A method, system and electronic device for measuring the diffusion coefficient of a target gas

Abstract

This specification provides a method, system, and electronic device for measuring the diffusion coefficient of a target gas, which relates to the field of measurement technology. The method uses a Y-shaped microfluidic chip. First, the microchannel is filled with the target oil. Then, the third opening is blocked, the first opening is opened, and the auxiliary gas is injected from the second opening to displace the target oil in the first and second branches. Next, the third opening is blocked, the first opening is opened, the target gas is injected from the second opening and the timing starts. After a predetermined time, the pressure in the microchannel is reduced below the bubble point pressure so that the target gas dissolved in the oil precipitates. Finally, the diffusion coefficient of the target gas is calculated based on the distance between the bubble farthest from the target point and the target point and the preset time. This solution can effectively displace the excess target oil, establish a controllable and easily observable gas-liquid contact point, and set a base point for measuring the diffusion length; it can simply and quickly obtain the diffusion coefficient of the target gas in the pore crude oil with a small amount of calculation.

Description

Technical Field

[0001] This application relates to the field of measurement technologies, and particularly to a method, system, and electronic device for measuring the diffusion coefficient of a target gas. Background Art

[0002] Carbon dioxide (CO 2 ) plays an important role in the exploitation of oil and gas (especially shale oil), mainly reflected in the following aspects: 1. Improving the recovery rate of crude oil: CO 2 dissolves in crude oil, which can reduce the viscosity of crude oil and cause the crude oil to expand, making it easier to flow and improving the recovery rate; CO 2 can also be used as a displacing agent to drive the crude oil out of the reservoir rock; CO 2 dissolves in the minerals in the reservoir rock, which can change the structure of the rock, thereby increasing the permeability of the reservoir and facilitating the flow of crude oil; 2. Enhancing the maintenance of formation pressure: Injecting CO 2 can increase the pressure of the reservoir, offset the pressure drop during the crude oil exploitation process, and maintain the production of the oil well. Determining the diffusion coefficient of CO 2 in the micro-nano pores of shale oil is the basis for studying the mechanism of CO 2 huff and puff production increase and designing reasonable production process parameters for shale oil.

[0003] Currently, the main method for measuring the diffusion coefficient of CO 2 in crude oil is the pressure decay method. This method injects CO 2 into a cylinder filled with crude oil, and CO 2 gradually diffuses and dissolves in the crude oil, resulting in a decrease in gas pressure. The experiment indirectly calculates the diffusion coefficient by recording the gas pressure in the cylinder in real time and combining Fick's law.

[0004] However, in the shale micro-nano scale reservoir space, the molecular mean free path of shale pore fluid is restricted by the pore space and is in a "confined" state. The above-mentioned pressure decay method using a cylinder obtains the bulk diffusion coefficient, that is, the diffusion coefficient of CO 2 in an aggregate of CO 2 diffusing into the crude oil bulk. This bulk diffusion coefficient is difficult to characterize the diffusion state of CO 2 under "confined" conditions in the micro-nano pores of the shale reservoir. In addition, the existing pressure decay method requires a cumbersome experimental process and complex inversion formulas, and requires extremely high airtightness, and the experimental conditions are relatively harsh. Summary of the Invention

[0005] This specification provides a method, system, and electronic device for measuring the diffusion coefficient of a target gas to accurately measure the diffusion coefficient of the target gas in the micro-nano pores of shale oil, and reduce the cumbersome degree and complexity of the measurement method.

[0006] To solve the above technical problems, the first aspect of this specification provides a method for measuring the diffusion coefficient of a target gas, including: providing a Y-shaped microfluidic chip, wherein the microchannels in the Y-shaped microfluidic chip include a first branch, a second branch, and a third branch, and the first branch, the second branch, and the third branch intersect at a target point; filling the microchannels in the Y-shaped microfluidic chip with a target oil; blocking the opening of the third branch, opening the opening of the first branch, and simultaneously injecting an auxiliary gas from the opening of the second branch to displace the target oil on the path from the opening of the second branch to the opening of the first branch; blocking the opening of the third branch, opening the opening of the first branch, injecting the target gas from the opening of the second branch, and then starting timing; after a preset time period, controlling the pressure in the microchannels of the Y-shaped microfluidic chip to drop below the bubble point pressure to cause the target gas dissolved in the target oil to precipitate; observing the distance between the farthest bubble from the target point on the third branch and the target point; calculating the diffusion coefficient of the target gas in the target oil based on the distance and the preset time period.

