Method, chip and system for measuring diffusion coefficient of target gas

Abstract

The invention provides a method, a chip and a system for measuring the diffusion coefficient of target gas, and relates to the technical field of measurement, the method adopts a Y-shaped micro-fluidic chip, a micro-channel is filled with a target oil body, then a third opening is blocked, a first opening is opened, auxiliary gas is injected from a second opening to displace the target oil body in a first branch and a second branch, and the diffusion coefficient of the target gas is measured. Then the third opening is blocked, the first opening is opened, target gas is injected from the second opening, timing is started, and the pressure in the micro-channel is reduced to be below bubble point pressure after a preset duration so that the target gas dissolved in the oil body can be separated out; finally, the diffusion coefficient of the target gas is calculated according to the distance between the bubble farthest from the target point and the target point and the preset duration. According to the scheme, redundant target oil bodies can be effectively discharged, a controllable and easy-to-observe gas-liquid contact point is established, and a base point is set for measuring the diffusion length; the diffusion coefficient of the target gas in the pore crude oil can be simply and rapidly obtained, and the calculated amount is small.

Description

Technical Field

[0001] The present application relates to the field of measurement technology, and in particular to a method, chip and system for measuring the diffusion coefficient of a target gas. Background Art

[0002] Carbon dioxide (CO2) plays an important role in oil and gas (especially shale oil) extraction, mainly in the following aspects: 1. Improve crude oil recovery: CO2 dissolved in crude oil can reduce crude oil viscosity and make crude oil swell, so that it is easier to flow and improve recovery; CO2 can also be used as a displacement agent to drive crude oil out of reservoir rocks; CO2 dissolved in minerals in reservoir rocks can change the structure of rocks, thereby increasing the permeability of the reservoir and facilitating the flow of crude oil; 2. Enhance the maintenance of formation pressure: CO2 injection can increase reservoir pressure, offset the pressure drop during crude oil extraction, and maintain the output of oil wells. Clarifying the diffusion coefficient of CO2 in the micro-nano pores of shale oil is the basis for studying the CO2 throughput mechanism and designing reasonable production process parameters for shale oil.

[0003] At present, the main method for measuring the diffusion coefficient of CO2 in crude oil is the pressure decay method. This method injects CO2 into a cylinder containing crude oil, and CO2 gradually diffuses and dissolves in the crude oil, causing the gas pressure to decrease. The experiment records the gas pressure in the cylinder in real time and indirectly calculates the diffusion coefficient in combination with Fick's law.

[0004] However, in the micro-nano-scale storage space of shale, the molecular free path of shale pore fluid is limited 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 CO2 in a CO2 aggregate to the crude oil body. This bulk diffusion coefficient is difficult to characterize the CO2 diffusion state under "confined" conditions in the micro-nano pores of shale reservoirs. In addition, the existing pressure decay method requires cumbersome experimental processes and complex inversion formulas, and requires extremely high air tightness, and the experimental conditions are relatively harsh. Summary of the invention

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

[0006] To solve the above technical problems, the first aspect of the present specification provides a method for measuring the diffusion coefficient of a target gas, comprising: providing 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, 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 a target oil body; blocking the opening of the third branch, opening the opening of the first branch, and injecting 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; 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, controlling the pressure in the microchannel of the Y-shaped microfluidic chip to drop to below the bubble point pressure so that the target gas dissolved in the target oil body precipitates; observing the distance between the bubble on the third branch farthest from the target point and the target point; and calculating the diffusion coefficient of the target gas in the target oil body according to the distance and the preset time.

[0007] In some embodiments, the diffusion coefficient of the target gas in the target oil body is calculated 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.

[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, the process 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: regulating the pressure in the Y-type microfluidic chip through a back pressure system; after injecting auxiliary gas into the Y-type microfluidic chip, opening a pressure buffer system arranged on the pipeline of the back pressure system to provide a stable pressure in the chip for the subsequent injection of target gas; wherein, 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 controlled by adjusting the position of the valve core.

