Liquid drop surface action testing method based on acoustic suspension technology and application

Abstract

The invention provides a liquid drop surface action testing method based on an acoustic suspension technology and application, the liquid drop surface action testing method adopts the acoustic suspension technology to realize high-frequency deformation of liquid drops without external force interference, and the high-frequency surface expansion modulus of a surfactant is measured and calculated; according to the method, the liquid drop deformation hindering error caused by needle contact in a traditional oscillation dropping method is avoided, the defects that the high-surfactant concentration low-frequency expansion modulus value is small, and the foam stability correlation is poor are overcome, the foam performance of the chemical oil displacement formula can be rapidly and accurately evaluated, and research and development of the chemical oil displacement formula are guided.

Description

Technical Field

[0001] The invention relates to the technical field of oil production, and in particular to a droplet surface effect testing method based on acoustic suspension technology and its application. Background Art

[0002] Among the many methods of chemical flooding to improve oil field recovery, foam flooding is an important technical means to improve oil recovery. Foam consists of gas and liquid. During the flooding process, foam is injected into the reservoir. The gas in the foam forms a dispersed phase in the porous medium, and the liquid forms a continuous phase, which act together on the crude oil in the reservoir. It effectively reduces the mobility ratio between the displacement phase (foam) and the displaced phase (crude oil), reduces the fingering phenomenon during the displacement process, and makes the displacement fluid move forward more evenly, thereby improving the sweep efficiency. At the same time, the foam can preferentially enter the high permeability layer and form a plug in it. This can reduce the cross-flow of the displacement fluid in the high permeability layer, force the displacement fluid to enter the low permeability layer, and thus improve the recovery of the low permeability layer. In addition, when the foam flows in the reservoir, it will generate shear force on the crude oil on the rock surface, causing the crude oil to peel off from the rock surface. At the same time, the surfactant in the foam can reduce the interfacial tension between the crude oil and the rock, further improving the oil washing efficiency.

[0003] In foam flooding, in addition to low surface tension, interfacial film strength is also an important parameter for regulating foam stability. Interfacial film strength determines the stability and durability of the surfactant. When the interfacial film strength is high, the surfactant molecules are more closely arranged on the gas-liquid interface, forming a more stable and durable membrane structure. This stability can prevent the desorption of surfactant molecules, maintain the continuous existence of a low tension state, and achieve better oil recovery effects during the recovery process.

[0004] At present, the main test methods for interfacial film strength are oscillating drop interface expansion rheology test method. The oscillating drop interface expansion rheology test method is to determine the surface / interface expansion rheological properties by oscillating the suspended bubbles / droplets and using the drop shape analysis method. CN102954927A, CN202195997U, Zhang Lei et al. (Acta Physico-Chimica Sinica, 2007, 23(10):1652-1656), in which the interface is obtained by the contact between the droplet (or bubble) at the end of the capillary and another liquid in the container. The size of the droplet (or bubble) changes by the movement of the piston controlled by the motor connected to the capillary, thereby changing the area of ​​the interface. No additional force measuring device is required. The shape of the droplet (or bubble) captured by the camera can be processed by software to simultaneously obtain the surface area and dynamic surface tension. This test method has limitations. The end of the capillary is always in contact with the droplet, which limits the actual deformation of the droplet during expansion and compression. Secondly, the oscillating drop interface expansion rheology test method is only applicable to experiments with a frequency lower than 0.1Hz.

[0005] Acoustic levitation is an emerging technology that uses the force generated by sound waves to resist gravity and achieve the suspension of objects. The force generated by sound waves is called acoustic radiation pressure. Acoustic radiation pressure can make common solid liquids with a density hundreds or even tens of thousands of times greater than that of air overcome the earth's gravity and suspend in the air. It can also position bubbles with very low density at a certain position in the liquid without floating on the liquid surface. On this basis, by controlling the transformation of sound waves, droplets can produce regular deformation in the sound field.