[0007] In some embodiments, calculating the diffusion coefficient of the target gas in the target oil based on the distance and the preset time period includes calculating the diffusion coefficient of the target gas in the target oil through the following formula: D = L 2 / (4t), where D represents the diffusion coefficient of the target gas in the target oil, L represents the distance between the farthest bubble from the target point on the third branch and the target point, and t represents the preset time period.

[0008] In some embodiments, before blocking the opening of the third branch, opening the opening of the first branch, and injecting the target gas from the opening of the second branch, it further includes: blocking the opening of the second branch, opening the opening of the first branch, and injecting the target oil from the opening of the third branch.

[0009] In some embodiments, the method further includes: adjusting the pressure in the Y-shaped microfluidic chip through a backpressure system; after injecting the auxiliary gas into the Y-shaped microfluidic chip, turning on a pressure buffer system provided on the pipeline of the backpressure system to provide a stable pressure inside the chip for subsequent injection of the target gas; wherein the first valve body of the backpressure system is filled with a liquid medium, a constant pressure is applied to the valve core of the first valve body externally, and the pressure in the Y-shaped microfluidic chip is adjusted by adjusting the position of the valve core; the second valve body of the pressure buffer system is filled with a gaseous medium, a constant pressure is applied to the valve core of the second valve body externally, and the pressure in the Y-shaped microfluidic chip is adjusted by adjusting the position of the valve core.

[0010] The second aspect of this specification provides a measurement system for the diffusion coefficient of a target gas, a Y-shaped microfluidic chip. The microchannels in the Y-shaped microfluidic chip include a first branch, a second branch, and a third branch. The first branch, the second branch, and the third branch intersect at a target point; an injection system for injecting a target oil body, an auxiliary gas, and a target gas into the Y-shaped microfluidic chip; a switching device for switching the communication channel between the injection system and the Y-shaped microfluidic chip; a pressure regulating device for regulating the pressure in the microchannels; an observation device for observing the distance between the farthest bubble from the target point on the third branch and the target point; and a calculation device for calculating the diffusion coefficient of the target gas in the target oil body according to the distance and the preset duration.

[0011] In some embodiments, the system further includes: a backpressure system including a first valve body filled with a liquid medium inside, and a constant pressure is applied to the valve core of the first valve body externally. The pressure in the Y-shaped microfluidic chip is regulated by adjusting the position of the valve core; and / or, a pressure buffer system including a second valve body filled with a gaseous medium inside, and a constant pressure is applied to the valve core of the second valve body externally. The pressure in the Y-shaped microfluidic chip is regulated by adjusting the position of the valve core.

[0012] In some embodiments, the observation device includes a microscope and a high-speed camera.

[0013] In some embodiments, the system further includes a thermostatic chamber, and the Y-shaped microfluidic chip is placed in the thermostatic chamber.

[0014] The third aspect of this specification provides an electronic device, including: a memory and a processor, which are communicatively connected to each other. The memory stores computer instructions, and the processor realizes the method for measuring the diffusion coefficient of the target gas according to any one of the first aspect by executing the computer instructions.

[0015] The method, system, and electronic device for measuring the diffusion coefficient of a target gas provided in this specification use a microfluidic chip with a Y-shaped design. First, the microchannel is filled with the target oil, then the third opening (i.e., the opening of the third branch) is blocked, the first opening (i.e., the opening of the first branch) is opened, and an auxiliary gas is injected from the second opening (i.e., the opening of the second branch) to displace the target oil in the first and second branches. Then, the third opening is blocked, the first opening is opened, and the target gas is injected from the second opening, and timing is started. After a predetermined time period, the pressure in the microchannel is reduced below the bubble point pressure so that the target gas dissolved in the target oil precipitates. Finally, the diffusion coefficient of the target gas is calculated based on the distance between the bubble farthest from the target point on the third branch and the target point and the predetermined time period. This solution can effectively displace the excess target oil, establish a controllable and easily observable gas-liquid contact point between the target oil and the target gas, and set a base point for measuring the diffusion length; it can simply and quickly obtain the diffusion coefficient of the target gas in the pore crude oil with a small amount of calculation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 It is a flowchart of a method for measuring the diffusion coefficient of a target gas provided in this specification;

[0018] Figure 2 It is a top view of a Y-shaped microfluidic chip provided in this specification;

[0019] Figure 3 It is another flowchart of a method for measuring the diffusion coefficient of a target gas provided in this specification;

[0020] Figure 4 It is a structural diagram of a system for measuring the diffusion coefficient of a target gas provided in this specification;

[0021] Figure 5 It is a schematic structural diagram of an electronic device provided in this specification. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] To enable those skilled in the art to better understand the technical solutions in this application, the following will clearly and completely describe the technical solutions in the embodiments of this application in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the scope of protection of this application.

