A device and method for stability experiment of co2 microbubble in porous medium

Abstract

The application provides a CO2 micro-bubble porous medium stability experiment device and method, and belongs to the technical field of CO2 enhanced oil recovery and storage. The inflow end of a fluid channel is connected with a micro-bubble inlet channel and a pure continuous phase inlet channel respectively, the inflow end of a porous medium micro-model is connected with the fluid channel, the outflow end of the porous medium micro-model is connected with the inflow end of a bubble group trapping channel, and the outflow end of the bubble group trapping channel is connected with the outflow end of the fluid channel and a fluid outflow channel respectively. The application can investigate the CO2 bubble stability without convection and the CO2 bubble stability under convection, reduces the observation experiment difficulty, and can realize the purpose of observing the dynamic stability of the bubble group.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of CO2 enhanced recovery and storage, and particularly relates to a device and method for stability experiment of CO2 micro-bubbles in porous media. BACKGROUND

[0002] The existing technologies for studying the stability of micro-bubbles include electrolytic test pieces, probes, and orifice plates, which mainly connect the power supply negative pole through a power supply lead and connect the power supply positive pole through a carbon rod to test the growth process and residence of micro-bubbles in the bubble pits.

[0003] Chinese patent publication CN112026984A discloses an electrolytic micro-bubble stability observation test device, which relates to the field of active drag reduction of underwater vehicles and comprises a micro-bubble stability observation platform, an electronic flowmeter, and a stepless speed regulation water pump. The micro-bubble stability observation platform is internally provided with a trapezoidal diffuser section, an energy dissipation orifice plate, a honeycomb flow straightener, a screen, an electrolytic observation test piece with micro-nano pits, a spring probe, and a carbon rod in sequence along the fluid motion direction. The micro-bubble stability observation platform is connected with the electronic flowmeter and the stepless speed regulation water pump through a water passage. The spring probe is connected with the power supply negative pole through a power supply lead, and the carbon rod is connected with the power supply positive pole. The trapezoidal diffuser section, the energy dissipation orifice plate, the honeycomb flow straightener, and the screen have the effects of flow stabilization, energy dissipation, vertical direction straightening, and horizontal direction straightening, so that the dynamic water flow reaches a stable state, which is conducive to the stable residence of micro-bubbles and the observation of the growth process and residence of micro-bubbles in the micro-nano pits under micro-scale conditions.

[0004] Chinese patent publication CN112403543A discloses an acoustic microfluidic chip for micro-bubble separation, which comprises a T-shaped channel. One inlet of the T-shaped channel is used to inject a continuous phase, and the other inlet is used to inject a dispersed phase. A interdigital transducer is arranged beside a section of pipeline where the continuous phase and the dispersed phase meet. The interdigital transducer generates an acoustic surface wave that covers the diameter of the pipeline, so that the dispersed phase passing through the section of pipeline is divided into two parts under the action of the acoustic radiation force generated by the interdigital transducer. The interdigital transducer of the present application has a focusing feature that can generate higher energy than general interdigital transducers, so that the narrow acoustic surface wave energy generated is stronger, and the micro-bubbles are better divided into two parts. At the same time, the present application changes the structure of the inlet end and adds a circular buffer area at the inlet, which avoids the separation of the chip and the substrate due to excessive pressure in the channel, and enhances the stability of the overall experiment.

[0005] The above two devices can only observe the static single bubble condition, and the implementation difficulty is high, and the micro-bubble group and its dynamic stability cannot be observed. SUMMARY

[0006] The present application aims at solving the problems existing in the prior art, and provides a CO2 micro-bubble porous medium stability experiment device and method, which solves the problems that the existing device and method can only observe a single static bubble, and the implementation is difficult, and the micro-bubble group and its dynamic stability cannot be observed.

[0007] The present application is realized by the following technical solutions:

[0008] In a first aspect, the present application provides a CO2 micro-bubble porous medium stability experiment device, comprising: a porous medium micro-model, a micro-bubble inlet channel, a pure continuous phase inlet channel, a bubble group trapping channel, and a fluid outlet channel.