[0010] The second aspect of the present specification provides a diffusion coefficient measurement chip for a target gas, wherein the diffusion coefficient measurement chip is a Y-type microfluidic chip, wherein the microchannel in the Y-type 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; the Y-type microfluidic chip is used to measure the diffusion coefficient of the target gas; the width of the microchannel in the Y-type microfluidic chip is in the micron 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-type microfluidic chip, and the width direction is perpendicular to the fluid flow direction, and perpendicular to the thickness direction of the fluid.

[0011] The third aspect of the present specification provides a target gas diffusion coefficient measurement system, a Y-type microfluidic chip, the microchannel in the Y-type microfluidic chip includes 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, used to inject a target oil body, an auxiliary gas, and a target gas into the Y-type microfluidic chip; a switching device, used to switch the connecting channel between the injection system and the Y-type microfluidic chip; a pressure regulating device, used to regulate the pressure in the microchannel; an observation device, used to observe the distance between the bubble on the third branch farthest from the target point and the target point; a calculation device, used to calculate the diffusion coefficient of the target gas in the target oil body according to the distance and the preset time.

[0012] In some embodiments, the system further includes: a back pressure system, including a first valve body, the interior of the first valve body is filled with liquid medium, 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; and / or, a pressure buffer system, including a second valve body, the interior of the second valve body is filled with 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-type microfluidic chip is adjusted by adjusting the position of the valve core.

[0013] In some embodiments, the observation device includes a microscope and a high-speed camera.

[0014] In some embodiments, the system further comprises a constant temperature chamber, wherein the Y-shaped microfluidic chip is placed in the constant temperature chamber.

[0015] The fourth aspect of this specification provides an electronic device, comprising: a memory and a processor, 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 described in any one of the first aspects by executing the computer instructions.

[0016] The target gas diffusion coefficient measurement method, chip and system provided in this specification adopt a Y-shaped microfluidic chip, first fill the microchannel with target oil, then block the third opening (i.e. the opening of the third branch), open the first opening (i.e. the opening of the first branch) and inject auxiliary gas from the second opening (i.e. the opening of the second branch) to displace the target oil in the first branch and the second branch, then block the third opening, open the first opening and inject the target gas from the second opening, and start timing, after a predetermined time, reduce the pressure in the microchannel to below the bubble point pressure so that the target gas dissolved in the target oil can precipitate, and finally calculate the diffusion coefficient of the target gas according to the distance between the bubble farthest from the target point on the third branch and the target point and the preset time. This scheme can effectively expel excess target oil, establish a controllable and easy-to-observe 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 porous crude oil, and the calculation amount is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some implementation methods recorded in this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] Figure 1 A flow chart of a method for measuring the diffusion coefficient of a target gas provided in this specification; Figure 2 A top view of the Y-shaped microfluidic chip provided in this specification; Figure 3 Another flow chart of the method for measuring the diffusion coefficient of the target gas provided in this specification; Figure 4 A structural diagram of a target gas diffusion coefficient measurement system provided in this specification; Figure 5 This is a schematic diagram of the structure of the electronic device provided in this manual. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this application.

[0020] In order to accurately measure the diffusion coefficient of the target gas in the micro-nano pores of shale oil and reduce the tediousness and complexity of the measurement method, this specification provides a method for measuring the diffusion coefficient of the target gas. This method can be used to measure the diffusion coefficient of the target gas in shale oil or other crude oil, and can also be used for the diffusion coefficient of other target gases in the target oil body.

[0021] like Figure 1 As shown, the method for measuring the diffusion coefficient of the target gas includes the following steps S10 to S60.

[0022] S10: providing a Y-shaped microfluidic chip, 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.

[0023] like Figure 2 As shown, the Y-shaped microfluidic chip includes three openings A, B, and C. The internal microchannel 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.

[0024] Although Figure 2 The branches shown in the figure are straight lines, but the shape of the branches is not limited to a straight line, and may also be a curve or a broken line.

[0025] S20: Filling the microchannel in the Y-shaped microfluidic chip with target oil bodies.

[0026] Theoretically, any two openings of the Y-shaped microfluidic chip can be opened, and the target oil body can be injected from the other opening to fill the microfluidic chip with oil bodies.

