Device and method for evaluating the performance of weak gel in blocking large pores

Abstract

The application relates to a device and a method for evaluating the performance of a weak gel in plugging a large pore channel, which comprises sequentially connected fluid injection devices, a sand filling pipe physical model and fluid collection devices; the sand filling pipe physical model and the fluid collection devices are arranged in a constant temperature device; the fluid injection devices comprise fluid injection pumps and first and second piston containers connected with the fluid injection pumps respectively; the sand filling pipe physical model comprises a plexiglass pipe, one end of the plexiglass pipe is an inlet end, and the other end is an outlet end; the inlet end is provided with an inlet end pipe cover, and the outlet end is provided with an outlet end pipe cover; the output ends of the first and second piston containers are connected to the inlet end after being mixed; the plexiglass pipe is internally provided with glass beads with the same particle size, the particle size of the glass beads is 0.4-4.0 mm; the glass beads are not cemented and are in point contact, and the glass beads are in cubic packing or rhombohedral packing or mixed packing of the two, and the pores between the glass beads are in irregular shapes. The application quantitatively studies the influence of the pore channel radius on the plugging performance of the weak gel.

Description

Technical Field

[0001] This invention belongs to the field of tertiary oil recovery technology and relates to weak gel profile control laboratory experimental technology, specifically a device and method for evaluating the performance of weak gel in sealing large channels. Background Technology

[0002] Due to differences in original sedimentation and artificial fracturing, the reservoir exhibits strong heterogeneity. After long-term waterflooding development, dominant flow channels easily form within the oil layer. Injected water then flows along these channels, leading to low waterflooding sweep efficiency, rapid rise in well water cut, and even sudden water flooding. Weak gels are formed by the cross-linking reaction of low-concentration polymers and cross-linking agents. They possess a spatial network structure with intertwined molecules and high apparent viscosity, effectively sealing large pores. Widely used in oilfield profile control, they have achieved excellent oil stabilization and water control effects.

[0003] The laboratory uses core displacement to evaluate the plugging performance of weak gels, but existing experimental setups for evaluating the plugging performance of weak gels on large-pore reservoirs have two technical problems. One is the core physical model simulating the development of large-pore reservoirs, which has a permeability greater than 10... m m 2 First, the pressure response value of water permeability is small and cannot be used to calculate the pore radius. There is a lack of methods to quantify the size of large pores in oil reservoirs, thus making it impossible to evaluate the impact of pore radius on the sealing performance of weak gels. Second, existing experimental setups use metal tubes filled with sand or core holders as core physical models, which cannot observe the seepage characteristics of fluids in large pore models. Therefore, it is impossible to study the morphology of the water drive front, water channeling paths, and the migration patterns of weak gels after sealing large pores with weak gels. Summary of the Invention

[0004] The present invention aims to address the above-mentioned problems by proposing an apparatus and method for evaluating the performance of weak gels in sealing large pores, which features the ability to quantify the size of large pores and observe fluid seepage characteristics in real time.

[0005] The technical solution of this invention is as follows:

[0006] (i) This invention proposes a device for evaluating the performance of weak gels in sealing large pores.

[0007] An apparatus for evaluating the performance of weak gels in sealing large pores includes a fluid injection device, a sand-filled tube physical model, and a fluid collection device connected in sequence; the sand-filled tube physical model and the fluid collection device are placed in a constant temperature device; the fluid injection device includes a fluid injection pump and a first piston container and a second piston container respectively connected to the fluid injection pump; the sand-filled tube physical model includes an acrylic tube, one end of which is an inlet end and the other end is an outlet end, the inlet end is provided with an inlet end cap, and the outlet end is provided with an outlet end cap; the output ends of the first piston container and the second piston container are mixed and connected to the inlet end; the acrylic tube contains glass beads of the same particle size, 0.4-4.0 mm in diameter; the glass beads are not bonded together and are in point contact, stacked in cubic, rhombohedral, or mixed stacking patterns, and the pores between the glass beads are irregularly shaped.

[0008] The output ends of the first piston container and the second piston container are connected to the inlet end through a mixing pipe.