[0009] The inflow end of the fluid channel is in communication with the micro-bubble inlet channel and the pure continuous phase inlet channel, respectively; the inflow end of the porous medium micro-model is in communication with the fluid channel; the outflow end of the porous medium micro-model is in communication with the inflow end of the bubble group trapping channel; and the outflow end of the bubble group trapping channel is in communication with the outflow end of the fluid channel and the fluid outlet channel, respectively.

[0010] The present application is further improved in that,

[0011] The inflow end of the bubble group trapping channel is provided with a first valve, which is used for controlling the opening and closing of the bubble group trapping channel.

[0012] The present application is further improved in that,

[0013] The outflow end of the fluid channel is provided with a second valve, which is used for controlling the opening and closing of the fluid channel.

[0014] The present application is further improved in that,

[0015] A third valve is arranged on the fluid outlet channel, which is used for controlling the system pressure of the whole device.

[0016] In a second aspect, the present application provides a CO2 micro-bubble porous medium stability experiment method, which uses the CO2 micro-bubble porous medium stability experiment device to detect the stability of CO2 micro-bubble porous medium.

[0017] The present application is further improved in that,

[0018] The experiment method specifically comprises the following steps:

[0019] (1) Preliminary preparation: 3D printing of a porous medium micro-model and assembly of a stability experiment device;

[0020] (2) Pre-saturation: open the first and second valves, fill the porous medium micro-model with water through the pure continuous phase inlet channel, and adjust the pressure through the third valve, with the pressure controlled at 0MPa-30MPa;

[0021] (3) Bubble group trapping: close the second valve, inject a micro-bubble group into the porous medium micro-model through the micro-bubble inlet channel;

[0022] (4) Initial environment setting: when the micro-bubbles fill the porous medium micro-model, stop injecting the micro-bubbles, and simultaneously open the first and second valves to pass the continuous phase through the pure continuous phase inlet channel until the micro-bubbles in the channel outside the porous medium micro-model are driven out, and then close the first and second valves;

[0023] (5) Initial state determination: record and analyze the initial distribution and initial morphology of the micro-bubble group in the porous medium micro-model;

[0024] (6) Quasi-static bubble dissolution without convection: close the first valve, inject the unsaturated continuous phase fluid through the micro-bubble inlet channel and flow out from the fluid channel;

[0025] (7) Quasi-static bubble dissolution under convection: close the second valve, inject the unsaturated continuous phase fluid through the pure continuous phase inlet channel and flow out from the bubble group trapping channel;

[0026] (8) Dissolution dynamic data acquisition: record the changes of the bubble group morphology and distribution under the conditions of steps (6) and (7), and perform real-time analysis to determine the stability.

[0027] The further improvement of the present application is that,

[0028] In step (4), when the continuous phase is passed through the pure continuous phase inlet channel, the flow rate is 0μm / s-500μm / s, and the continuous phase is water or crude oil.

[0029] The further improvement of the present application is that,

[0030] In step (5), the initial distribution and initial morphology of the micro-bubble group in the porous medium micro-model are recorded and analyzed, and the specific operation is as follows:

[0031] The size of the initial micro-bubbles, the bubble formation time or lifetime, and the distribution of the micro-bubble group are recorded.

[0032] The further improvement of the present application is that,

[0033] In step (6), the unsaturated continuous phase fluid is injected through the micro-bubble inlet channel, and the specific operation is as follows:

[0034] Water or crude oil is injected through the micro-bubble inlet channel at a flow rate of 0μm / s-500μm / s.

[0035] Further improvement of the present application is that,

[0036] In step (7), the unsaturated continuous phase fluid is injected through the pure continuous phase access channel, and the specific operation is as follows:

[0037] Water or crude oil is injected through the pure continuous phase access channel at a flow rate of 0-500 um / s.