[0023] To accurately measure the diffusion coefficient of a target gas in the micro-nano pores of shale oil, reduce the complexity and tediousness of the measurement method, this specification provides a method for measuring the diffusion coefficient of a target gas. This method can be used to measure the diffusion coefficient of a target gas in shale oil or other crude oils, and can also be used to measure the diffusion coefficient of other target gases in a target oil body.

[0024] As Figure 1 shown, the method for measuring the diffusion coefficient of a target gas includes the following S10 to S60.

[0025] S10: Provide a Y-shaped microfluidic chip. The microchannels in the Y-shaped microfluidic chip include a first branch, a second branch, and a third branch. The first branch, the second branch, and the third branch intersect at a target point.

[0026] As Figure 2 shown, the Y-shaped microfluidic chip includes three openings A, B, and C. The internal microchannels can be divided into a first branch AO, a second branch BO, and a third branch CO based on the intersection point. The three branches intersect at the target point O.

[0027] Although Figure 2 the branches shown in are straight, the shape of each branch is not limited to being straight and can also be curved or zigzag.

[0028] S20: Fill the microchannels in the Y-shaped microfluidic chip with a target oil body.

[0029] Theoretically, any two openings of the Y-shaped microfluidic chip can be opened, and a target oil body can be injected from the other opening, so that the microchannel chip can be filled with the oil body.

[0030] The target oil body can be shale oil or other types of fluids with relatively high viscosity.

[0031] S30: Block the opening of the third branch, open the opening of the first branch, and at the same time inject an auxiliary gas from the opening of the second branch to displace the target oil body on the path from the opening of the second branch to the opening of the first branch.

[0032] As Figure 2As described above, the opening C can be blocked, the opening A can be opened, and auxiliary gas can be injected from the opening B to displace the target fluid on the path from the opening B to the opening A, that is, to displace the target oil on the second branch BO and the first branch AO.

[0033] It should be noted that in order to prevent the target oil on the third branch CO from continuously flowing into the first branch AO at the target point O when injecting auxiliary gas to displace the target oil on the second branch BO and the first branch AO, the voltage of the third opening C should be kept constant.

[0034] In addition, the width and depth of the microchannel should be designed according to the viscosity of the target oil, so that at the designed width and depth, the surface tension of the target oil can keep the target oil in the third branch CO.

[0035] In some embodiments, the width of the microchannel in the Y-shaped microfluidic chip can be designed to be in the micrometer range, and the depth of the microchannel can be designed to be in the nanometer range. Among them, the depth direction is parallel to the thickness direction of the Y-shaped microfluidic chip, the width direction is perpendicular to the fluid flow direction, and is perpendicular to the thickness direction of the fluid. Figure 2 The left side in the figure is the top view of the Y-shaped microfluidic chip, that is, the schematic diagram seen from one side of the chip cover plate, and the rectangle on the right side is the side view of the microchannel within the left dashed box, that is, the cross-sectional schematic diagram of the microchannel within the dashed box seen from the side where the letter C is located in the figure. Figure 2

[0036] By designing the width of the microchannel in the Y-shaped microfluidic chip to be in the micrometer range and the depth of the microchannel to be in the nanometer range, the cross-section of the microchannel at the target point O can be made closer to the pore characteristics in tight oil such as shale oil, so as to more realistically simulate the diffusion coefficient of the target gas in tight oil. The micrometer-level channel width can meet the observation range of an optical microscope, and the nanometer-level depth keeps the target oil in a "confined state". The "confined state" can characterize the micro-nano pore structure in the target oil such as shale oil, so as to more realistically simulate the storage conditions of the actual target oil such as shale oil.

[0037] The auxiliary gas is used to displace the target oil in the first branch and the second branch and maintain the pressure in the first branch and the second branch to prepare for injecting the target gas. The auxiliary gas can be nitrogen N 2 , nitrogen hardly reacts chemically with the target oil, hardly dissolves in the target oil, and does not react chemically with the subsequently injected CO 2 . In addition to nitrogen, other gases with similar properties can also be used as the auxiliary gas.

