated chambers for the differential pressure sensor 9.

[0055] (6) Test displacement

[0056] Open the upstream valve 3, upstream valve 7, downstream valve 11, and downstream trunk valve 14 on the main line, and close the first vent valve 4. Fill the magnetic stirrer 1 with the oil-water mixture, set the peristaltic pump 2 to 4 ml / min for displacement, adjust the valve on the glass oil-water separator 13 so that the balance 12 shows a reading, ensure that the liquid level at the top of the separated oil in the oil-water mixture is just stable at the branch pipe orifice, take readings through the balance 12. When the total sum of the oil and water is consistent with the total amount of the added oil-water mixture, it indicates that the core is in a saturated state and the displacement is in a stable stage, and only then are the data accurate. After that, the experiment ends after 30 minutes of displacement. During the whole process, the data collector 10 collects data and performs real-time calculations. The experiment shows that when displacing an oil-water mixture with 70% water content, the oil-phase permeability is 3.4 Darcy, the water-phase permeability is 2.8 Darcy, the total volume of the water balance at the outlet is 375 ml, the total volume of the oil balance at the outlet is 240 ml, and the total water content of the outlet liquid is 60.9%. Compared with the 70% water content at the inlet, it decreases by 9 percentage points, indicating that the coated sand artificial core has the function of oil permeability and water resistance.

[0057] It should be noted that when the displacement medium is single water or kerosene, the magnetic stirrer 1 is no longer started, and at the same time, the valve on the glass oil-water separator 13 is fully opened, and the water or kerosene only flows into the main pipe.

[0058] After the whole experiment is completed, close all the valves.

[0059] In this embodiment, the first vent valve 4 constitutes the vent valve of the main line.

[0060] In this embodiment, the peristaltic pump constitutes a delivery pump capable of pressurized liquid delivery. In other embodiments, the delivery pump can be a plunger pump, etc.

[0061] In this embodiment, the magnetic stirrer 1 constitutes an oil-water mixing structure capable of mixing oil and water. It should be noted that when the displacement liquid is pure oil or pure water, the oil-water mixing structure can be deactivated. In other embodiments, the oil-water mixing structure can include a container, and a stirring impeller is provided in the container, and the mixing of oil and water is realized by the rotation of the stirring impeller. In other embodiments, when the displacement liquid is pure oil or pure water, the oil-water mixing structure can be cancelled.

[0062] In this embodiment, the two balances 12 constitute a metering structure for metering the separated oil and water. In other embodiments, in order to meter the flow rates of oil and water, an electromagnetic flowmeter can be directly used for metering, and the electromagnetic flowmeter is connected to the outlet of the oil-water separation structure.

[0063] In this embodiment, the glass oil-water separator 13 constitutes an oil-water separation structure for separating oil and water from the liquid flowing out of the sample physical model assembly, that is, an oil-water separator. The oil-water separation structure and the metering structure together form a metering assembly. In other embodiments, the oil-water separation structure can be an oil-water separator, such as a centrifugal extractor, etc. The metering structure receives the oil and water separated by the oil-water separation structure. In other embodiments, when the displacement liquid is pure oil or pure water, the oil-water separation structure in the metering assembly can be cancelled, and only the metering structure is retained. At this time, only one metering structure is needed, and the metering structure directly enters the process.

[0064] In this embodiment, the test device includes a first pressure gauge 6. The first pressure gauge 6 is used to compare with the differential pressure sensor 9 for calibration, and the first pressure gauge 6 constitutes a main line pressure gauge.

[0065] In this embodiment, the test device includes an upstream main line valve 3. When the upstream main line valve 3 is closed, it can protect the delivery pump. In other embodiments, the upstream main line valve is cancelled. The upstream of the sample physical model assembly relies on the delivery pump for pressure maintenance, and the downstream relies on the downstream valve for pressure maintenance.

[0066] In this embodiment, the sample physical model assembly includes a core holder. In other embodiments, the sample physical model assembly includes a sand-packed tube. When in use, the coated sand is filled into the sand-packed tube. At this time, structures such as an annulus pressure pump can be cancelled. In actual use, the sample physical model assembly includes both a sand-packed tube and a core holder. The two are selectively connected to the process during use. For convenient and rapid replacement, both ends of the core holder and the sand-packed tube are docked with other structures in the process using quick connectors.

[0067] Specific embodiments of the method for testing the effective permeability of the coated sand of the present invention:

[0068] The method for testing the effective permeability of the coated sand is the same as the testing method in the above-mentioned test device, and will not be elaborated here.