[0006] It can be seen that the characterization of foam stability of oil displacement formula is an urgent problem to be solved in the field of using foam flooding to improve sweep efficiency. Efficient and reliable new indoor testing equipment and screening technology have broad oil field field demand and good social benefits. Summary of the invention

[0007] In view of the problems existing in the prior art, the present invention provides a droplet surface effect testing method and application based on acoustic levitation technology. The droplet surface effect testing method adopts acoustic levitation technology to realize high-frequency deformation of droplets without external force interference, measures and calculates the high-frequency surface expansion modulus of surfactants, avoids the droplet deformation obstruction error caused by needle contact in the traditional oscillating drop method, overcomes the shortcomings of small low-frequency expansion modulus value at high surfactant concentration and poor correlation with foam stability, can quickly and accurately evaluate the foam performance of chemical flooding formulas, and guide the research and development of chemical flooding formulas.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for testing the surface effect of a droplet based on acoustic levitation technology. The method is performed using an acoustic levitation device. After a test droplet is suspended in the sound field of the acoustic levitation device, the amplitude, frequency, and type of sound wave are adjusted to cause the test droplet to undergo regular deformation sound. The droplet is suspended by high-frequency sound waves, and the suspended droplet is automatically identified and the appearance contour of the droplet is automatically analyzed to study the properties of non-contact, non-polluting droplets under the influence of high-frequency vibrations.

[0010] The droplet surface effect test method comprises: injecting a test droplet into an acoustic field through a micro-injector, setting a modulation mode, and changing the acoustic wave to transform according to a certain pattern rule; adjusting the acoustic wave transformation frequency within a certain range so that the droplet itself and the acoustic field vibration are resonantly coupled, and the droplet is in a double-chord oscillation state; stopping the acoustic field disturbance, recording the droplet from a periodic change to a stable state, and calculating the high-frequency surface expansion modulus of the droplet.

[0011] The high-frequency surface dilation modulus of the droplet is another method to describe the strength of the interfacial film. The larger the dilation modulus, the higher the strength of the surface film and the better the foam performance of the oil displacement system.

[0012] The droplet surface effect test method based on acoustic levitation technology described in the present invention uses acoustic levitation technology to calculate the high-frequency surface expansion modulus of a single test droplet. On the one hand, the expansion and compression of the droplet can be achieved by adjusting the amplitude and frequency. On the other hand, the contact between the device and the droplet is avoided, and the force and deformation of the test droplet surface can be truly reflected. This test method is closer to the actual reservoir geological conditions and will provide more practical and reliable help for the optimization of chemical flooding formulas.

[0013] Preferably, when the acoustic suspension device is used to observe the droplets, the sound wave frequency is set to 38.220KHz, and a micro-injector is used to inject a test droplet of 2-10μL into the sound field, and the test droplet is stably suspended by adjusting the distance between the sound source and the reflection end, for example, it can be 2μL, 3μL, 4μL, 5μL, 8μL or 10μL, etc., but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable. The present invention preferably uses a micro-injector to place a 5μL test droplet into the sound field, which is convenient for testing and research.

[0014] The high-frequency surface dilation modulus in the present invention is defined as the variation of surface tension with surface area under high-frequency sound field disturbance.

[0015] Preferably, a single test droplet is suspended in a vertical acoustic field to calculate the high-frequency surface dilation modulus, which has the advantages of high frequency and no external interference.

[0016] Preferably, the modulation mode includes adjusting the sound wave to transform in a sinusoidal wave mode, with a transformation amplitude range of 10%-50%, so that the droplet surface presents a sinusoidal response in the sound field, for example, it can be 10%, 15%, 20%, 30%, 40% or 50%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] Preferably, for the modulation setting, the type of sound wave is adjusted to a sine wave, the sound wave amplitude is 50%, and the oscillation frequency is in the range of 80-120 Hz to match the calculation of the droplet size and surface tension. For example, it can be 80 Hz, 90 Hz, 95 Hz, 100 Hz, 110 Hz or 120 Hz, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0018] Preferably, according to the volume size of the droplet, the conversion frequency range of the sound wave is 80 Hz to 120 Hz; the conversion frequency of the sound wave is adjusted to start from 80 Hz, and change 1-5 Hz each time until the droplet's own oscillation is coupled with the sound field oscillation and is in a double-string oscillation state, for example, it can be 1 Hz, 1.5 Hz, 2 Hz, 3 Hz, 4 Hz or 5 Hz, but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0019] Preferably, the frequency of the sound wave conversion is adjusted so that the droplet to be tested reaches a double-chord oscillation state in the sound field, and the frequency conversion is increased by 1 Hz each time until the droplet exhibits a double-chord oscillation state.