[0038] S40: Block the opening of the third branch, open the opening of the first branch, inject the target gas from the opening of the second branch, and then start timing.

[0039] As shown Figure 2 in the figure, the opening C can be blocked, the opening A can be opened, and the target gas can be injected from the opening B.

[0040] Timing can be started immediately after the injection of the target gas begins. That is, it is assumed that when the target gas starts to be injected, CO 2 quickly reaches the intersection point O and begins to gradually dissolve in the target oil body. Timing can also be started after a delay after the injection of the target gas. That is, it is assumed that after the target oil body starts to be injected, CO 2 waits for a period of time before reaching the intersection point O and begins to gradually dissolve in the target oil body.

[0041] In some embodiments, in order to more accurately determine the moment to start timing, as Figure 3 shown in the figure, S80 can be executed before S40: block the opening of the second branch, open the opening of the first branch, and inject the target oil body from the opening of the third branch. Correspondingly, S40 can be S41: block the opening of the third branch, open the opening of the first branch, inject the target gas from the opening of the second branch, and start timing when it is observed that the oil body at the target point is displaced.

[0042] After the injection of the auxiliary gas, the first branch AO and the second branch BO are filled with gas. At this time, it is difficult to determine where the front end of the target gas has moved when injecting the target gas, so it is impossible to accurately determine the moment to start timing. Before injecting the target gas, first inject the target oil body into the third branch CO, which can make all or most of the first branch AO and part of the second branch be filled with the target oil body that is convenient for observation near the target point (i.e., the bifurcation point O). Thus, after injecting the target gas, it can be determined whether the front end of the target gas has moved to the target point according to the displaced part of the target oil body that is convenient for observation. That is, the displacement of the target oil body at the target point indicates that the front end of the target gas has reached the target point, and at this time the target gas begins to dissolve in the target oil body. Therefore, by setting the above S80 and S41, the moment to start timing can be determined more accurately, and thus the diffusion time can be determined more accurately.

[0043] The target gas is the gas used to measure the diffusion coefficient, which can be CO 2 , or other types of gases for which the diffusion coefficient needs to be measured.

[0044] The method for measuring the diffusion coefficient of the target gas provided in this specification first injects an auxiliary gas to displace the target oil in the two branches, and then injects the target gas to displace the auxiliary gas in the two branches, rather than directly injecting the target gas to displace the target oil in the two branches. This setting can ensure that after the target gas is injected into the microchannel, it will displace the auxiliary gas in the first branch and the second branch, and form an interface between the target gas and the target oil at the intersection point O of the three branches, that is, control the target gas to start dissolving in the target oil at the intersection point O.

[0045] S50: After a preset time duration, control the pressure in the microchannel of the Y-shaped microfluidic chip to drop below the bubble point pressure, so that the target gas dissolved in the target oil precipitates.

[0046] This preset time duration can be determined according to experimental experience. Usually, the preset time duration can be determined according to the temperature and the length of the microchannel of the Y-shaped microfluidic chip, generally ranging from a few minutes to 1 hour.

[0047] Before the pressure drops below the bubble point, the target gas dissolves in the target oil in the form of molecules, and in this case, no bubbles will appear.

[0048] In a gas-liquid mixture system, the bubble point pressure refers to the pressure at which the mixture changes from a single liquid phase to a coexistence state of gas-liquid two phases at a specific temperature. That is to say, the bubble point pressure is the pressure point at which the liquid mixture starts to form bubbles at a given temperature. Once the pressure drops below the bubble point pressure, bubbles will start to form in the liquid mixture, marking the transition of the mixture from a single liquid phase to a coexistence state of gas-liquid two phases. Therefore, after the pressure in the microchannel is dropped below the bubble point pressure in S50, the target gas dissolved in the target oil begins to form bubbles.

[0049] S60: Observe the distance between the farthest bubble from the target point on the third branch and the target point.

[0050] S70: Calculate the diffusion coefficient of the target gas in the target oil according to the distance and the preset time duration.

[0051] The diffusion coefficient of the target gas describes the diffusion speed of the target gas molecules in the liquid. The diffusion coefficient describes the diffusion behavior of gas molecules, and the diffusion coefficient can be calculated through the diffusion distance and diffusion time of gas molecules.

[0052] According to Fick's second law describing the diffusion behavior of substances in a medium:

[0053] (1)

[0054] The boundary conditions at this time are:

[0055] t = 0: x > 0, c = 0

[0056] For t > 0: when x = 0, c = c0; when x = +∞, c = 0.