[0069] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still make modifications to the technical solutions described in the foregoing embodiments without creative efforts, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for testing the effective permeability of coated sand, characterized in that: The following steps are involved: Step 1: Heating and stirring: Stir the displacement fluid to make the temperature of the displacement fluid reach the design requirement; Step 2: Mainline exhaust: connect the manufactured coated sand filling pipe or coated sand artificial core to the process, close the upstream valve (7) and downstream valve (11) of the differential pressure sensor (9) as well as the downstream valve (14) of the mainline and the mainline vent valve, and use the displacement fluid to pressure-displace. After displacement, open the mainline vent valve to release the pressure; Step 3: exhaust the differential pressure sensor (9): close the downstream valve (14) of the trunk line and the trunk vent valve, open the upstream valve (7) and downstream valve (11) of the differential pressure sensor (9) and the isolation valve of the differential pressure sensor (9), and open the trunk vent valve to release the pressure after displacing the differential pressure sensor (9) with the displacement fluid; Step 4: Calibration of the differential pressure sensor (9): Adjust the differential pressure sensor (9) so that the displayed value of the differential pressure sensor (9) is 0; Step 5: Displacement test: Close the isolation valve of the differential pressure sensor (9) to form two isolation chambers in the differential pressure sensor (9), use a delivery pump to pump the displacement fluid into the coated sand filling pipe or the coated sand artificial core for displacement, and use a metering component to measure the liquid flowing out of the coated sand filling pipe or the coated sand artificial core. During the test, data from the delivery pump, the differential pressure sensor (9), and the metering component are collected and the permeability is calculated according to Darcy's law.

2. The effective permeability test method of coated sand according to claim 1, wherein: When exhausting the main line and the differential pressure sensor (9), repeat the process several times to improve the exhaust effect.

3. The effective permeability testing method of coated sand according to claim 1, characterized in that: When collecting data, when the reading of the metering component is consistent with the reading of the delivery pump, data collection and calculation will begin.

4. The effective permeability testing method of coated sand according to claim 1 or 2 or 3, characterized in that: The metering component includes an oil-water separator and two metering structures for respectively metering oil and water. During the test, data of the two metering structures are collected.

5. A testing device for the effective permeability of coated sand, characterized in that: The test device comprises a sample model component, wherein the sample model component is a core holder (15), the core holder is connected to an annular pressure pump, and the core holder (15) is used to hold a core made of coated sand. The test device also comprises a differential pressure monitoring pipeline (8) connected to the upstream and downstream of the sample model component, the differential pressure monitoring pipeline (8) is provided with a differential pressure sensor (9) for monitoring the pressure difference between the upstream and downstream of the sample model component, and the differential pressure monitoring pipeline (8) is provided with an upstream valve (7) upstream of the differential pressure sensor (9), and a downstream valve (11) downstream of the differential pressure sensor (9); the test device The test device also includes a heating and stirring structure and a delivery pump located upstream of the sample model component. The heating and stirring structure is used to heat and stir the displacement fluid. The delivery pump is used to pump the displacement fluid in the heating and stirring structure into the sample model component. A pressure gauge for calibration with the differential pressure sensor (9) is also provided between the delivery pump and the sample model component. The test device also includes a main line vent valve located upstream of the sample model component and a main line downstream valve (14) located downstream of the differential pressure sensor (9). The test device also includes a metering component for metering the liquid flowing out of the coated sand artificial core.

6. The effective permeability testing device for coated sand according to claim 5, characterized in that: The test device further includes an upstream main line valve (3) located between the delivery pump and the sample physical model assembly. The upstream main line valve (3) is used to open during displacement to allow liquid to enter the sample physical model assembly, and is also used to close during pressure holding of the sample physical model assembly to prevent the liquid in the sample physical model assembly from flowing back and impacting the delivery pump.

7. The effective permeability testing device for coated sand according to claim 5 or 6, characterized in that: The heating and stirring structure is a magnetic stirrer (1).

8. The effective permeability testing device for coated sand according to claim 5 or 6, characterized in that: The metering assembly includes an oil-water separation structure and a metering structure. The oil-water separation structure is used to separate the oil-water mixture flowing out of the sample physical model assembly, and the metering structure is used to meter the separated oil and water.

9. The effective permeability testing device for coated sand according to claim 8, characterized in that: The oil-water separation structure is a glass oil-water separator (13). The glass oil-water separator (13) includes a main pipe and a branch pipe connected to the main pipe. A valve for controlling the opening of the branch pipe is provided on the main pipe, and by adjusting the opening of the valve, the top surface of the oil is located at the intersection of the main pipe and the branch pipe.

10. The effective permeability testing device for coated sand according to claim 8, characterized in that: The metering structure includes a balance (12). The balance (12) is used to receive the separated oil and water and conduct weighing and metering.

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