[0009] The fluid injection pump is connected to the input ends of the first piston container and the second piston container respectively through a first six-way valve. The output ends of the first piston container and the second piston container are connected to the input end of the mixing pipe respectively through a second six-way valve. The output end of the mixing pipe is connected to the inlet end. The outlet end is connected to the fluid collection device through a fourth six-way valve.

[0010] The constant temperature device is a constant temperature chamber, used to heat the physical model of the sand-filled tube, causing the weak gel inside to gel.

[0011] The inlet end cap and outlet end cap are connected to the plexiglass tube by threads.

[0012] The sand-filled tube physical model also includes a camera for filming the plexiglass tube, used to observe the fluid seepage characteristics in the sand-filled tube physical model in real time; the output end of the mixing pipe is connected to the inlet end via a third six-way valve, which is also connected to a pressure sensor; an external computer is also included, with both the camera and pressure sensor connected to the computer for storing and processing information fed back from the camera and pressure sensor; the fluid collection device is also equipped with a viscometer for measuring the apparent viscosity of the weak gel collected by the fluid collection device. After the weak gel in the sand-filled tube physical model gels, a small amount of dye is added to the injected water for staining, followed by subsequent water flooding; the pressure sensor is used to measure the pressure changes during the experiment, and the camera is used to record the fluid seepage characteristics in the sand-filled tube physical model in real time, used to study the morphology of the water flooding front, water channeling path, and migration law of the weak gel after the weak gel blocks the large pores.

[0013] The physical model of the sand-filled pipe is also equipped with a support at the bottom.

[0014] (ii) This invention proposes a method for evaluating the performance of weak gels in sealing large pores.

[0015] A method for evaluating the performance of weak gels in blocking large pores, using the apparatus described in (I) for evaluating the performance of weak gels in blocking large pores, the specific process of which is as follows:

[0016] The pores between the glass beads are irregular in shape. If the irregular pores are converted according to the principle of equal volume and equivalent to a capillary model, then the equivalent pore radius is equal to the capillary model radius.

[0017] The cross-sectional area of ​​the physical model of the sand-filled pipe is A , length is L The acrylic tube contains particles of the same size and specifications. D The glass beads have a porosity of f The pore volume of the physical model of a sand-filled tube filled with glass beads of the same size is: V 1;

[0018] V 1= φAL (1)

[0019] Eight 1 / 8 glass beads constitute a capillary model, meaning the number of glass beads in the cross-section of the sand-filled tube physical model is the same as the number in the capillary model. Let the number of glass beads in the cross-section of the sand-filled tube physical model be... n S The number of capillary models within the cross-section of the physical model of the sand-filled pipe is . n S indivual;

[0020] The length of the capillary model is the same as that of the physical model of the sand-filled pipe. L Assume that along the axial direction of the physical model of the sand-filled pipe there is n L If there are several glass beads, then:

[0021] L = n L D (2)

[0022] The total amount of glass beads is n Then we have:

[0023] n = n L n S (3)

[0024] Let the radius of the capillary model be... r Because the volume of the capillary model is the same as the pore volume. V1. They are equal, that is:

[0025] n S ( πr 2 ) L = φAL (4)

[0026] Substituting formulas (2) and (3) into formula (4), we get:

[0027] n ( πr 2 ) D = φAL (5)

[0028] The mass of the physical model of the sand-filled pipe without glass beads is M 0. The total mass of the physical model of a sand-filled tube filled with glass beads of the same size is 0. M 1. The mass of a single glass bead is m Then we have:

[0029] n =( M 1- M 0) / m (6)

[0030] Combining equations (5) and (6), we get:

[0031] (7)

[0032] The equivalent pore radius of the large pores between glass beads can be obtained by formula (7).

[0033] The technical advantages of this invention are as follows:

[0034] 1. The device and method for evaluating the performance of weak gel in sealing large pores proposed in this invention can quantify the size of large pores in the physical model of sand-filled pipes, and realize the quantitative study of the influence of pore radius on the sealing performance of weak gel.