[0027] The target oil body may be shale oil or other types of fluids with high viscosity.

[0028] S30: blocking the opening of the third branch, opening the opening of the first branch, and injecting 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.

[0029] like Figure 2 As described above, the opening C can be blocked, the opening A can be opened, and the 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.

[0030] It should be noted that in order to prevent the target oil on the third branch CO from continuously flowing from the target point O into the first branch AO when the auxiliary gas is injected 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 unchanged.

[0031] In addition, the width and depth of the microchannel should be designed according to the viscosity of the target oil, so that the surface tension of the target oil can maintain the target oil in the third branch CO under the designed width and depth.

[0032] In some embodiments, the width of the microchannel in the Y-shaped microfluidic chip can be designed to be micrometer-level, and the depth of the microchannel can be nanometer-level, 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. Figure 2 The left side of the figure is a top view of the Y-shaped microfluidic chip, that is, a schematic diagram viewed from the side of the chip cover. The rectangle on the right is a side view of the microchannel in the dotted box on the left, that is, from the Figure 2 Schematic diagram of the cross-section of the microchannel in the dotted box viewed from the side where the letter C is located.

[0033] By designing the width of the microchannel in the Y-type microfluidic chip to be micrometer-level and the depth of the microchannel to be nanometer-level, 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, thereby being able 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 puts the target oil body in a "confined state". The "confined state" can characterize the micro-nano pore structure in target oil bodies such as shale oil, thereby more realistically simulating the storage conditions of actual target oil bodies such as shale oil.

[0034] 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 the injection of the target gas. The auxiliary gas can be nitrogen N2, which hardly reacts chemically with the target oil, is almost insoluble in the target oil, and does not react chemically with the subsequently injected CO2. In addition to nitrogen, the auxiliary gas can also be other types of gases with similar properties.

[0035] S40: 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 the timing.

[0036] like Figure 2 As shown, opening C can be blocked, opening A can be opened, and the target gas can be injected from opening B.

[0037] The timing can be started immediately after the injection of the target gas begins, that is, it is assumed that when the injection of the target gas begins, CO2 quickly reaches the intersection point O and begins to gradually dissolve in the target oil. The timing can also be started after a delay of a period of time after the injection of the target gas, that is, it is assumed that after the injection of the target oil begins, CO2 waits for a period of time before reaching the intersection point O and begins to gradually dissolve in the target oil.

[0038] In some embodiments, in order to more accurately determine the time to start timing, such as Figure 3 As shown, S80 may be performed before S40: plugging 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. Accordingly, S40 may be S41: plugging 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, and starting the timing when the oil at the target point is observed to be displaced.

[0039] After the auxiliary gas is injected, 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 to when the target gas is injected, and thus it is impossible to accurately determine the time to start timing. Before injecting the target gas, the target oil body is first injected into the third branch CO, so that all or most of the first branch AO and part of the second branch are filled with the target oil body that is easy to observe near the target point (i.e., the bifurcation point O). Therefore, after the target gas is injected, it can be determined whether the front end of the target gas has moved to the target point based on the displaced part of the target oil body that is easy to observe. That is, if the target oil body at the target point is displaced, it means 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 time to start timing can be determined more accurately, thereby more accurately determining the diffusion time.

[0040] The target gas is a gas used to measure the diffusion coefficient, which may be CO2 or other types of gases whose diffusion coefficients need to be measured.

[0041] The method for measuring the diffusion coefficient of the target gas provided in this specification is to first inject an auxiliary gas to displace the target oil body in the two branches, and then inject the target gas to displace the auxiliary gas in the two branches, rather than directly injecting the target gas to displace the target oil body 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 body at the intersection O of the three branches, that is, control the target gas to begin to dissolve in the target oil body at the intersection O.

[0042] S50: After a preset time period, the pressure in the microchannel of the Y-shaped microfluidic chip is controlled to drop below the bubble point pressure, so that the target gas dissolved in the target oil body is precipitated.

[0043] The preset time length can be determined based on experimental experience. Typically, the preset time length can be determined based on the temperature and the length of the microchannel of the Y-shaped microfluidic chip, and is generally between several minutes and 1 hour.