[0020] Preferably, when measuring the high-frequency surface dilation modulus, the test droplet must be in a non-contact high-frequency double-chord oscillation state in the sound field, that is, the monitored droplet change frequency must be the result of the superposition of the sound field and its own oscillation frequency, and the actual droplet change frequency is less than the frequency of the sound field change.

[0021] Preferably, the calculated high-frequency surface dilation modulus is the high-frequency surface dilation modulus obtained by calculating the surface tension by observing the decaying oscillation and then bringing in the stable double-chord oscillation before the decaying oscillation.

[0022] Preferably, the high-frequency surface extension modulus obtained by the acoustic suspension device is measured in a vertical sound field of uniaxial acoustic suspension.

[0023] Preferably, the surfactant concentration of the test droplet is in the range of 0.01%-1%, for example, it can be 0.01%, 0.1%, 0.2%, 0.3%, 0.7%, 0.9% or 1%, etc., but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 0.3%.

[0024] As a preferred technical solution of the present invention, the test method is carried out using an acoustic suspension device. After the test droplet is suspended in the sound field of the acoustic suspension device, the amplitude, frequency and sound wave type are adjusted to make the test droplet produce regular deformation sound, the droplet is suspended by high-frequency sound waves, and the suspended droplet is automatically identified, and the appearance contour of the droplet is automatically analyzed to study the properties of non-contact and non-polluting droplets under the influence of high-frequency vibration; when the droplet is observed using the acoustic suspension device, the sound wave frequency is set to 38.220KHz, and a micro-syringe is used to inject 2-10μL of test droplets with a surfactant concentration of 0.01%-1% into the sound field, and the test droplet is stably suspended by adjusting the distance between the sound source and the reflection end;

[0025] The droplet surface effect test method comprises: injecting a test droplet into an acoustic field through a micro-injector, setting a modulation mode, adjusting the acoustic wave to transform in a sinusoidal wave mode, and the transformation amplitude range is 10%-50%, so that the droplet surface presents a sinusoidal response in the acoustic field; according to the volume of the droplet, the transformation frequency of the acoustic wave ranges from 80Hz to 120Hz; adjusting the transformation frequency of the acoustic wave to start from 80Hz, and transforming 1-5Hz each time until the droplet's own oscillation is coupled with the acoustic field oscillation and is in a double-chord oscillation state; stopping the acoustic field disturbance, recording the droplet from a periodic change to a stable state, and calculating the high-frequency surface expansion modulus of the droplet;

[0026] The high-frequency surface expansion modulus is calculated by observing the decay oscillation and calculating the surface tension, and then bringing the stable double-chord oscillation before the decay oscillation into the high-frequency surface expansion modulus obtained by calculation;

[0027] The high-frequency surface extension modulus obtained by the acoustic suspension device is measured in the vertical acoustic field of the uniaxial acoustic suspension.

[0028] In a second aspect, the present invention also provides a use of a droplet surface effect test method based on acoustic levitation technology as described in the first aspect, wherein the droplet surface effect test method is used to evaluate the foam performance of chemical oil recovery formulas, guide the optimization of chemical oil recovery formulas and their application in chemical flooding to enhance oil recovery.