[0057] Therefore, the distribution of the target gas in the third branch is as follows:

[0058] (2)

[0059] In the above formulas (1) and (2), x is the distance from the oil-gas two-phase contact surface, C(x, t) is the solubility of the target gas in the target oil body at a distance x at diffusion time t, D is the diffusion coefficient, c o is the solubility of the target gas at the oil-gas two-phase contact surface, and erf is the error function.

[0060] Since the diffusion distance refers to the distance from the initial diffusion position to the position where the solubility approaches 0, let C(x, t) = 0, then x = 2√(Dt) 1 / 2 . Therefore, the diffusion length L = 2√(Dt) 1 / 2 , and the diffusion coefficient can be converted to D = L 2 ² / (4t).

[0061] That is, the above S70 can calculate the diffusion coefficient of the target gas in the target oil body according to the following formula: D = L 2 ² / (4t), where D represents the diffusion coefficient of the target gas in the target oil body, L represents the distance between the bubble farthest from the target point on the third branch and the target point, and t represents the preset time duration.

[0062] The Y-shaped microfluidic chip is formed by bonding a substrate and a cover body. The substrate is provided with a Y-shaped channel, the cover body is made of a transparent material, and a Y-shaped microchannel is formed after the substrate and the cover body are bonded. In some embodiments, after starting to inject the target gas and before S70, an image of the surface of the Y-shaped microfluidic chip can also be captured by a high-speed camera, and the positions of the bubbles and the target point in each image can be sequentially identified by a computer, and the bubble farthest from the target point can be determined according to the recognition results. The distance L between the bubble farthest from the target point and the target point can also be determined by a computer image processing method.

[0063] In some embodiments, the method for measuring the diffusion coefficient of the target gas adjusts the pressure in the Y-shaped microfluidic chip through a backpressure system; after injecting an auxiliary gas into the Y-shaped microfluidic chip, a pressure buffer system provided on the pipeline of the backpressure system is turned on to provide a stable pressure inside the chip for subsequent injection of the target gas.

[0064] Among them, the interior of the first valve body of the backpressure system is filled with a liquid medium, and a constant pressure is applied externally to the valve core of the first valve body. The pressure in the Y-shaped microfluidic chip is adjusted by adjusting the position of the valve core; the interior of the second valve body of the pressure buffer system is filled with a gaseous medium, and a constant pressure is applied externally to the valve core of the second valve body. The pressure in the Y-shaped microfluidic chip is adjusted by adjusting the position of the valve core.

[0065] That is to say, the pressure control principles of the backpressure system and the pressure buffer system are different. The backpressure system adjusts the pressure through a liquid medium, while the pressure buffer system buffers through a gaseous medium. The backpressure system can be applied to situations where the system pressure changes greatly. The pressure buffer system can respond to pressure changes more quickly for adjustment, preventing the problem of too rapid system pressure drop caused by the sensitivity problem of the backpressure valve, and can timely supplement the system pressure, so that the system pressure is stably released during the pressure reduction process.

[0066] To implement the above method for measuring the diffusion coefficient of a target gas, this specification also provides a system for measuring the diffusion coefficient of a target gas. The system for measuring the diffusion coefficient of a target gas includes a Y-shaped microfluidic chip, an injection system, a switching device 30, a pressure regulating device, an observation device, and a calculation device.

[0067] The microchannels in the Y-shaped microfluidic chip include a first branch, a second branch, and a third branch, and the first branch, the second branch, and the third branch intersect at a target point. The description of the Y-shaped microfluidic chip can refer to the above text.

[0068] The injection system is used to inject a target oil body, an auxiliary gas, and a target gas into the Y-shaped microfluidic chip. As Figure 4 shown, the injection system may specifically include an injection pump 1 and a target oil body reservoir 31, an auxiliary gas reservoir 32, and a target gas reservoir 33. The injection pump 1 can be a plunger pump.

[0069] The switching device is used to switch the communication channel between the injection system and the Y-shaped microfluidic chip. As Figure 4 shown, the switching device may specifically include a six-way valve 2 and a six-way valve 4, etc.

[0070] The pressure regulating device is used to regulate the pressure in the microchannels. The pressure regulating device can be a circulating pressure control system, and the circulating pressure control system is communicated with the microchannels of the Y-shaped microfluidic chip.