[0038] Further improvement of the present application is that:

[0039] Step (8) dissolves dynamic data acquisition: record the changes of bubble group morphology and distribution under the conditions of steps (6) and (7), and perform real-time analysis to determine the stability, and the specific operation is as follows:

[0040] The size of the micro-bubbles, the bubble formation time or the life span, the distribution of the micro-bubble group under the conditions of steps (6) and (7) are recorded, and compared with the initial state in the porous medium micro-model, if most of the bubbles do not have dissolution phenomenon, the size of the micro-bubbles is in the range of 30-500 um, and the bubble group in the porous medium micro-model is uniformly distributed or the micro-bubbles with a size of 100 um are aggregated into sub-micro-bubbles with a size of 500 um and are not dissolved, it is a stable state, otherwise it is an unstable state.

[0041] Compared with the prior art, the present application has the following beneficial effects:

[0042] In view of the problems that the existing micro-bubble stability test method can only observe static single bubble, the implementation difficulty is large, and the micro-bubble group and its dynamic stability cannot be observed, the present application designs an experimental device and method for testing the stability of micro-bubbles in porous media, which can investigate the stability of CO2 bubbles without convection and the stability of CO2 bubbles under convection, reduce the observation difficulty of the experiment, and realize the purpose of observing the dynamic stability of the bubble group.

[0043] The present application investigates the dissolution of bubble groups under two conditions:

[0044] (1) CO2 bubble stability without convection. For the application situation that local flow rate is extremely small and Pe number is extremely low due to plugging. This situation generally exists in low permeability areas. At this time, molecular diffusion is the main way of dissolution.

[0045] (2) CO2 bubble stability under convection. For the application situation that bubbles are trapped and retained, but the continuous phase still passes through this area at an observable flow rate. This situation generally occurs in high permeability areas that are plugged. At this time, convection dispersion is the main way of dissolution. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1is a structural diagram of a stability experiment device of CO2 micro-bubble in porous medium provided by the present application.

[0047] In the figure, 1 is a micro model of porous medium, 2 is a micro-bubble entering channel, 3 is a pure continuous phase entering channel, 4 is a trapped bubble group channel, 5 is a first valve, 6 is a fluid channel, 7 is a second valve, 8 is a third valve, and 9 is a fluid outflow channel. DETAILED DESCRIPTION

[0048] The present application will be further described in detail below in combination with the drawings:

[0049] The present application provides a stability experiment device and method of CO2 micro-bubble in porous medium, and illustrates the stability of CO2 micro-bubble group under different convection conditions, temperature and pressure conditions and pore sizes; the experiment method is that first, the bubble group is injected into the porous medium, and after the flow is stopped, it is placed in an unsaturated open boundary, and the evolution of the bubble group is observed under constant pressure conditions, the evolution of saturation, bubble shape and spatial distribution is directly observed and recorded, the life of static micro-bubble in the porous medium is obtained, and the influence of temperature, salinity, pressure, pore structure and continuous phase flow rate on the dissolution of CO2 micro-bubble is explored.

[0050] In particular, the present application investigates the dissolution of bubble groups in two cases:

[0051] (1) CO2 bubble stability without convection. It is aimed at the application situation that the local flow rate is extremely small and the Pe number is extremely low due to plugging. This situation generally exists in low permeability areas. At this time, molecular diffusion is the main way of dissolution.

[0052] (2) CO2 bubble stability under convection. It is aimed at the application situation that the bubble is trapped and retained, but the continuous phase still passes through this area at an observable flow rate. This situation generally occurs in the plugged area of high permeability. At this time, convection dispersion is the main way of dissolution.

[0053] The present application provides a stability experiment device of CO2 micro-bubble in porous medium, and the structural implementation of the stability experiment device is as follows:

[0054]

Example 1

[0055] As shown in Figure 1 , the experiment device of the present application comprises: a micro model of porous medium 1, a micro-bubble entering channel 2, a pure continuous phase entering channel 3, a trapped bubble group channel 4, a first valve 5, a fluid channel 6, a second valve 7, a third valve 8 and a fluid outflow channel 9. The micro model of porous medium 1 is visualized, similar to an etched model.