[0044] Before the pressure drops below the bubble point, the target gas is dissolved in the target oil in the form of molecules, and no bubbles appear in this case.

[0045] 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 gas-liquid coexistence state at a specific temperature. In other words, the bubble point pressure is the pressure point at which bubbles begin to form in a liquid mixture at a given temperature. Once the pressure drops below the bubble point pressure, bubbles begin to form in the liquid mixture, indicating that the mixture changes from a single liquid phase to a gas-liquid coexistence state. Therefore, after S50 reduces the pressure in the microchannel to below the bubble point pressure, the target gas dissolved in the target oil body begins to form bubbles.

[0046] S60: Observe the distance between the bubble farthest from the target point on the third branch and the target point.

[0047] S70: Calculating the diffusion coefficient of the target gas in the target oil body according to the distance and the preset time.

[0048] The diffusion coefficient of the target gas describes the diffusion rate of the target gas molecules in the liquid. The diffusion coefficient describes the diffusion behavior of the gas molecules and can be calculated by the diffusion distance and diffusion time of the gas molecules.

[0049] According to Fick's second law describing the diffusion behavior of substances in a medium: (1) The boundary conditions at this time are: t = 0: x>0, c = 0; t>0: x = 0, c=c0; x=+∞, c = 0.

[0050] Therefore, the distribution of the target gas in the third branch is: (2) 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 at a distance x during diffusion t, D is the diffusion coefficient, and c o is the solubility of the target gas at the oil-gas two-phase contact surface, and erf is the error function.

[0051] Since the diffusion distance refers to the distance from the initial diffusion position to the position where the solubility is close to 0, if C(x,t)=0, we can get x=2(Dt) -2 Therefore, the diffusion length L = 2 (Dt) -2 , the diffusion coefficient can be converted to D = L 2 / (4t).

[0052] 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 / (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.

[0053] The Y-shaped microfluidic chip is formed by bonding a substrate and a cover body, wherein a Y-shaped groove is provided in the substrate, the cover body is made of a transparent material, and the substrate and the cover body are bonded to form a Y-shaped microchannel. In some embodiments, after the target gas is injected, before S70, an image of the surface of the Y-shaped microfluidic chip can be taken by a high-speed camera, and the positions of the bubbles and the target points in each image can be identified in turn by a computer, and the bubble farthest from the target point can be determined according to the identification result. 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.

[0054] In some embodiments, the diffusion coefficient measurement method of the target gas adjusts the pressure in the Y-type microfluidic chip through a back pressure system; after injecting auxiliary gas into the Y-type microfluidic chip, the pressure buffer system arranged on the pipeline of the back pressure system is turned on to provide a stable pressure inside the chip for the subsequent injection of the target gas.

[0055] 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.

[0056] That is to say, the pressure control principles of the back pressure system and the pressure buffer system are different. The back pressure system adjusts the pressure through liquid medium, while the pressure buffer system uses gaseous medium for buffering. The back pressure system can be used in situations where the system pressure changes greatly. The pressure buffer system can respond to pressure changes more quickly and adjust them, preventing the system pressure from dropping too fast due to the sensitivity of the back pressure valve. The system pressure can be replenished in time, so that the system pressure is released stably during the pressure reduction process.

[0057] In order to implement the above-mentioned target gas diffusion coefficient measurement method, this specification also provides a target gas diffusion coefficient measurement system, which includes a Y-type microfluidic chip, an injection system, a switching device 30, a pressure regulating device, an observation device and a calculation device.

[0058] The microchannel in the Y-shaped microfluidic chip includes 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. The description of the Y-shaped microfluidic chip can refer to the above.

[0059] The injection system is used to inject the target oil, auxiliary gas and target gas into the Y-shaped microfluidic chip. Figure 4 As shown, the injection system may specifically include an injection pump 1, a target oil reservoir 31, an auxiliary gas reservoir 32, and a target gas reservoir 33. The injection pump 1 may be a plunger pump.

[0060] The switching device is used to switch the communication channel between the injection system and the Y-shaped microfluidic chip. Figure 4 As shown, the switching device may specifically include a six-way valve 2 and a six-way valve 4 and the like.