[0035] 2. The device for evaluating the performance of weak gel in blocking large channels proposed in this invention has a visualization function, which can observe the water-drive front morphology and water channeling path after the weak gel blocks the large channels in real time, and reveal the migration law of weak gel under water drive in large channels.

[0036] 3. The device proposed in this invention for evaluating the blocking performance of weak gels in macropores can obtain the blocking performance and migration law of weak gels in macropores of different sizes, providing guidance for optimizing system formulation, determining reagent dosage, and improving process parameters. Attached Figure Description

[0037] Figure 1A schematic diagram of the device used to evaluate the performance of weak gels in sealing large pores.

[0038] Figure 2 This is a side view of the physical model of the sand-filled pipe.

[0039] Figure 3 A schematic diagram illustrating the transformation of the pores formed by the accumulation of glass beads into a capillary model.

[0040] Reference numerals: 1. Fluid injection pump; 2. First six-way valve; 3. First piston container; 4. Second piston container; 5. Second six-way valve; 6. Third six-way valve; 7. Pressure sensor; 8. Physical model of sand-filled pipe; 9. Camera; 10. Fourth six-way valve; 11. Fluid collection device; 12. Thermostatic chamber; 81. Inlet end; 82. Inlet end cap; 83. Glass bead; 84. Support; 85. Acrylic tube; 86. Outlet end cap; 87. Outlet end. Detailed Implementation

[0041] Example 1

[0042] An apparatus for evaluating the performance of weak gel in sealing large pores includes a fluid injection device, a sand-filled tube physical model 8, and a fluid collection device 11 connected in sequence. The sand-filled tube physical model 8 and the fluid collection device 11 are placed in a constant temperature device. The fluid injection device includes a fluid injection pump 1 and a first piston container 3 and a second piston container 4 connected to the fluid injection pump 1 respectively. The sand-filled tube physical model 8 includes an acrylic tube 85, with one end being an inlet end 81 and the other end being an outlet end 87. The inlet end 81 is provided with an inlet end cap 82, and the outlet end 87 is provided with an outlet end cap 86. The output ends of the first piston container 3 and the second piston container 4 are mixed and connected to the inlet end 81. The acrylic tube 85 contains glass beads 83 of the same particle size, with a particle size of 0.4-4.0 mm. The glass beads 83 are not bonded together and are in point contact, stacked in cubic, rhombohedral, or mixed stacking arrangements. The pores between the glass beads 83 are irregular in shape.

[0043] Using the apparatus provided in this embodiment, the equivalent channel radius of the large pores between glass beads 83 is determined. The specific process is as follows:

[0044] The pores between the glass beads 83 are irregular in shape. The irregular pores are converted according to the principle of equal volume and equivalent to a capillary model. Then the equivalent pore radius is equal to the capillary model radius.

[0045] The cross-sectional area of ​​the physical model 8 of the sand-filled pipe is A , length is L ; The 85mm acrylic tube contains particles of the same size and specifications. D The glass beads 83 have a porosity of f The pore volume of the physical model 8 of the sand-filled pipe filled with glass beads of the same size (83) is: V 1;

[0046] V 1= φAL (1)

[0047] Eight 1 / 8 glass beads 83 constitute a capillary model, meaning the number of glass beads 83 in the cross-section of the sand-filled tube physical model 8 is the same as the number in the capillary model. Let the number of glass beads 83 in the cross-section of the sand-filled tube physical model 8 be... n S The number of capillary models within the cross-section of the sand-filled pipe physical model 8 is 1. n S indivual;

[0048] The length of the capillary model is the same as that of the sand-filled pipe physical model 8. L Assume that along the axial direction of the physical model of the sand-filled pipe there are 8 n L If there are 83 glass beads, then:

[0049] L = n L D (2)

[0050] The total amount of glass beads 83 is n Then we have:

[0051] n = n L n S (3)

[0052] Let the radius of the capillary model be... r Because the volume of the capillary model is the same as the pore volume. V 1. They are equal, that is:

[0053] n S ( πr 2 ) L = φAL (4)

[0054] Substituting formulas (2) and (3) into formula (4), we get:

[0055] n ( πr 2 ) D = φAL (5)

[0056] The mass of the physical model 8 of the sand-filled pipe without glass beads 83 is M 0. The total mass of the physical model 8, filled with 83 glass beads of the same particle size, is 0. M 1. The mass of a single glass bead 83 is m Then we have:

[0057] n =( M 1- M 0) / m (6)

[0058] Combining equations (5) and (6), we get:

[0059] (7)

[0060] The equivalent pore radius of the large pore between glass beads 83 can be obtained by formula (7).