[0071] The observation device is used to observe the distance between the bubble farthest from the target point on the third branch and the target point. In order to capture the rapid change state of the bubble, the observation device should have a rapid capture function; in order to observe tiny bubbles more clearly, the observation device should have a high magnification effect. In some embodiments, the observation device can adopt a microscope combined with a high-speed camera.

[0072] The calculation device is used to calculate the diffusion coefficient of the target gas in the target oil body according to the distance and the preset duration. That is, the calculation device is used to execute the above S70.

[0073] In some embodiments, the diffusion coefficient measurement system of the target gas further includes: a back pressure system and / or a pressure buffer system. The back pressure system includes a first valve body, the inside of the first valve body is filled with a liquid medium, a constant pressure is applied to the valve core of the first valve body externally, and the pressure in the Y-shaped microfluidic chip is adjusted by adjusting the position of the valve core. The pressure buffer system includes a second valve body, the inside of the second valve body is filled with a gaseous medium, a constant pressure is applied to the valve core of the second valve body externally, and the pressure in the Y-shaped microfluidic chip is adjusted by adjusting the position of the valve core.

[0074] In some embodiments, the observation device includes a microscope and a high-speed camera.

[0075] In some embodiments, the system further includes a constant temperature chamber, and the Y-shaped microfluidic chip is placed in the constant temperature chamber. By setting up the constant temperature chamber, the high-temperature environment of the target oil body in the formation can be simulated.

[0076] Combined Figure 4 with 2 CO 2 as the target gas, nitrogen N

[0077] as the auxiliary gas, and shale oil as the target oil body, an embodiment of the method for measuring the diffusion coefficient of the target gas will be specifically introduced below.

[0078] Step (1): After cleaning and drying the experimental chip, put the chip into the high-temperature and high-pressure chamber 6, turn on the circulating temperature and pressure control system 7, set the temperature to the experimental temperature, and turn on the vacuum pump 10 to evacuate for 2 hours.

[0079] In step (3), the regulating valve 8 is connected to the pressure sensor 9, and shale oil is continuously injected until the pressure sensor 9 reaches the set experimental pressure. Then, the shale oil connecting valve is closed and the injection is stopped. The cyclic temperature and pressure control system 7 can continuously track the pressure sensor 9 and establish a pressure difference of 2 MPa to prevent the chip from being crushed due to an excessive pressure difference between the confining pressure and the pore pressure.

[0080] In step (4), the back pressure valve is adjusted to be slightly less than the experimental pressure. Valve 11 is opened, and six-way valves 2 and 4 are adjusted to connect to N 2 , and N is injected at a constant speed 2 to expel the oil from the "V" shaped area (i.e., the first branch and the second branch) at the head of the "Y" type chip.

[0081] In step (5), valve 11 is closed, and valves 12 and 13 are opened to allow N 2 to fill the pressure buffer system 14, which can stabilize the pressure inside the chip during the subsequent CO 2 injection process and prevent the system pressure from dropping too fast due to the sensitivity problem of the back pressure valve.

[0082] In step (6), six-way valves 2 and 4 are adjusted to connect the shale oil, and a small section of shale oil is injected. Then, six-way valves 2 and 4 are adjusted again to connect to CO 2 , and CO is continuously injected 2 .

[0083] In step (7), when it is observed in the monitoring system that a section of shale oil liquid passes through the head of the "Y" type chip (i.e., the first branch and the second branch), it indicates that CO 2 starts to contact the crude oil in the test pipeline. Six-way valve 4 and valve 12 are closed, and the timing starts.

[0084] In step (8), after a period of time t, the pressure of the back pressure valve is adjusted to be below the bubble point pressure, and valve 12 is opened. A mobile microscope equipped with a high-speed camera takes pictures of the experimental flow channel inside the chip. In Figure 4 , 5 represents the combination of the mobile microscope and the high-speed camera, and 16 represents the computer.

[0085] In step (9), after the pressure inside the chip is relieved, the CO 2 dissolved in the shale oil precipitates to form bubbles through diffusion, and the bubble L at the farthest distance from the CO 2 -shale oil contact point is measured.

[0086] In step (10), the diffusion coefficient of the target gas in the target oil is calculated according to the formula D = L 2 / (4t).

[0087] For the description and functions of the above-mentioned diffusion coefficient measurement system of the target gas, please refer to the content in the part of the diffusion coefficient measurement method of the target gas for understanding, and will not be elaborated here.