[0029] The droplet surface effect test method based on acoustic levitation technology described in the present invention adopts acoustic levitation technology to realize high-frequency deformation of droplets without external force interference, measures and calculates the high-frequency surface expansion modulus of surfactants, avoids the droplet deformation obstruction error caused by needle contact in the traditional oscillating drop method, overcomes the shortcomings of small low-frequency expansion modulus value at high surfactant concentration and poor correlation with foam stability, can quickly and accurately evaluate the foam performance of chemical flooding formulas, and guide the research and development of chemical flooding formulas.

[0030] Compared with the prior art, the present invention has at least the following beneficial effects:

[0031] (1) Compared with the existing hanging drop method, the droplet surface effect test method based on acoustic levitation technology provided by the present invention can more realistically show the existence state of the droplet under the actual formation state, avoiding the obstruction of the needle to the droplet deformation. At the same time, the easy-to-operate test method can more quickly and accurately evaluate the foam performance of the chemical flooding formula and guide the research and development of chemical flooding formula;

[0032] (2) Compared with the existing hanging drop interface expansion rheology test method, the foam flooding system screening method and application based on acoustic levitation expansion rheology technology provided by the present invention can meet the requirements of droplet surface film strength characterization within a high concentration range. The test droplets will continuously expand and compress under the action of the sound field, and the characterization interval is expanded from f≤0.1Hz to 50Hz. It can better reveal the response of the material to deformation in an extremely short time, and more sensitively detect changes in the material microstructure, and has a stronger correlation with the foam stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a curve of volume change over time when the droplet of sodium sulfate of alkyl alcohol polyoxypropylene ether decays in Example 1 of the present invention.

[0034] Figure 2This is a curve diagram of the change of surface tension and surface area of ​​sodium alkyl alcohol polyoxypropylene ether sulfate over time when it is stable in Example 1 of the present invention.

[0035] Figure 3 This is a picture of the expansion of a droplet of sodium sulfate of alkyl alcohol polyoxypropylene ether in a vertical sound field in Example 1 of the present invention.

[0036] Figure 4 This is a compressed picture of a droplet of sodium sulfate of alkyl alcohol polyoxypropylene ether in a vertical sound field in Example 1 of the present invention.

[0037] Figure 5 It is the correlation fitting of the high-frequency surface expansion modulus of the acoustic suspension in Example 1 of the present invention and the low-frequency surface expansion modulus of the hanging drop relative to the foam half-life. DETAILED DESCRIPTION

[0038] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0039] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0040] Example 1

[0041] This embodiment provides a droplet surface effect test method based on acoustic levitation technology. The test method is performed using an acoustic levitation device. After the test droplet is suspended in the sound field of the acoustic levitation device, the amplitude, frequency and sound wave type are adjusted to make the test droplet produce regular deformation sound, the droplet is suspended by high-frequency sound waves, and the suspended droplet is automatically identified and the appearance contour of the droplet is automatically analyzed to study the properties of non-contact and non-polluting droplets under the influence of high-frequency vibrations.

[0042] The droplet surface effect test method comprises:

[0043] (1) Prepare a 0.3% sodium sulfate solution of alkyl alcohol polyoxypropylene ether with distilled water, place a 10 μL droplet into a vertical acoustic field using a microinjector, and adjust the distance between the sound source and the reflection end to ensure that a single test droplet is stably suspended. The droplet is located in the center of the acoustic field under the action of acoustic tweezers;

[0044] (2) Selecting a sine wave as the acoustic field waveform, with a fixed frequency of 80 Hz and an amplitude of 50%, so that a single surfactant droplet undergoes regular deformation;

[0045] (3) The frequency was adjusted from 80 Hz to 120 Hz at 1 Hz intervals until the droplet showed a double-chord oscillation state. The modulation was turned off and a computer and a high-magnification camera were used to monitor and record in real time the droplet's recovery from a deformed state to a stable state. The volume V, surface area A, change frequency f and time t of a single test droplet were recorded, and the attenuation characteristic time τ was calculated.

[0046] (4) The calculation formula of high-frequency surface expansion modulus is as follows:

[0047] The actual oscillation frequency of a single test droplet is calculated as follows: f1 = (f + (2π (1 / τ)) -2 ) 1 / 2 .