[0061] The pressure regulating device is used to regulate the pressure in the microchannel. The pressure regulating device can be a cyclic pressure control system, which is connected to the microchannel of the Y-shaped microfluidic chip.

[0062] 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 be able to capture the rapid change of the bubble, the observation device should have a rapid capture function; in order to be able to observe the tiny bubbles more clearly, the observation device should have a high magnification effect. In some embodiments, the observation device can use a microscope with a high-speed camera.

[0063] 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 time. That is, the calculation device is used to execute the above S70.

[0064] In some embodiments, the target gas diffusion coefficient measurement system further includes: a back pressure system and / or a pressure buffer system. The back pressure system includes a first valve body, the first valve body is filled with a liquid medium, 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 pressure buffer system includes a second valve body, 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-type microfluidic chip is adjusted by adjusting the position of the valve core.

[0065] In some embodiments, the observation device includes a microscope and a high-speed camera.

[0066] In some embodiments, the system further comprises a constant temperature chamber, wherein 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.

[0067] Combination Figure 4 , below, taking the target gas as CO2, the auxiliary gas as nitrogen N2, and the target oil body as shale oil as an example, an embodiment of a method for measuring the diffusion coefficient of the target gas is specifically introduced.

[0068] Step (1) After cleaning and drying the experimental chip, the chip is placed in a high-temperature and high-pressure chamber 6, the circulating temperature and pressure control system 7 is turned on, the temperature is set to the experimental temperature, and the vacuum pump 10 is turned on to evacuate the chamber for 2 hours.

[0069] Step (2) Start the injection pump 1, open the six-way valve 2 and the six-way valve 4 connected to the shale oil, and adjust the valve 8 to empty, inject shale oil at a constant speed until oil drops appear at the outlet of the valve 8, indicating that the chip channel and the pipeline have been emptied, and close the valve 8.

[0070] Step (3) adjust valve 8 to connect pressure sensor 9, continue to inject shale oil until pressure sensor 9 reaches the set experimental pressure, close the valve connected to shale oil, and stop injection; the circulating temperature and pressure control system 7 can continuously track pressure sensor 9 and establish a 2 MPa pressure difference to prevent the chip from being crushed due to excessive pressure difference between confining pressure and pore pressure.

[0071] Step (4) Adjust the back pressure valve to a setting slightly lower than the test pressure, open valve 11, adjust six-way valve 2 and six-way valve 4 to connect N2, and inject N2 at a constant rate to drive out the oil in the "V"-shaped area (i.e., the first branch and the second branch) at the head of the "Y"-shaped chip.

[0072] Step (5) closes valve 11, and opens valves 12 and 13 to allow N2 to fill the pressure buffer system 14, so as to stabilize the pressure in the chip during the subsequent CO2 injection process and prevent the system pressure from dropping too quickly due to the sensitivity problem of the back pressure valve.

[0073] Step (6) adjust the six-way valve 2 and the six-way valve 4 to connect the shale oil, inject a small section of shale oil, then adjust the six-way valve 2 and the six-way valve 4 to connect CO2, and continue to inject CO2.

[0074] Step (7) When a section of shale oil liquid is observed to pass through the head of the "Y"-shaped chip (i.e., the first branch and the second branch) in the monitoring system, it means that CO2 begins to contact the crude oil in the test pipeline, and the six-way valve 4 and valve 12 are closed, and the timing starts.

[0075] Step (8) After a period of time t, adjust the back pressure valve pressure 15 to below the bubble point pressure, open the valve 12, and use a mobile microscope with a high-speed camera to take pictures of the experimental flow channel in the chip. Figure 4 In the figure, 5 represents a combination of a mobile microscope and a high-speed camera, and 16 represents a computer.

[0076] After the pressure in the chip is released in step (9), CO2 dissolved in the shale oil is diffused and precipitated to form bubbles, and the bubble L farthest from the contact point between CO2 and shale oil is measured.

[0077] Step (10) According to the formula D=L 2 / (4t) Calculate the diffusion coefficient of the target gas in the target oil body.