[0056] The inflow end of the fluid channel 6 is communicated with the micro-bubble inlet channel 2 and the pure continuous phase inlet channel 3 respectively, the inflow end of the porous medium micro-model 1 is communicated with the fluid channel 6, the outflow end of the porous medium micro-model 1 is communicated with the inflow end of the bubble group trapping channel 4, and the outflow end of the bubble group trapping channel 4 is communicated with the outflow end of the fluid channel 6 and the fluid outflow channel 9 respectively.

[0057] Further, the inflow end of the bubble group trapping channel 4 is provided with a first valve 5, and the first valve 5 is used for controlling the opening and closing of the bubble group trapping channel 4.

[0058] Further, the outflow end of the fluid channel 6 is provided with a second valve 7, and the second valve 7 is used for controlling the opening and closing of the fluid channel 6.

[0059] Further, the third valve 8 is arranged on the fluid outflow channel 9, and the third valve 8 is used for controlling the system pressure of the whole device.

[0060] In use, the first valve 5 and the second valve 7 are opened, water is filled into the porous medium micro-model 1 through the pure continuous phase inlet channel 3, the pressure is adjusted through the third valve 8 to be 0MPa-30MPa, then the second valve 7 is closed, the micro-bubble group is injected into the porous medium micro-model 1 through the micro-bubble inlet channel 2, the injection is stopped after the micro-bubble group is filled, and at the same time, the first valve 5 and the second valve 7 are opened, the continuous phase is introduced from the pure continuous phase inlet channel 3 until the micro-bubbles in the channel outside the porous medium micro-model 1 are driven away, then the first valve 5 and the second valve 7 are closed, the initial distribution and the initial shape of the micro-bubble group in the porous medium micro-model 1 are recorded and observed, the CO2 bubble stability under the conditions of no convection or convection is respectively investigated, the size of the micro-bubbles, the bubble forming time (life span) and the distribution of the micro-bubble group under the two conditions are recorded, and the initial state in the porous medium micro-model 1 is compared, if most of the bubbles do not have dissolution phenomenon, the size of the micro-bubbles is in the range of 30μm-500μm, and the bubble group in the porous medium micro-model 1 is uniformly distributed or the bubbles with a size of 100μm or less are aggregated into sub-micro-bubbles with a size of 500μm and do not dissolve, then it is in a stable state, otherwise it is in an unstable state.

[0061] The application provides a CO2 micro-bubble porous medium stability experiment method, which is realized by using the above stability experiment device.

[0062]

Example 2

[0063] The experiment method specifically includes the following steps.

[0064] (1) Preliminary preparation: 3D printing of the porous medium micro-model and assembly of the stability experiment device.

[0065] After the experimental device is assembled, the booster, vacuum pump and gas conveying equipment are connected to the micro-bubble inlet channel 2, which is used to pressurize, vacuumize and convey gas for the experimental device.

[0066] (2) Pre-saturation: open the first valve 5 and the second valve 7, fill the porous medium micro-model 1 with water through the pure continuous phase inlet channel 3, and adjust the pressure through the third valve 8, with the pressure requirement controlled at 0MPa-30MPa;

[0067] (3) Capture bubble group: connect the CO2 micro-bubble generator to the inlet end of the micro-bubble inlet channel 2, close the second valve 7, and inject the micro-bubble group into the porous medium micro-model 1 through the micro-bubble inlet channel 2;

[0068] (4) Initial environment setting: when the porous medium micro-model 1 is filled with micro-bubbles, stop injecting micro-bubbles, and open the first valve 5 and the second valve 7 to pass the continuous phase from the pure continuous phase inlet channel 3 until the micro-bubbles in the channel outside the porous medium micro-model 1 are driven out (that is, only the porous medium micro-model 1 has micro-bubbles, and the other channels are continuous phase), and then close the first valve 5 and the second valve 7;

[0069] Further, when the continuous phase is passed from the pure continuous phase inlet channel 3, the flow rate is 0μm / s-500μm / s.

[0070] Further, the continuous phase is water or crude oil, etc.

[0071] (5) Determine the initial state: record and analyze the initial distribution and initial morphology of the micro-bubble group in the porous medium micro-model 1;

[0072] Specifically, the size of the initial micro-bubble, the bubble formation time (lifetime), and the distribution of the micro-bubble group are recorded, preferably, the initial micro-bubble size is 30μm-500μm, and the micro-bubbles are uniformly distributed in the porous medium micro-model 1.