[0088] This specification also provides a diffusion coefficient measurement chip for a target gas. The diffusion coefficient measurement chip is a Y-shaped microfluidic chip. The microchannels in the Y-shaped microfluidic chip include a first branch, a second branch, and a third branch. The first branch, the second branch, and the third branch intersect at a target point. The Y-shaped microfluidic chip is used to measure the diffusion coefficient of the target gas.

[0089] In some embodiments, the width of the microchannels in the Y-shaped microfluidic chip is at the micron (μm) level, and the depth of the microchannels is at the nanometer (nm) level. Among them, the depth direction is parallel to the thickness direction of the Y-shaped microfluidic chip, the width direction is perpendicular to the fluid flow direction, and is perpendicular to the thickness direction of the fluid.

[0090] The description and functions of the above diffusion coefficient measurement chip for the target gas can be understood by referring to the content of the diffusion coefficient measurement method and system for the target gas, and will not be elaborated here.

[0091] An embodiment of the present invention also provides an electronic device, as Figure 5 shown. The electronic device may include a processor 501 and a memory 502. The processor 501 and the memory 502 may be connected through a bus or other means. Figure 5 Here, the case of connection through a bus is taken as an example.

[0092] The processor 501 may be a central processing unit (CPU). The processor 501 may also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. chips, or a combination of the above various types of chips.

[0093] The memory 502, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and modules, such as the program instructions / modules corresponding to the diffusion coefficient measurement method for the target gas in the embodiments of the present invention. The processor 501 executes various functional applications and data processing of the processor by running the non-transitory software programs, instructions, and modules stored in the memory 502, that is, implements the diffusion coefficient measurement method for the target gas in the above method embodiments.

[0094] The memory 502 may include a program storage area and a data storage area. The program storage area may store an operating system and application programs required for at least one function. The data storage area may store data created by the processor 501 and the like. In addition, the memory 502 may include a high-speed random access memory and may also include a non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some embodiments, the memory 502 may optionally include a memory remotely disposed relative to the processor 501, and these remote memories may be connected to the processor 501 through a network. Examples of the above networks include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0095] The one or more modules are stored in the memory 502 and, when executed by the processor 501, perform the method for measuring the diffusion coefficient of the target gas in the embodiment as Figure 1 shown.

[0096] For specific details of the above electronic device, reference may be made to the corresponding descriptions and effects in the method and system embodiments, which will not be elaborated here.

[0097] This specification also provides a computer storage medium storing computer program instructions, and when the computer program instructions are executed, the steps of the above method for measuring the diffusion coefficient of the target gas are implemented.

[0098] This specification also provides a computer program product including a computer program, and when the computer program is executed by a processor, the steps of the above method for measuring the diffusion coefficient of the target gas are implemented.

[0099] Those skilled in the art can understand that all or part of the processes in the above method embodiments can be completed by instructing relevant hardware through a computer program. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the above method embodiments. Among them, the storage medium can be a magnetic disk, an optical disc, a read-only memory (ROM), a random access memory (RAM), a flash memory, a hard disk drive (HDD), or a solid-state drive (SSD), etc.; the storage medium can also include a combination of the above types of memories.

[0100] Each embodiment in this specification is described in a progressive manner. For the same or similar parts between each embodiment, reference can be made to each other. The key point of each embodiment is to illustrate the differences from other embodiments.

[0101] The systems, devices, modules or units described in the above embodiments can be specifically implemented by computer chips or entities, or by products with certain functions.

[0102] For the convenience of description, when describing the above devices, they are divided into various units according to functions and described separately. Of course, when implementing the present application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0103] From the description of the above embodiments, those skilled in the art can clearly understand that the present application can be implemented by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods of certain parts of various embodiments of the present application.

[0104] The present application can be used in many general or special computer system environments or configurations. For example: personal computers, server computers, handheld devices or portable devices, tablet devices, multi-processor systems, microprocessor-based systems, set-top boxes, programmable consumer electronic devices, network PCs, minicomputers, mainframe computers, distributed computing environments including any of the above systems or devices, and so on.

[0105] The present application can be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. The present application can also be practiced in a distributed computing environment, where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules can be located in local and remote computer storage media including storage devices.

[0106] Although the present application is depicted by the embodiments, those of ordinary skill in the art know that the present application has many variations and changes without departing from the spirit of the present application. It is hoped that the appended claims will cover these variations and changes without departing from the spirit of the present application.