[0078] The description and functions of the above-mentioned target gas diffusion coefficient measurement system can be understood by referring to the content of the target gas diffusion coefficient measurement method part, which will not be repeated here.

[0079] This specification also provides a diffusion coefficient measurement chip for a target gas, wherein the diffusion coefficient measurement chip is a Y-shaped microfluidic chip, 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; the Y-shaped microfluidic chip is used to measure the diffusion coefficient of the target gas.

[0080] In some embodiments, the width of the microchannel in the Y-shaped microfluidic chip is in the micrometer (μm) level, and the depth of the microchannel is in the nanometer (nm) level; 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.

[0081] The description and function of the above-mentioned target gas diffusion coefficient measurement chip can be understood by referring to the content of the target gas diffusion coefficient measurement method and system part, which will not be repeated here.

[0082] The embodiment of the present invention further provides an electronic device, such as Figure 5 As shown, the electronic device may include a processor 501 and a memory 502, wherein the processor 501 and the memory 502 may be connected via a bus or other means. Figure 5 The example of connecting through bus is taken in the following.

[0083] The processor 501 may be a central processing unit (CPU). The processor 501 may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or a combination of the above chips.

[0084] The memory 502 is a non-transient computer-readable storage medium that can be used to store non-transient software programs, non-transient computer executable programs and modules, such as program instructions / modules corresponding to the method for measuring the diffusion coefficient of the target gas in the embodiment of the present invention. The processor 501 executes various functional applications and data processing of the processor by running the non-transient software programs, instructions and modules stored in the memory 502, that is, the method for measuring the diffusion coefficient of the target gas in the above method embodiment is implemented.

[0085] The memory 502 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required by at least one function; the data storage area may store data created by the processor 501, etc. In addition, the memory 502 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some embodiments, the memory 502 may optionally include a memory remotely arranged relative to the processor 501, and these remote memories may be connected to the processor 501 via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0086] The one or more modules are stored in the memory 502, and when executed by the processor 501, the following is performed: Figure 1 The diffusion coefficient measurement method of the target gas in the illustrated embodiment.

[0087] The specific details of the above electronic device can be understood by referring to the corresponding descriptions and effects in the method and system embodiments, and will not be repeated here.

[0088] The present specification also provides a computer storage medium, wherein the computer storage medium stores computer program instructions, and when the computer program instructions are executed, the steps of the above-mentioned method for measuring the diffusion coefficient of the target gas are implemented.

[0089] The present specification also provides a computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the steps of the above-mentioned method for measuring the diffusion coefficient of the target gas are implemented.

[0090] Those skilled in the art can understand that the implementation of all or part of the processes in the above-mentioned embodiments can be completed by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, the storage medium can be a disk, an optical disk, 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-mentioned types of memory.

[0091] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0092] The systems, devices, modules or units described in the above embodiments may be implemented by computer chips or entities, or by products with certain functions.

[0093] For the convenience of description, the above device is described in various units according to their functions. Of course, when implementing the present application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0094] It can be known from the description of the above implementation methods that 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 can be essentially or partly contributed to the prior art in the form of a software product, which can be stored in a storage medium such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute certain parts of the methods of each implementation method of the present application.

[0095] The present application can be used in many general or special computer system environments or configurations, such as personal computers, server computers, handheld or portable devices, tablet devices, multiprocessor 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, etc.

[0096] The present application may 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 may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules may be located in local and remote computer storage media, including storage devices.

[0097] Although the present application has been described through embodiments, those skilled in the art will appreciate that there are many modifications and variations to the present application without departing from the spirit of the present application, and it is intended that the appended claims include these modifications and variations 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 chip for measuring the diffusion coefficient of a target gas, characterized in that: The diffusion coefficient measurement chip is a Y-shaped microfluidic chip, and the microchannel in the Y-shaped microfluidic chip includes 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 Y-shaped microfluidic chip is used to measure the diffusion coefficient of the target gas; 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.

6. A target gas diffusion coefficient measurement system, characterized in that: 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.

7. The system according to claim 6, 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 7, characterized in that The observation device comprises a microscope and a high-speed camera.

9. The system according to claim 6, 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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