[0073] (6) Non-convective quasi-static bubble dissolution: close the first valve 5, inject unsaturated continuous phase fluid at a very small speed through the micro-bubble inlet channel 2 and flow out from the fluid channel 6, on the one hand to ensure that the boundary of the connection between the porous medium observation area 1 and the fluid channel 6 maintains a constant concentration (here the concentration has no specific range, as long as it is constant.), on the other hand to avoid the influence of convection on the porous medium micro-model 1, and purely through diffusion to take away the dissolved CO2 gas;

[0074] Convection will change the size, lifetime and distribution of the micro-bubbles in the porous medium micro-model 1, leading to experimental failure, so convection should be avoided to affect the porous medium micro-model 1.

[0075] In step (6), the unsaturated continuous phase fluid is injected through the micro-bubble entry channel, and the specific operation is as follows: water or crude oil is injected through the micro-bubble entry channel in sections at a flow rate of 0-500 μm / s.

[0076] In step (6), the unsaturated continuous phase fluid is injected through the micro-bubble entry channel, and the specific operation is as follows: water or crude oil is injected through the micro-bubble entry channel in sections at a flow rate of 0-500 μm / s.

[0077] (7) Dissolution of the quasi-static bubble under convection: the second valve 7 is closed, the unsaturated continuous phase fluid is injected through the pure continuous phase entry channel 3 at a very small speed and flows out from the bubble group trapping channel 4, and the dissolved CO2 gas is carried away by convection;

[0078] In step (7), the unsaturated continuous phase fluid is injected through the pure continuous phase entry channel, and the specific operation is as follows: water or crude oil is injected through the pure continuous phase entry channel in sections at a flow rate of 0-500 μm / s.

[0079] (8) Dissolution dynamic data acquisition: the changes of the bubble group morphology and distribution under the two conditions of steps (6) and (7) are recorded and analyzed in real time to determine whether the state is stable.

[0080] Specifically,

[0081] The size of the micro-bubble, the bubble formation time (life span), and the distribution of the micro-bubble group under the two conditions of steps (6) and (7) are recorded, and compared with the initial state in the porous medium micro-model 1. If most of the bubbles do not have dissolution phenomenon, the size of the micro-bubble is in the range of 30-500 μm, and the bubble group in the porous medium micro-model 1 is uniformly distributed or the bubbles with a size of 100 μm or less are aggregated into sub-micro-bubbles with a size of 500 μm and do not dissolve, then the state is stable. Otherwise, the state is unstable.

[0082] The experimental device and method for testing the stability of micro-bubbles in a porous medium provided by the application solve the problems of the prior art micro-bubble stability testing method, such as being able to only observe a static single bubble, having a large implementation difficulty, and being unable to observe a micro-bubble group and its dynamic stability. The application can investigate the CO2 bubble stability without convection and the CO2 bubble stability under convection, reduces the observation experiment difficulty, and can achieve the purpose of observing the dynamic stability of the bubble group.

[0083] In the description of the application, unless otherwise explicitly specified and limited, the terms "connected", "connected" should be understood in a broad sense, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be mechanically connected, or electrically connected; can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0084] In the description of the present application, unless otherwise specified, the terms "upper", "lower", "left", "right", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0085] Finally, it should be noted that the above technical solutions are only one embodiment of the present application, and for those skilled in the art, on the basis of the application disclosed application method and principle, various types of improvements or modifications can be easily made, and are not limited to the methods described in the above specific embodiments of the present application, therefore the above described method is only preferred, and does not have the meaning of limitation.