[0061] Example 2

[0062] Based on Example 1, it also includes:

[0063] The output ends of the first piston container 3 and the second piston container 4 are connected to the inlet end 81 via a mixing pipe. The fluid injection pump 1 is connected to the input ends of the first piston container 3 and the second piston container 4 via a first six-way valve 2. The output ends of the first piston container 3 and the second piston container 4 are connected to the input end of the mixing pipe via a second six-way valve 5. The output end of the mixing pipe is connected to the inlet end 81. The outlet end 87 is connected to the fluid collection device 11 via a fourth six-way valve 10. The temperature control device is a temperature control chamber 12, used to heat the sand-filled tube physical model 8, causing the weak gel inside to gel. The inlet end cap 82 and the outlet end cap 86 are connected to the plexiglass tube 85 via threads.

[0064] Example 3

[0065] Based on Example 2, it also includes:

[0066] The sand-filled tube physical model 8 also includes a camera 9 for filming the plexiglass tube 85, used to observe the seepage characteristics of the fluid in the sand-filled tube physical model 8 in real time; the output end of the mixing pipe is connected to the inlet end 81 through a third six-way valve 6, which is also connected to a pressure sensor 7; it also includes an external computer, with both the camera 9 and the pressure sensor 7 connected to the computer for storing and processing the information fed back by the camera 9 and the pressure sensor 7; the fluid collection device 11 is also equipped with a viscometer for measuring the apparent viscosity of the weak gel collected by the fluid collection device 11. After the weak gel in the sand-filled tube physical model 8 gels, a small amount of dye is added to the injected water for staining, followed by subsequent water flooding; the pressure sensor 7 is used to measure the pressure changes during the experiment, and the camera 9 is used to record the fluid seepage characteristics in the sand-filled tube physical model 8 in real time, used to study the morphology of the water flooding front, the water channeling path, and the migration law of the weak gel after the weak gel blocks the large pores. The bottom of the sand tube physical model is also equipped with a support 84.

[0067] Specific application examples

[0068] 1. First, weigh the mass of the physical model 8 of the sand-filled tube without glass beads 83. M 0. Fill the physical model 8 with glass beads of the same particle size 8 and weigh their total mass. M 1. Weigh a certain number of glass beads 83 of this particle size specification, then divide the mass by the quantity to obtain the mass of a single glass bead 83. m ;

[0069] 2. According to Figure 1 Connect the device for evaluating the performance of weak gel in sealing large pores, turn on the fluid injection pump 1, and pump the injection water in the second piston container 4 into the sand-filled tube physical model 8 for saturation. Measure the porosity of the sand-filled tube physical model 8. f Substitute the parameters into formula (7) to obtain the equivalent pore radius of the physical model 8 of the sand-filled pipe for the glass beads of this particle size 83.

[0070] 3. After obtaining the equivalent pore radius of the sand-filled tube physical model 8 filled with glass beads 83 of this particle size, drain the saturated injected water from the sand-filled tube physical model 8, and then pump the weak gel in the first piston container 3 into the sand-filled tube physical model 8.

[0071] 4. Start the constant temperature device to the design temperature, and let the physical model 8 filled with sand stand for 24 hours to allow the weak gel to fully gel.

[0072] 5. The injected water is stained with a dye and injected into the sand-filled tube physical model 8 at a set pump speed. The pressure change during the experiment is measured using a pressure sensor 7, and the fluid seepage characteristics in the sand-filled tube physical model 8 are recorded in real time using a camera 9.