[0048] The surface tension calculation formula is: γ=3πρVf1 2 / 8.

[0049] High frequency surface extension modulus ε h The calculation formula is: h =dγ / dlnA.

[0050] The curve of volume change over time when the droplet of alkyl alcohol polyoxypropylene ether sodium sulfate decays in this embodiment is as follows: Figure 1 As shown, from Figure 1 It can be seen that the droplets produce regular attenuation oscillations under the action of the sound field.

[0051] The curve of the change of surface tension and surface area of ​​sodium alkyl alcohol polyoxypropylene ether sulfate over time when it is stable in this embodiment is as follows Figure 2 As shown, from Figure 2 It can be seen that in the stable state, the surface of the droplet produces standard sinusoidal oscillations under the action of the acoustic field.

[0052] Figure 3 and Figure 4 They are pictures of the expansion and compression of the sodium sulfate droplet of alkyl alcohol polyoxypropylene ether in the vertical sound field in this embodiment.

[0053] In this embodiment, four surfactant solutions, octadecyl sulfobetaine, sodium dodecyl sulfate, polyethylene glycol octylphenyl ether and sodium alkyl alcohol polyoxypropylene ether sulfate, were selected to carry out the above-mentioned droplet surface effect test method based on acoustic levitation technology to obtain the high-frequency surface expansion modulus of the droplets of each system.

[0054] At the same time, for comparison purposes, the four prepared surfactant solutions were also subjected to low-frequency surface dilation modulus measurements and foam half-life experiments.

[0055] The low-frequency surface expansion modulus measurement method includes: pouring the prepared four surfactant solutions into the water tank of the hanging drop device respectively, controlling the syringe to bulge a 6μL bubble in the water tank, setting the amplitude to 30% and the frequency to 0.1Hz, oscillating the bubble, and calculating the low-frequency surface expansion modulus of the droplet.

[0056] The foam half-life test method includes: taking 200ml of the prepared surfactant solution, setting the speed of the Brookfield foam meter to 5000r / min. Pour the solution into the Brookfield foam meter, turn on the switch and start timing, remove it after one minute and pour it into a measuring cylinder, observe the time when the amount of water under the foam reaches 100ml, which is the half-life of the foam.

[0057] The results of high frequency surface dilation modulus, low frequency surface dilation modulus and foam half-life are shown in Table 1.

[0058] Table 1

[0059]

[0060] The correlation between the high-frequency surface dilation modulus of acoustic levitation and the low-frequency surface dilation modulus of hanging drops with respect to the foam half-life is fitted as follows: Figure 5 shown.

[0061] Through fitting the two, it is found that the low-frequency expansion modulus obtained by the hanging drop method is smaller due to its lower frequency, so it is not accurate enough to distinguish the foaming ability of different oil recovery formulas at high concentrations, and has little guiding significance for the screening of oil recovery formulas. The high-frequency expansion modulus obtained by the acoustic levitation method has a better fitting effect on the correlation with foam stability, has a better correspondence with the actual foam half-life, and can better distinguish the foaming ability of different oil recovery systems.

[0062] In addition, compared with the hanging drop method, the acoustic levitation method has the advantage of non-contact, avoiding the contact of droplets, thus eliminating the difficulty of cleaning the device. At the same time, its operation is simple, and data can be obtained more concisely and quickly, improving the work efficiency of evaluating the foam performance of surface chemical flooding formulations.

[0063] In summary, the droplet surface effect test method based on acoustic levitation technology provided by the present invention enables the test droplets to contact each other under the drive of the sound field, avoiding external force interference on the test droplets by needles, capillaries, etc., and can more accurately evaluate the foam performance of chemical oil recovery formulas, guide the optimization of foam oil recovery formulas and their application in chemical flooding to enhance oil recovery, and is suitable for large-scale promotion and application.