Claims

1. A method for measuring the diffusion coefficient of a target gas, characterized in that: include: A Y-shaped microfluidic chip is provided, wherein a microchannel in the Y-shaped microfluidic chip comprises a first branch, a second branch, and a third branch, wherein the first branch, the second branch, and the third branch intersect at a target point; Filling the microchannel in the Y-shaped microfluidic chip with target oil bodies; The opening of the third branch is blocked, the opening of the first branch is opened, and at the same time, auxiliary gas is injected from the opening of the second branch to displace the target oil body on the path from the opening of the second branch to the opening of the first branch; Block the opening of the third branch, open the opening of the first branch, inject the target gas from the opening of the second branch, and then start timing; After a preset time, controlling the pressure in the microchannel of the Y-shaped microfluidic chip to drop below the bubble point pressure, so that the target gas dissolved in the target oil body is precipitated; Observe the distance between the bubble farthest from the target point on the third branch and the target point; The diffusion coefficient of the target gas in the target oil body is calculated according to the distance and the preset time.

2. The method according to claim 1, characterized in that Calculating the diffusion coefficient of the target gas in the target oil body according to the distance and the preset time, including calculating the diffusion coefficient of the target gas in the target oil body by the following formula: D=L 2 / (4t), where D represents the diffusion coefficient of the target gas in the target oil body, L represents the distance between the bubble farthest from the target point on the third branch and the target point, and t represents the preset time.

3. The method according to claim 1, characterized in that: Before blocking the opening of the third branch, opening the opening of the first branch, and injecting the target gas from the opening of the second branch, the method further includes: The opening of the second branch is blocked, the opening of the first branch is opened, and the target oil body is injected from the opening of the third branch.

4. The method according to claim 1, characterized in that The method further comprises: regulating the pressure in the Y-shaped microfluidic chip by a back pressure system; After injecting the auxiliary gas into the Y-shaped microfluidic chip, opening the pressure buffer system disposed on the pipeline of the back pressure system to provide a stable pressure inside the chip for subsequent injection of the target gas; Among them, the first valve body of the back pressure system is filled with liquid medium, and a constant pressure is applied to the valve core of the first valve body from the outside, and the pressure in the Y-type microfluidic chip is adjusted by adjusting the position of the valve core; the second valve body of the pressure buffer system is filled with gaseous medium, and a constant pressure is applied to the valve core of the second valve body from the outside, and the pressure in the Y-type microfluidic chip is adjusted by adjusting the position of the valve core.

5. A target gas diffusion coefficient measurement system, characterized in that: Used to implement the method according to any one of claims 1 to 4; the system comprises: A Y-shaped microfluidic chip, wherein the microchannel in the Y-shaped microfluidic chip comprises a first branch, a second branch, and a third branch, and the first branch, the second branch, and the third branch intersect at a target point; An injection system, used for injecting target oil, auxiliary gas and target gas into the Y-shaped microfluidic chip; A switching device, used for switching the communication channel between the injection system and the Y-shaped microfluidic chip; A pressure regulating device, used for regulating the pressure in the microfluidic channel; An observation device, used for observing the distance between the bubble farthest from the target point on the third branch and the target point; The calculation device is used to calculate the diffusion coefficient of the target gas in the target oil body according to the distance.

6. The system according to claim 5, characterized in that The width of the microchannel in the Y-shaped microfluidic chip is in the micrometer order, and the depth of the microchannel is in the nanometer order; wherein the depth direction is parallel to the thickness direction of the Y-shaped microfluidic chip, and the width direction is perpendicular to the fluid flow direction and perpendicular to the thickness direction of the fluid.

7. The system according to claim 5, characterized in that The system further comprises: A back pressure system comprises a first valve body, wherein the first valve body is filled with a liquid medium, a constant pressure is applied to a valve core of the first valve body from the outside, and the pressure in the Y-shaped microfluidic chip is adjusted by adjusting the position of the valve core; and / or, The pressure buffer system comprises a second valve body, wherein the interior of the second valve body is filled with a gaseous medium, a constant pressure is applied to the valve core of the second valve body from the outside, and the pressure in the Y-shaped microfluidic chip is conditioned by adjusting the position of the valve core.

8. The system according to claim 5, characterized in that The observation device comprises a microscope and a high-speed camera.

9. The system according to claim 5, characterized in that The system also includes a constant temperature chamber, in which the Y-shaped microfluidic chip is placed.

10. An electronic device, characterized in that: include: A memory and a processor, wherein the processor and the memory are communicatively connected to each other, the memory stores computer instructions, and the processor implements the method for measuring the diffusion coefficient of the target gas according to any one of claims 1 to 4 by executing the computer instructions.

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