[0073] 6. Collect the produced weak gel using the fluid collection device 11, and measure the apparent viscosity of the produced weak gel using a viscometer;

[0074] 7. After the experiment is completed, clean the physical model 8 of the sand-filled pipe, and repeat steps 1 to 6 above to complete the weak gel plugging performance experiment under other equivalent pore radius conditions. Based on data such as pressure, images and apparent viscosity, comprehensively analyze the weak gel plugging performance.

Claims

1. A method for evaluating the performance of a weak gel in sealing large pores, comprising an apparatus for evaluating the performance of a weak gel in sealing large pores, the apparatus comprising a fluid injection device, a sand-filled tube physical model (8), and a fluid collection device (11) connected in sequence; the sand-filled tube physical model (8) and the fluid collection device (11) are placed in a constant temperature device; characterized in that: The fluid injection device includes a fluid injection pump (1) and a first piston container (3) and a second piston container (4) respectively connected to the fluid injection pump (1); the sand-filled pipe physical model (8) includes an organic glass tube (85), one end of which is an inlet end (81) and the other end is an outlet end (87). The inlet end (81) is provided with an inlet end cap (82), and the outlet end (87) is provided with an outlet end cap (86); the output ends of the first piston container (3) and the second piston container (4) are mixed and connected to the inlet end (81); the organic glass tube (85) contains glass beads (83) with the same particle size, the glass beads (83) having a particle size of 0.4-4.0mm; the glass beads (83) are not bonded together and are in point contact, stacked in cubic, rhombohedral, or mixed stacks, and the pores between the glass beads (83) are irregular in shape; The specific process for evaluating the performance of weak gels in sealing large-pore channels using an application evaluation device is as follows: The pores between the glass beads (83) are irregular in shape. The irregular pores are converted according to the principle of equal volume and equivalent to capillary models. Then the equivalent pore radius is equal to the capillary model radius. The cross-sectional area of ​​the physical model (8) of the sand-filled pipe is A, the length is L, and the mass of the physical model (8) of the sand-filled pipe without glass beads (83) is M0. The organic glass tube (85) contains glass beads (83) with the same particle size specification D. The porosity is φ, the mass of a single glass bead (83) is m, and the total mass of the physical model (8) of the sand-filled tube filled with glass beads (83) of the same particle size is M1. (7) The equivalent pore radius between the large pores of the glass beads (83) can be obtained by equation (7).

2. The method for evaluating the performance of a weak gel for plugging large pores according to claim 1, characterized in that: The output ends of the first piston container (3) and the second piston container (4) are connected to the inlet end (81) through a mixing pipe.

3. The method for evaluating the performance of plugging large pore channels by weak gel according to claim 2, characterized in that: The fluid injection pump (1) is connected to the input ends of the first piston container (3) and the second piston container (4) through the first six-way valve (2). The output ends of the first piston container (3) and the second piston container (4) are connected to the input end of the mixing pipe through the second six-way valve (5). The output end of the mixing pipe is connected to the inlet end (81). The outlet end (87) is connected to the fluid collection device (11) through the fourth six-way valve (10).

4. The method for evaluating the performance of plugging large pore channels by weak gel according to claim 3, characterized in that: The temperature control device is a temperature control chamber (12).

5. The method for evaluating the performance of a weak gel for plugging large pores according to claim 4, characterized in that: The inlet end cap (82) and outlet end cap (86) are connected to the plexiglass tube (85) by threads.

6. The method for evaluating the performance of weak gels in blocking large pores according to claim 5, characterized in that: The physical model (8) of the sand-filled pipe also includes a camera (9) for filming the plexiglass tube (85); the output end of the mixing pipe is connected to the inlet end (81) through a third six-way valve (6), and the third six-way valve (6) is also connected to a pressure sensor (7); it also includes an external computer, and the camera (9) and the pressure sensor (7) are both connected to the computer; the fluid collection device (11) is also equipped with a viscometer.

7. The method for evaluating the performance of weak gels in blocking large pores according to claim 6, characterized in that: The physical model of the sand pipe is also equipped with a support (84) at the bottom.

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