[0064] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A droplet surface effect testing method based on acoustic levitation technology, characterized in that: The test method is carried out by using an acoustic suspension device. After the test droplet is suspended in the sound field of the acoustic suspension device, the amplitude, frequency and sound wave type are adjusted to make the test droplet deform regularly, the droplet is suspended by high-frequency sound waves, and the suspended droplet is automatically identified and the appearance contour of the droplet is automatically analyzed to study the properties of non-contact and non-contamination droplets under the influence of high-frequency vibration. The droplet surface effect test method comprises: injecting a test droplet into an acoustic field through a micro-injector, setting a modulation mode, and changing the acoustic wave to transform according to a certain pattern rule; adjusting the acoustic wave transformation frequency within a certain range so that the droplet itself and the acoustic field vibration are resonantly coupled, and the droplet is in a double-chord oscillation state; stopping the acoustic field disturbance, recording the droplet from a periodic change to a stable state, and calculating the high-frequency surface expansion modulus of the droplet.

2. The droplet surface effect testing method according to claim 1, characterized in that: When the acoustic suspension device is used to observe droplets, the sound wave frequency is set to 38.220 KHz, and a test droplet of 2-10 μL in size is injected into the sound field using a micro-syringe. The test droplet is stably suspended by adjusting the distance between the sound source and the reflection end.

3. The droplet surface effect testing method according to claim 1 or 2, characterized in that: The modulation mode includes adjusting the sound wave to transform in a sinusoidal wave mode, with the transformation amplitude interval being 10%-50%, so that the surface of the droplet presents a sinusoidal response in the sound field.

4. The droplet surface effect testing method according to any one of claims 1 to 3, characterized in that: Depending on the size of the droplet, the frequency conversion of the sound wave ranges from 80Hz to 120Hz; the frequency conversion of the sound wave is adjusted starting from 80Hz, with a conversion of 1-5Hz each time, until the droplet's own oscillation is coupled with the sound field oscillation and is in a double-string oscillation state.

5. The droplet surface effect testing method according to any one of claims 1 to 4, characterized in that: When measuring the high-frequency surface dilation modulus, the test droplet must be in a non-contact high-frequency double-chord oscillation state in the sound field, that is, the monitored droplet change frequency must be the result of the superposition of the sound field and its own oscillation frequency, and the actual droplet change frequency is less than the frequency of the sound field change.

6. The droplet surface effect testing method according to any one of claims 1 to 5, characterized in that: The high-frequency surface expansion modulus is calculated by observing the decaying oscillation and calculating the surface tension, and then bringing in the stable double-chord oscillation before the decaying oscillation to obtain the high-frequency surface expansion modulus.

7. The droplet surface effect testing method according to any one of claims 1 to 6, characterized in that: The high-frequency surface extension modulus obtained by the acoustic suspension device is measured in the vertical acoustic field of the uniaxial acoustic suspension.

8. The droplet surface effect testing method according to any one of claims 1 to 7, characterized in that: The concentration of the surfactant in the test droplet is in the range of 0.01% to 1%, preferably 0.3%.

9. The droplet surface effect testing method according to any one of claims 1 to 8, characterized in that: The droplet surface effect test method comprises: A test droplet with a volume of 10 μL and a surfactant concentration of 0.3% was injected into the acoustic field through a micro-syringe; the modulation mode was set, and the sound wave was adjusted to transform in a sinusoidal wave mode with a transformation amplitude of 50%, so that the droplet surface presented a sinusoidal response in the acoustic field; the transformation frequency of the sound wave was adjusted to start from 80 Hz, with a transformation of 1 Hz each time, until the droplet's own oscillation was coupled with the acoustic field oscillation and was in a double-chord oscillation state; the acoustic field disturbance was stopped, and the droplet's change from periodic to stable state was recorded, and the high-frequency surface expansion modulus of the droplet was calculated.

10. A use of the droplet surface effect testing method based on acoustic levitation technology as claimed in any one of claims 1 to 9, characterized in that: The droplet surface effect test method is used to evaluate the foam performance of chemical flooding formulations, guide the optimization of foam flooding formulations and their application in chemical flooding to enhance oil recovery.

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