Claims

1. A method for stability experiment of CO2 microbubbles in porous media, characterized in that, The method adopts a stability experimental device in CO2 micro-bubble porous medium to detect the stability in CO2 micro-bubble porous medium, and the experimental device comprises: a porous medium micro-model, a micro-bubble inlet channel, a pure continuous phase inlet channel, a bubble group trapping channel, a fluid channel and a fluid outlet channel; the inflow end of the fluid channel is in communication with the micro-bubble inlet channel and the pure continuous phase inlet channel respectively, the inflow end of the porous medium micro-model is in communication with the fluid channel, the outflow end of the porous medium micro-model is in communication with the inflow end of the bubble group trapping channel, and the outflow end of the bubble group trapping channel is in communication with the outflow end of the fluid channel and the fluid outlet channel respectively; the inflow end of the bubble group trapping channel is provided with a first valve, the outflow end of the fluid channel is provided with a second valve, and the fluid outlet channel is provided with a third valve; the experimental method specifically comprises the following steps: (1) preliminary preparation: 3D printing of a porous medium micro-model and assembly of a stability experimental device; (2) pre-saturation: opening the first valve and the second valve, filling the porous medium micro-model with water through the pure continuous phase inlet channel, and adjusting the pressure through the third valve, with the pressure controlled at 0MPa-30MPa; (3) bubble group trapping: closing the second valve, and injecting a micro-bubble group into the porous medium micro-model through the micro-bubble inlet channel; (4) initial environment setting: when the porous medium micro-model is filled with micro-bubbles, stopping the injection of micro-bubbles, and opening the first valve and the second valve to pass the continuous phase from the pure continuous phase inlet channel until the micro-bubbles in the channel outside the porous medium micro-model are driven away, and then closing the first valve and the second valve; (5) determination of initial state: recording and analyzing the initial distribution and initial morphology of the micro-bubble group in the porous medium micro-model; (6) quasi-static bubble dissolution under non-convection: closing the first valve, injecting unsaturated continuous phase fluid through the micro-bubble inlet channel and flowing out from the fluid channel; (7) quasi-static bubble dissolution under convection: closing the second valve, injecting unsaturated continuous phase fluid through the pure continuous phase inlet channel and flowing out from the bubble group trapping channel; (8) dissolution dynamic data acquisition: recording the changes of the bubble group morphology and distribution under the conditions of steps (6) and (7), and performing real-time analysis to determine the stability.

2. The method of claim 1, wherein the CO2 microbubble porous medium is prepared by the method of claim 1. In step (4), when the continuous phase is passed from the pure continuous phase inlet channel, the flow rate is 0μm / s-500μm / s, and the continuous phase is water or crude oil.

3. The method of claim 2, wherein the CO2 microbubble porous medium is a porous medium having a pore size of 1-1000 nm. In step (5), the initial distribution and initial morphology of the micro-bubble group in the porous medium micro-model are recorded and analyzed, and the specific operation is to record the size of the initial micro-bubbles, the bubble formation time or life, and the distribution of the micro-bubble group.

4. The method of claim 3, wherein the CO2 microbubble porous medium is a porous medium having a pore size of 1-1000 nm. In step (6), unsaturated continuous phase fluid is injected through the micro-bubble inlet channel, and the specific operation is to inject water or crude oil through the micro-bubble inlet channel in sections at a flow rate of 0μm / s-500μm / s.

5. The method of claim 3, wherein the CO2 microbubble porous medium is prepared by the method of claim 1. In step (7), the unsaturated continuous phase fluid is injected through the pure continuous phase entry channel at a flow rate of 0 μm / s to 500 μm / s.

6. A CO2 microbubble stability test method in a porous medium according to claim 4 or 5, characterized in that: In step (8), the dynamic data acquisition is performed: the changes of the bubble group shape and distribution in the two cases of steps (6) and (7) are recorded, and real-time analysis is performed to determine the stability, and the specific operation is as follows: The size of the micro-bubbles, the bubble formation time or life, and the distribution of the micro-bubble group in the two cases of steps (6) and (7) are recorded, and compared with the initial state in the porous medium micro-model. If most of the bubbles do not have dissolution phenomenon, the micro-bubble size is in the range of 30 μm to 500 μm, and the bubble group in the porous medium micro-model is uniformly distributed or the micro-bubbles with a size of 100 μm or less are aggregated into sub-micro-bubbles with a size of 500 μm and do not dissolve, then it is a stable state; otherwise, it is an unstable state.

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